/* Thread edges through blocks and update the control flow and SSA graphs.
|
/* Thread edges through blocks and update the control flow and SSA graphs.
|
Copyright (C) 2004, 2005, 2006, 2007 Free Software Foundation, Inc.
|
Copyright (C) 2004, 2005, 2006, 2007 Free Software Foundation, Inc.
|
|
|
This file is part of GCC.
|
This file is part of GCC.
|
|
|
GCC is free software; you can redistribute it and/or modify
|
GCC is free software; you can redistribute it and/or modify
|
it under the terms of the GNU General Public License as published by
|
it under the terms of the GNU General Public License as published by
|
the Free Software Foundation; either version 3, or (at your option)
|
the Free Software Foundation; either version 3, or (at your option)
|
any later version.
|
any later version.
|
|
|
GCC is distributed in the hope that it will be useful,
|
GCC is distributed in the hope that it will be useful,
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
GNU General Public License for more details.
|
GNU General Public License for more details.
|
|
|
You should have received a copy of the GNU General Public License
|
You should have received a copy of the GNU General Public License
|
along with GCC; see the file COPYING3. If not see
|
along with GCC; see the file COPYING3. If not see
|
<http://www.gnu.org/licenses/>. */
|
<http://www.gnu.org/licenses/>. */
|
|
|
#include "config.h"
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#include "config.h"
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#include "system.h"
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#include "system.h"
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#include "coretypes.h"
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#include "coretypes.h"
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#include "tm.h"
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#include "tm.h"
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#include "tree.h"
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#include "tree.h"
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#include "flags.h"
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#include "flags.h"
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#include "rtl.h"
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#include "rtl.h"
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#include "tm_p.h"
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#include "tm_p.h"
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#include "ggc.h"
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#include "ggc.h"
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#include "basic-block.h"
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#include "basic-block.h"
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#include "output.h"
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#include "output.h"
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#include "expr.h"
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#include "expr.h"
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#include "function.h"
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#include "function.h"
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#include "diagnostic.h"
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#include "diagnostic.h"
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#include "tree-flow.h"
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#include "tree-flow.h"
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#include "tree-dump.h"
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#include "tree-dump.h"
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#include "tree-pass.h"
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#include "tree-pass.h"
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#include "cfgloop.h"
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#include "cfgloop.h"
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|
|
/* Given a block B, update the CFG and SSA graph to reflect redirecting
|
/* Given a block B, update the CFG and SSA graph to reflect redirecting
|
one or more in-edges to B to instead reach the destination of an
|
one or more in-edges to B to instead reach the destination of an
|
out-edge from B while preserving any side effects in B.
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out-edge from B while preserving any side effects in B.
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|
|
i.e., given A->B and B->C, change A->B to be A->C yet still preserve the
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i.e., given A->B and B->C, change A->B to be A->C yet still preserve the
|
side effects of executing B.
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side effects of executing B.
|
|
|
1. Make a copy of B (including its outgoing edges and statements). Call
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1. Make a copy of B (including its outgoing edges and statements). Call
|
the copy B'. Note B' has no incoming edges or PHIs at this time.
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the copy B'. Note B' has no incoming edges or PHIs at this time.
|
|
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2. Remove the control statement at the end of B' and all outgoing edges
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2. Remove the control statement at the end of B' and all outgoing edges
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except B'->C.
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except B'->C.
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|
|
3. Add a new argument to each PHI in C with the same value as the existing
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3. Add a new argument to each PHI in C with the same value as the existing
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argument associated with edge B->C. Associate the new PHI arguments
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argument associated with edge B->C. Associate the new PHI arguments
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with the edge B'->C.
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with the edge B'->C.
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|
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4. For each PHI in B, find or create a PHI in B' with an identical
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4. For each PHI in B, find or create a PHI in B' with an identical
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PHI_RESULT. Add an argument to the PHI in B' which has the same
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PHI_RESULT. Add an argument to the PHI in B' which has the same
|
value as the PHI in B associated with the edge A->B. Associate
|
value as the PHI in B associated with the edge A->B. Associate
|
the new argument in the PHI in B' with the edge A->B.
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the new argument in the PHI in B' with the edge A->B.
|
|
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5. Change the edge A->B to A->B'.
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5. Change the edge A->B to A->B'.
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|
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5a. This automatically deletes any PHI arguments associated with the
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5a. This automatically deletes any PHI arguments associated with the
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edge A->B in B.
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edge A->B in B.
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|
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5b. This automatically associates each new argument added in step 4
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5b. This automatically associates each new argument added in step 4
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with the edge A->B'.
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with the edge A->B'.
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|
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6. Repeat for other incoming edges into B.
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6. Repeat for other incoming edges into B.
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|
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7. Put the duplicated resources in B and all the B' blocks into SSA form.
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7. Put the duplicated resources in B and all the B' blocks into SSA form.
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|
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Note that block duplication can be minimized by first collecting the
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Note that block duplication can be minimized by first collecting the
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the set of unique destination blocks that the incoming edges should
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the set of unique destination blocks that the incoming edges should
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be threaded to. Block duplication can be further minimized by using
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be threaded to. Block duplication can be further minimized by using
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B instead of creating B' for one destination if all edges into B are
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B instead of creating B' for one destination if all edges into B are
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going to be threaded to a successor of B.
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going to be threaded to a successor of B.
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|
|
We further reduce the number of edges and statements we create by
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We further reduce the number of edges and statements we create by
|
not copying all the outgoing edges and the control statement in
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not copying all the outgoing edges and the control statement in
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step #1. We instead create a template block without the outgoing
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step #1. We instead create a template block without the outgoing
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edges and duplicate the template. */
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edges and duplicate the template. */
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|
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|
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/* Steps #5 and #6 of the above algorithm are best implemented by walking
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/* Steps #5 and #6 of the above algorithm are best implemented by walking
|
all the incoming edges which thread to the same destination edge at
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all the incoming edges which thread to the same destination edge at
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the same time. That avoids lots of table lookups to get information
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the same time. That avoids lots of table lookups to get information
|
for the destination edge.
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for the destination edge.
|
|
|
To realize that implementation we create a list of incoming edges
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To realize that implementation we create a list of incoming edges
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which thread to the same outgoing edge. Thus to implement steps
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which thread to the same outgoing edge. Thus to implement steps
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#5 and #6 we traverse our hash table of outgoing edge information.
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#5 and #6 we traverse our hash table of outgoing edge information.
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For each entry we walk the list of incoming edges which thread to
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For each entry we walk the list of incoming edges which thread to
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the current outgoing edge. */
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the current outgoing edge. */
|
|
|
struct el
|
struct el
|
{
|
{
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edge e;
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edge e;
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struct el *next;
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struct el *next;
|
};
|
};
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|
|
/* Main data structure recording information regarding B's duplicate
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/* Main data structure recording information regarding B's duplicate
|
blocks. */
|
blocks. */
|
|
|
/* We need to efficiently record the unique thread destinations of this
|
/* We need to efficiently record the unique thread destinations of this
|
block and specific information associated with those destinations. We
|
block and specific information associated with those destinations. We
|
may have many incoming edges threaded to the same outgoing edge. This
|
may have many incoming edges threaded to the same outgoing edge. This
|
can be naturally implemented with a hash table. */
|
can be naturally implemented with a hash table. */
|
|
|
struct redirection_data
|
struct redirection_data
|
{
|
{
|
/* A duplicate of B with the trailing control statement removed and which
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/* A duplicate of B with the trailing control statement removed and which
|
targets a single successor of B. */
|
targets a single successor of B. */
|
basic_block dup_block;
|
basic_block dup_block;
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|
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/* An outgoing edge from B. DUP_BLOCK will have OUTGOING_EDGE->dest as
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/* An outgoing edge from B. DUP_BLOCK will have OUTGOING_EDGE->dest as
|
its single successor. */
|
its single successor. */
|
edge outgoing_edge;
|
edge outgoing_edge;
|
|
|
/* A list of incoming edges which we want to thread to
|
/* A list of incoming edges which we want to thread to
|
OUTGOING_EDGE->dest. */
|
OUTGOING_EDGE->dest. */
|
struct el *incoming_edges;
|
struct el *incoming_edges;
|
|
|
/* Flag indicating whether or not we should create a duplicate block
|
/* Flag indicating whether or not we should create a duplicate block
|
for this thread destination. This is only true if we are threading
|
for this thread destination. This is only true if we are threading
|
all incoming edges and thus are using BB itself as a duplicate block. */
|
all incoming edges and thus are using BB itself as a duplicate block. */
|
bool do_not_duplicate;
|
bool do_not_duplicate;
|
};
|
};
|
|
|
/* Main data structure to hold information for duplicates of BB. */
|
/* Main data structure to hold information for duplicates of BB. */
|
static htab_t redirection_data;
|
static htab_t redirection_data;
|
|
|
/* Data structure of information to pass to hash table traversal routines. */
|
/* Data structure of information to pass to hash table traversal routines. */
|
struct local_info
|
struct local_info
|
{
|
{
|
/* The current block we are working on. */
|
/* The current block we are working on. */
|
basic_block bb;
|
basic_block bb;
|
|
|
/* A template copy of BB with no outgoing edges or control statement that
|
/* A template copy of BB with no outgoing edges or control statement that
|
we use for creating copies. */
|
we use for creating copies. */
|
basic_block template_block;
|
basic_block template_block;
|
|
|
/* TRUE if we thread one or more jumps, FALSE otherwise. */
|
/* TRUE if we thread one or more jumps, FALSE otherwise. */
|
bool jumps_threaded;
|
bool jumps_threaded;
|
};
|
};
|
|
|
/* Passes which use the jump threading code register jump threading
|
/* Passes which use the jump threading code register jump threading
|
opportunities as they are discovered. We keep the registered
|
opportunities as they are discovered. We keep the registered
|
jump threading opportunities in this vector as edge pairs
|
jump threading opportunities in this vector as edge pairs
|
(original_edge, target_edge). */
|
(original_edge, target_edge). */
|
DEF_VEC_ALLOC_P(edge,heap);
|
DEF_VEC_ALLOC_P(edge,heap);
|
static VEC(edge,heap) *threaded_edges;
|
static VEC(edge,heap) *threaded_edges;
|
|
|
|
|
/* Jump threading statistics. */
|
/* Jump threading statistics. */
|
|
|
struct thread_stats_d
|
struct thread_stats_d
|
{
|
{
|
unsigned long num_threaded_edges;
|
unsigned long num_threaded_edges;
|
};
|
};
|
|
|
struct thread_stats_d thread_stats;
|
struct thread_stats_d thread_stats;
|
|
|
|
|
/* Remove the last statement in block BB if it is a control statement
|
/* Remove the last statement in block BB if it is a control statement
|
Also remove all outgoing edges except the edge which reaches DEST_BB.
|
Also remove all outgoing edges except the edge which reaches DEST_BB.
|
If DEST_BB is NULL, then remove all outgoing edges. */
|
If DEST_BB is NULL, then remove all outgoing edges. */
|
|
|
static void
|
static void
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remove_ctrl_stmt_and_useless_edges (basic_block bb, basic_block dest_bb)
|
remove_ctrl_stmt_and_useless_edges (basic_block bb, basic_block dest_bb)
|
{
|
{
|
block_stmt_iterator bsi;
|
block_stmt_iterator bsi;
|
edge e;
|
edge e;
|
edge_iterator ei;
|
edge_iterator ei;
|
|
|
bsi = bsi_last (bb);
|
bsi = bsi_last (bb);
|
|
|
/* If the duplicate ends with a control statement, then remove it.
|
/* If the duplicate ends with a control statement, then remove it.
|
|
|
Note that if we are duplicating the template block rather than the
|
Note that if we are duplicating the template block rather than the
|
original basic block, then the duplicate might not have any real
|
original basic block, then the duplicate might not have any real
|
statements in it. */
|
statements in it. */
|
if (!bsi_end_p (bsi)
|
if (!bsi_end_p (bsi)
|
&& bsi_stmt (bsi)
|
&& bsi_stmt (bsi)
|
&& (TREE_CODE (bsi_stmt (bsi)) == COND_EXPR
|
&& (TREE_CODE (bsi_stmt (bsi)) == COND_EXPR
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|| TREE_CODE (bsi_stmt (bsi)) == GOTO_EXPR
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|| TREE_CODE (bsi_stmt (bsi)) == GOTO_EXPR
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|| TREE_CODE (bsi_stmt (bsi)) == SWITCH_EXPR))
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|| TREE_CODE (bsi_stmt (bsi)) == SWITCH_EXPR))
|
bsi_remove (&bsi, true);
|
bsi_remove (&bsi, true);
|
|
|
for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
|
for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
|
{
|
{
|
if (e->dest != dest_bb)
|
if (e->dest != dest_bb)
|
remove_edge (e);
|
remove_edge (e);
|
else
|
else
|
ei_next (&ei);
|
ei_next (&ei);
|
}
|
}
|
}
|
}
|
|
|
/* Create a duplicate of BB which only reaches the destination of the edge
|
/* Create a duplicate of BB which only reaches the destination of the edge
|
stored in RD. Record the duplicate block in RD. */
|
stored in RD. Record the duplicate block in RD. */
|
|
|
static void
|
static void
|
create_block_for_threading (basic_block bb, struct redirection_data *rd)
|
create_block_for_threading (basic_block bb, struct redirection_data *rd)
|
{
|
{
|
/* We can use the generic block duplication code and simply remove
|
/* We can use the generic block duplication code and simply remove
|
the stuff we do not need. */
|
the stuff we do not need. */
|
rd->dup_block = duplicate_block (bb, NULL, NULL);
|
rd->dup_block = duplicate_block (bb, NULL, NULL);
|
|
|
/* Zero out the profile, since the block is unreachable for now. */
|
/* Zero out the profile, since the block is unreachable for now. */
|
rd->dup_block->frequency = 0;
|
rd->dup_block->frequency = 0;
|
rd->dup_block->count = 0;
|
rd->dup_block->count = 0;
|
|
|
/* The call to duplicate_block will copy everything, including the
|
/* The call to duplicate_block will copy everything, including the
|
useless COND_EXPR or SWITCH_EXPR at the end of BB. We just remove
|
useless COND_EXPR or SWITCH_EXPR at the end of BB. We just remove
|
the useless COND_EXPR or SWITCH_EXPR here rather than having a
|
the useless COND_EXPR or SWITCH_EXPR here rather than having a
|
specialized block copier. We also remove all outgoing edges
|
specialized block copier. We also remove all outgoing edges
|
from the duplicate block. The appropriate edge will be created
|
from the duplicate block. The appropriate edge will be created
|
later. */
|
later. */
|
remove_ctrl_stmt_and_useless_edges (rd->dup_block, NULL);
|
remove_ctrl_stmt_and_useless_edges (rd->dup_block, NULL);
|
}
|
}
|
|
|
/* Hashing and equality routines for our hash table. */
|
/* Hashing and equality routines for our hash table. */
|
static hashval_t
|
static hashval_t
|
redirection_data_hash (const void *p)
|
redirection_data_hash (const void *p)
|
{
|
{
|
edge e = ((struct redirection_data *)p)->outgoing_edge;
|
edge e = ((struct redirection_data *)p)->outgoing_edge;
|
return e->dest->index;
|
return e->dest->index;
|
}
|
}
|
|
|
static int
|
static int
|
redirection_data_eq (const void *p1, const void *p2)
|
redirection_data_eq (const void *p1, const void *p2)
|
{
|
{
|
edge e1 = ((struct redirection_data *)p1)->outgoing_edge;
|
edge e1 = ((struct redirection_data *)p1)->outgoing_edge;
|
edge e2 = ((struct redirection_data *)p2)->outgoing_edge;
|
edge e2 = ((struct redirection_data *)p2)->outgoing_edge;
|
|
|
return e1 == e2;
|
return e1 == e2;
|
}
|
}
|
|
|
/* Given an outgoing edge E lookup and return its entry in our hash table.
|
/* Given an outgoing edge E lookup and return its entry in our hash table.
|
|
|
If INSERT is true, then we insert the entry into the hash table if
|
If INSERT is true, then we insert the entry into the hash table if
|
it is not already present. INCOMING_EDGE is added to the list of incoming
|
it is not already present. INCOMING_EDGE is added to the list of incoming
|
edges associated with E in the hash table. */
|
edges associated with E in the hash table. */
|
|
|
static struct redirection_data *
|
static struct redirection_data *
|
lookup_redirection_data (edge e, edge incoming_edge, enum insert_option insert)
|
lookup_redirection_data (edge e, edge incoming_edge, enum insert_option insert)
|
{
|
{
|
void **slot;
|
void **slot;
|
struct redirection_data *elt;
|
struct redirection_data *elt;
|
|
|
/* Build a hash table element so we can see if E is already
|
/* Build a hash table element so we can see if E is already
|
in the table. */
|
in the table. */
|
elt = XNEW (struct redirection_data);
|
elt = XNEW (struct redirection_data);
|
elt->outgoing_edge = e;
|
elt->outgoing_edge = e;
|
elt->dup_block = NULL;
|
elt->dup_block = NULL;
|
elt->do_not_duplicate = false;
|
elt->do_not_duplicate = false;
|
elt->incoming_edges = NULL;
|
elt->incoming_edges = NULL;
|
|
|
slot = htab_find_slot (redirection_data, elt, insert);
|
slot = htab_find_slot (redirection_data, elt, insert);
|
|
|
/* This will only happen if INSERT is false and the entry is not
|
/* This will only happen if INSERT is false and the entry is not
|
in the hash table. */
|
in the hash table. */
|
if (slot == NULL)
|
if (slot == NULL)
|
{
|
{
|
free (elt);
|
free (elt);
|
return NULL;
|
return NULL;
|
}
|
}
|
|
|
/* This will only happen if E was not in the hash table and
|
/* This will only happen if E was not in the hash table and
|
INSERT is true. */
|
INSERT is true. */
|
if (*slot == NULL)
|
if (*slot == NULL)
|
{
|
{
|
*slot = (void *)elt;
|
*slot = (void *)elt;
|
elt->incoming_edges = XNEW (struct el);
|
elt->incoming_edges = XNEW (struct el);
|
elt->incoming_edges->e = incoming_edge;
|
elt->incoming_edges->e = incoming_edge;
|
elt->incoming_edges->next = NULL;
|
elt->incoming_edges->next = NULL;
|
return elt;
|
return elt;
|
}
|
}
|
/* E was in the hash table. */
|
/* E was in the hash table. */
|
else
|
else
|
{
|
{
|
/* Free ELT as we do not need it anymore, we will extract the
|
/* Free ELT as we do not need it anymore, we will extract the
|
relevant entry from the hash table itself. */
|
relevant entry from the hash table itself. */
|
free (elt);
|
free (elt);
|
|
|
/* Get the entry stored in the hash table. */
|
/* Get the entry stored in the hash table. */
|
elt = (struct redirection_data *) *slot;
|
elt = (struct redirection_data *) *slot;
|
|
|
/* If insertion was requested, then we need to add INCOMING_EDGE
|
/* If insertion was requested, then we need to add INCOMING_EDGE
|
to the list of incoming edges associated with E. */
|
to the list of incoming edges associated with E. */
|
if (insert)
|
if (insert)
|
{
|
{
|
struct el *el = XNEW (struct el);
|
struct el *el = XNEW (struct el);
|
el->next = elt->incoming_edges;
|
el->next = elt->incoming_edges;
|
el->e = incoming_edge;
|
el->e = incoming_edge;
|
elt->incoming_edges = el;
|
elt->incoming_edges = el;
|
}
|
}
|
|
|
return elt;
|
return elt;
|
}
|
}
|
}
|
}
|
|
|
/* Given a duplicate block and its single destination (both stored
|
/* Given a duplicate block and its single destination (both stored
|
in RD). Create an edge between the duplicate and its single
|
in RD). Create an edge between the duplicate and its single
|
destination.
|
destination.
|
|
|
Add an additional argument to any PHI nodes at the single
|
Add an additional argument to any PHI nodes at the single
|
destination. */
|
destination. */
|
|
|
static void
|
static void
|
create_edge_and_update_destination_phis (struct redirection_data *rd)
|
create_edge_and_update_destination_phis (struct redirection_data *rd)
|
{
|
{
|
edge e = make_edge (rd->dup_block, rd->outgoing_edge->dest, EDGE_FALLTHRU);
|
edge e = make_edge (rd->dup_block, rd->outgoing_edge->dest, EDGE_FALLTHRU);
|
tree phi;
|
tree phi;
|
|
|
e->probability = REG_BR_PROB_BASE;
|
e->probability = REG_BR_PROB_BASE;
|
e->count = rd->dup_block->count;
|
e->count = rd->dup_block->count;
|
|
|
/* If there are any PHI nodes at the destination of the outgoing edge
|
/* If there are any PHI nodes at the destination of the outgoing edge
|
from the duplicate block, then we will need to add a new argument
|
from the duplicate block, then we will need to add a new argument
|
to them. The argument should have the same value as the argument
|
to them. The argument should have the same value as the argument
|
associated with the outgoing edge stored in RD. */
|
associated with the outgoing edge stored in RD. */
|
for (phi = phi_nodes (e->dest); phi; phi = PHI_CHAIN (phi))
|
for (phi = phi_nodes (e->dest); phi; phi = PHI_CHAIN (phi))
|
{
|
{
|
int indx = rd->outgoing_edge->dest_idx;
|
int indx = rd->outgoing_edge->dest_idx;
|
add_phi_arg (phi, PHI_ARG_DEF (phi, indx), e);
|
add_phi_arg (phi, PHI_ARG_DEF (phi, indx), e);
|
}
|
}
|
}
|
}
|
|
|
/* Hash table traversal callback routine to create duplicate blocks. */
|
/* Hash table traversal callback routine to create duplicate blocks. */
|
|
|
static int
|
static int
|
create_duplicates (void **slot, void *data)
|
create_duplicates (void **slot, void *data)
|
{
|
{
|
struct redirection_data *rd = (struct redirection_data *) *slot;
|
struct redirection_data *rd = (struct redirection_data *) *slot;
|
struct local_info *local_info = (struct local_info *)data;
|
struct local_info *local_info = (struct local_info *)data;
|
|
|
/* If this entry should not have a duplicate created, then there's
|
/* If this entry should not have a duplicate created, then there's
|
nothing to do. */
|
nothing to do. */
|
if (rd->do_not_duplicate)
|
if (rd->do_not_duplicate)
|
return 1;
|
return 1;
|
|
|
/* Create a template block if we have not done so already. Otherwise
|
/* Create a template block if we have not done so already. Otherwise
|
use the template to create a new block. */
|
use the template to create a new block. */
|
if (local_info->template_block == NULL)
|
if (local_info->template_block == NULL)
|
{
|
{
|
create_block_for_threading (local_info->bb, rd);
|
create_block_for_threading (local_info->bb, rd);
|
local_info->template_block = rd->dup_block;
|
local_info->template_block = rd->dup_block;
|
|
|
/* We do not create any outgoing edges for the template. We will
|
/* We do not create any outgoing edges for the template. We will
|
take care of that in a later traversal. That way we do not
|
take care of that in a later traversal. That way we do not
|
create edges that are going to just be deleted. */
|
create edges that are going to just be deleted. */
|
}
|
}
|
else
|
else
|
{
|
{
|
create_block_for_threading (local_info->template_block, rd);
|
create_block_for_threading (local_info->template_block, rd);
|
|
|
/* Go ahead and wire up outgoing edges and update PHIs for the duplicate
|
/* Go ahead and wire up outgoing edges and update PHIs for the duplicate
|
block. */
|
block. */
|
create_edge_and_update_destination_phis (rd);
|
create_edge_and_update_destination_phis (rd);
|
}
|
}
|
|
|
/* Keep walking the hash table. */
|
/* Keep walking the hash table. */
|
return 1;
|
return 1;
|
}
|
}
|
|
|
/* We did not create any outgoing edges for the template block during
|
/* We did not create any outgoing edges for the template block during
|
block creation. This hash table traversal callback creates the
|
block creation. This hash table traversal callback creates the
|
outgoing edge for the template block. */
|
outgoing edge for the template block. */
|
|
|
static int
|
static int
|
fixup_template_block (void **slot, void *data)
|
fixup_template_block (void **slot, void *data)
|
{
|
{
|
struct redirection_data *rd = (struct redirection_data *) *slot;
|
struct redirection_data *rd = (struct redirection_data *) *slot;
|
struct local_info *local_info = (struct local_info *)data;
|
struct local_info *local_info = (struct local_info *)data;
|
|
|
/* If this is the template block, then create its outgoing edges
|
/* If this is the template block, then create its outgoing edges
|
and halt the hash table traversal. */
|
and halt the hash table traversal. */
|
if (rd->dup_block && rd->dup_block == local_info->template_block)
|
if (rd->dup_block && rd->dup_block == local_info->template_block)
|
{
|
{
|
create_edge_and_update_destination_phis (rd);
|
create_edge_and_update_destination_phis (rd);
|
return 0;
|
return 0;
|
}
|
}
|
|
|
return 1;
|
return 1;
|
}
|
}
|
|
|
/* Not all jump threading requests are useful. In particular some
|
/* Not all jump threading requests are useful. In particular some
|
jump threading requests can create irreducible regions which are
|
jump threading requests can create irreducible regions which are
|
undesirable.
|
undesirable.
|
|
|
This routine will examine the BB's incoming edges for jump threading
|
This routine will examine the BB's incoming edges for jump threading
|
requests which, if acted upon, would create irreducible regions. Any
|
requests which, if acted upon, would create irreducible regions. Any
|
such jump threading requests found will be pruned away. */
|
such jump threading requests found will be pruned away. */
|
|
|
static void
|
static void
|
prune_undesirable_thread_requests (basic_block bb)
|
prune_undesirable_thread_requests (basic_block bb)
|
{
|
{
|
edge e;
|
edge e;
|
edge_iterator ei;
|
edge_iterator ei;
|
bool may_create_irreducible_region = false;
|
bool may_create_irreducible_region = false;
|
unsigned int num_outgoing_edges_into_loop = 0;
|
unsigned int num_outgoing_edges_into_loop = 0;
|
|
|
/* For the heuristics below, we need to know if BB has more than
|
/* For the heuristics below, we need to know if BB has more than
|
one outgoing edge into a loop. */
|
one outgoing edge into a loop. */
|
FOR_EACH_EDGE (e, ei, bb->succs)
|
FOR_EACH_EDGE (e, ei, bb->succs)
|
num_outgoing_edges_into_loop += ((e->flags & EDGE_LOOP_EXIT) == 0);
|
num_outgoing_edges_into_loop += ((e->flags & EDGE_LOOP_EXIT) == 0);
|
|
|
if (num_outgoing_edges_into_loop > 1)
|
if (num_outgoing_edges_into_loop > 1)
|
{
|
{
|
edge backedge = NULL;
|
edge backedge = NULL;
|
|
|
/* Consider the effect of threading the edge (0, 1) to 2 on the left
|
/* Consider the effect of threading the edge (0, 1) to 2 on the left
|
CFG to produce the right CFG:
|
CFG to produce the right CFG:
|
|
|
|
|
0 0
|
0 0
|
| |
|
| |
|
1<--+ 2<--------+
|
1<--+ 2<--------+
|
/ \ | | |
|
/ \ | | |
|
2 3 | 4<----+ |
|
2 3 | 4<----+ |
|
\ / | / \ | |
|
\ / | / \ | |
|
4---+ E 1-- | --+
|
4---+ E 1-- | --+
|
| | |
|
| | |
|
E 3---+
|
E 3---+
|
|
|
|
|
Threading the (0, 1) edge to 2 effectively creates two loops
|
Threading the (0, 1) edge to 2 effectively creates two loops
|
(2, 4, 1) and (4, 1, 3) which are neither disjoint nor nested.
|
(2, 4, 1) and (4, 1, 3) which are neither disjoint nor nested.
|
This is not good.
|
This is not good.
|
|
|
However, we do need to be able to thread (0, 1) to 2 or 3
|
However, we do need to be able to thread (0, 1) to 2 or 3
|
in the left CFG below (which creates the middle and right
|
in the left CFG below (which creates the middle and right
|
CFGs with nested loops).
|
CFGs with nested loops).
|
|
|
0 0 0
|
0 0 0
|
| | |
|
| | |
|
1<--+ 2<----+ 3<-+<-+
|
1<--+ 2<----+ 3<-+<-+
|
/| | | | | | |
|
/| | | | | | |
|
2 | | 3<-+ | 1--+ |
|
2 | | 3<-+ | 1--+ |
|
\| | | | | | |
|
\| | | | | | |
|
3---+ 1--+--+ 2-----+
|
3---+ 1--+--+ 2-----+
|
|
|
|
|
A safe heuristic appears to be to only allow threading if BB
|
A safe heuristic appears to be to only allow threading if BB
|
has a single incoming backedge from one of its direct successors. */
|
has a single incoming backedge from one of its direct successors. */
|
|
|
FOR_EACH_EDGE (e, ei, bb->preds)
|
FOR_EACH_EDGE (e, ei, bb->preds)
|
{
|
{
|
if (e->flags & EDGE_DFS_BACK)
|
if (e->flags & EDGE_DFS_BACK)
|
{
|
{
|
if (backedge)
|
if (backedge)
|
{
|
{
|
backedge = NULL;
|
backedge = NULL;
|
break;
|
break;
|
}
|
}
|
else
|
else
|
{
|
{
|
backedge = e;
|
backedge = e;
|
}
|
}
|
}
|
}
|
}
|
}
|
|
|
if (backedge && find_edge (bb, backedge->src))
|
if (backedge && find_edge (bb, backedge->src))
|
;
|
;
|
else
|
else
|
may_create_irreducible_region = true;
|
may_create_irreducible_region = true;
|
}
|
}
|
else
|
else
|
{
|
{
|
edge dest = NULL;
|
edge dest = NULL;
|
|
|
/* If we thread across the loop entry block (BB) into the
|
/* If we thread across the loop entry block (BB) into the
|
loop and BB is still reached from outside the loop, then
|
loop and BB is still reached from outside the loop, then
|
we would create an irreducible CFG. Consider the effect
|
we would create an irreducible CFG. Consider the effect
|
of threading the edge (1, 4) to 5 on the left CFG to produce
|
of threading the edge (1, 4) to 5 on the left CFG to produce
|
the right CFG
|
the right CFG
|
|
|
0 0
|
0 0
|
/ \ / \
|
/ \ / \
|
1 2 1 2
|
1 2 1 2
|
\ / | |
|
\ / | |
|
4<----+ 5<->4
|
4<----+ 5<->4
|
/ \ | |
|
/ \ | |
|
E 5---+ E
|
E 5---+ E
|
|
|
|
|
Threading the (1, 4) edge to 5 creates two entry points
|
Threading the (1, 4) edge to 5 creates two entry points
|
into the loop (4, 5) (one from block 1, the other from
|
into the loop (4, 5) (one from block 1, the other from
|
block 2). A classic irreducible region.
|
block 2). A classic irreducible region.
|
|
|
So look at all of BB's incoming edges which are not
|
So look at all of BB's incoming edges which are not
|
backedges and which are not threaded to the loop exit.
|
backedges and which are not threaded to the loop exit.
|
If that subset of incoming edges do not all thread
|
If that subset of incoming edges do not all thread
|
to the same block, then threading any of them will create
|
to the same block, then threading any of them will create
|
an irreducible region. */
|
an irreducible region. */
|
|
|
FOR_EACH_EDGE (e, ei, bb->preds)
|
FOR_EACH_EDGE (e, ei, bb->preds)
|
{
|
{
|
edge e2;
|
edge e2;
|
|
|
/* We ignore back edges for now. This may need refinement
|
/* We ignore back edges for now. This may need refinement
|
as threading a backedge creates an inner loop which
|
as threading a backedge creates an inner loop which
|
we would need to verify has a single entry point.
|
we would need to verify has a single entry point.
|
|
|
If all backedges thread to new locations, then this
|
If all backedges thread to new locations, then this
|
block will no longer have incoming backedges and we
|
block will no longer have incoming backedges and we
|
need not worry about creating irreducible regions
|
need not worry about creating irreducible regions
|
by threading through BB. I don't think this happens
|
by threading through BB. I don't think this happens
|
enough in practice to worry about it. */
|
enough in practice to worry about it. */
|
if (e->flags & EDGE_DFS_BACK)
|
if (e->flags & EDGE_DFS_BACK)
|
continue;
|
continue;
|
|
|
/* If the incoming edge threads to the loop exit, then it
|
/* If the incoming edge threads to the loop exit, then it
|
is clearly safe. */
|
is clearly safe. */
|
e2 = e->aux;
|
e2 = e->aux;
|
if (e2 && (e2->flags & EDGE_LOOP_EXIT))
|
if (e2 && (e2->flags & EDGE_LOOP_EXIT))
|
continue;
|
continue;
|
|
|
/* E enters the loop header and is not threaded. We can
|
/* E enters the loop header and is not threaded. We can
|
not allow any other incoming edges to thread into
|
not allow any other incoming edges to thread into
|
the loop as that would create an irreducible region. */
|
the loop as that would create an irreducible region. */
|
if (!e2)
|
if (!e2)
|
{
|
{
|
may_create_irreducible_region = true;
|
may_create_irreducible_region = true;
|
break;
|
break;
|
}
|
}
|
|
|
/* We know that this incoming edge threads to a block inside
|
/* We know that this incoming edge threads to a block inside
|
the loop. This edge must thread to the same target in
|
the loop. This edge must thread to the same target in
|
the loop as any previously seen threaded edges. Otherwise
|
the loop as any previously seen threaded edges. Otherwise
|
we will create an irreducible region. */
|
we will create an irreducible region. */
|
if (!dest)
|
if (!dest)
|
dest = e2;
|
dest = e2;
|
else if (e2 != dest)
|
else if (e2 != dest)
|
{
|
{
|
may_create_irreducible_region = true;
|
may_create_irreducible_region = true;
|
break;
|
break;
|
}
|
}
|
}
|
}
|
}
|
}
|
|
|
/* If we might create an irreducible region, then cancel any of
|
/* If we might create an irreducible region, then cancel any of
|
the jump threading requests for incoming edges which are
|
the jump threading requests for incoming edges which are
|
not backedges and which do not thread to the exit block. */
|
not backedges and which do not thread to the exit block. */
|
if (may_create_irreducible_region)
|
if (may_create_irreducible_region)
|
{
|
{
|
FOR_EACH_EDGE (e, ei, bb->preds)
|
FOR_EACH_EDGE (e, ei, bb->preds)
|
{
|
{
|
edge e2;
|
edge e2;
|
|
|
/* Ignore back edges. */
|
/* Ignore back edges. */
|
if (e->flags & EDGE_DFS_BACK)
|
if (e->flags & EDGE_DFS_BACK)
|
continue;
|
continue;
|
|
|
e2 = e->aux;
|
e2 = e->aux;
|
|
|
/* If this incoming edge was not threaded, then there is
|
/* If this incoming edge was not threaded, then there is
|
nothing to do. */
|
nothing to do. */
|
if (!e2)
|
if (!e2)
|
continue;
|
continue;
|
|
|
/* If this incoming edge threaded to the loop exit,
|
/* If this incoming edge threaded to the loop exit,
|
then it can be ignored as it is safe. */
|
then it can be ignored as it is safe. */
|
if (e2->flags & EDGE_LOOP_EXIT)
|
if (e2->flags & EDGE_LOOP_EXIT)
|
continue;
|
continue;
|
|
|
if (e2)
|
if (e2)
|
{
|
{
|
/* This edge threaded into the loop and the jump thread
|
/* This edge threaded into the loop and the jump thread
|
request must be cancelled. */
|
request must be cancelled. */
|
if (dump_file && (dump_flags & TDF_DETAILS))
|
if (dump_file && (dump_flags & TDF_DETAILS))
|
fprintf (dump_file, " Not threading jump %d --> %d to %d\n",
|
fprintf (dump_file, " Not threading jump %d --> %d to %d\n",
|
e->src->index, e->dest->index, e2->dest->index);
|
e->src->index, e->dest->index, e2->dest->index);
|
e->aux = NULL;
|
e->aux = NULL;
|
}
|
}
|
}
|
}
|
}
|
}
|
}
|
}
|
|
|
/* Hash table traversal callback to redirect each incoming edge
|
/* Hash table traversal callback to redirect each incoming edge
|
associated with this hash table element to its new destination. */
|
associated with this hash table element to its new destination. */
|
|
|
static int
|
static int
|
redirect_edges (void **slot, void *data)
|
redirect_edges (void **slot, void *data)
|
{
|
{
|
struct redirection_data *rd = (struct redirection_data *) *slot;
|
struct redirection_data *rd = (struct redirection_data *) *slot;
|
struct local_info *local_info = (struct local_info *)data;
|
struct local_info *local_info = (struct local_info *)data;
|
struct el *next, *el;
|
struct el *next, *el;
|
|
|
/* Walk over all the incoming edges associated associated with this
|
/* Walk over all the incoming edges associated associated with this
|
hash table entry. */
|
hash table entry. */
|
for (el = rd->incoming_edges; el; el = next)
|
for (el = rd->incoming_edges; el; el = next)
|
{
|
{
|
edge e = el->e;
|
edge e = el->e;
|
|
|
/* Go ahead and free this element from the list. Doing this now
|
/* Go ahead and free this element from the list. Doing this now
|
avoids the need for another list walk when we destroy the hash
|
avoids the need for another list walk when we destroy the hash
|
table. */
|
table. */
|
next = el->next;
|
next = el->next;
|
free (el);
|
free (el);
|
|
|
/* Go ahead and clear E->aux. It's not needed anymore and failure
|
/* Go ahead and clear E->aux. It's not needed anymore and failure
|
to clear it will cause all kinds of unpleasant problems later. */
|
to clear it will cause all kinds of unpleasant problems later. */
|
e->aux = NULL;
|
e->aux = NULL;
|
|
|
thread_stats.num_threaded_edges++;
|
thread_stats.num_threaded_edges++;
|
|
|
if (rd->dup_block)
|
if (rd->dup_block)
|
{
|
{
|
edge e2;
|
edge e2;
|
|
|
if (dump_file && (dump_flags & TDF_DETAILS))
|
if (dump_file && (dump_flags & TDF_DETAILS))
|
fprintf (dump_file, " Threaded jump %d --> %d to %d\n",
|
fprintf (dump_file, " Threaded jump %d --> %d to %d\n",
|
e->src->index, e->dest->index, rd->dup_block->index);
|
e->src->index, e->dest->index, rd->dup_block->index);
|
|
|
rd->dup_block->count += e->count;
|
rd->dup_block->count += e->count;
|
rd->dup_block->frequency += EDGE_FREQUENCY (e);
|
rd->dup_block->frequency += EDGE_FREQUENCY (e);
|
EDGE_SUCC (rd->dup_block, 0)->count += e->count;
|
EDGE_SUCC (rd->dup_block, 0)->count += e->count;
|
/* Redirect the incoming edge to the appropriate duplicate
|
/* Redirect the incoming edge to the appropriate duplicate
|
block. */
|
block. */
|
e2 = redirect_edge_and_branch (e, rd->dup_block);
|
e2 = redirect_edge_and_branch (e, rd->dup_block);
|
flush_pending_stmts (e2);
|
flush_pending_stmts (e2);
|
|
|
if ((dump_file && (dump_flags & TDF_DETAILS))
|
if ((dump_file && (dump_flags & TDF_DETAILS))
|
&& e->src != e2->src)
|
&& e->src != e2->src)
|
fprintf (dump_file, " basic block %d created\n", e2->src->index);
|
fprintf (dump_file, " basic block %d created\n", e2->src->index);
|
}
|
}
|
else
|
else
|
{
|
{
|
if (dump_file && (dump_flags & TDF_DETAILS))
|
if (dump_file && (dump_flags & TDF_DETAILS))
|
fprintf (dump_file, " Threaded jump %d --> %d to %d\n",
|
fprintf (dump_file, " Threaded jump %d --> %d to %d\n",
|
e->src->index, e->dest->index, local_info->bb->index);
|
e->src->index, e->dest->index, local_info->bb->index);
|
|
|
/* We are using BB as the duplicate. Remove the unnecessary
|
/* We are using BB as the duplicate. Remove the unnecessary
|
outgoing edges and statements from BB. */
|
outgoing edges and statements from BB. */
|
remove_ctrl_stmt_and_useless_edges (local_info->bb,
|
remove_ctrl_stmt_and_useless_edges (local_info->bb,
|
rd->outgoing_edge->dest);
|
rd->outgoing_edge->dest);
|
|
|
/* And fixup the flags on the single remaining edge. */
|
/* And fixup the flags on the single remaining edge. */
|
single_succ_edge (local_info->bb)->flags
|
single_succ_edge (local_info->bb)->flags
|
&= ~(EDGE_TRUE_VALUE | EDGE_FALSE_VALUE | EDGE_ABNORMAL);
|
&= ~(EDGE_TRUE_VALUE | EDGE_FALSE_VALUE | EDGE_ABNORMAL);
|
single_succ_edge (local_info->bb)->flags |= EDGE_FALLTHRU;
|
single_succ_edge (local_info->bb)->flags |= EDGE_FALLTHRU;
|
}
|
}
|
}
|
}
|
|
|
/* Indicate that we actually threaded one or more jumps. */
|
/* Indicate that we actually threaded one or more jumps. */
|
if (rd->incoming_edges)
|
if (rd->incoming_edges)
|
local_info->jumps_threaded = true;
|
local_info->jumps_threaded = true;
|
|
|
return 1;
|
return 1;
|
}
|
}
|
|
|
/* Return true if this block has no executable statements other than
|
/* Return true if this block has no executable statements other than
|
a simple ctrl flow instruction. When the number of outgoing edges
|
a simple ctrl flow instruction. When the number of outgoing edges
|
is one, this is equivalent to a "forwarder" block. */
|
is one, this is equivalent to a "forwarder" block. */
|
|
|
static bool
|
static bool
|
redirection_block_p (basic_block bb)
|
redirection_block_p (basic_block bb)
|
{
|
{
|
block_stmt_iterator bsi;
|
block_stmt_iterator bsi;
|
|
|
/* Advance to the first executable statement. */
|
/* Advance to the first executable statement. */
|
bsi = bsi_start (bb);
|
bsi = bsi_start (bb);
|
while (!bsi_end_p (bsi)
|
while (!bsi_end_p (bsi)
|
&& (TREE_CODE (bsi_stmt (bsi)) == LABEL_EXPR
|
&& (TREE_CODE (bsi_stmt (bsi)) == LABEL_EXPR
|
|| IS_EMPTY_STMT (bsi_stmt (bsi))))
|
|| IS_EMPTY_STMT (bsi_stmt (bsi))))
|
bsi_next (&bsi);
|
bsi_next (&bsi);
|
|
|
/* Check if this is an empty block. */
|
/* Check if this is an empty block. */
|
if (bsi_end_p (bsi))
|
if (bsi_end_p (bsi))
|
return true;
|
return true;
|
|
|
/* Test that we've reached the terminating control statement. */
|
/* Test that we've reached the terminating control statement. */
|
return bsi_stmt (bsi)
|
return bsi_stmt (bsi)
|
&& (TREE_CODE (bsi_stmt (bsi)) == COND_EXPR
|
&& (TREE_CODE (bsi_stmt (bsi)) == COND_EXPR
|
|| TREE_CODE (bsi_stmt (bsi)) == GOTO_EXPR
|
|| TREE_CODE (bsi_stmt (bsi)) == GOTO_EXPR
|
|| TREE_CODE (bsi_stmt (bsi)) == SWITCH_EXPR);
|
|| TREE_CODE (bsi_stmt (bsi)) == SWITCH_EXPR);
|
}
|
}
|
|
|
/* BB is a block which ends with a COND_EXPR or SWITCH_EXPR and when BB
|
/* BB is a block which ends with a COND_EXPR or SWITCH_EXPR and when BB
|
is reached via one or more specific incoming edges, we know which
|
is reached via one or more specific incoming edges, we know which
|
outgoing edge from BB will be traversed.
|
outgoing edge from BB will be traversed.
|
|
|
We want to redirect those incoming edges to the target of the
|
We want to redirect those incoming edges to the target of the
|
appropriate outgoing edge. Doing so avoids a conditional branch
|
appropriate outgoing edge. Doing so avoids a conditional branch
|
and may expose new optimization opportunities. Note that we have
|
and may expose new optimization opportunities. Note that we have
|
to update dominator tree and SSA graph after such changes.
|
to update dominator tree and SSA graph after such changes.
|
|
|
The key to keeping the SSA graph update manageable is to duplicate
|
The key to keeping the SSA graph update manageable is to duplicate
|
the side effects occurring in BB so that those side effects still
|
the side effects occurring in BB so that those side effects still
|
occur on the paths which bypass BB after redirecting edges.
|
occur on the paths which bypass BB after redirecting edges.
|
|
|
We accomplish this by creating duplicates of BB and arranging for
|
We accomplish this by creating duplicates of BB and arranging for
|
the duplicates to unconditionally pass control to one specific
|
the duplicates to unconditionally pass control to one specific
|
successor of BB. We then revector the incoming edges into BB to
|
successor of BB. We then revector the incoming edges into BB to
|
the appropriate duplicate of BB.
|
the appropriate duplicate of BB.
|
|
|
BB and its duplicates will have assignments to the same set of
|
BB and its duplicates will have assignments to the same set of
|
SSA_NAMEs. Right now, we just call into update_ssa to update the
|
SSA_NAMEs. Right now, we just call into update_ssa to update the
|
SSA graph for those names.
|
SSA graph for those names.
|
|
|
We are also going to experiment with a true incremental update
|
We are also going to experiment with a true incremental update
|
scheme for the duplicated resources. One of the interesting
|
scheme for the duplicated resources. One of the interesting
|
properties we can exploit here is that all the resources set
|
properties we can exploit here is that all the resources set
|
in BB will have the same IDFS, so we have one IDFS computation
|
in BB will have the same IDFS, so we have one IDFS computation
|
per block with incoming threaded edges, which can lower the
|
per block with incoming threaded edges, which can lower the
|
cost of the true incremental update algorithm. */
|
cost of the true incremental update algorithm. */
|
|
|
static bool
|
static bool
|
thread_block (basic_block bb)
|
thread_block (basic_block bb)
|
{
|
{
|
/* E is an incoming edge into BB that we may or may not want to
|
/* E is an incoming edge into BB that we may or may not want to
|
redirect to a duplicate of BB. */
|
redirect to a duplicate of BB. */
|
edge e;
|
edge e;
|
edge_iterator ei;
|
edge_iterator ei;
|
struct local_info local_info;
|
struct local_info local_info;
|
|
|
/* FOUND_BACKEDGE indicates that we found an incoming backedge
|
/* FOUND_BACKEDGE indicates that we found an incoming backedge
|
into BB, in which case we may ignore certain jump threads
|
into BB, in which case we may ignore certain jump threads
|
to avoid creating irreducible regions. */
|
to avoid creating irreducible regions. */
|
bool found_backedge = false;
|
bool found_backedge = false;
|
|
|
/* ALL indicates whether or not all incoming edges into BB should
|
/* ALL indicates whether or not all incoming edges into BB should
|
be threaded to a duplicate of BB. */
|
be threaded to a duplicate of BB. */
|
bool all = true;
|
bool all = true;
|
|
|
/* If optimizing for size, only thread this block if we don't have
|
/* If optimizing for size, only thread this block if we don't have
|
to duplicate it or it's an otherwise empty redirection block. */
|
to duplicate it or it's an otherwise empty redirection block. */
|
if (optimize_size
|
if (optimize_size
|
&& EDGE_COUNT (bb->preds) > 1
|
&& EDGE_COUNT (bb->preds) > 1
|
&& !redirection_block_p (bb))
|
&& !redirection_block_p (bb))
|
{
|
{
|
FOR_EACH_EDGE (e, ei, bb->preds)
|
FOR_EACH_EDGE (e, ei, bb->preds)
|
e->aux = NULL;
|
e->aux = NULL;
|
return false;
|
return false;
|
}
|
}
|
|
|
/* To avoid scanning a linear array for the element we need we instead
|
/* To avoid scanning a linear array for the element we need we instead
|
use a hash table. For normal code there should be no noticeable
|
use a hash table. For normal code there should be no noticeable
|
difference. However, if we have a block with a large number of
|
difference. However, if we have a block with a large number of
|
incoming and outgoing edges such linear searches can get expensive. */
|
incoming and outgoing edges such linear searches can get expensive. */
|
redirection_data = htab_create (EDGE_COUNT (bb->succs),
|
redirection_data = htab_create (EDGE_COUNT (bb->succs),
|
redirection_data_hash,
|
redirection_data_hash,
|
redirection_data_eq,
|
redirection_data_eq,
|
free);
|
free);
|
|
|
FOR_EACH_EDGE (e, ei, bb->preds)
|
FOR_EACH_EDGE (e, ei, bb->preds)
|
found_backedge |= ((e->flags & EDGE_DFS_BACK) != 0);
|
found_backedge |= ((e->flags & EDGE_DFS_BACK) != 0);
|
|
|
/* If BB has incoming backedges, then threading across BB might
|
/* If BB has incoming backedges, then threading across BB might
|
introduce an irreducible region, which would be undesirable
|
introduce an irreducible region, which would be undesirable
|
as that inhibits various optimizations later. Prune away
|
as that inhibits various optimizations later. Prune away
|
any jump threading requests which we know will result in
|
any jump threading requests which we know will result in
|
an irreducible region. */
|
an irreducible region. */
|
if (found_backedge)
|
if (found_backedge)
|
prune_undesirable_thread_requests (bb);
|
prune_undesirable_thread_requests (bb);
|
|
|
/* Record each unique threaded destination into a hash table for
|
/* Record each unique threaded destination into a hash table for
|
efficient lookups. */
|
efficient lookups. */
|
FOR_EACH_EDGE (e, ei, bb->preds)
|
FOR_EACH_EDGE (e, ei, bb->preds)
|
{
|
{
|
if (!e->aux)
|
if (!e->aux)
|
{
|
{
|
all = false;
|
all = false;
|
}
|
}
|
else
|
else
|
{
|
{
|
edge e2 = e->aux;
|
edge e2 = e->aux;
|
update_bb_profile_for_threading (e->dest, EDGE_FREQUENCY (e),
|
update_bb_profile_for_threading (e->dest, EDGE_FREQUENCY (e),
|
e->count, e->aux);
|
e->count, e->aux);
|
|
|
/* Insert the outgoing edge into the hash table if it is not
|
/* Insert the outgoing edge into the hash table if it is not
|
already in the hash table. */
|
already in the hash table. */
|
lookup_redirection_data (e2, e, INSERT);
|
lookup_redirection_data (e2, e, INSERT);
|
}
|
}
|
}
|
}
|
|
|
/* If we are going to thread all incoming edges to an outgoing edge, then
|
/* If we are going to thread all incoming edges to an outgoing edge, then
|
BB will become unreachable. Rather than just throwing it away, use
|
BB will become unreachable. Rather than just throwing it away, use
|
it for one of the duplicates. Mark the first incoming edge with the
|
it for one of the duplicates. Mark the first incoming edge with the
|
DO_NOT_DUPLICATE attribute. */
|
DO_NOT_DUPLICATE attribute. */
|
if (all)
|
if (all)
|
{
|
{
|
edge e = EDGE_PRED (bb, 0)->aux;
|
edge e = EDGE_PRED (bb, 0)->aux;
|
lookup_redirection_data (e, NULL, NO_INSERT)->do_not_duplicate = true;
|
lookup_redirection_data (e, NULL, NO_INSERT)->do_not_duplicate = true;
|
}
|
}
|
|
|
/* Now create duplicates of BB.
|
/* Now create duplicates of BB.
|
|
|
Note that for a block with a high outgoing degree we can waste
|
Note that for a block with a high outgoing degree we can waste
|
a lot of time and memory creating and destroying useless edges.
|
a lot of time and memory creating and destroying useless edges.
|
|
|
So we first duplicate BB and remove the control structure at the
|
So we first duplicate BB and remove the control structure at the
|
tail of the duplicate as well as all outgoing edges from the
|
tail of the duplicate as well as all outgoing edges from the
|
duplicate. We then use that duplicate block as a template for
|
duplicate. We then use that duplicate block as a template for
|
the rest of the duplicates. */
|
the rest of the duplicates. */
|
local_info.template_block = NULL;
|
local_info.template_block = NULL;
|
local_info.bb = bb;
|
local_info.bb = bb;
|
local_info.jumps_threaded = false;
|
local_info.jumps_threaded = false;
|
htab_traverse (redirection_data, create_duplicates, &local_info);
|
htab_traverse (redirection_data, create_duplicates, &local_info);
|
|
|
/* The template does not have an outgoing edge. Create that outgoing
|
/* The template does not have an outgoing edge. Create that outgoing
|
edge and update PHI nodes as the edge's target as necessary.
|
edge and update PHI nodes as the edge's target as necessary.
|
|
|
We do this after creating all the duplicates to avoid creating
|
We do this after creating all the duplicates to avoid creating
|
unnecessary edges. */
|
unnecessary edges. */
|
htab_traverse (redirection_data, fixup_template_block, &local_info);
|
htab_traverse (redirection_data, fixup_template_block, &local_info);
|
|
|
/* The hash table traversals above created the duplicate blocks (and the
|
/* The hash table traversals above created the duplicate blocks (and the
|
statements within the duplicate blocks). This loop creates PHI nodes for
|
statements within the duplicate blocks). This loop creates PHI nodes for
|
the duplicated blocks and redirects the incoming edges into BB to reach
|
the duplicated blocks and redirects the incoming edges into BB to reach
|
the duplicates of BB. */
|
the duplicates of BB. */
|
htab_traverse (redirection_data, redirect_edges, &local_info);
|
htab_traverse (redirection_data, redirect_edges, &local_info);
|
|
|
/* Done with this block. Clear REDIRECTION_DATA. */
|
/* Done with this block. Clear REDIRECTION_DATA. */
|
htab_delete (redirection_data);
|
htab_delete (redirection_data);
|
redirection_data = NULL;
|
redirection_data = NULL;
|
|
|
/* Indicate to our caller whether or not any jumps were threaded. */
|
/* Indicate to our caller whether or not any jumps were threaded. */
|
return local_info.jumps_threaded;
|
return local_info.jumps_threaded;
|
}
|
}
|
|
|
/* Walk through the registered jump threads and convert them into a
|
/* Walk through the registered jump threads and convert them into a
|
form convenient for this pass.
|
form convenient for this pass.
|
|
|
Any block which has incoming edges threaded to outgoing edges
|
Any block which has incoming edges threaded to outgoing edges
|
will have its entry in THREADED_BLOCK set.
|
will have its entry in THREADED_BLOCK set.
|
|
|
Any threaded edge will have its new outgoing edge stored in the
|
Any threaded edge will have its new outgoing edge stored in the
|
original edge's AUX field.
|
original edge's AUX field.
|
|
|
This form avoids the need to walk all the edges in the CFG to
|
This form avoids the need to walk all the edges in the CFG to
|
discover blocks which need processing and avoids unnecessary
|
discover blocks which need processing and avoids unnecessary
|
hash table lookups to map from threaded edge to new target. */
|
hash table lookups to map from threaded edge to new target. */
|
|
|
static void
|
static void
|
mark_threaded_blocks (bitmap threaded_blocks)
|
mark_threaded_blocks (bitmap threaded_blocks)
|
{
|
{
|
unsigned int i;
|
unsigned int i;
|
|
|
for (i = 0; i < VEC_length (edge, threaded_edges); i += 2)
|
for (i = 0; i < VEC_length (edge, threaded_edges); i += 2)
|
{
|
{
|
edge e = VEC_index (edge, threaded_edges, i);
|
edge e = VEC_index (edge, threaded_edges, i);
|
edge e2 = VEC_index (edge, threaded_edges, i + 1);
|
edge e2 = VEC_index (edge, threaded_edges, i + 1);
|
|
|
e->aux = e2;
|
e->aux = e2;
|
bitmap_set_bit (threaded_blocks, e->dest->index);
|
bitmap_set_bit (threaded_blocks, e->dest->index);
|
}
|
}
|
}
|
}
|
|
|
|
|
/* Walk through all blocks and thread incoming edges to the appropriate
|
/* Walk through all blocks and thread incoming edges to the appropriate
|
outgoing edge for each edge pair recorded in THREADED_EDGES.
|
outgoing edge for each edge pair recorded in THREADED_EDGES.
|
|
|
It is the caller's responsibility to fix the dominance information
|
It is the caller's responsibility to fix the dominance information
|
and rewrite duplicated SSA_NAMEs back into SSA form.
|
and rewrite duplicated SSA_NAMEs back into SSA form.
|
|
|
Returns true if one or more edges were threaded, false otherwise. */
|
Returns true if one or more edges were threaded, false otherwise. */
|
|
|
bool
|
bool
|
thread_through_all_blocks (void)
|
thread_through_all_blocks (void)
|
{
|
{
|
bool retval = false;
|
bool retval = false;
|
unsigned int i;
|
unsigned int i;
|
bitmap_iterator bi;
|
bitmap_iterator bi;
|
bitmap threaded_blocks;
|
bitmap threaded_blocks;
|
|
|
if (threaded_edges == NULL)
|
if (threaded_edges == NULL)
|
return false;
|
return false;
|
|
|
threaded_blocks = BITMAP_ALLOC (NULL);
|
threaded_blocks = BITMAP_ALLOC (NULL);
|
memset (&thread_stats, 0, sizeof (thread_stats));
|
memset (&thread_stats, 0, sizeof (thread_stats));
|
|
|
mark_threaded_blocks (threaded_blocks);
|
mark_threaded_blocks (threaded_blocks);
|
|
|
EXECUTE_IF_SET_IN_BITMAP (threaded_blocks, 0, i, bi)
|
EXECUTE_IF_SET_IN_BITMAP (threaded_blocks, 0, i, bi)
|
{
|
{
|
basic_block bb = BASIC_BLOCK (i);
|
basic_block bb = BASIC_BLOCK (i);
|
|
|
if (EDGE_COUNT (bb->preds) > 0)
|
if (EDGE_COUNT (bb->preds) > 0)
|
retval |= thread_block (bb);
|
retval |= thread_block (bb);
|
}
|
}
|
|
|
if (dump_file && (dump_flags & TDF_STATS))
|
if (dump_file && (dump_flags & TDF_STATS))
|
fprintf (dump_file, "\nJumps threaded: %lu\n",
|
fprintf (dump_file, "\nJumps threaded: %lu\n",
|
thread_stats.num_threaded_edges);
|
thread_stats.num_threaded_edges);
|
|
|
BITMAP_FREE (threaded_blocks);
|
BITMAP_FREE (threaded_blocks);
|
threaded_blocks = NULL;
|
threaded_blocks = NULL;
|
VEC_free (edge, heap, threaded_edges);
|
VEC_free (edge, heap, threaded_edges);
|
threaded_edges = NULL;
|
threaded_edges = NULL;
|
return retval;
|
return retval;
|
}
|
}
|
|
|
/* Register a jump threading opportunity. We queue up all the jump
|
/* Register a jump threading opportunity. We queue up all the jump
|
threading opportunities discovered by a pass and update the CFG
|
threading opportunities discovered by a pass and update the CFG
|
and SSA form all at once.
|
and SSA form all at once.
|
|
|
E is the edge we can thread, E2 is the new target edge. ie, we
|
E is the edge we can thread, E2 is the new target edge. ie, we
|
are effectively recording that E->dest can be changed to E2->dest
|
are effectively recording that E->dest can be changed to E2->dest
|
after fixing the SSA graph. */
|
after fixing the SSA graph. */
|
|
|
void
|
void
|
register_jump_thread (edge e, edge e2)
|
register_jump_thread (edge e, edge e2)
|
{
|
{
|
if (threaded_edges == NULL)
|
if (threaded_edges == NULL)
|
threaded_edges = VEC_alloc (edge, heap, 10);
|
threaded_edges = VEC_alloc (edge, heap, 10);
|
|
|
VEC_safe_push (edge, heap, threaded_edges, e);
|
VEC_safe_push (edge, heap, threaded_edges, e);
|
VEC_safe_push (edge, heap, threaded_edges, e2);
|
VEC_safe_push (edge, heap, threaded_edges, e2);
|
}
|
}
|
|
|
