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/* Expands front end tree to back end RTL for GCC Copyright (C) 1987, 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007 Free Software Foundation, Inc. This file is part of GCC. GCC is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3, or (at your option) any later version. GCC is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with GCC; see the file COPYING3. If not see <http://www.gnu.org/licenses/>. */ /* This file handles the generation of rtl code from tree structure above the level of expressions, using subroutines in exp*.c and emit-rtl.c. The functions whose names start with `expand_' are called by the expander to generate RTL instructions for various kinds of constructs. */ #include "config.h" #include "system.h" #include "coretypes.h" #include "tm.h" #include "rtl.h" #include "hard-reg-set.h" #include "tree.h" #include "tm_p.h" #include "flags.h" #include "except.h" #include "function.h" #include "insn-config.h" #include "expr.h" #include "libfuncs.h" #include "recog.h" #include "machmode.h" #include "toplev.h" #include "output.h" #include "ggc.h" #include "langhooks.h" #include "predict.h" #include "optabs.h" #include "target.h" #include "regs.h" /* Functions and data structures for expanding case statements. */ /* Case label structure, used to hold info on labels within case statements. We handle "range" labels; for a single-value label as in C, the high and low limits are the same. We start with a vector of case nodes sorted in ascending order, and the default label as the last element in the vector. Before expanding to RTL, we transform this vector into a list linked via the RIGHT fields in the case_node struct. Nodes with higher case values are later in the list. Switch statements can be output in three forms. A branch table is used if there are more than a few labels and the labels are dense within the range between the smallest and largest case value. If a branch table is used, no further manipulations are done with the case node chain. The alternative to the use of a branch table is to generate a series of compare and jump insns. When that is done, we use the LEFT, RIGHT, and PARENT fields to hold a binary tree. Initially the tree is totally unbalanced, with everything on the right. We balance the tree with nodes on the left having lower case values than the parent and nodes on the right having higher values. We then output the tree in order. For very small, suitable switch statements, we can generate a series of simple bit test and branches instead. */ struct case_node GTY(()) { struct case_node *left; /* Left son in binary tree */ struct case_node *right; /* Right son in binary tree; also node chain */ struct case_node *parent; /* Parent of node in binary tree */ tree low; /* Lowest index value for this label */ tree high; /* Highest index value for this label */ tree code_label; /* Label to jump to when node matches */ }; typedef struct case_node case_node; typedef struct case_node *case_node_ptr; /* These are used by estimate_case_costs and balance_case_nodes. */ /* This must be a signed type, and non-ANSI compilers lack signed char. */ static short cost_table_[129]; static int use_cost_table; static int cost_table_initialized; /* Special care is needed because we allow -1, but TREE_INT_CST_LOW is unsigned. */ #define COST_TABLE(I) cost_table_[(unsigned HOST_WIDE_INT) ((I) + 1)] static int n_occurrences (int, const char *); static bool tree_conflicts_with_clobbers_p (tree, HARD_REG_SET *); static void expand_nl_goto_receiver (void); static bool check_operand_nalternatives (tree, tree); static bool check_unique_operand_names (tree, tree); static char *resolve_operand_name_1 (char *, tree, tree); static void expand_null_return_1 (void); static void expand_value_return (rtx); static int estimate_case_costs (case_node_ptr); static bool lshift_cheap_p (void); static int case_bit_test_cmp (const void *, const void *); static void emit_case_bit_tests (tree, tree, tree, tree, case_node_ptr, rtx); static void balance_case_nodes (case_node_ptr *, case_node_ptr); static int node_has_low_bound (case_node_ptr, tree); static int node_has_high_bound (case_node_ptr, tree); static int node_is_bounded (case_node_ptr, tree); static void emit_case_nodes (rtx, case_node_ptr, rtx, tree); static struct case_node *add_case_node (struct case_node *, tree, tree, tree, tree); /* Return the rtx-label that corresponds to a LABEL_DECL, creating it if necessary. */ rtx label_rtx (tree label) { gcc_assert (TREE_CODE (label) == LABEL_DECL); if (!DECL_RTL_SET_P (label)) { rtx r = gen_label_rtx (); SET_DECL_RTL (label, r); if (FORCED_LABEL (label) || DECL_NONLOCAL (label)) LABEL_PRESERVE_P (r) = 1; } return DECL_RTL (label); } /* As above, but also put it on the forced-reference list of the function that contains it. */ rtx force_label_rtx (tree label) { rtx ref = label_rtx (label); tree function = decl_function_context (label); struct function *p; gcc_assert (function); if (function != current_function_decl) p = find_function_data (function); else p = cfun; p->expr->x_forced_labels = gen_rtx_EXPR_LIST (VOIDmode, ref, p->expr->x_forced_labels); return ref; } /* Add an unconditional jump to LABEL as the next sequential instruction. */ void emit_jump (rtx label) { do_pending_stack_adjust (); emit_jump_insn (gen_jump (label)); emit_barrier (); } /* Emit code to jump to the address specified by the pointer expression EXP. */ void expand_computed_goto (tree exp) { rtx x = expand_normal (exp); x = convert_memory_address (Pmode, x); do_pending_stack_adjust (); emit_indirect_jump (x); } /* Handle goto statements and the labels that they can go to. */ /* Specify the location in the RTL code of a label LABEL, which is a LABEL_DECL tree node. This is used for the kind of label that the user can jump to with a goto statement, and for alternatives of a switch or case statement. RTL labels generated for loops and conditionals don't go through here; they are generated directly at the RTL level, by other functions below. Note that this has nothing to do with defining label *names*. Languages vary in how they do that and what that even means. */ void expand_label (tree label) { rtx label_r = label_rtx (label); do_pending_stack_adjust (); emit_label (label_r); if (DECL_NAME (label)) LABEL_NAME (DECL_RTL (label)) = IDENTIFIER_POINTER (DECL_NAME (label)); if (DECL_NONLOCAL (label)) { expand_nl_goto_receiver (); nonlocal_goto_handler_labels = gen_rtx_EXPR_LIST (VOIDmode, label_r, nonlocal_goto_handler_labels); } if (FORCED_LABEL (label)) forced_labels = gen_rtx_EXPR_LIST (VOIDmode, label_r, forced_labels); if (DECL_NONLOCAL (label) || FORCED_LABEL (label)) maybe_set_first_label_num (label_r); } /* Generate RTL code for a `goto' statement with target label LABEL. LABEL should be a LABEL_DECL tree node that was or will later be defined with `expand_label'. */ void expand_goto (tree label) { #ifdef ENABLE_CHECKING /* Check for a nonlocal goto to a containing function. Should have gotten translated to __builtin_nonlocal_goto. */ tree context = decl_function_context (label); gcc_assert (!context || context == current_function_decl); #endif emit_jump (label_rtx (label)); } /* Return the number of times character C occurs in string S. */ static int n_occurrences (int c, const char *s) { int n = 0; while (*s) n += (*s++ == c); return n; } /* Generate RTL for an asm statement (explicit assembler code). STRING is a STRING_CST node containing the assembler code text, or an ADDR_EXPR containing a STRING_CST. VOL nonzero means the insn is volatile; don't optimize it. */ static void expand_asm (tree string, int vol) { rtx body; if (TREE_CODE (string) == ADDR_EXPR) string = TREE_OPERAND (string, 0); body = gen_rtx_ASM_INPUT (VOIDmode, ggc_strdup (TREE_STRING_POINTER (string))); MEM_VOLATILE_P (body) = vol; emit_insn (body); } /* Parse the output constraint pointed to by *CONSTRAINT_P. It is the OPERAND_NUMth output operand, indexed from zero. There are NINPUTS inputs and NOUTPUTS outputs to this extended-asm. Upon return, *ALLOWS_MEM will be TRUE iff the constraint allows the use of a memory operand. Similarly, *ALLOWS_REG will be TRUE iff the constraint allows the use of a register operand. And, *IS_INOUT will be true if the operand is read-write, i.e., if it is used as an input as well as an output. If *CONSTRAINT_P is not in canonical form, it will be made canonical. (Note that `+' will be replaced with `=' as part of this process.) Returns TRUE if all went well; FALSE if an error occurred. */ bool parse_output_constraint (const char **constraint_p, int operand_num, int ninputs, int noutputs, bool *allows_mem, bool *allows_reg, bool *is_inout) { const char *constraint = *constraint_p; const char *p; /* Assume the constraint doesn't allow the use of either a register or memory. */ *allows_mem = false; *allows_reg = false; /* Allow the `=' or `+' to not be at the beginning of the string, since it wasn't explicitly documented that way, and there is a large body of code that puts it last. Swap the character to the front, so as not to uglify any place else. */ p = strchr (constraint, '='); if (!p) p = strchr (constraint, '+'); /* If the string doesn't contain an `=', issue an error message. */ if (!p) { error ("output operand constraint lacks %<=%>"); return false; } /* If the constraint begins with `+', then the operand is both read from and written to. */ *is_inout = (*p == '+'); /* Canonicalize the output constraint so that it begins with `='. */ if (p != constraint || *is_inout) { char *buf; size_t c_len = strlen (constraint); if (p != constraint) warning (0, "output constraint %qc for operand %d " "is not at the beginning", *p, operand_num); /* Make a copy of the constraint. */ buf = alloca (c_len + 1); strcpy (buf, constraint); /* Swap the first character and the `=' or `+'. */ buf[p - constraint] = buf[0]; /* Make sure the first character is an `='. (Until we do this, it might be a `+'.) */ buf[0] = '='; /* Replace the constraint with the canonicalized string. */ *constraint_p = ggc_alloc_string (buf, c_len); constraint = *constraint_p; } /* Loop through the constraint string. */ for (p = constraint + 1; *p; p += CONSTRAINT_LEN (*p, p)) switch (*p) { case '+': case '=': error ("operand constraint contains incorrectly positioned " "%<+%> or %<=%>"); return false; case '%': if (operand_num + 1 == ninputs + noutputs) { error ("%<%%%> constraint used with last operand"); return false; } break; case 'V': case 'm': case 'o': *allows_mem = true; break; case '?': case '!': case '*': case '&': case '#': case 'E': case 'F': case 'G': case 'H': case 's': case 'i': case 'n': case 'I': case 'J': case 'K': case 'L': case 'M': case 'N': case 'O': case 'P': case ',': break; case '0': case '1': case '2': case '3': case '4': case '5': case '6': case '7': case '8': case '9': case '[': error ("matching constraint not valid in output operand"); return false; case '<': case '>': /* ??? Before flow, auto inc/dec insns are not supposed to exist, excepting those that expand_call created. So match memory and hope. */ *allows_mem = true; break; case 'g': case 'X': *allows_reg = true; *allows_mem = true; break; case 'p': case 'r': *allows_reg = true; break; default: if (!ISALPHA (*p)) break; if (REG_CLASS_FROM_CONSTRAINT (*p, p) != NO_REGS) *allows_reg = true; #ifdef EXTRA_CONSTRAINT_STR else if (EXTRA_ADDRESS_CONSTRAINT (*p, p)) *allows_reg = true; else if (EXTRA_MEMORY_CONSTRAINT (*p, p)) *allows_mem = true; else { /* Otherwise we can't assume anything about the nature of the constraint except that it isn't purely registers. Treat it like "g" and hope for the best. */ *allows_reg = true; *allows_mem = true; } #endif break; } return true; } /* Similar, but for input constraints. */ bool parse_input_constraint (const char **constraint_p, int input_num, int ninputs, int noutputs, int ninout, const char * const * constraints, bool *allows_mem, bool *allows_reg) { const char *constraint = *constraint_p; const char *orig_constraint = constraint; size_t c_len = strlen (constraint); size_t j; bool saw_match = false; /* Assume the constraint doesn't allow the use of either a register or memory. */ *allows_mem = false; *allows_reg = false; /* Make sure constraint has neither `=', `+', nor '&'. */ for (j = 0; j < c_len; j += CONSTRAINT_LEN (constraint[j], constraint+j)) switch (constraint[j]) { case '+': case '=': case '&': if (constraint == orig_constraint) { error ("input operand constraint contains %qc", constraint[j]); return false; } break; case '%': if (constraint == orig_constraint && input_num + 1 == ninputs - ninout) { error ("%<%%%> constraint used with last operand"); return false; } break; case 'V': case 'm': case 'o': *allows_mem = true; break; case '<': case '>': case '?': case '!': case '*': case '#': case 'E': case 'F': case 'G': case 'H': case 's': case 'i': case 'n': case 'I': case 'J': case 'K': case 'L': case 'M': case 'N': case 'O': case 'P': case ',': break; /* Whether or not a numeric constraint allows a register is decided by the matching constraint, and so there is no need to do anything special with them. We must handle them in the default case, so that we don't unnecessarily force operands to memory. */ case '0': case '1': case '2': case '3': case '4': case '5': case '6': case '7': case '8': case '9': { char *end; unsigned long match; saw_match = true; match = strtoul (constraint + j, &end, 10); if (match >= (unsigned long) noutputs) { error ("matching constraint references invalid operand number"); return false; } /* Try and find the real constraint for this dup. Only do this if the matching constraint is the only alternative. */ if (*end == '\0' && (j == 0 || (j == 1 && constraint[0] == '%'))) { constraint = constraints[match]; *constraint_p = constraint; c_len = strlen (constraint); j = 0; /* ??? At the end of the loop, we will skip the first part of the matched constraint. This assumes not only that the other constraint is an output constraint, but also that the '=' or '+' come first. */ break; } else j = end - constraint; /* Anticipate increment at end of loop. */ j--; } /* Fall through. */ case 'p': case 'r': *allows_reg = true; break; case 'g': case 'X': *allows_reg = true; *allows_mem = true; break; default: if (! ISALPHA (constraint[j])) { error ("invalid punctuation %qc in constraint", constraint[j]); return false; } if (REG_CLASS_FROM_CONSTRAINT (constraint[j], constraint + j) != NO_REGS) *allows_reg = true; #ifdef EXTRA_CONSTRAINT_STR else if (EXTRA_ADDRESS_CONSTRAINT (constraint[j], constraint + j)) *allows_reg = true; else if (EXTRA_MEMORY_CONSTRAINT (constraint[j], constraint + j)) *allows_mem = true; else { /* Otherwise we can't assume anything about the nature of the constraint except that it isn't purely registers. Treat it like "g" and hope for the best. */ *allows_reg = true; *allows_mem = true; } #endif break; } if (saw_match && !*allows_reg) warning (0, "matching constraint does not allow a register"); return true; } /* Return DECL iff there's an overlap between *REGS and DECL, where DECL can be an asm-declared register. Called via walk_tree. */ static tree decl_overlaps_hard_reg_set_p (tree *declp, int *walk_subtrees ATTRIBUTE_UNUSED, void *data) { tree decl = *declp; const HARD_REG_SET *regs = data; if (TREE_CODE (decl) == VAR_DECL) { if (DECL_HARD_REGISTER (decl) && REG_P (DECL_RTL (decl)) && REGNO (DECL_RTL (decl)) < FIRST_PSEUDO_REGISTER) { rtx reg = DECL_RTL (decl); unsigned int regno; for (regno = REGNO (reg); regno < (REGNO (reg) + hard_regno_nregs[REGNO (reg)][GET_MODE (reg)]); regno++) if (TEST_HARD_REG_BIT (*regs, regno)) return decl; } walk_subtrees = 0; } else if (TYPE_P (decl) || TREE_CODE (decl) == PARM_DECL) walk_subtrees = 0; return NULL_TREE; } /* If there is an overlap between *REGS and DECL, return the first overlap found. */ tree tree_overlaps_hard_reg_set (tree decl, HARD_REG_SET *regs) { return walk_tree (&decl, decl_overlaps_hard_reg_set_p, regs, NULL); } /* Check for overlap between registers marked in CLOBBERED_REGS and anything inappropriate in T. Emit error and return the register variable definition for error, NULL_TREE for ok. */ static bool tree_conflicts_with_clobbers_p (tree t, HARD_REG_SET *clobbered_regs) { /* Conflicts between asm-declared register variables and the clobber list are not allowed. */ tree overlap = tree_overlaps_hard_reg_set (t, clobbered_regs); if (overlap) { error ("asm-specifier for variable %qs conflicts with asm clobber list", IDENTIFIER_POINTER (DECL_NAME (overlap))); /* Reset registerness to stop multiple errors emitted for a single variable. */ DECL_REGISTER (overlap) = 0; return true; } return false; } /* Generate RTL for an asm statement with arguments. STRING is the instruction template. OUTPUTS is a list of output arguments (lvalues); INPUTS a list of inputs. Each output or input has an expression in the TREE_VALUE and and a tree list in TREE_PURPOSE which in turn contains a constraint name in TREE_VALUE (or NULL_TREE) and a constraint string in TREE_PURPOSE. CLOBBERS is a list of STRING_CST nodes each naming a hard register that is clobbered by this insn. Not all kinds of lvalue that may appear in OUTPUTS can be stored directly. Some elements of OUTPUTS may be replaced with trees representing temporary values. The caller should copy those temporary values to the originally specified lvalues. VOL nonzero means the insn is volatile; don't optimize it. */ static void expand_asm_operands (tree string, tree outputs, tree inputs, tree clobbers, int vol, location_t locus) { rtvec argvec, constraintvec; rtx body; int ninputs = list_length (inputs); int noutputs = list_length (outputs); int ninout; int nclobbers; HARD_REG_SET clobbered_regs; int clobber_conflict_found = 0; tree tail; tree t; int i; /* Vector of RTX's of evaluated output operands. */ rtx *output_rtx = alloca (noutputs * sizeof (rtx)); int *inout_opnum = alloca (noutputs * sizeof (int)); rtx *real_output_rtx = alloca (noutputs * sizeof (rtx)); enum machine_mode *inout_mode = alloca (noutputs * sizeof (enum machine_mode)); const char **constraints = alloca ((noutputs + ninputs) * sizeof (const char *)); int old_generating_concat_p = generating_concat_p; /* An ASM with no outputs needs to be treated as volatile, for now. */ if (noutputs == 0) vol = 1; if (! check_operand_nalternatives (outputs, inputs)) return; string = resolve_asm_operand_names (string, outputs, inputs); /* Collect constraints. */ i = 0; for (t = outputs; t ; t = TREE_CHAIN (t), i++) constraints[i] = TREE_STRING_POINTER (TREE_VALUE (TREE_PURPOSE (t))); for (t = inputs; t ; t = TREE_CHAIN (t), i++) constraints[i] = TREE_STRING_POINTER (TREE_VALUE (TREE_PURPOSE (t))); /* Sometimes we wish to automatically clobber registers across an asm. Case in point is when the i386 backend moved from cc0 to a hard reg -- maintaining source-level compatibility means automatically clobbering the flags register. */ clobbers = targetm.md_asm_clobbers (outputs, inputs, clobbers); /* Count the number of meaningful clobbered registers, ignoring what we would ignore later. */ nclobbers = 0; CLEAR_HARD_REG_SET (clobbered_regs); for (tail = clobbers; tail; tail = TREE_CHAIN (tail)) { const char *regname; if (TREE_VALUE (tail) == error_mark_node) return; regname = TREE_STRING_POINTER (TREE_VALUE (tail)); i = decode_reg_name (regname); if (i >= 0 || i == -4) ++nclobbers; else if (i == -2) error ("unknown register name %qs in %<asm%>", regname); /* Mark clobbered registers. */ if (i >= 0) { /* Clobbering the PIC register is an error. */ if (i == (int) PIC_OFFSET_TABLE_REGNUM) { error ("PIC register %qs clobbered in %<asm%>", regname); return; } SET_HARD_REG_BIT (clobbered_regs, i); } } /* First pass over inputs and outputs checks validity and sets mark_addressable if needed. */ ninout = 0; for (i = 0, tail = outputs; tail; tail = TREE_CHAIN (tail), i++) { tree val = TREE_VALUE (tail); tree type = TREE_TYPE (val); const char *constraint; bool is_inout; bool allows_reg; bool allows_mem; /* If there's an erroneous arg, emit no insn. */ if (type == error_mark_node) return; /* Try to parse the output constraint. If that fails, there's no point in going further. */ constraint = constraints[i]; if (!parse_output_constraint (&constraint, i, ninputs, noutputs, &allows_mem, &allows_reg, &is_inout)) return; if (! allows_reg && (allows_mem || is_inout || (DECL_P (val) && REG_P (DECL_RTL (val)) && GET_MODE (DECL_RTL (val)) != TYPE_MODE (type)))) lang_hooks.mark_addressable (val); if (is_inout) ninout++; } ninputs += ninout; if (ninputs + noutputs > MAX_RECOG_OPERANDS) { error ("more than %d operands in %<asm%>", MAX_RECOG_OPERANDS); return; } for (i = 0, tail = inputs; tail; i++, tail = TREE_CHAIN (tail)) { bool allows_reg, allows_mem; const char *constraint; /* If there's an erroneous arg, emit no insn, because the ASM_INPUT would get VOIDmode and that could cause a crash in reload. */ if (TREE_TYPE (TREE_VALUE (tail)) == error_mark_node) return; constraint = constraints[i + noutputs]; if (! parse_input_constraint (&constraint, i, ninputs, noutputs, ninout, constraints, &allows_mem, &allows_reg)) return; if (! allows_reg && allows_mem) lang_hooks.mark_addressable (TREE_VALUE (tail)); } /* Second pass evaluates arguments. */ ninout = 0; for (i = 0, tail = outputs; tail; tail = TREE_CHAIN (tail), i++) { tree val = TREE_VALUE (tail); tree type = TREE_TYPE (val); bool is_inout; bool allows_reg; bool allows_mem; rtx op; bool ok; ok = parse_output_constraint (&constraints[i], i, ninputs, noutputs, &allows_mem, &allows_reg, &is_inout); gcc_assert (ok); /* If an output operand is not a decl or indirect ref and our constraint allows a register, make a temporary to act as an intermediate. Make the asm insn write into that, then our caller will copy it to the real output operand. Likewise for promoted variables. */ generating_concat_p = 0; real_output_rtx[i] = NULL_RTX; if ((TREE_CODE (val) == INDIRECT_REF && allows_mem) || (DECL_P (val) && (allows_mem || REG_P (DECL_RTL (val))) && ! (REG_P (DECL_RTL (val)) && GET_MODE (DECL_RTL (val)) != TYPE_MODE (type))) || ! allows_reg || is_inout) { op = expand_expr (val, NULL_RTX, VOIDmode, EXPAND_WRITE); if (MEM_P (op)) op = validize_mem (op); if (! allows_reg && !MEM_P (op)) error ("output number %d not directly addressable", i); if ((! allows_mem && MEM_P (op)) || GET_CODE (op) == CONCAT) { real_output_rtx[i] = op; op = gen_reg_rtx (GET_MODE (op)); if (is_inout) emit_move_insn (op, real_output_rtx[i]); } } else { op = assign_temp (type, 0, 0, 1); op = validize_mem (op); TREE_VALUE (tail) = make_tree (type, op); } output_rtx[i] = op; generating_concat_p = old_generating_concat_p; if (is_inout) { inout_mode[ninout] = TYPE_MODE (type); inout_opnum[ninout++] = i; } if (tree_conflicts_with_clobbers_p (val, &clobbered_regs)) clobber_conflict_found = 1; } /* Make vectors for the expression-rtx, constraint strings, and named operands. */ argvec = rtvec_alloc (ninputs); constraintvec = rtvec_alloc (ninputs); body = gen_rtx_ASM_OPERANDS ((noutputs == 0 ? VOIDmode : GET_MODE (output_rtx[0])), ggc_strdup (TREE_STRING_POINTER (string)), empty_string, 0, argvec, constraintvec, locus); MEM_VOLATILE_P (body) = vol; /* Eval the inputs and put them into ARGVEC. Put their constraints into ASM_INPUTs and store in CONSTRAINTS. */ for (i = 0, tail = inputs; tail; tail = TREE_CHAIN (tail), ++i) { bool allows_reg, allows_mem; const char *constraint; tree val, type; rtx op; bool ok; constraint = constraints[i + noutputs]; ok = parse_input_constraint (&constraint, i, ninputs, noutputs, ninout, constraints, &allows_mem, &allows_reg); gcc_assert (ok); generating_concat_p = 0; val = TREE_VALUE (tail); type = TREE_TYPE (val); /* EXPAND_INITIALIZER will not generate code for valid initializer constants, but will still generate code for other types of operand. This is the behavior we want for constant constraints. */ op = expand_expr (val, NULL_RTX, VOIDmode, allows_reg ? EXPAND_NORMAL : allows_mem ? EXPAND_MEMORY : EXPAND_INITIALIZER); /* Never pass a CONCAT to an ASM. */ if (GET_CODE (op) == CONCAT) op = force_reg (GET_MODE (op), op); else if (MEM_P (op)) op = validize_mem (op); if (asm_operand_ok (op, constraint) <= 0) { if (allows_reg && TYPE_MODE (type) != BLKmode) op = force_reg (TYPE_MODE (type), op); else if (!allows_mem) warning (0, "asm operand %d probably doesn%'t match constraints", i + noutputs); else if (MEM_P (op)) { /* We won't recognize either volatile memory or memory with a queued address as available a memory_operand at this point. Ignore it: clearly this *is* a memory. */ } else { warning (0, "use of memory input without lvalue in " "asm operand %d is deprecated", i + noutputs); if (CONSTANT_P (op)) { rtx mem = force_const_mem (TYPE_MODE (type), op); if (mem) op = validize_mem (mem); else op = force_reg (TYPE_MODE (type), op); } if (REG_P (op) || GET_CODE (op) == SUBREG || GET_CODE (op) == CONCAT) { tree qual_type = build_qualified_type (type, (TYPE_QUALS (type) | TYPE_QUAL_CONST)); rtx memloc = assign_temp (qual_type, 1, 1, 1); memloc = validize_mem (memloc); emit_move_insn (memloc, op); op = memloc; } } } generating_concat_p = old_generating_concat_p; ASM_OPERANDS_INPUT (body, i) = op; ASM_OPERANDS_INPUT_CONSTRAINT_EXP (body, i) = gen_rtx_ASM_INPUT (TYPE_MODE (type), ggc_strdup (constraints[i + noutputs])); if (tree_conflicts_with_clobbers_p (val, &clobbered_regs)) clobber_conflict_found = 1; } /* Protect all the operands from the queue now that they have all been evaluated. */ generating_concat_p = 0; /* For in-out operands, copy output rtx to input rtx. */ for (i = 0; i < ninout; i++) { int j = inout_opnum[i]; char buffer[16]; ASM_OPERANDS_INPUT (body, ninputs - ninout + i) = output_rtx[j]; sprintf (buffer, "%d", j); ASM_OPERANDS_INPUT_CONSTRAINT_EXP (body, ninputs - ninout + i) = gen_rtx_ASM_INPUT (inout_mode[i], ggc_strdup (buffer)); } generating_concat_p = old_generating_concat_p; /* Now, for each output, construct an rtx (set OUTPUT (asm_operands INSN OUTPUTCONSTRAINT OUTPUTNUMBER ARGVEC CONSTRAINTS OPNAMES)) If there is more than one, put them inside a PARALLEL. */ if (noutputs == 1 && nclobbers == 0) { ASM_OPERANDS_OUTPUT_CONSTRAINT (body) = ggc_strdup (constraints[0]); emit_insn (gen_rtx_SET (VOIDmode, output_rtx[0], body)); } else if (noutputs == 0 && nclobbers == 0) { /* No output operands: put in a raw ASM_OPERANDS rtx. */ emit_insn (body); } else { rtx obody = body; int num = noutputs; if (num == 0) num = 1; body = gen_rtx_PARALLEL (VOIDmode, rtvec_alloc (num + nclobbers)); /* For each output operand, store a SET. */ for (i = 0, tail = outputs; tail; tail = TREE_CHAIN (tail), i++) { XVECEXP (body, 0, i) = gen_rtx_SET (VOIDmode, output_rtx[i], gen_rtx_ASM_OPERANDS (GET_MODE (output_rtx[i]), ggc_strdup (TREE_STRING_POINTER (string)), ggc_strdup (constraints[i]), i, argvec, constraintvec, locus)); MEM_VOLATILE_P (SET_SRC (XVECEXP (body, 0, i))) = vol; } /* If there are no outputs (but there are some clobbers) store the bare ASM_OPERANDS into the PARALLEL. */ if (i == 0) XVECEXP (body, 0, i++) = obody; /* Store (clobber REG) for each clobbered register specified. */ for (tail = clobbers; tail; tail = TREE_CHAIN (tail)) { const char *regname = TREE_STRING_POINTER (TREE_VALUE (tail)); int j = decode_reg_name (regname); rtx clobbered_reg; if (j < 0) { if (j == -3) /* `cc', which is not a register */ continue; if (j == -4) /* `memory', don't cache memory across asm */ { XVECEXP (body, 0, i++) = gen_rtx_CLOBBER (VOIDmode, gen_rtx_MEM (BLKmode, gen_rtx_SCRATCH (VOIDmode))); continue; } /* Ignore unknown register, error already signaled. */ continue; } /* Use QImode since that's guaranteed to clobber just one reg. */ clobbered_reg = gen_rtx_REG (QImode, j); /* Do sanity check for overlap between clobbers and respectively input and outputs that hasn't been handled. Such overlap should have been detected and reported above. */ if (!clobber_conflict_found) { int opno; /* We test the old body (obody) contents to avoid tripping over the under-construction body. */ for (opno = 0; opno < noutputs; opno++) if (reg_overlap_mentioned_p (clobbered_reg, output_rtx[opno])) internal_error ("asm clobber conflict with output operand"); for (opno = 0; opno < ninputs - ninout; opno++) if (reg_overlap_mentioned_p (clobbered_reg, ASM_OPERANDS_INPUT (obody, opno))) internal_error ("asm clobber conflict with input operand"); } XVECEXP (body, 0, i++) = gen_rtx_CLOBBER (VOIDmode, clobbered_reg); } emit_insn (body); } /* For any outputs that needed reloading into registers, spill them back to where they belong. */ for (i = 0; i < noutputs; ++i) if (real_output_rtx[i]) emit_move_insn (real_output_rtx[i], output_rtx[i]); free_temp_slots (); } void expand_asm_expr (tree exp) { int noutputs, i; tree outputs, tail; tree *o; if (ASM_INPUT_P (exp)) { expand_asm (ASM_STRING (exp), ASM_VOLATILE_P (exp)); return; } outputs = ASM_OUTPUTS (exp); noutputs = list_length (outputs); /* o[I] is the place that output number I should be written. */ o = (tree *) alloca (noutputs * sizeof (tree)); /* Record the contents of OUTPUTS before it is modified. */ for (i = 0, tail = outputs; tail; tail = TREE_CHAIN (tail), i++) o[i] = TREE_VALUE (tail); /* Generate the ASM_OPERANDS insn; store into the TREE_VALUEs of OUTPUTS some trees for where the values were actually stored. */ expand_asm_operands (ASM_STRING (exp), outputs, ASM_INPUTS (exp), ASM_CLOBBERS (exp), ASM_VOLATILE_P (exp), input_location); /* Copy all the intermediate outputs into the specified outputs. */ for (i = 0, tail = outputs; tail; tail = TREE_CHAIN (tail), i++) { if (o[i] != TREE_VALUE (tail)) { expand_assignment (o[i], TREE_VALUE (tail)); free_temp_slots (); /* Restore the original value so that it's correct the next time we expand this function. */ TREE_VALUE (tail) = o[i]; } } } /* A subroutine of expand_asm_operands. Check that all operands have the same number of alternatives. Return true if so. */ static bool check_operand_nalternatives (tree outputs, tree inputs) { if (outputs || inputs) { tree tmp = TREE_PURPOSE (outputs ? outputs : inputs); int nalternatives = n_occurrences (',', TREE_STRING_POINTER (TREE_VALUE (tmp))); tree next = inputs; if (nalternatives + 1 > MAX_RECOG_ALTERNATIVES) { error ("too many alternatives in %<asm%>"); return false; } tmp = outputs; while (tmp) { const char *constraint = TREE_STRING_POINTER (TREE_VALUE (TREE_PURPOSE (tmp))); if (n_occurrences (',', constraint) != nalternatives) { error ("operand constraints for %<asm%> differ " "in number of alternatives"); return false; } if (TREE_CHAIN (tmp)) tmp = TREE_CHAIN (tmp); else tmp = next, next = 0; } } return true; } /* A subroutine of expand_asm_operands. Check that all operand names are unique. Return true if so. We rely on the fact that these names are identifiers, and so have been canonicalized by get_identifier, so all we need are pointer comparisons. */ static bool check_unique_operand_names (tree outputs, tree inputs) { tree i, j; for (i = outputs; i ; i = TREE_CHAIN (i)) { tree i_name = TREE_PURPOSE (TREE_PURPOSE (i)); if (! i_name) continue; for (j = TREE_CHAIN (i); j ; j = TREE_CHAIN (j)) if (simple_cst_equal (i_name, TREE_PURPOSE (TREE_PURPOSE (j)))) goto failure; } for (i = inputs; i ; i = TREE_CHAIN (i)) { tree i_name = TREE_PURPOSE (TREE_PURPOSE (i)); if (! i_name) continue; for (j = TREE_CHAIN (i); j ; j = TREE_CHAIN (j)) if (simple_cst_equal (i_name, TREE_PURPOSE (TREE_PURPOSE (j)))) goto failure; for (j = outputs; j ; j = TREE_CHAIN (j)) if (simple_cst_equal (i_name, TREE_PURPOSE (TREE_PURPOSE (j)))) goto failure; } return true; failure: error ("duplicate asm operand name %qs", TREE_STRING_POINTER (TREE_PURPOSE (TREE_PURPOSE (i)))); return false; } /* A subroutine of expand_asm_operands. Resolve the names of the operands in *POUTPUTS and *PINPUTS to numbers, and replace the name expansions in STRING and in the constraints to those numbers. */ tree resolve_asm_operand_names (tree string, tree outputs, tree inputs) { char *buffer; char *p; const char *c; tree t; check_unique_operand_names (outputs, inputs); /* Substitute [<name>] in input constraint strings. There should be no named operands in output constraints. */ for (t = inputs; t ; t = TREE_CHAIN (t)) { c = TREE_STRING_POINTER (TREE_VALUE (TREE_PURPOSE (t))); if (strchr (c, '[') != NULL) { p = buffer = xstrdup (c); while ((p = strchr (p, '[')) != NULL) p = resolve_operand_name_1 (p, outputs, inputs); TREE_VALUE (TREE_PURPOSE (t)) = build_string (strlen (buffer), buffer); free (buffer); } } /* Now check for any needed substitutions in the template. */ c = TREE_STRING_POINTER (string); while ((c = strchr (c, '%')) != NULL) { if (c[1] == '[') break; else if (ISALPHA (c[1]) && c[2] == '[') break; else { c += 1; continue; } } if (c) { /* OK, we need to make a copy so we can perform the substitutions. Assume that we will not need extra space--we get to remove '[' and ']', which means we cannot have a problem until we have more than 999 operands. */ buffer = xstrdup (TREE_STRING_POINTER (string)); p = buffer + (c - TREE_STRING_POINTER (string)); while ((p = strchr (p, '%')) != NULL) { if (p[1] == '[') p += 1; else if (ISALPHA (p[1]) && p[2] == '[') p += 2; else { p += 1; continue; } p = resolve_operand_name_1 (p, outputs, inputs); } string = build_string (strlen (buffer), buffer); free (buffer); } return string; } /* A subroutine of resolve_operand_names. P points to the '[' for a potential named operand of the form [<name>]. In place, replace the name and brackets with a number. Return a pointer to the balance of the string after substitution. */ static char * resolve_operand_name_1 (char *p, tree outputs, tree inputs) { char *q; int op; tree t; size_t len; /* Collect the operand name. */ q = strchr (p, ']'); if (!q) { error ("missing close brace for named operand"); return strchr (p, '\0'); } len = q - p - 1; /* Resolve the name to a number. */ for (op = 0, t = outputs; t ; t = TREE_CHAIN (t), op++) { tree name = TREE_PURPOSE (TREE_PURPOSE (t)); if (name) { const char *c = TREE_STRING_POINTER (name); if (strncmp (c, p + 1, len) == 0 && c[len] == '\0') goto found; } } for (t = inputs; t ; t = TREE_CHAIN (t), op++) { tree name = TREE_PURPOSE (TREE_PURPOSE (t)); if (name) { const char *c = TREE_STRING_POINTER (name); if (strncmp (c, p + 1, len) == 0 && c[len] == '\0') goto found; } } *q = '\0'; error ("undefined named operand %qs", p + 1); op = 0; found: /* Replace the name with the number. Unfortunately, not all libraries get the return value of sprintf correct, so search for the end of the generated string by hand. */ sprintf (p, "%d", op); p = strchr (p, '\0'); /* Verify the no extra buffer space assumption. */ gcc_assert (p <= q); /* Shift the rest of the buffer down to fill the gap. */ memmove (p, q + 1, strlen (q + 1) + 1); return p; } /* Generate RTL to evaluate the expression EXP. */ void expand_expr_stmt (tree exp) { rtx value; tree type; value = expand_expr (exp, const0_rtx, VOIDmode, 0); type = TREE_TYPE (exp); /* If all we do is reference a volatile value in memory, copy it to a register to be sure it is actually touched. */ if (value && MEM_P (value) && TREE_THIS_VOLATILE (exp)) { if (TYPE_MODE (type) == VOIDmode) ; else if (TYPE_MODE (type) != BLKmode) value = copy_to_reg (value); else { rtx lab = gen_label_rtx (); /* Compare the value with itself to reference it. */ emit_cmp_and_jump_insns (value, value, EQ, expand_normal (TYPE_SIZE (type)), BLKmode, 0, lab); emit_label (lab); } } /* Free any temporaries used to evaluate this expression. */ free_temp_slots (); } /* Warn if EXP contains any computations whose results are not used. Return 1 if a warning is printed; 0 otherwise. LOCUS is the (potential) location of the expression. */ int warn_if_unused_value (tree exp, location_t locus) { restart: if (TREE_USED (exp) || TREE_NO_WARNING (exp)) return 0; /* Don't warn about void constructs. This includes casting to void, void function calls, and statement expressions with a final cast to void. */ if (VOID_TYPE_P (TREE_TYPE (exp))) return 0; if (EXPR_HAS_LOCATION (exp)) locus = EXPR_LOCATION (exp); switch (TREE_CODE (exp)) { case PREINCREMENT_EXPR: case POSTINCREMENT_EXPR: case PREDECREMENT_EXPR: case POSTDECREMENT_EXPR: case MODIFY_EXPR: case INIT_EXPR: case TARGET_EXPR: case CALL_EXPR: case TRY_CATCH_EXPR: case WITH_CLEANUP_EXPR: case EXIT_EXPR: case VA_ARG_EXPR: return 0; case BIND_EXPR: /* For a binding, warn if no side effect within it. */ exp = BIND_EXPR_BODY (exp); goto restart; case SAVE_EXPR: exp = TREE_OPERAND (exp, 0); goto restart; case TRUTH_ORIF_EXPR: case TRUTH_ANDIF_EXPR: /* In && or ||, warn if 2nd operand has no side effect. */ exp = TREE_OPERAND (exp, 1); goto restart; case COMPOUND_EXPR: if (warn_if_unused_value (TREE_OPERAND (exp, 0), locus)) return 1; /* Let people do `(foo (), 0)' without a warning. */ if (TREE_CONSTANT (TREE_OPERAND (exp, 1))) return 0; exp = TREE_OPERAND (exp, 1); goto restart; case COND_EXPR: /* If this is an expression with side effects, don't warn; this case commonly appears in macro expansions. */ if (TREE_SIDE_EFFECTS (exp)) return 0; goto warn; case INDIRECT_REF: /* Don't warn about automatic dereferencing of references, since the user cannot control it. */ if (TREE_CODE (TREE_TYPE (TREE_OPERAND (exp, 0))) == REFERENCE_TYPE) { exp = TREE_OPERAND (exp, 0); goto restart; } /* Fall through. */ default: /* Referencing a volatile value is a side effect, so don't warn. */ if ((DECL_P (exp) || REFERENCE_CLASS_P (exp)) && TREE_THIS_VOLATILE (exp)) return 0; /* If this is an expression which has no operands, there is no value to be unused. There are no such language-independent codes, but front ends may define such. */ if (EXPRESSION_CLASS_P (exp) && TREE_CODE_LENGTH (TREE_CODE (exp)) == 0) return 0; warn: warning (0, "%Hvalue computed is not used", &locus); return 1; } } /* Generate RTL to return from the current function, with no value. (That is, we do not do anything about returning any value.) */ void expand_null_return (void) { /* If this function was declared to return a value, but we didn't, clobber the return registers so that they are not propagated live to the rest of the function. */ clobber_return_register (); expand_null_return_1 (); } /* Generate RTL to return directly from the current function. (That is, we bypass any return value.) */ void expand_naked_return (void) { rtx end_label; clear_pending_stack_adjust (); do_pending_stack_adjust (); end_label = naked_return_label; if (end_label == 0) end_label = naked_return_label = gen_label_rtx (); emit_jump (end_label); } /* Generate RTL to return from the current function, with value VAL. */ static void expand_value_return (rtx val) { /* Copy the value to the return location unless it's already there. */ rtx return_reg = DECL_RTL (DECL_RESULT (current_function_decl)); if (return_reg != val) { tree type = TREE_TYPE (DECL_RESULT (current_function_decl)); if (targetm.calls.promote_function_return (TREE_TYPE (current_function_decl))) { int unsignedp = TYPE_UNSIGNED (type); enum machine_mode old_mode = DECL_MODE (DECL_RESULT (current_function_decl)); enum machine_mode mode = promote_mode (type, old_mode, &unsignedp, 1); if (mode != old_mode) val = convert_modes (mode, old_mode, val, unsignedp); } if (GET_CODE (return_reg) == PARALLEL) emit_group_load (return_reg, val, type, int_size_in_bytes (type)); else emit_move_insn (return_reg, val); } expand_null_return_1 (); } /* Output a return with no value. */ static void expand_null_return_1 (void) { clear_pending_stack_adjust (); do_pending_stack_adjust (); emit_jump (return_label); } /* Generate RTL to evaluate the expression RETVAL and return it from the current function. */ void expand_return (tree retval) { rtx result_rtl; rtx val = 0; tree retval_rhs; /* If function wants no value, give it none. */ if (TREE_CODE (TREE_TYPE (TREE_TYPE (current_function_decl))) == VOID_TYPE) { expand_normal (retval); expand_null_return (); return; } if (retval == error_mark_node) { /* Treat this like a return of no value from a function that returns a value. */ expand_null_return (); return; } else if ((TREE_CODE (retval) == MODIFY_EXPR || TREE_CODE (retval) == INIT_EXPR) && TREE_CODE (TREE_OPERAND (retval, 0)) == RESULT_DECL) retval_rhs = TREE_OPERAND (retval, 1); else retval_rhs = retval; result_rtl = DECL_RTL (DECL_RESULT (current_function_decl)); /* If we are returning the RESULT_DECL, then the value has already been stored into it, so we don't have to do anything special. */ if (TREE_CODE (retval_rhs) == RESULT_DECL) expand_value_return (result_rtl); /* If the result is an aggregate that is being returned in one (or more) registers, load the registers here. The compiler currently can't handle copying a BLKmode value into registers. We could put this code in a more general area (for use by everyone instead of just function call/return), but until this feature is generally usable it is kept here (and in expand_call). */ else if (retval_rhs != 0 && TYPE_MODE (TREE_TYPE (retval_rhs)) == BLKmode && REG_P (result_rtl)) { int i; unsigned HOST_WIDE_INT bitpos, xbitpos; unsigned HOST_WIDE_INT padding_correction = 0; unsigned HOST_WIDE_INT bytes = int_size_in_bytes (TREE_TYPE (retval_rhs)); int n_regs = (bytes + UNITS_PER_WORD - 1) / UNITS_PER_WORD; unsigned int bitsize = MIN (TYPE_ALIGN (TREE_TYPE (retval_rhs)), BITS_PER_WORD); rtx *result_pseudos = alloca (sizeof (rtx) * n_regs); rtx result_reg, src = NULL_RTX, dst = NULL_RTX; rtx result_val = expand_normal (retval_rhs); enum machine_mode tmpmode, result_reg_mode; if (bytes == 0) { expand_null_return (); return; } /* If the structure doesn't take up a whole number of words, see whether the register value should be padded on the left or on the right. Set PADDING_CORRECTION to the number of padding bits needed on the left side. In most ABIs, the structure will be returned at the least end of the register, which translates to right padding on little-endian targets and left padding on big-endian targets. The opposite holds if the structure is returned at the most significant end of the register. */ if (bytes % UNITS_PER_WORD != 0 && (targetm.calls.return_in_msb (TREE_TYPE (retval_rhs)) ? !BYTES_BIG_ENDIAN : BYTES_BIG_ENDIAN)) padding_correction = (BITS_PER_WORD - ((bytes % UNITS_PER_WORD) * BITS_PER_UNIT)); /* Copy the structure BITSIZE bits at a time. */ for (bitpos = 0, xbitpos = padding_correction; bitpos < bytes * BITS_PER_UNIT; bitpos += bitsize, xbitpos += bitsize) { /* We need a new destination pseudo each time xbitpos is on a word boundary and when xbitpos == padding_correction (the first time through). */ if (xbitpos % BITS_PER_WORD == 0 || xbitpos == padding_correction) { /* Generate an appropriate register. */ dst = gen_reg_rtx (word_mode); result_pseudos[xbitpos / BITS_PER_WORD] = dst; /* Clear the destination before we move anything into it. */ emit_move_insn (dst, CONST0_RTX (GET_MODE (dst))); } /* We need a new source operand each time bitpos is on a word boundary. */ if (bitpos % BITS_PER_WORD == 0) src = operand_subword_force (result_val, bitpos / BITS_PER_WORD, BLKmode); /* Use bitpos for the source extraction (left justified) and xbitpos for the destination store (right justified). */ store_bit_field (dst, bitsize, xbitpos % BITS_PER_WORD, word_mode, extract_bit_field (src, bitsize, bitpos % BITS_PER_WORD, 1, NULL_RTX, word_mode, word_mode)); } tmpmode = GET_MODE (result_rtl); if (tmpmode == BLKmode) { /* Find the smallest integer mode large enough to hold the entire structure and use that mode instead of BLKmode on the USE insn for the return register. */ for (tmpmode = GET_CLASS_NARROWEST_MODE (MODE_INT); tmpmode != VOIDmode; tmpmode = GET_MODE_WIDER_MODE (tmpmode)) /* Have we found a large enough mode? */ if (GET_MODE_SIZE (tmpmode) >= bytes) break; /* A suitable mode should have been found. */ gcc_assert (tmpmode != VOIDmode); PUT_MODE (result_rtl, tmpmode); } if (GET_MODE_SIZE (tmpmode) < GET_MODE_SIZE (word_mode)) result_reg_mode = word_mode; else result_reg_mode = tmpmode; result_reg = gen_reg_rtx (result_reg_mode); for (i = 0; i < n_regs; i++) emit_move_insn (operand_subword (result_reg, i, 0, result_reg_mode), result_pseudos[i]); if (tmpmode != result_reg_mode) result_reg = gen_lowpart (tmpmode, result_reg); expand_value_return (result_reg); } else if (retval_rhs != 0 && !VOID_TYPE_P (TREE_TYPE (retval_rhs)) && (REG_P (result_rtl) || (GET_CODE (result_rtl) == PARALLEL))) { /* Calculate the return value into a temporary (usually a pseudo reg). */ tree ot = TREE_TYPE (DECL_RESULT (current_function_decl)); tree nt = build_qualified_type (ot, TYPE_QUALS (ot) | TYPE_QUAL_CONST); val = assign_temp (nt, 0, 0, 1); val = expand_expr (retval_rhs, val, GET_MODE (val), 0); val = force_not_mem (val); /* Return the calculated value. */ expand_value_return (val); } else { /* No hard reg used; calculate value into hard return reg. */ expand_expr (retval, const0_rtx, VOIDmode, 0); expand_value_return (result_rtl); } } /* Given a pointer to a BLOCK node return nonzero if (and only if) the node in question represents the outermost pair of curly braces (i.e. the "body block") of a function or method. For any BLOCK node representing a "body block" of a function or method, the BLOCK_SUPERCONTEXT of the node will point to another BLOCK node which represents the outermost (function) scope for the function or method (i.e. the one which includes the formal parameters). The BLOCK_SUPERCONTEXT of *that* node in turn will point to the relevant FUNCTION_DECL node. */ int is_body_block (tree stmt) { if (lang_hooks.no_body_blocks) return 0; if (TREE_CODE (stmt) == BLOCK) { tree parent = BLOCK_SUPERCONTEXT (stmt); if (parent && TREE_CODE (parent) == BLOCK) { tree grandparent = BLOCK_SUPERCONTEXT (parent); if (grandparent && TREE_CODE (grandparent) == FUNCTION_DECL) return 1; } } return 0; } /* Emit code to restore vital registers at the beginning of a nonlocal goto handler. */ static void expand_nl_goto_receiver (void) { /* Clobber the FP when we get here, so we have to make sure it's marked as used by this function. */ emit_insn (gen_rtx_USE (VOIDmode, hard_frame_pointer_rtx)); /* Mark the static chain as clobbered here so life information doesn't get messed up for it. */ emit_insn (gen_rtx_CLOBBER (VOIDmode, static_chain_rtx)); #ifdef HAVE_nonlocal_goto if (! HAVE_nonlocal_goto) #endif /* First adjust our frame pointer to its actual value. It was previously set to the start of the virtual area corresponding to the stacked variables when we branched here and now needs to be adjusted to the actual hardware fp value. Assignments are to virtual registers are converted by instantiate_virtual_regs into the corresponding assignment to the underlying register (fp in this case) that makes the original assignment true. So the following insn will actually be decrementing fp by STARTING_FRAME_OFFSET. */ emit_move_insn (virtual_stack_vars_rtx, hard_frame_pointer_rtx); #if ARG_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM if (fixed_regs[ARG_POINTER_REGNUM]) { #ifdef ELIMINABLE_REGS /* If the argument pointer can be eliminated in favor of the frame pointer, we don't need to restore it. We assume here that if such an elimination is present, it can always be used. This is the case on all known machines; if we don't make this assumption, we do unnecessary saving on many machines. */ static const struct elims {const int from, to;} elim_regs[] = ELIMINABLE_REGS; size_t i; for (i = 0; i < ARRAY_SIZE (elim_regs); i++) if (elim_regs[i].from == ARG_POINTER_REGNUM && elim_regs[i].to == HARD_FRAME_POINTER_REGNUM) break; if (i == ARRAY_SIZE (elim_regs)) #endif { /* Now restore our arg pointer from the address at which it was saved in our stack frame. */ emit_move_insn (virtual_incoming_args_rtx, copy_to_reg (get_arg_pointer_save_area (cfun))); } } #endif #ifdef HAVE_nonlocal_goto_receiver if (HAVE_nonlocal_goto_receiver) emit_insn (gen_nonlocal_goto_receiver ()); #endif /* @@@ This is a kludge. Not all machine descriptions define a blockage insn, but we must not allow the code we just generated to be reordered by scheduling. Specifically, the update of the frame pointer must happen immediately, not later. So emit an ASM_INPUT to act as blockage insn. */ emit_insn (gen_rtx_ASM_INPUT (VOIDmode, "")); } /* Generate RTL for the automatic variable declaration DECL. (Other kinds of declarations are simply ignored if seen here.) */ void expand_decl (tree decl) { tree type; type = TREE_TYPE (decl); /* For a CONST_DECL, set mode, alignment, and sizes from those of the type in case this node is used in a reference. */ if (TREE_CODE (decl) == CONST_DECL) { DECL_MODE (decl) = TYPE_MODE (type); DECL_ALIGN (decl) = TYPE_ALIGN (type); DECL_SIZE (decl) = TYPE_SIZE (type); DECL_SIZE_UNIT (decl) = TYPE_SIZE_UNIT (type); return; } /* Otherwise, only automatic variables need any expansion done. Static and external variables, and external functions, will be handled by `assemble_variable' (called from finish_decl). TYPE_DECL requires nothing. PARM_DECLs are handled in `assign_parms'. */ if (TREE_CODE (decl) != VAR_DECL) return; if (TREE_STATIC (decl) || DECL_EXTERNAL (decl)) return; /* Create the RTL representation for the variable. */ if (type == error_mark_node) SET_DECL_RTL (decl, gen_rtx_MEM (BLKmode, const0_rtx)); else if (DECL_SIZE (decl) == 0) /* Variable with incomplete type. */ { rtx x; if (DECL_INITIAL (decl) == 0) /* Error message was already done; now avoid a crash. */ x = gen_rtx_MEM (BLKmode, const0_rtx); else /* An initializer is going to decide the size of this array. Until we know the size, represent its address with a reg. */ x = gen_rtx_MEM (BLKmode, gen_reg_rtx (Pmode)); set_mem_attributes (x, decl, 1); SET_DECL_RTL (decl, x); } else if (use_register_for_decl (decl)) { /* Automatic variable that can go in a register. */ int unsignedp = TYPE_UNSIGNED (type); enum machine_mode reg_mode = promote_mode (type, DECL_MODE (decl), &unsignedp, 0); SET_DECL_RTL (decl, gen_reg_rtx (reg_mode)); /* Note if the object is a user variable. */ if (!DECL_ARTIFICIAL (decl)) { mark_user_reg (DECL_RTL (decl)); /* Trust user variables which have a pointer type to really be pointers. Do not trust compiler generated temporaries as our type system is totally busted as it relates to pointer arithmetic which translates into lots of compiler generated objects with pointer types, but which are not really pointers. */ if (POINTER_TYPE_P (type)) mark_reg_pointer (DECL_RTL (decl), TYPE_ALIGN (TREE_TYPE (TREE_TYPE (decl)))); } } else if (TREE_CODE (DECL_SIZE_UNIT (decl)) == INTEGER_CST && ! (flag_stack_check && ! STACK_CHECK_BUILTIN && 0 < compare_tree_int (DECL_SIZE_UNIT (decl), STACK_CHECK_MAX_VAR_SIZE))) { /* Variable of fixed size that goes on the stack. */ rtx oldaddr = 0; rtx addr; rtx x; /* If we previously made RTL for this decl, it must be an array whose size was determined by the initializer. The old address was a register; set that register now to the proper address. */ if (DECL_RTL_SET_P (decl)) { gcc_assert (MEM_P (DECL_RTL (decl))); gcc_assert (REG_P (XEXP (DECL_RTL (decl), 0))); oldaddr = XEXP (DECL_RTL (decl), 0); } /* Set alignment we actually gave this decl. */ DECL_ALIGN (decl) = (DECL_MODE (decl) == BLKmode ? BIGGEST_ALIGNMENT : GET_MODE_BITSIZE (DECL_MODE (decl))); DECL_USER_ALIGN (decl) = 0; x = assign_temp (decl, 1, 1, 1); set_mem_attributes (x, decl, 1); SET_DECL_RTL (decl, x); if (oldaddr) { addr = force_operand (XEXP (DECL_RTL (decl), 0), oldaddr); if (addr != oldaddr) emit_move_insn (oldaddr, addr); } } else /* Dynamic-size object: must push space on the stack. */ { rtx address, size, x; /* Record the stack pointer on entry to block, if have not already done so. */ do_pending_stack_adjust (); /* Compute the variable's size, in bytes. This will expand any needed SAVE_EXPRs for the first time. */ size = expand_normal (DECL_SIZE_UNIT (decl)); free_temp_slots (); /* Allocate space on the stack for the variable. Note that DECL_ALIGN says how the variable is to be aligned and we cannot use it to conclude anything about the alignment of the size. */ address = allocate_dynamic_stack_space (size, NULL_RTX, TYPE_ALIGN (TREE_TYPE (decl))); /* Reference the variable indirect through that rtx. */ x = gen_rtx_MEM (DECL_MODE (decl), address); set_mem_attributes (x, decl, 1); SET_DECL_RTL (decl, x); /* Indicate the alignment we actually gave this variable. */ #ifdef STACK_BOUNDARY DECL_ALIGN (decl) = STACK_BOUNDARY; #else DECL_ALIGN (decl) = BIGGEST_ALIGNMENT; #endif DECL_USER_ALIGN (decl) = 0; } } /* Emit code to save the current value of stack. */ rtx expand_stack_save (void) { rtx ret = NULL_RTX; do_pending_stack_adjust (); emit_stack_save (SAVE_BLOCK, &ret, NULL_RTX); return ret; } /* Emit code to restore the current value of stack. */ void expand_stack_restore (tree var) { rtx sa = DECL_RTL (var); emit_stack_restore (SAVE_BLOCK, sa, NULL_RTX); } /* DECL is an anonymous union. CLEANUP is a cleanup for DECL. DECL_ELTS is the list of elements that belong to DECL's type. In each, the TREE_VALUE is a VAR_DECL, and the TREE_PURPOSE a cleanup. */ void expand_anon_union_decl (tree decl, tree cleanup ATTRIBUTE_UNUSED, tree decl_elts) { rtx x; tree t; /* If any of the elements are addressable, so is the entire union. */ for (t = decl_elts; t; t = TREE_CHAIN (t)) if (TREE_ADDRESSABLE (TREE_VALUE (t))) { TREE_ADDRESSABLE (decl) = 1; break; } expand_decl (decl); x = DECL_RTL (decl); /* Go through the elements, assigning RTL to each. */ for (t = decl_elts; t; t = TREE_CHAIN (t)) { tree decl_elt = TREE_VALUE (t); enum machine_mode mode = TYPE_MODE (TREE_TYPE (decl_elt)); rtx decl_rtl; /* If any of the elements are addressable, so is the entire union. */ if (TREE_USED (decl_elt)) TREE_USED (decl) = 1; /* Propagate the union's alignment to the elements. */ DECL_ALIGN (decl_elt) = DECL_ALIGN (decl); DECL_USER_ALIGN (decl_elt) = DECL_USER_ALIGN (decl); /* If the element has BLKmode and the union doesn't, the union is aligned such that the element doesn't need to have BLKmode, so change the element's mode to the appropriate one for its size. */ if (mode == BLKmode && DECL_MODE (decl) != BLKmode) DECL_MODE (decl_elt) = mode = mode_for_size_tree (DECL_SIZE (decl_elt), MODE_INT, 1); if (mode == GET_MODE (x)) decl_rtl = x; else if (MEM_P (x)) /* (SUBREG (MEM ...)) at RTL generation time is invalid, so we instead create a new MEM rtx with the proper mode. */ decl_rtl = adjust_address_nv (x, mode, 0); else { gcc_assert (REG_P (x)); decl_rtl = gen_lowpart_SUBREG (mode, x); } SET_DECL_RTL (decl_elt, decl_rtl); } } /* Do the insertion of a case label into case_list. The labels are fed to us in descending order from the sorted vector of case labels used in the tree part of the middle end. So the list we construct is sorted in ascending order. The bounds on the case range, LOW and HIGH, are converted to case's index type TYPE. */ static struct case_node * add_case_node (struct case_node *head, tree type, tree low, tree high, tree label) { tree min_value, max_value; struct case_node *r; gcc_assert (TREE_CODE (low) == INTEGER_CST); gcc_assert (!high || TREE_CODE (high) == INTEGER_CST); min_value = TYPE_MIN_VALUE (type); max_value = TYPE_MAX_VALUE (type); /* If there's no HIGH value, then this is not a case range; it's just a simple case label. But that's just a degenerate case range. If the bounds are equal, turn this into the one-value case. */ if (!high || tree_int_cst_equal (low, high)) { /* If the simple case value is unreachable, ignore it. */ if ((TREE_CODE (min_value) == INTEGER_CST && tree_int_cst_compare (low, min_value) < 0) || (TREE_CODE (max_value) == INTEGER_CST && tree_int_cst_compare (low, max_value) > 0)) return head; low = fold_convert (type, low); high = low; } else { /* If the entire case range is unreachable, ignore it. */ if ((TREE_CODE (min_value) == INTEGER_CST && tree_int_cst_compare (high, min_value) < 0) || (TREE_CODE (max_value) == INTEGER_CST && tree_int_cst_compare (low, max_value) > 0)) return head; /* If the lower bound is less than the index type's minimum value, truncate the range bounds. */ if (TREE_CODE (min_value) == INTEGER_CST && tree_int_cst_compare (low, min_value) < 0) low = min_value; low = fold_convert (type, low); /* If the upper bound is greater than the index type's maximum value, truncate the range bounds. */ if (TREE_CODE (max_value) == INTEGER_CST && tree_int_cst_compare (high, max_value) > 0) high = max_value; high = fold_convert (type, high); } /* Add this label to the chain. Make sure to drop overflow flags. */ r = ggc_alloc (sizeof (struct case_node)); r->low = build_int_cst_wide (TREE_TYPE (low), TREE_INT_CST_LOW (low), TREE_INT_CST_HIGH (low)); r->high = build_int_cst_wide (TREE_TYPE (high), TREE_INT_CST_LOW (high), TREE_INT_CST_HIGH (high)); r->code_label = label; r->parent = r->left = NULL; r->right = head; return r; } /* Maximum number of case bit tests. */ #define MAX_CASE_BIT_TESTS 3 /* By default, enable case bit tests on targets with ashlsi3. */ #ifndef CASE_USE_BIT_TESTS #define CASE_USE_BIT_TESTS (ashl_optab->handlers[word_mode].insn_code \ != CODE_FOR_nothing) #endif /* A case_bit_test represents a set of case nodes that may be selected from using a bit-wise comparison. HI and LO hold the integer to be tested against, LABEL contains the label to jump to upon success and BITS counts the number of case nodes handled by this test, typically the number of bits set in HI:LO. */ struct case_bit_test { HOST_WIDE_INT hi; HOST_WIDE_INT lo; rtx label; int bits; }; /* Determine whether "1 << x" is relatively cheap in word_mode. */ static bool lshift_cheap_p (void) { static bool init = false; static bool cheap = true; if (!init) { rtx reg = gen_rtx_REG (word_mode, 10000); int cost = rtx_cost (gen_rtx_ASHIFT (word_mode, const1_rtx, reg), SET); cheap = cost < COSTS_N_INSNS (3); init = true; } return cheap; } /* Comparison function for qsort to order bit tests by decreasing number of case nodes, i.e. the node with the most cases gets tested first. */ static int case_bit_test_cmp (const void *p1, const void *p2) { const struct case_bit_test *d1 = p1; const struct case_bit_test *d2 = p2; if (d2->bits != d1->bits) return d2->bits - d1->bits; /* Stabilize the sort. */ return CODE_LABEL_NUMBER (d2->label) - CODE_LABEL_NUMBER (d1->label); } /* Expand a switch statement by a short sequence of bit-wise comparisons. "switch(x)" is effectively converted into "if ((1 << (x-MINVAL)) & CST)" where CST and MINVAL are integer constants. INDEX_EXPR is the value being switched on, which is of type INDEX_TYPE. MINVAL is the lowest case value of in the case nodes, of INDEX_TYPE type, and RANGE is highest value minus MINVAL, also of type INDEX_TYPE. NODES is the set of case nodes, and DEFAULT_LABEL is the label to branch to should none of the cases match. There *MUST* be MAX_CASE_BIT_TESTS or less unique case node targets. */ static void emit_case_bit_tests (tree index_type, tree index_expr, tree minval, tree range, case_node_ptr nodes, rtx default_label) { struct case_bit_test test[MAX_CASE_BIT_TESTS]; enum machine_mode mode; rtx expr, index, label; unsigned int i,j,lo,hi; struct case_node *n; unsigned int count; count = 0; for (n = nodes; n; n = n->right) { label = label_rtx (n->code_label); for (i = 0; i < count; i++) if (label == test[i].label) break; if (i == count) { gcc_assert (count < MAX_CASE_BIT_TESTS); test[i].hi = 0; test[i].lo = 0; test[i].label = label; test[i].bits = 1; count++; } else test[i].bits++; lo = tree_low_cst (fold_build2 (MINUS_EXPR, index_type, n->low, minval), 1); hi = tree_low_cst (fold_build2 (MINUS_EXPR, index_type, n->high, minval), 1); for (j = lo; j <= hi; j++) if (j >= HOST_BITS_PER_WIDE_INT) test[i].hi |= (HOST_WIDE_INT) 1 << (j - HOST_BITS_PER_INT); else test[i].lo |= (HOST_WIDE_INT) 1 << j; } qsort (test, count, sizeof(*test), case_bit_test_cmp); index_expr = fold_build2 (MINUS_EXPR, index_type, fold_convert (index_type, index_expr), fold_convert (index_type, minval)); index = expand_normal (index_expr); do_pending_stack_adjust (); mode = TYPE_MODE (index_type); expr = expand_normal (range); emit_cmp_and_jump_insns (index, expr, GTU, NULL_RTX, mode, 1, default_label); index = convert_to_mode (word_mode, index, 0); index = expand_binop (word_mode, ashl_optab, const1_rtx, index, NULL_RTX, 1, OPTAB_WIDEN); for (i = 0; i < count; i++) { expr = immed_double_const (test[i].lo, test[i].hi, word_mode); expr = expand_binop (word_mode, and_optab, index, expr, NULL_RTX, 1, OPTAB_WIDEN); emit_cmp_and_jump_insns (expr, const0_rtx, NE, NULL_RTX, word_mode, 1, test[i].label); } emit_jump (default_label); } #ifndef HAVE_casesi #define HAVE_casesi 0 #endif #ifndef HAVE_tablejump #define HAVE_tablejump 0 #endif /* Terminate a case (Pascal/Ada) or switch (C) statement in which ORIG_INDEX is the expression to be tested. If ORIG_TYPE is not NULL, it is the original ORIG_INDEX type as given in the source before any compiler conversions. Generate the code to test it and jump to the right place. */ void expand_case (tree exp) { tree minval = NULL_TREE, maxval = NULL_TREE, range = NULL_TREE; rtx default_label = 0; struct case_node *n; unsigned int count, uniq; rtx index; rtx table_label; int ncases; rtx *labelvec; int i, fail; rtx before_case, end, lab; tree vec = SWITCH_LABELS (exp); tree orig_type = TREE_TYPE (exp); tree index_expr = SWITCH_COND (exp); tree index_type = TREE_TYPE (index_expr); int unsignedp = TYPE_UNSIGNED (index_type); /* The insn after which the case dispatch should finally be emitted. Zero for a dummy. */ rtx start; /* A list of case labels; it is first built as a list and it may then be rearranged into a nearly balanced binary tree. */ struct case_node *case_list = 0; /* Label to jump to if no case matches. */ tree default_label_decl; /* The switch body is lowered in gimplify.c, we should never have switches with a non-NULL SWITCH_BODY here. */ gcc_assert (!SWITCH_BODY (exp)); gcc_assert (SWITCH_LABELS (exp)); do_pending_stack_adjust (); /* An ERROR_MARK occurs for various reasons including invalid data type. */ if (index_type != error_mark_node) { tree elt; bitmap label_bitmap; /* cleanup_tree_cfg removes all SWITCH_EXPR with their index expressions being INTEGER_CST. */ gcc_assert (TREE_CODE (index_expr) != INTEGER_CST); /* The default case is at the end of TREE_VEC. */ elt = TREE_VEC_ELT (vec, TREE_VEC_LENGTH (vec) - 1); gcc_assert (!CASE_HIGH (elt)); gcc_assert (!CASE_LOW (elt)); default_label_decl = CASE_LABEL (elt); for (i = TREE_VEC_LENGTH (vec) - 1; --i >= 0; ) { tree low, high; elt = TREE_VEC_ELT (vec, i); low = CASE_LOW (elt); gcc_assert (low); high = CASE_HIGH (elt); /* Discard empty ranges. */ if (high && INT_CST_LT (high, low)) continue; case_list = add_case_node (case_list, index_type, low, high, CASE_LABEL (elt)); } before_case = start = get_last_insn (); default_label = label_rtx (default_label_decl); /* Get upper and lower bounds of case values. */ uniq = 0; count = 0; label_bitmap = BITMAP_ALLOC (NULL); for (n = case_list; n; n = n->right) { /* Count the elements and track the largest and smallest of them (treating them as signed even if they are not). */ if (count++ == 0) { minval = n->low; maxval = n->high; } else { if (INT_CST_LT (n->low, minval)) minval = n->low; if (INT_CST_LT (maxval, n->high)) maxval = n->high; } /* A range counts double, since it requires two compares. */ if (! tree_int_cst_equal (n->low, n->high)) count++; /* If we have not seen this label yet, then increase the number of unique case node targets seen. */ lab = label_rtx (n->code_label); if (!bitmap_bit_p (label_bitmap, CODE_LABEL_NUMBER (lab))) { bitmap_set_bit (label_bitmap, CODE_LABEL_NUMBER (lab)); uniq++; } } BITMAP_FREE (label_bitmap); /* cleanup_tree_cfg removes all SWITCH_EXPR with a single destination, such as one with a default case only. However, it doesn't remove cases that are out of range for the switch type, so we may still get a zero here. */ if (count == 0) { emit_jump (default_label); return; } /* Compute span of values. */ range = fold_build2 (MINUS_EXPR, index_type, maxval, minval); /* Try implementing this switch statement by a short sequence of bit-wise comparisons. However, we let the binary-tree case below handle constant index expressions. */ if (CASE_USE_BIT_TESTS && ! TREE_CONSTANT (index_expr) && compare_tree_int (range, GET_MODE_BITSIZE (word_mode)) < 0 && compare_tree_int (range, 0) > 0 && lshift_cheap_p () && ((uniq == 1 && count >= 3) || (uniq == 2 && count >= 5) || (uniq == 3 && count >= 6))) { /* Optimize the case where all the case values fit in a word without having to subtract MINVAL. In this case, we can optimize away the subtraction. */ if (compare_tree_int (minval, 0) > 0 && compare_tree_int (maxval, GET_MODE_BITSIZE (word_mode)) < 0) { minval = build_int_cst (index_type, 0); range = maxval; } emit_case_bit_tests (index_type, index_expr, minval, range, case_list, default_label); } /* If range of values is much bigger than number of values, make a sequence of conditional branches instead of a dispatch. If the switch-index is a constant, do it this way because we can optimize it. */ else if (count < case_values_threshold () || compare_tree_int (range, (optimize_size ? 3 : 10) * count) > 0 /* RANGE may be signed, and really large ranges will show up as negative numbers. */ || compare_tree_int (range, 0) < 0 #ifndef ASM_OUTPUT_ADDR_DIFF_ELT || flag_pic #endif || !flag_jump_tables || TREE_CONSTANT (index_expr) /* If neither casesi or tablejump is available, we can only go this way. */ || (!HAVE_casesi && !HAVE_tablejump)) { index = expand_normal (index_expr); /* If the index is a short or char that we do not have an insn to handle comparisons directly, convert it to a full integer now, rather than letting each comparison generate the conversion. */ if (GET_MODE_CLASS (GET_MODE (index)) == MODE_INT && ! have_insn_for (COMPARE, GET_MODE (index))) { enum machine_mode wider_mode; for (wider_mode = GET_MODE (index); wider_mode != VOIDmode; wider_mode = GET_MODE_WIDER_MODE (wider_mode)) if (have_insn_for (COMPARE, wider_mode)) { index = convert_to_mode (wider_mode, index, unsignedp); break; } } do_pending_stack_adjust (); if (MEM_P (index)) index = copy_to_reg (index); /* We generate a binary decision tree to select the appropriate target code. This is done as follows: The list of cases is rearranged into a binary tree, nearly optimal assuming equal probability for each case. The tree is transformed into RTL, eliminating redundant test conditions at the same time. If program flow could reach the end of the decision tree an unconditional jump to the default code is emitted. */ use_cost_table = (TREE_CODE (orig_type) != ENUMERAL_TYPE && estimate_case_costs (case_list)); balance_case_nodes (&case_list, NULL); emit_case_nodes (index, case_list, default_label, index_type); emit_jump (default_label); } else { table_label = gen_label_rtx (); if (! try_casesi (index_type, index_expr, minval, range, table_label, default_label)) { bool ok; /* Index jumptables from zero for suitable values of minval to avoid a subtraction. */ if (! optimize_size && compare_tree_int (minval, 0) > 0 && compare_tree_int (minval, 3) < 0) { minval = build_int_cst (index_type, 0); range = maxval; } ok = try_tablejump (index_type, index_expr, minval, range, table_label, default_label); gcc_assert (ok); } /* Get table of labels to jump to, in order of case index. */ ncases = tree_low_cst (range, 0) + 1; labelvec = alloca (ncases * sizeof (rtx)); memset (labelvec, 0, ncases * sizeof (rtx)); for (n = case_list; n; n = n->right) { /* Compute the low and high bounds relative to the minimum value since that should fit in a HOST_WIDE_INT while the actual values may not. */ HOST_WIDE_INT i_low = tree_low_cst (fold_build2 (MINUS_EXPR, index_type, n->low, minval), 1); HOST_WIDE_INT i_high = tree_low_cst (fold_build2 (MINUS_EXPR, index_type, n->high, minval), 1); HOST_WIDE_INT i; for (i = i_low; i <= i_high; i ++) labelvec[i] = gen_rtx_LABEL_REF (Pmode, label_rtx (n->code_label)); } /* Fill in the gaps with the default. */ for (i = 0; i < ncases; i++) if (labelvec[i] == 0) labelvec[i] = gen_rtx_LABEL_REF (Pmode, default_label); /* Output the table. */ emit_label (table_label); if (CASE_VECTOR_PC_RELATIVE || flag_pic) emit_jump_insn (gen_rtx_ADDR_DIFF_VEC (CASE_VECTOR_MODE, gen_rtx_LABEL_REF (Pmode, table_label), gen_rtvec_v (ncases, labelvec), const0_rtx, const0_rtx)); else emit_jump_insn (gen_rtx_ADDR_VEC (CASE_VECTOR_MODE, gen_rtvec_v (ncases, labelvec))); /* Record no drop-through after the table. */ emit_barrier (); } before_case = NEXT_INSN (before_case); end = get_last_insn (); fail = squeeze_notes (&before_case, &end); gcc_assert (!fail); reorder_insns (before_case, end, start); } free_temp_slots (); } /* Generate code to jump to LABEL if OP0 and OP1 are equal in mode MODE. */ static void do_jump_if_equal (enum machine_mode mode, rtx op0, rtx op1, rtx label, int unsignedp) { do_compare_rtx_and_jump (op0, op1, EQ, unsignedp, mode, NULL_RTX, NULL_RTX, label); } /* Not all case values are encountered equally. This function uses a heuristic to weight case labels, in cases where that looks like a reasonable thing to do. Right now, all we try to guess is text, and we establish the following weights: chars above space: 16 digits: 16 default: 12 space, punct: 8 tab: 4 newline: 2 other "\" chars: 1 remaining chars: 0 If we find any cases in the switch that are not either -1 or in the range of valid ASCII characters, or are control characters other than those commonly used with "\", don't treat this switch scanning text. Return 1 if these nodes are suitable for cost estimation, otherwise return 0. */ static int estimate_case_costs (case_node_ptr node) { tree min_ascii = integer_minus_one_node; tree max_ascii = build_int_cst (TREE_TYPE (node->high), 127); case_node_ptr n; int i; /* If we haven't already made the cost table, make it now. Note that the lower bound of the table is -1, not zero. */ if (! cost_table_initialized) { cost_table_initialized = 1; for (i = 0; i < 128; i++) { if (ISALNUM (i)) COST_TABLE (i) = 16; else if (ISPUNCT (i)) COST_TABLE (i) = 8; else if (ISCNTRL (i)) COST_TABLE (i) = -1; } COST_TABLE (' ') = 8; COST_TABLE ('\t') = 4; COST_TABLE ('\0') = 4; COST_TABLE ('\n') = 2; COST_TABLE ('\f') = 1; COST_TABLE ('\v') = 1; COST_TABLE ('\b') = 1; } /* See if all the case expressions look like text. It is text if the constant is >= -1 and the highest constant is <= 127. Do all comparisons as signed arithmetic since we don't want to ever access cost_table with a value less than -1. Also check that none of the constants in a range are strange control characters. */ for (n = node; n; n = n->right) { if ((INT_CST_LT (n->low, min_ascii)) || INT_CST_LT (max_ascii, n->high)) return 0; for (i = (HOST_WIDE_INT) TREE_INT_CST_LOW (n->low); i <= (HOST_WIDE_INT) TREE_INT_CST_LOW (n->high); i++) if (COST_TABLE (i) < 0) return 0; } /* All interesting values are within the range of interesting ASCII characters. */ return 1; } /* Take an ordered list of case nodes and transform them into a near optimal binary tree, on the assumption that any target code selection value is as likely as any other. The transformation is performed by splitting the ordered list into two equal sections plus a pivot. The parts are then attached to the pivot as left and right branches. Each branch is then transformed recursively. */ static void balance_case_nodes (case_node_ptr *head, case_node_ptr parent) { case_node_ptr np; np = *head; if (np) { int cost = 0; int i = 0; int ranges = 0; case_node_ptr *npp; case_node_ptr left; /* Count the number of entries on branch. Also count the ranges. */ while (np) { if (!tree_int_cst_equal (np->low, np->high)) { ranges++; if (use_cost_table) cost += COST_TABLE (TREE_INT_CST_LOW (np->high)); } if (use_cost_table) cost += COST_TABLE (TREE_INT_CST_LOW (np->low)); i++; np = np->right; } if (i > 2) { /* Split this list if it is long enough for that to help. */ npp = head; left = *npp; if (use_cost_table) { /* Find the place in the list that bisects the list's total cost, Here I gets half the total cost. */ int n_moved = 0; i = (cost + 1) / 2; while (1) { /* Skip nodes while their cost does not reach that amount. */ if (!tree_int_cst_equal ((*npp)->low, (*npp)->high)) i -= COST_TABLE (TREE_INT_CST_LOW ((*npp)->high)); i -= COST_TABLE (TREE_INT_CST_LOW ((*npp)->low)); if (i <= 0) break; npp = &(*npp)->right; n_moved += 1; } if (n_moved == 0) { /* Leave this branch lopsided, but optimize left-hand side and fill in `parent' fields for right-hand side. */ np = *head; np->parent = parent; balance_case_nodes (&np->left, np); for (; np->right; np = np->right) np->right->parent = np; return; } } /* If there are just three nodes, split at the middle one. */ else if (i == 3) npp = &(*npp)->right; else { /* Find the place in the list that bisects the list's total cost, where ranges count as 2. Here I gets half the total cost. */ i = (i + ranges + 1) / 2; while (1) { /* Skip nodes while their cost does not reach that amount. */ if (!tree_int_cst_equal ((*npp)->low, (*npp)->high)) i--; i--; if (i <= 0) break; npp = &(*npp)->right; } } *head = np = *npp; *npp = 0; np->parent = parent; np->left = left; /* Optimize each of the two split parts. */ balance_case_nodes (&np->left, np); balance_case_nodes (&np->right, np); } else { /* Else leave this branch as one level, but fill in `parent' fields. */ np = *head; np->parent = parent; for (; np->right; np = np->right) np->right->parent = np; } } } /* Search the parent sections of the case node tree to see if a test for the lower bound of NODE would be redundant. INDEX_TYPE is the type of the index expression. The instructions to generate the case decision tree are output in the same order as nodes are processed so it is known that if a parent node checks the range of the current node minus one that the current node is bounded at its lower span. Thus the test would be redundant. */ static int node_has_low_bound (case_node_ptr node, tree index_type) { tree low_minus_one; case_node_ptr pnode; /* If the lower bound of this node is the lowest value in the index type, we need not test it. */ if (tree_int_cst_equal (node->low, TYPE_MIN_VALUE (index_type))) return 1; /* If this node has a left branch, the value at the left must be less than that at this node, so it cannot be bounded at the bottom and we need not bother testing any further. */ if (node->left) return 0; low_minus_one = fold_build2 (MINUS_EXPR, TREE_TYPE (node->low), node->low, build_int_cst (TREE_TYPE (node->low), 1)); /* If the subtraction above overflowed, we can't verify anything. Otherwise, look for a parent that tests our value - 1. */ if (! tree_int_cst_lt (low_minus_one, node->low)) return 0; for (pnode = node->parent; pnode; pnode = pnode->parent) if (tree_int_cst_equal (low_minus_one, pnode->high)) return 1; return 0; } /* Search the parent sections of the case node tree to see if a test for the upper bound of NODE would be redundant. INDEX_TYPE is the type of the index expression. The instructions to generate the case decision tree are output in the same order as nodes are processed so it is known that if a parent node checks the range of the current node plus one that the current node is bounded at its upper span. Thus the test would be redundant. */ static int node_has_high_bound (case_node_ptr node, tree index_type) { tree high_plus_one; case_node_ptr pnode; /* If there is no upper bound, obviously no test is needed. */ if (TYPE_MAX_VALUE (index_type) == NULL) return 1; /* If the upper bound of this node is the highest value in the type of the index expression, we need not test against it. */ if (tree_int_cst_equal (node->high, TYPE_MAX_VALUE (index_type))) return 1; /* If this node has a right branch, the value at the right must be greater than that at this node, so it cannot be bounded at the top and we need not bother testing any further. */ if (node->right) return 0; high_plus_one = fold_build2 (PLUS_EXPR, TREE_TYPE (node->high), node->high, build_int_cst (TREE_TYPE (node->high), 1)); /* If the addition above overflowed, we can't verify anything. Otherwise, look for a parent that tests our value + 1. */ if (! tree_int_cst_lt (node->high, high_plus_one)) return 0; for (pnode = node->parent; pnode; pnode = pnode->parent) if (tree_int_cst_equal (high_plus_one, pnode->low)) return 1; return 0; } /* Search the parent sections of the case node tree to see if both tests for the upper and lower bounds of NODE would be redundant. */ static int node_is_bounded (case_node_ptr node, tree index_type) { return (node_has_low_bound (node, index_type) && node_has_high_bound (node, index_type)); } /* Emit step-by-step code to select a case for the value of INDEX. The thus generated decision tree follows the form of the case-node binary tree NODE, whose nodes represent test conditions. INDEX_TYPE is the type of the index of the switch. Care is taken to prune redundant tests from the decision tree by detecting any boundary conditions already checked by emitted rtx. (See node_has_high_bound, node_has_low_bound and node_is_bounded, above.) Where the test conditions can be shown to be redundant we emit an unconditional jump to the target code. As a further optimization, the subordinates of a tree node are examined to check for bounded nodes. In this case conditional and/or unconditional jumps as a result of the boundary check for the current node are arranged to target the subordinates associated code for out of bound conditions on the current node. We can assume that when control reaches the code generated here, the index value has already been compared with the parents of this node, and determined to be on the same side of each parent as this node is. Thus, if this node tests for the value 51, and a parent tested for 52, we don't need to consider the possibility of a value greater than 51. If another parent tests for the value 50, then this node need not test anything. */ static void emit_case_nodes (rtx index, case_node_ptr node, rtx default_label, tree index_type) { /* If INDEX has an unsigned type, we must make unsigned branches. */ int unsignedp = TYPE_UNSIGNED (index_type); enum machine_mode mode = GET_MODE (index); enum machine_mode imode = TYPE_MODE (index_type); /* Handle indices detected as constant during RTL expansion. */ if (mode == VOIDmode) mode = imode; /* See if our parents have already tested everything for us. If they have, emit an unconditional jump for this node. */ if (node_is_bounded (node, index_type)) emit_jump (label_rtx (node->code_label)); else if (tree_int_cst_equal (node->low, node->high)) { /* Node is single valued. First see if the index expression matches this node and then check our children, if any. */ do_jump_if_equal (mode, index, convert_modes (mode, imode, expand_normal (node->low), unsignedp), label_rtx (node->code_label), unsignedp); if (node->right != 0 && node->left != 0) { /* This node has children on both sides. Dispatch to one side or the other by comparing the index value with this node's value. If one subtree is bounded, check that one first, so we can avoid real branches in the tree. */ if (node_is_bounded (node->right, index_type)) { emit_cmp_and_jump_insns (index, convert_modes (mode, imode, expand_normal (node->high), unsignedp), GT, NULL_RTX, mode, unsignedp, label_rtx (node->right->code_label)); emit_case_nodes (index, node->left, default_label, index_type); } else if (node_is_bounded (node->left, index_type)) { emit_cmp_and_jump_insns (index, convert_modes (mode, imode, expand_normal (node->high), unsignedp), LT, NULL_RTX, mode, unsignedp, label_rtx (node->left->code_label)); emit_case_nodes (index, node->right, default_label, index_type); } /* If both children are single-valued cases with no children, finish up all the work. This way, we can save one ordered comparison. */ else if (tree_int_cst_equal (node->right->low, node->right->high) && node->right->left == 0 && node->right->right == 0 && tree_int_cst_equal (node->left->low, node->left->high) && node->left->left == 0 && node->left->right == 0) { /* Neither node is bounded. First distinguish the two sides; then emit the code for one side at a time. */ /* See if the value matches what the right hand side wants. */ do_jump_if_equal (mode, index, convert_modes (mode, imode, expand_normal (node->right->low), unsignedp), label_rtx (node->right->code_label), unsignedp); /* See if the value matches what the left hand side wants. */ do_jump_if_equal (mode, index, convert_modes (mode, imode, expand_normal (node->left->low), unsignedp), label_rtx (node->left->code_label), unsignedp); } else { /* Neither node is bounded. First distinguish the two sides; then emit the code for one side at a time. */ tree test_label = build_decl (LABEL_DECL, NULL_TREE, NULL_TREE); /* See if the value is on the right. */ emit_cmp_and_jump_insns (index, convert_modes (mode, imode, expand_normal (node->high), unsignedp), GT, NULL_RTX, mode, unsignedp, label_rtx (test_label)); /* Value must be on the left. Handle the left-hand subtree. */ emit_case_nodes (index, node->left, default_label, index_type); /* If left-hand subtree does nothing, go to default. */ emit_jump (default_label); /* Code branches here for the right-hand subtree. */ expand_label (test_label); emit_case_nodes (index, node->right, default_label, index_type); } } else if (node->right != 0 && node->left == 0) { /* Here we have a right child but no left so we issue a conditional branch to default and process the right child. Omit the conditional branch to default if the right child does not have any children and is single valued; it would cost too much space to save so little time. */ if (node->right->right || node->right->left || !tree_int_cst_equal (node->right->low, node->right->high)) { if (!node_has_low_bound (node, index_type)) { emit_cmp_and_jump_insns (index, convert_modes (mode, imode, expand_normal (node->high), unsignedp), LT, NULL_RTX, mode, unsignedp, default_label); } emit_case_nodes (index, node->right, default_label, index_type); } else /* We cannot process node->right normally since we haven't ruled out the numbers less than this node's value. So handle node->right explicitly. */ do_jump_if_equal (mode, index, convert_modes (mode, imode, expand_normal (node->right->low), unsignedp), label_rtx (node->right->code_label), unsignedp); } else if (node->right == 0 && node->left != 0) { /* Just one subtree, on the left. */ if (node->left->left || node->left->right || !tree_int_cst_equal (node->left->low, node->left->high)) { if (!node_has_high_bound (node, index_type)) { emit_cmp_and_jump_insns (index, convert_modes (mode, imode, expand_normal (node->high), unsignedp), GT, NULL_RTX, mode, unsignedp, default_label); } emit_case_nodes (index, node->left, default_label, index_type); } else /* We cannot process node->left normally since we haven't ruled out the numbers less than this node's value. So handle node->left explicitly. */ do_jump_if_equal (mode, index, convert_modes (mode, imode, expand_normal (node->left->low), unsignedp), label_rtx (node->left->code_label), unsignedp); } } else { /* Node is a range. These cases are very similar to those for a single value, except that we do not start by testing whether this node is the one to branch to. */ if (node->right != 0 && node->left != 0) { /* Node has subtrees on both sides. If the right-hand subtree is bounded, test for it first, since we can go straight there. Otherwise, we need to make a branch in the control structure, then handle the two subtrees. */ tree test_label = 0; if (node_is_bounded (node->right, index_type)) /* Right hand node is fully bounded so we can eliminate any testing and branch directly to the target code. */ emit_cmp_and_jump_insns (index, convert_modes (mode, imode, expand_normal (node->high), unsignedp), GT, NULL_RTX, mode, unsignedp, label_rtx (node->right->code_label)); else { /* Right hand node requires testing. Branch to a label where we will handle it later. */ test_label = build_decl (LABEL_DECL, NULL_TREE, NULL_TREE); emit_cmp_and_jump_insns (index, convert_modes (mode, imode, expand_normal (node->high), unsignedp), GT, NULL_RTX, mode, unsignedp, label_rtx (test_label)); } /* Value belongs to this node or to the left-hand subtree. */ emit_cmp_and_jump_insns (index, convert_modes (mode, imode, expand_normal (node->low), unsignedp), GE, NULL_RTX, mode, unsignedp, label_rtx (node->code_label)); /* Handle the left-hand subtree. */ emit_case_nodes (index, node->left, default_label, index_type); /* If right node had to be handled later, do that now. */ if (test_label) { /* If the left-hand subtree fell through, don't let it fall into the right-hand subtree. */ emit_jump (default_label); expand_label (test_label); emit_case_nodes (index, node->right, default_label, index_type); } } else if (node->right != 0 && node->left == 0) { /* Deal with values to the left of this node, if they are possible. */ if (!node_has_low_bound (node, index_type)) { emit_cmp_and_jump_insns (index, convert_modes (mode, imode, expand_normal (node->low), unsignedp), LT, NULL_RTX, mode, unsignedp, default_label); } /* Value belongs to this node or to the right-hand subtree. */ emit_cmp_and_jump_insns (index, convert_modes (mode, imode, expand_normal (node->high), unsignedp), LE, NULL_RTX, mode, unsignedp, label_rtx (node->code_label)); emit_case_nodes (index, node->right, default_label, index_type); } else if (node->right == 0 && node->left != 0) { /* Deal with values to the right of this node, if they are possible. */ if (!node_has_high_bound (node, index_type)) { emit_cmp_and_jump_insns (index, convert_modes (mode, imode, expand_normal (node->high), unsignedp), GT, NULL_RTX, mode, unsignedp, default_label); } /* Value belongs to this node or to the left-hand subtree. */ emit_cmp_and_jump_insns (index, convert_modes (mode, imode, expand_normal (node->low), unsignedp), GE, NULL_RTX, mode, unsignedp, label_rtx (node->code_label)); emit_case_nodes (index, node->left, default_label, index_type); } else { /* Node has no children so we check low and high bounds to remove redundant tests. Only one of the bounds can exist, since otherwise this node is bounded--a case tested already. */ int high_bound = node_has_high_bound (node, index_type); int low_bound = node_has_low_bound (node, index_type); if (!high_bound && low_bound) { emit_cmp_and_jump_insns (index, convert_modes (mode, imode, expand_normal (node->high), unsignedp), GT, NULL_RTX, mode, unsignedp, default_label); } else if (!low_bound && high_bound) { emit_cmp_and_jump_insns (index, convert_modes (mode, imode, expand_normal (node->low), unsignedp), LT, NULL_RTX, mode, unsignedp, default_label); } else if (!low_bound && !high_bound) { /* Widen LOW and HIGH to the same width as INDEX. */ tree type = lang_hooks.types.type_for_mode (mode, unsignedp); tree low = build1 (CONVERT_EXPR, type, node->low); tree high = build1 (CONVERT_EXPR, type, node->high); rtx low_rtx, new_index, new_bound; /* Instead of doing two branches, emit one unsigned branch for (index-low) > (high-low). */ low_rtx = expand_expr (low, NULL_RTX, mode, EXPAND_NORMAL); new_index = expand_simple_binop (mode, MINUS, index, low_rtx, NULL_RTX, unsignedp, OPTAB_WIDEN); new_bound = expand_expr (fold_build2 (MINUS_EXPR, type, high, low), NULL_RTX, mode, EXPAND_NORMAL); emit_cmp_and_jump_insns (new_index, new_bound, GT, NULL_RTX, mode, 1, default_label); } emit_jump (label_rtx (node->code_label)); } } }
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