URL
https://opencores.org/ocsvn/openrisc/openrisc/trunk
Subversion Repositories openrisc
[/] [openrisc/] [trunk/] [gnu-dev/] [or1k-gcc/] [gcc/] [resource.c] - Rev 751
Go to most recent revision | Compare with Previous | Blame | View Log
/* Definitions for computing resource usage of specific insns. Copyright (C) 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010 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/>. */ #include "config.h" #include "system.h" #include "coretypes.h" #include "tm.h" #include "diagnostic-core.h" #include "rtl.h" #include "tm_p.h" #include "hard-reg-set.h" #include "function.h" #include "regs.h" #include "flags.h" #include "output.h" #include "resource.h" #include "except.h" #include "insn-attr.h" #include "params.h" #include "df.h" /* This structure is used to record liveness information at the targets or fallthrough insns of branches. We will most likely need the information at targets again, so save them in a hash table rather than recomputing them each time. */ struct target_info { int uid; /* INSN_UID of target. */ struct target_info *next; /* Next info for same hash bucket. */ HARD_REG_SET live_regs; /* Registers live at target. */ int block; /* Basic block number containing target. */ int bb_tick; /* Generation count of basic block info. */ }; #define TARGET_HASH_PRIME 257 /* Indicates what resources are required at the beginning of the epilogue. */ static struct resources start_of_epilogue_needs; /* Indicates what resources are required at function end. */ static struct resources end_of_function_needs; /* Define the hash table itself. */ static struct target_info **target_hash_table = NULL; /* For each basic block, we maintain a generation number of its basic block info, which is updated each time we move an insn from the target of a jump. This is the generation number indexed by block number. */ static int *bb_ticks; /* Marks registers possibly live at the current place being scanned by mark_target_live_regs. Also used by update_live_status. */ static HARD_REG_SET current_live_regs; /* Marks registers for which we have seen a REG_DEAD note but no assignment. Also only used by the next two functions. */ static HARD_REG_SET pending_dead_regs; static void update_live_status (rtx, const_rtx, void *); static int find_basic_block (rtx, int); static rtx next_insn_no_annul (rtx); static rtx find_dead_or_set_registers (rtx, struct resources*, rtx*, int, struct resources, struct resources); /* Utility function called from mark_target_live_regs via note_stores. It deadens any CLOBBERed registers and livens any SET registers. */ static void update_live_status (rtx dest, const_rtx x, void *data ATTRIBUTE_UNUSED) { int first_regno, last_regno; int i; if (!REG_P (dest) && (GET_CODE (dest) != SUBREG || !REG_P (SUBREG_REG (dest)))) return; if (GET_CODE (dest) == SUBREG) { first_regno = subreg_regno (dest); last_regno = first_regno + subreg_nregs (dest); } else { first_regno = REGNO (dest); last_regno = END_HARD_REGNO (dest); } if (GET_CODE (x) == CLOBBER) for (i = first_regno; i < last_regno; i++) CLEAR_HARD_REG_BIT (current_live_regs, i); else for (i = first_regno; i < last_regno; i++) { SET_HARD_REG_BIT (current_live_regs, i); CLEAR_HARD_REG_BIT (pending_dead_regs, i); } } /* Find the number of the basic block with correct live register information that starts closest to INSN. Return -1 if we couldn't find such a basic block or the beginning is more than SEARCH_LIMIT instructions before INSN. Use SEARCH_LIMIT = -1 for an unlimited search. The delay slot filling code destroys the control-flow graph so, instead of finding the basic block containing INSN, we search backwards toward a BARRIER where the live register information is correct. */ static int find_basic_block (rtx insn, int search_limit) { /* Scan backwards to the previous BARRIER. Then see if we can find a label that starts a basic block. Return the basic block number. */ for (insn = prev_nonnote_insn (insn); insn && !BARRIER_P (insn) && search_limit != 0; insn = prev_nonnote_insn (insn), --search_limit) ; /* The closest BARRIER is too far away. */ if (search_limit == 0) return -1; /* The start of the function. */ else if (insn == 0) return ENTRY_BLOCK_PTR->next_bb->index; /* See if any of the upcoming CODE_LABELs start a basic block. If we reach anything other than a CODE_LABEL or note, we can't find this code. */ for (insn = next_nonnote_insn (insn); insn && LABEL_P (insn); insn = next_nonnote_insn (insn)) if (BLOCK_FOR_INSN (insn)) return BLOCK_FOR_INSN (insn)->index; return -1; } /* Similar to next_insn, but ignores insns in the delay slots of an annulled branch. */ static rtx next_insn_no_annul (rtx insn) { if (insn) { /* If INSN is an annulled branch, skip any insns from the target of the branch. */ if (JUMP_P (insn) && INSN_ANNULLED_BRANCH_P (insn) && NEXT_INSN (PREV_INSN (insn)) != insn) { rtx next = NEXT_INSN (insn); enum rtx_code code = GET_CODE (next); while ((code == INSN || code == JUMP_INSN || code == CALL_INSN) && INSN_FROM_TARGET_P (next)) { insn = next; next = NEXT_INSN (insn); code = GET_CODE (next); } } insn = NEXT_INSN (insn); if (insn && NONJUMP_INSN_P (insn) && GET_CODE (PATTERN (insn)) == SEQUENCE) insn = XVECEXP (PATTERN (insn), 0, 0); } return insn; } /* Given X, some rtl, and RES, a pointer to a `struct resource', mark which resources are referenced by the insn. If INCLUDE_DELAYED_EFFECTS is TRUE, resources used by the called routine will be included for CALL_INSNs. */ void mark_referenced_resources (rtx x, struct resources *res, bool include_delayed_effects) { enum rtx_code code = GET_CODE (x); int i, j; unsigned int r; const char *format_ptr; /* Handle leaf items for which we set resource flags. Also, special-case CALL, SET and CLOBBER operators. */ switch (code) { case CONST: case CONST_INT: case CONST_DOUBLE: case CONST_FIXED: case CONST_VECTOR: case PC: case SYMBOL_REF: case LABEL_REF: return; case SUBREG: if (!REG_P (SUBREG_REG (x))) mark_referenced_resources (SUBREG_REG (x), res, false); else { unsigned int regno = subreg_regno (x); unsigned int last_regno = regno + subreg_nregs (x); gcc_assert (last_regno <= FIRST_PSEUDO_REGISTER); for (r = regno; r < last_regno; r++) SET_HARD_REG_BIT (res->regs, r); } return; case REG: gcc_assert (HARD_REGISTER_P (x)); add_to_hard_reg_set (&res->regs, GET_MODE (x), REGNO (x)); return; case MEM: /* If this memory shouldn't change, it really isn't referencing memory. */ if (MEM_READONLY_P (x)) res->unch_memory = 1; else res->memory = 1; res->volatil |= MEM_VOLATILE_P (x); /* Mark registers used to access memory. */ mark_referenced_resources (XEXP (x, 0), res, false); return; case CC0: res->cc = 1; return; case UNSPEC_VOLATILE: case TRAP_IF: case ASM_INPUT: /* Traditional asm's are always volatile. */ res->volatil = 1; break; case ASM_OPERANDS: res->volatil |= MEM_VOLATILE_P (x); /* For all ASM_OPERANDS, we must traverse the vector of input operands. We can not just fall through here since then we would be confused by the ASM_INPUT rtx inside ASM_OPERANDS, which do not indicate traditional asms unlike their normal usage. */ for (i = 0; i < ASM_OPERANDS_INPUT_LENGTH (x); i++) mark_referenced_resources (ASM_OPERANDS_INPUT (x, i), res, false); return; case CALL: /* The first operand will be a (MEM (xxx)) but doesn't really reference memory. The second operand may be referenced, though. */ mark_referenced_resources (XEXP (XEXP (x, 0), 0), res, false); mark_referenced_resources (XEXP (x, 1), res, false); return; case SET: /* Usually, the first operand of SET is set, not referenced. But registers used to access memory are referenced. SET_DEST is also referenced if it is a ZERO_EXTRACT. */ mark_referenced_resources (SET_SRC (x), res, false); x = SET_DEST (x); if (GET_CODE (x) == ZERO_EXTRACT || GET_CODE (x) == STRICT_LOW_PART) mark_referenced_resources (x, res, false); else if (GET_CODE (x) == SUBREG) x = SUBREG_REG (x); if (MEM_P (x)) mark_referenced_resources (XEXP (x, 0), res, false); return; case CLOBBER: return; case CALL_INSN: if (include_delayed_effects) { /* A CALL references memory, the frame pointer if it exists, the stack pointer, any global registers and any registers given in USE insns immediately in front of the CALL. However, we may have moved some of the parameter loading insns into the delay slot of this CALL. If so, the USE's for them don't count and should be skipped. */ rtx insn = PREV_INSN (x); rtx sequence = 0; int seq_size = 0; int i; /* If we are part of a delay slot sequence, point at the SEQUENCE. */ if (NEXT_INSN (insn) != x) { sequence = PATTERN (NEXT_INSN (insn)); seq_size = XVECLEN (sequence, 0); gcc_assert (GET_CODE (sequence) == SEQUENCE); } res->memory = 1; SET_HARD_REG_BIT (res->regs, STACK_POINTER_REGNUM); if (frame_pointer_needed) { SET_HARD_REG_BIT (res->regs, FRAME_POINTER_REGNUM); #if !HARD_FRAME_POINTER_IS_FRAME_POINTER SET_HARD_REG_BIT (res->regs, HARD_FRAME_POINTER_REGNUM); #endif } for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) if (global_regs[i]) SET_HARD_REG_BIT (res->regs, i); /* Check for a REG_SETJMP. If it exists, then we must assume that this call can need any register. This is done to be more conservative about how we handle setjmp. We assume that they both use and set all registers. Using all registers ensures that a register will not be considered dead just because it crosses a setjmp call. A register should be considered dead only if the setjmp call returns nonzero. */ if (find_reg_note (x, REG_SETJMP, NULL)) SET_HARD_REG_SET (res->regs); { rtx link; for (link = CALL_INSN_FUNCTION_USAGE (x); link; link = XEXP (link, 1)) if (GET_CODE (XEXP (link, 0)) == USE) { for (i = 1; i < seq_size; i++) { rtx slot_pat = PATTERN (XVECEXP (sequence, 0, i)); if (GET_CODE (slot_pat) == SET && rtx_equal_p (SET_DEST (slot_pat), XEXP (XEXP (link, 0), 0))) break; } if (i >= seq_size) mark_referenced_resources (XEXP (XEXP (link, 0), 0), res, false); } } } /* ... fall through to other INSN processing ... */ case INSN: case JUMP_INSN: #ifdef INSN_REFERENCES_ARE_DELAYED if (! include_delayed_effects && INSN_REFERENCES_ARE_DELAYED (x)) return; #endif /* No special processing, just speed up. */ mark_referenced_resources (PATTERN (x), res, include_delayed_effects); return; default: break; } /* Process each sub-expression and flag what it needs. */ format_ptr = GET_RTX_FORMAT (code); for (i = 0; i < GET_RTX_LENGTH (code); i++) switch (*format_ptr++) { case 'e': mark_referenced_resources (XEXP (x, i), res, include_delayed_effects); break; case 'E': for (j = 0; j < XVECLEN (x, i); j++) mark_referenced_resources (XVECEXP (x, i, j), res, include_delayed_effects); break; } } /* A subroutine of mark_target_live_regs. Search forward from TARGET looking for registers that are set before they are used. These are dead. Stop after passing a few conditional jumps, and/or a small number of unconditional branches. */ static rtx find_dead_or_set_registers (rtx target, struct resources *res, rtx *jump_target, int jump_count, struct resources set, struct resources needed) { HARD_REG_SET scratch; rtx insn, next; rtx jump_insn = 0; int i; for (insn = target; insn; insn = next) { rtx this_jump_insn = insn; next = NEXT_INSN (insn); /* If this instruction can throw an exception, then we don't know where we might end up next. That means that we have to assume that whatever we have already marked as live really is live. */ if (can_throw_internal (insn)) break; switch (GET_CODE (insn)) { case CODE_LABEL: /* After a label, any pending dead registers that weren't yet used can be made dead. */ AND_COMPL_HARD_REG_SET (pending_dead_regs, needed.regs); AND_COMPL_HARD_REG_SET (res->regs, pending_dead_regs); CLEAR_HARD_REG_SET (pending_dead_regs); continue; case BARRIER: case NOTE: continue; case INSN: if (GET_CODE (PATTERN (insn)) == USE) { /* If INSN is a USE made by update_block, we care about the underlying insn. Any registers set by the underlying insn are live since the insn is being done somewhere else. */ if (INSN_P (XEXP (PATTERN (insn), 0))) mark_set_resources (XEXP (PATTERN (insn), 0), res, 0, MARK_SRC_DEST_CALL); /* All other USE insns are to be ignored. */ continue; } else if (GET_CODE (PATTERN (insn)) == CLOBBER) continue; else if (GET_CODE (PATTERN (insn)) == SEQUENCE) { /* An unconditional jump can be used to fill the delay slot of a call, so search for a JUMP_INSN in any position. */ for (i = 0; i < XVECLEN (PATTERN (insn), 0); i++) { this_jump_insn = XVECEXP (PATTERN (insn), 0, i); if (JUMP_P (this_jump_insn)) break; } } default: break; } if (JUMP_P (this_jump_insn)) { if (jump_count++ < 10) { if (any_uncondjump_p (this_jump_insn) || ANY_RETURN_P (PATTERN (this_jump_insn))) { next = JUMP_LABEL (this_jump_insn); if (ANY_RETURN_P (next)) next = NULL_RTX; if (jump_insn == 0) { jump_insn = insn; if (jump_target) *jump_target = JUMP_LABEL (this_jump_insn); } } else if (any_condjump_p (this_jump_insn)) { struct resources target_set, target_res; struct resources fallthrough_res; /* We can handle conditional branches here by following both paths, and then IOR the results of the two paths together, which will give us registers that are dead on both paths. Since this is expensive, we give it a much higher cost than unconditional branches. The cost was chosen so that we will follow at most 1 conditional branch. */ jump_count += 4; if (jump_count >= 10) break; mark_referenced_resources (insn, &needed, true); /* For an annulled branch, mark_set_resources ignores slots filled by instructions from the target. This is correct if the branch is not taken. Since we are following both paths from the branch, we must also compute correct info if the branch is taken. We do this by inverting all of the INSN_FROM_TARGET_P bits, calling mark_set_resources, and then inverting the INSN_FROM_TARGET_P bits again. */ if (GET_CODE (PATTERN (insn)) == SEQUENCE && INSN_ANNULLED_BRANCH_P (this_jump_insn)) { for (i = 1; i < XVECLEN (PATTERN (insn), 0); i++) INSN_FROM_TARGET_P (XVECEXP (PATTERN (insn), 0, i)) = ! INSN_FROM_TARGET_P (XVECEXP (PATTERN (insn), 0, i)); target_set = set; mark_set_resources (insn, &target_set, 0, MARK_SRC_DEST_CALL); for (i = 1; i < XVECLEN (PATTERN (insn), 0); i++) INSN_FROM_TARGET_P (XVECEXP (PATTERN (insn), 0, i)) = ! INSN_FROM_TARGET_P (XVECEXP (PATTERN (insn), 0, i)); mark_set_resources (insn, &set, 0, MARK_SRC_DEST_CALL); } else { mark_set_resources (insn, &set, 0, MARK_SRC_DEST_CALL); target_set = set; } target_res = *res; COPY_HARD_REG_SET (scratch, target_set.regs); AND_COMPL_HARD_REG_SET (scratch, needed.regs); AND_COMPL_HARD_REG_SET (target_res.regs, scratch); fallthrough_res = *res; COPY_HARD_REG_SET (scratch, set.regs); AND_COMPL_HARD_REG_SET (scratch, needed.regs); AND_COMPL_HARD_REG_SET (fallthrough_res.regs, scratch); if (!ANY_RETURN_P (JUMP_LABEL (this_jump_insn))) find_dead_or_set_registers (JUMP_LABEL (this_jump_insn), &target_res, 0, jump_count, target_set, needed); find_dead_or_set_registers (next, &fallthrough_res, 0, jump_count, set, needed); IOR_HARD_REG_SET (fallthrough_res.regs, target_res.regs); AND_HARD_REG_SET (res->regs, fallthrough_res.regs); break; } else break; } else { /* Don't try this optimization if we expired our jump count above, since that would mean there may be an infinite loop in the function being compiled. */ jump_insn = 0; break; } } mark_referenced_resources (insn, &needed, true); mark_set_resources (insn, &set, 0, MARK_SRC_DEST_CALL); COPY_HARD_REG_SET (scratch, set.regs); AND_COMPL_HARD_REG_SET (scratch, needed.regs); AND_COMPL_HARD_REG_SET (res->regs, scratch); } return jump_insn; } /* Given X, a part of an insn, and a pointer to a `struct resource', RES, indicate which resources are modified by the insn. If MARK_TYPE is MARK_SRC_DEST_CALL, also mark resources potentially set by the called routine. If IN_DEST is nonzero, it means we are inside a SET. Otherwise, objects are being referenced instead of set. We never mark the insn as modifying the condition code unless it explicitly SETs CC0 even though this is not totally correct. The reason for this is that we require a SET of CC0 to immediately precede the reference to CC0. So if some other insn sets CC0 as a side-effect, we know it cannot affect our computation and thus may be placed in a delay slot. */ void mark_set_resources (rtx x, struct resources *res, int in_dest, enum mark_resource_type mark_type) { enum rtx_code code; int i, j; unsigned int r; const char *format_ptr; restart: code = GET_CODE (x); switch (code) { case NOTE: case BARRIER: case CODE_LABEL: case USE: case CONST_INT: case CONST_DOUBLE: case CONST_FIXED: case CONST_VECTOR: case LABEL_REF: case SYMBOL_REF: case CONST: case PC: /* These don't set any resources. */ return; case CC0: if (in_dest) res->cc = 1; return; case CALL_INSN: /* Called routine modifies the condition code, memory, any registers that aren't saved across calls, global registers and anything explicitly CLOBBERed immediately after the CALL_INSN. */ if (mark_type == MARK_SRC_DEST_CALL) { rtx link; res->cc = res->memory = 1; IOR_HARD_REG_SET (res->regs, regs_invalidated_by_call); for (link = CALL_INSN_FUNCTION_USAGE (x); link; link = XEXP (link, 1)) if (GET_CODE (XEXP (link, 0)) == CLOBBER) mark_set_resources (SET_DEST (XEXP (link, 0)), res, 1, MARK_SRC_DEST); /* Check for a REG_SETJMP. If it exists, then we must assume that this call can clobber any register. */ if (find_reg_note (x, REG_SETJMP, NULL)) SET_HARD_REG_SET (res->regs); } /* ... and also what its RTL says it modifies, if anything. */ case JUMP_INSN: case INSN: /* An insn consisting of just a CLOBBER (or USE) is just for flow and doesn't actually do anything, so we ignore it. */ #ifdef INSN_SETS_ARE_DELAYED if (mark_type != MARK_SRC_DEST_CALL && INSN_SETS_ARE_DELAYED (x)) return; #endif x = PATTERN (x); if (GET_CODE (x) != USE && GET_CODE (x) != CLOBBER) goto restart; return; case SET: /* If the source of a SET is a CALL, this is actually done by the called routine. So only include it if we are to include the effects of the calling routine. */ mark_set_resources (SET_DEST (x), res, (mark_type == MARK_SRC_DEST_CALL || GET_CODE (SET_SRC (x)) != CALL), mark_type); mark_set_resources (SET_SRC (x), res, 0, MARK_SRC_DEST); return; case CLOBBER: mark_set_resources (XEXP (x, 0), res, 1, MARK_SRC_DEST); return; case SEQUENCE: { rtx control = XVECEXP (x, 0, 0); bool annul_p = JUMP_P (control) && INSN_ANNULLED_BRANCH_P (control); mark_set_resources (control, res, 0, mark_type); for (i = XVECLEN (x, 0) - 1; i >= 0; --i) { rtx elt = XVECEXP (x, 0, i); if (!annul_p && INSN_FROM_TARGET_P (elt)) mark_set_resources (elt, res, 0, mark_type); } } return; case POST_INC: case PRE_INC: case POST_DEC: case PRE_DEC: mark_set_resources (XEXP (x, 0), res, 1, MARK_SRC_DEST); return; case PRE_MODIFY: case POST_MODIFY: mark_set_resources (XEXP (x, 0), res, 1, MARK_SRC_DEST); mark_set_resources (XEXP (XEXP (x, 1), 0), res, 0, MARK_SRC_DEST); mark_set_resources (XEXP (XEXP (x, 1), 1), res, 0, MARK_SRC_DEST); return; case SIGN_EXTRACT: case ZERO_EXTRACT: mark_set_resources (XEXP (x, 0), res, in_dest, MARK_SRC_DEST); mark_set_resources (XEXP (x, 1), res, 0, MARK_SRC_DEST); mark_set_resources (XEXP (x, 2), res, 0, MARK_SRC_DEST); return; case MEM: if (in_dest) { res->memory = 1; res->unch_memory |= MEM_READONLY_P (x); res->volatil |= MEM_VOLATILE_P (x); } mark_set_resources (XEXP (x, 0), res, 0, MARK_SRC_DEST); return; case SUBREG: if (in_dest) { if (!REG_P (SUBREG_REG (x))) mark_set_resources (SUBREG_REG (x), res, in_dest, mark_type); else { unsigned int regno = subreg_regno (x); unsigned int last_regno = regno + subreg_nregs (x); gcc_assert (last_regno <= FIRST_PSEUDO_REGISTER); for (r = regno; r < last_regno; r++) SET_HARD_REG_BIT (res->regs, r); } } return; case REG: if (in_dest) { gcc_assert (HARD_REGISTER_P (x)); add_to_hard_reg_set (&res->regs, GET_MODE (x), REGNO (x)); } return; case UNSPEC_VOLATILE: case ASM_INPUT: /* Traditional asm's are always volatile. */ res->volatil = 1; return; case TRAP_IF: res->volatil = 1; break; case ASM_OPERANDS: res->volatil |= MEM_VOLATILE_P (x); /* For all ASM_OPERANDS, we must traverse the vector of input operands. We can not just fall through here since then we would be confused by the ASM_INPUT rtx inside ASM_OPERANDS, which do not indicate traditional asms unlike their normal usage. */ for (i = 0; i < ASM_OPERANDS_INPUT_LENGTH (x); i++) mark_set_resources (ASM_OPERANDS_INPUT (x, i), res, in_dest, MARK_SRC_DEST); return; default: break; } /* Process each sub-expression and flag what it needs. */ format_ptr = GET_RTX_FORMAT (code); for (i = 0; i < GET_RTX_LENGTH (code); i++) switch (*format_ptr++) { case 'e': mark_set_resources (XEXP (x, i), res, in_dest, mark_type); break; case 'E': for (j = 0; j < XVECLEN (x, i); j++) mark_set_resources (XVECEXP (x, i, j), res, in_dest, mark_type); break; } } /* Return TRUE if INSN is a return, possibly with a filled delay slot. */ static bool return_insn_p (const_rtx insn) { if (JUMP_P (insn) && ANY_RETURN_P (PATTERN (insn))) return true; if (NONJUMP_INSN_P (insn) && GET_CODE (PATTERN (insn)) == SEQUENCE) return return_insn_p (XVECEXP (PATTERN (insn), 0, 0)); return false; } /* Set the resources that are live at TARGET. If TARGET is zero, we refer to the end of the current function and can return our precomputed value. Otherwise, we try to find out what is live by consulting the basic block information. This is tricky, because we must consider the actions of reload and jump optimization, which occur after the basic block information has been computed. Accordingly, we proceed as follows:: We find the previous BARRIER and look at all immediately following labels (with no intervening active insns) to see if any of them start a basic block. If we hit the start of the function first, we use block 0. Once we have found a basic block and a corresponding first insn, we can accurately compute the live status (by starting at a label following a BARRIER, we are immune to actions taken by reload and jump.) Then we scan all insns between that point and our target. For each CLOBBER (or for call-clobbered regs when we pass a CALL_INSN), mark the appropriate registers are dead. For a SET, mark them as live. We have to be careful when using REG_DEAD notes because they are not updated by such things as find_equiv_reg. So keep track of registers marked as dead that haven't been assigned to, and mark them dead at the next CODE_LABEL since reload and jump won't propagate values across labels. If we cannot find the start of a basic block (should be a very rare case, if it can happen at all), mark everything as potentially live. Next, scan forward from TARGET looking for things set or clobbered before they are used. These are not live. Because we can be called many times on the same target, save our results in a hash table indexed by INSN_UID. This is only done if the function init_resource_info () was invoked before we are called. */ void mark_target_live_regs (rtx insns, rtx target, struct resources *res) { int b = -1; unsigned int i; struct target_info *tinfo = NULL; rtx insn; rtx jump_insn = 0; rtx jump_target; HARD_REG_SET scratch; struct resources set, needed; /* Handle end of function. */ if (target == 0 || ANY_RETURN_P (target)) { *res = end_of_function_needs; return; } /* Handle return insn. */ else if (return_insn_p (target)) { *res = end_of_function_needs; mark_referenced_resources (target, res, false); return; } /* We have to assume memory is needed, but the CC isn't. */ res->memory = 1; res->volatil = res->unch_memory = 0; res->cc = 0; /* See if we have computed this value already. */ if (target_hash_table != NULL) { for (tinfo = target_hash_table[INSN_UID (target) % TARGET_HASH_PRIME]; tinfo; tinfo = tinfo->next) if (tinfo->uid == INSN_UID (target)) break; /* Start by getting the basic block number. If we have saved information, we can get it from there unless the insn at the start of the basic block has been deleted. */ if (tinfo && tinfo->block != -1 && ! INSN_DELETED_P (BB_HEAD (BASIC_BLOCK (tinfo->block)))) b = tinfo->block; } if (b == -1) b = find_basic_block (target, MAX_DELAY_SLOT_LIVE_SEARCH); if (target_hash_table != NULL) { if (tinfo) { /* If the information is up-to-date, use it. Otherwise, we will update it below. */ if (b == tinfo->block && b != -1 && tinfo->bb_tick == bb_ticks[b]) { COPY_HARD_REG_SET (res->regs, tinfo->live_regs); return; } } else { /* Allocate a place to put our results and chain it into the hash table. */ tinfo = XNEW (struct target_info); tinfo->uid = INSN_UID (target); tinfo->block = b; tinfo->next = target_hash_table[INSN_UID (target) % TARGET_HASH_PRIME]; target_hash_table[INSN_UID (target) % TARGET_HASH_PRIME] = tinfo; } } CLEAR_HARD_REG_SET (pending_dead_regs); /* If we found a basic block, get the live registers from it and update them with anything set or killed between its start and the insn before TARGET; this custom life analysis is really about registers so we need to use the LR problem. Otherwise, we must assume everything is live. */ if (b != -1) { regset regs_live = DF_LR_IN (BASIC_BLOCK (b)); rtx start_insn, stop_insn; /* Compute hard regs live at start of block. */ REG_SET_TO_HARD_REG_SET (current_live_regs, regs_live); /* Get starting and ending insn, handling the case where each might be a SEQUENCE. */ start_insn = (b == ENTRY_BLOCK_PTR->next_bb->index ? insns : BB_HEAD (BASIC_BLOCK (b))); stop_insn = target; if (NONJUMP_INSN_P (start_insn) && GET_CODE (PATTERN (start_insn)) == SEQUENCE) start_insn = XVECEXP (PATTERN (start_insn), 0, 0); if (NONJUMP_INSN_P (stop_insn) && GET_CODE (PATTERN (stop_insn)) == SEQUENCE) stop_insn = next_insn (PREV_INSN (stop_insn)); for (insn = start_insn; insn != stop_insn; insn = next_insn_no_annul (insn)) { rtx link; rtx real_insn = insn; enum rtx_code code = GET_CODE (insn); if (DEBUG_INSN_P (insn)) continue; /* If this insn is from the target of a branch, it isn't going to be used in the sequel. If it is used in both cases, this test will not be true. */ if ((code == INSN || code == JUMP_INSN || code == CALL_INSN) && INSN_FROM_TARGET_P (insn)) continue; /* If this insn is a USE made by update_block, we care about the underlying insn. */ if (code == INSN && GET_CODE (PATTERN (insn)) == USE && INSN_P (XEXP (PATTERN (insn), 0))) real_insn = XEXP (PATTERN (insn), 0); if (CALL_P (real_insn)) { /* CALL clobbers all call-used regs that aren't fixed except sp, ap, and fp. Do this before setting the result of the call live. */ AND_COMPL_HARD_REG_SET (current_live_regs, regs_invalidated_by_call); /* A CALL_INSN sets any global register live, since it may have been modified by the call. */ for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) if (global_regs[i]) SET_HARD_REG_BIT (current_live_regs, i); } /* Mark anything killed in an insn to be deadened at the next label. Ignore USE insns; the only REG_DEAD notes will be for parameters. But they might be early. A CALL_INSN will usually clobber registers used for parameters. It isn't worth bothering with the unlikely case when it won't. */ if ((NONJUMP_INSN_P (real_insn) && GET_CODE (PATTERN (real_insn)) != USE && GET_CODE (PATTERN (real_insn)) != CLOBBER) || JUMP_P (real_insn) || CALL_P (real_insn)) { for (link = REG_NOTES (real_insn); link; link = XEXP (link, 1)) if (REG_NOTE_KIND (link) == REG_DEAD && REG_P (XEXP (link, 0)) && REGNO (XEXP (link, 0)) < FIRST_PSEUDO_REGISTER) add_to_hard_reg_set (&pending_dead_regs, GET_MODE (XEXP (link, 0)), REGNO (XEXP (link, 0))); note_stores (PATTERN (real_insn), update_live_status, NULL); /* If any registers were unused after this insn, kill them. These notes will always be accurate. */ for (link = REG_NOTES (real_insn); link; link = XEXP (link, 1)) if (REG_NOTE_KIND (link) == REG_UNUSED && REG_P (XEXP (link, 0)) && REGNO (XEXP (link, 0)) < FIRST_PSEUDO_REGISTER) remove_from_hard_reg_set (¤t_live_regs, GET_MODE (XEXP (link, 0)), REGNO (XEXP (link, 0))); } else if (LABEL_P (real_insn)) { basic_block bb; /* A label clobbers the pending dead registers since neither reload nor jump will propagate a value across a label. */ AND_COMPL_HARD_REG_SET (current_live_regs, pending_dead_regs); CLEAR_HARD_REG_SET (pending_dead_regs); /* We must conservatively assume that all registers that used to be live here still are. The fallthrough edge may have left a live register uninitialized. */ bb = BLOCK_FOR_INSN (real_insn); if (bb) { HARD_REG_SET extra_live; REG_SET_TO_HARD_REG_SET (extra_live, DF_LR_IN (bb)); IOR_HARD_REG_SET (current_live_regs, extra_live); } } /* The beginning of the epilogue corresponds to the end of the RTL chain when there are no epilogue insns. Certain resources are implicitly required at that point. */ else if (NOTE_P (real_insn) && NOTE_KIND (real_insn) == NOTE_INSN_EPILOGUE_BEG) IOR_HARD_REG_SET (current_live_regs, start_of_epilogue_needs.regs); } COPY_HARD_REG_SET (res->regs, current_live_regs); if (tinfo != NULL) { tinfo->block = b; tinfo->bb_tick = bb_ticks[b]; } } else /* We didn't find the start of a basic block. Assume everything in use. This should happen only extremely rarely. */ SET_HARD_REG_SET (res->regs); CLEAR_RESOURCE (&set); CLEAR_RESOURCE (&needed); jump_insn = find_dead_or_set_registers (target, res, &jump_target, 0, set, needed); /* If we hit an unconditional branch, we have another way of finding out what is live: we can see what is live at the branch target and include anything used but not set before the branch. We add the live resources found using the test below to those found until now. */ if (jump_insn) { struct resources new_resources; rtx stop_insn = next_active_insn (jump_insn); if (!ANY_RETURN_P (jump_target)) jump_target = next_active_insn (jump_target); mark_target_live_regs (insns, jump_target, &new_resources); CLEAR_RESOURCE (&set); CLEAR_RESOURCE (&needed); /* Include JUMP_INSN in the needed registers. */ for (insn = target; insn != stop_insn; insn = next_active_insn (insn)) { mark_referenced_resources (insn, &needed, true); COPY_HARD_REG_SET (scratch, needed.regs); AND_COMPL_HARD_REG_SET (scratch, set.regs); IOR_HARD_REG_SET (new_resources.regs, scratch); mark_set_resources (insn, &set, 0, MARK_SRC_DEST_CALL); } IOR_HARD_REG_SET (res->regs, new_resources.regs); } if (tinfo != NULL) { COPY_HARD_REG_SET (tinfo->live_regs, res->regs); } } /* Initialize the resources required by mark_target_live_regs (). This should be invoked before the first call to mark_target_live_regs. */ void init_resource_info (rtx epilogue_insn) { int i; basic_block bb; /* Indicate what resources are required to be valid at the end of the current function. The condition code never is and memory always is. The stack pointer is needed unless EXIT_IGNORE_STACK is true and there is an epilogue that restores the original stack pointer from the frame pointer. Registers used to return the function value are needed. Registers holding global variables are needed. */ end_of_function_needs.cc = 0; end_of_function_needs.memory = 1; end_of_function_needs.unch_memory = 0; CLEAR_HARD_REG_SET (end_of_function_needs.regs); if (frame_pointer_needed) { SET_HARD_REG_BIT (end_of_function_needs.regs, FRAME_POINTER_REGNUM); #if !HARD_FRAME_POINTER_IS_FRAME_POINTER SET_HARD_REG_BIT (end_of_function_needs.regs, HARD_FRAME_POINTER_REGNUM); #endif } if (!(frame_pointer_needed && EXIT_IGNORE_STACK && epilogue_insn && !current_function_sp_is_unchanging)) SET_HARD_REG_BIT (end_of_function_needs.regs, STACK_POINTER_REGNUM); if (crtl->return_rtx != 0) mark_referenced_resources (crtl->return_rtx, &end_of_function_needs, true); for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) if (global_regs[i] #ifdef EPILOGUE_USES || EPILOGUE_USES (i) #endif ) SET_HARD_REG_BIT (end_of_function_needs.regs, i); /* The registers required to be live at the end of the function are represented in the flow information as being dead just prior to reaching the end of the function. For example, the return of a value might be represented by a USE of the return register immediately followed by an unconditional jump to the return label where the return label is the end of the RTL chain. The end of the RTL chain is then taken to mean that the return register is live. This sequence is no longer maintained when epilogue instructions are added to the RTL chain. To reconstruct the original meaning, the start of the epilogue (NOTE_INSN_EPILOGUE_BEG) is regarded as the point where these registers become live (start_of_epilogue_needs). If epilogue instructions are present, the registers set by those instructions won't have been processed by flow. Thus, those registers are additionally required at the end of the RTL chain (end_of_function_needs). */ start_of_epilogue_needs = end_of_function_needs; while ((epilogue_insn = next_nonnote_insn (epilogue_insn))) { mark_set_resources (epilogue_insn, &end_of_function_needs, 0, MARK_SRC_DEST_CALL); if (return_insn_p (epilogue_insn)) break; } /* Allocate and initialize the tables used by mark_target_live_regs. */ target_hash_table = XCNEWVEC (struct target_info *, TARGET_HASH_PRIME); bb_ticks = XCNEWVEC (int, last_basic_block); /* Set the BLOCK_FOR_INSN of each label that starts a basic block. */ FOR_EACH_BB (bb) if (LABEL_P (BB_HEAD (bb))) BLOCK_FOR_INSN (BB_HEAD (bb)) = bb; } /* Free up the resources allocated to mark_target_live_regs (). This should be invoked after the last call to mark_target_live_regs (). */ void free_resource_info (void) { basic_block bb; if (target_hash_table != NULL) { int i; for (i = 0; i < TARGET_HASH_PRIME; ++i) { struct target_info *ti = target_hash_table[i]; while (ti) { struct target_info *next = ti->next; free (ti); ti = next; } } free (target_hash_table); target_hash_table = NULL; } if (bb_ticks != NULL) { free (bb_ticks); bb_ticks = NULL; } FOR_EACH_BB (bb) if (LABEL_P (BB_HEAD (bb))) BLOCK_FOR_INSN (BB_HEAD (bb)) = NULL; } /* Clear any hashed information that we have stored for INSN. */ void clear_hashed_info_for_insn (rtx insn) { struct target_info *tinfo; if (target_hash_table != NULL) { for (tinfo = target_hash_table[INSN_UID (insn) % TARGET_HASH_PRIME]; tinfo; tinfo = tinfo->next) if (tinfo->uid == INSN_UID (insn)) break; if (tinfo) tinfo->block = -1; } } /* Increment the tick count for the basic block that contains INSN. */ void incr_ticks_for_insn (rtx insn) { int b = find_basic_block (insn, MAX_DELAY_SLOT_LIVE_SEARCH); if (b != -1) bb_ticks[b]++; } /* Add TRIAL to the set of resources used at the end of the current function. */ void mark_end_of_function_resources (rtx trial, bool include_delayed_effects) { mark_referenced_resources (trial, &end_of_function_needs, include_delayed_effects); }
Go to most recent revision | Compare with Previous | Blame | View Log