Jeff Law wrote:
> >+@item max-fsm-thread-path-insns
> >+Maximum number of instructions to copy when duplicating blocks on a
> >+finite state automaton jump thread path. The default is 100.
> >+
> >+@item max-fsm-thread-length
> >+Maximum number of basic blocks on a finite state automaton jump thread
> >+path. The default is 10.
> >+
> >+@item max-fsm-thread-paths
> >+Maximum number of new jump thread paths to create for a finite state
> >+automaton. The default is 50.
> Has there been any tuning on these defaults. I don't have any
> strong opinions about what they ought to be, this is more to get any
> such information recorded on the lists for historical purposes.
I have not tuned any of these defaults other than making sure that coremark is
still jump-threaded. gcc.dg/tree-ssa/ssa-dom-thread-7.c is a test-case that
will check that we always optimize coremark.
> I think it's worth a note in the debug dump anytime you abort
> threading when you hit a limit.
Done.
> I'm a bit worried about compile-time impacts of the all the
> recursion, but I'm willing to wait and see if it turns out to be a
> problem in practice.
Done, as Richi suggested, checking the flag_expensive_optimizations.
> >@@ -689,6 +692,12 @@ simplify_control_stmt_condition (edge e,
> > pass specific callback to try and simplify it further. */
> > if (cached_lhs && ! is_gimple_min_invariant (cached_lhs))
> > cached_lhs = (*simplify) (stmt, stmt);
> >+
> >+ /* We couldn't find an invariant. But, callers of this
> >+ function may be able to do something useful with the
> >+ unmodified destination. */
> >+ if (!cached_lhs)
> >+ cached_lhs = original_lhs;
> > }
> > else
> > cached_lhs = NULL;
> Can't you just use COND rather than stuffing its value away into
> ORIGINAL_LHS? CACHED_LHS may be better in some cases if it's an
> SSA_NAME (and it should be), but I doubt it matters in practice.
>
> Or is it the case that you have to have the original condition --
> without any context sensitive equivalences used to "simplify" the
> condition.
I think we need to start the search for FSM jump-threads with the original non
simplified condition.
> >+/* Return true if there is at least one path from START_BB to END_BB.
> >+ VISITED_BBS is used to make sure we don't fall into an infinite loop. */
> >+
> >+static bool
> >+fsm_find_thread_path (basic_block start_bb, basic_block end_bb,
> >+ vec<basic_block, va_gc> *&path,
> >+ hash_set<basic_block> *visited_bbs, int n_insns)
> Update comment to indicate how PATH is used to return a path from
> START_BB to END_BB.
Done.
> >+ for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi);
> >+ gsi_next (&gsi))
> >+ ++n_insns;
> Probably don't want to count labels and GIMPLE_NOPs. Probably do
> want to count non-virtual PHIs since those may end up as a copies or
> constant initializations.
Done.
>
> >+ if (j == 0)
> >+ kind = EDGE_START_FSM_THREAD;
> >+ else if (single_pred_p (e->src))
> >+ kind = EDGE_NO_COPY_SRC_BLOCK;
> >+ else {
> >+ kind = EDGE_COPY_SRC_JOINER_BLOCK;
> >+ ++joiners;
> >+ }
> Presumably the mis-formatting was added when you tracked the #
> joiners. AFAICT that is a write-only variable and ought to be
> removed. Along with the braces on the final ELSE which should
> restore proper formatting.
Done.
>
>
> >@@ -2343,6 +2493,55 @@ thread_through_all_blocks (bool may_peel_loop_headers)
> > threaded_blocks = BITMAP_ALLOC (NULL);
> > memset (&thread_stats, 0, sizeof (thread_stats));
> >
> >+ for (i = 0; i < paths.length ();)
> Comment before this loop. I can see what you're doing, but I'm
> already very familiar with this code. Basically what are you
> looking for in this loop and what do you do?
Done.
> Overall I think this is very very close and I really like the
> overall direction. There's a few minor issues noted above and with
> those addressed, I think we should be ready to go.
Thanks for your careful review. Please let me know if there still are things I
can improve in the attached patch.
The path passes bootstrap on x86_64-linux and powerpc64-linux, and regtest
except
a fail I have not seen in the past:
FAIL: gcc.c-torture/compile/pr27571.c -Os (internal compiler error)
I am still investigating why this fails: as far as I can see for now this is
because in copying the FSM path we create an internal loop that is then
discovered by the loop verifier as a natural loop and is not yet in the existing
loop sturctures. I will try to fix this in duplicate_seme by invalidating the
loop structure after we code generated all the FSM paths. I will submit an
updated patch when it passes regtest.
> Removing most of tree-ssa-threadupdate.c and using SEME duplication
> would be a huge step forward for making this code more
> understandable. I look forward to any work you do in this space in
> the future.
I will clean up the patch and I will submit it for review (for stage 1.)
Sebastian
>From 80fe8b173a0ca913d7a51594f99c232885640b8c Mon Sep 17 00:00:00 2001
From: Sebastian Pop <s....@samsung.com>
Date: Fri, 26 Sep 2014 14:54:20 -0500
Subject: [PATCH] extend jump thread for finite state automata PR 54742
Adapted from a patch from James Greenhalgh.
* params.def (max-fsm-thread-path-insns, max-fsm-thread-length,
max-fsm-thread-paths): New.
* doc/invoke.texi (max-fsm-thread-path-insns, max-fsm-thread-length,
max-fsm-thread-paths): Documented.
* tree-cfg.c (split_edge_bb_loc): Export.
* tree-cfg.h (split_edge_bb_loc): Declared extern.
* tree-ssa-threadedge.c (simplify_control_stmt_condition): Restore the
original value of cond when simplification fails.
(fsm_find_thread_path): New.
(fsm_find_control_statement_thread_paths): New.
(fsm_thread_through_normal_block): Call
find_control_statement_thread_paths.
* tree-ssa-threadupdate.c (dump_jump_thread_path): Pretty print
EDGE_FSM_THREAD.
(verify_seme): New.
(duplicate_seme_region): New.
(thread_through_all_blocks): Generate code for EDGE_FSM_THREAD edges
calling duplicate_seme_region.
* tree-ssa-threadupdate.h (jump_thread_edge_type): Add EDGE_FSM_THREAD.
* testsuite/gcc.dg/tree-ssa/ssa-dom-thread-6.c: New.
* testsuite/gcc.dg/tree-ssa/ssa-dom-thread-7.c: New.
---
gcc/doc/invoke.texi | 12 +
gcc/params.def | 15 ++
gcc/testsuite/gcc.dg/tree-ssa/ssa-dom-thread-6.c | 43 ++++
gcc/testsuite/gcc.dg/tree-ssa/ssa-dom-thread-7.c | 127 +++++++++++
gcc/tree-cfg.c | 2 +-
gcc/tree-cfg.h | 1 +
gcc/tree-ssa-threadedge.c | 264 +++++++++++++++++++++-
gcc/tree-ssa-threadupdate.c | 202 ++++++++++++++++-
gcc/tree-ssa-threadupdate.h | 1 +
9 files changed, 664 insertions(+), 3 deletions(-)
create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/ssa-dom-thread-6.c
create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/ssa-dom-thread-7.c
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 89edddb..074183f 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -10624,6 +10624,18 @@ large and significantly increase compile time at optimization level
@option{-O1} and higher. This parameter is a maximum nubmer of statements
in a single generated constructor. Default value is 5000.
+@item max-fsm-thread-path-insns
+Maximum number of instructions to copy when duplicating blocks on a
+finite state automaton jump thread path. The default is 100.
+
+@item max-fsm-thread-length
+Maximum number of basic blocks on a finite state automaton jump thread
+path. The default is 10.
+
+@item max-fsm-thread-paths
+Maximum number of new jump thread paths to create for a finite state
+automaton. The default is 50.
+
@end table
@end table
diff --git a/gcc/params.def b/gcc/params.def
index 9b21c07..edf3f53 100644
--- a/gcc/params.def
+++ b/gcc/params.def
@@ -1140,6 +1140,21 @@ DEFPARAM (PARAM_CHKP_MAX_CTOR_SIZE,
"Maximum number of statements to be included into a single static "
"constructor generated by Pointer Bounds Checker",
5000, 100, 0)
+
+DEFPARAM (PARAM_MAX_FSM_THREAD_PATH_INSNS,
+ "max-fsm-thread-path-insns",
+ "Maximum number of instructions to copy when duplicating blocks on a finite state automaton jump thread path",
+ 100, 1, 999999)
+
+DEFPARAM (PARAM_MAX_FSM_THREAD_LENGTH,
+ "max-fsm-thread-length",
+ "Maximum number of basic blocks on a finite state automaton jump thread path",
+ 10, 1, 999999)
+
+DEFPARAM (PARAM_MAX_FSM_THREAD_PATHS,
+ "max-fsm-thread-paths",
+ "Maximum number of new jump thread paths to create for a finite state automaton",
+ 50, 1, 999999)
/*
Local variables:
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/ssa-dom-thread-6.c b/gcc/testsuite/gcc.dg/tree-ssa/ssa-dom-thread-6.c
new file mode 100644
index 0000000..bb34a74
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/ssa-dom-thread-6.c
@@ -0,0 +1,43 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-dom1-details" } */
+/* { dg-final { scan-tree-dump-times "FSM" 6 "dom1" } } */
+/* { dg-final { cleanup-tree-dump "dom1" } } */
+
+int sum0, sum1, sum2, sum3;
+int foo (char *s, char **ret)
+{
+ int state=0;
+ char c;
+
+ for (; *s && state != 4; s++)
+ {
+ c = *s;
+ if (c == '*')
+ {
+ s++;
+ break;
+ }
+ switch (state)
+ {
+ case 0:
+ if (c == '+')
+ state = 1;
+ else if (c != '-')
+ sum0+=c;
+ break;
+ case 1:
+ if (c == '+')
+ state = 2;
+ else if (c == '-')
+ state = 0;
+ else
+ sum1+=c;
+ break;
+ default:
+ break;
+ }
+
+ }
+ *ret = s;
+ return state;
+}
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/ssa-dom-thread-7.c b/gcc/testsuite/gcc.dg/tree-ssa/ssa-dom-thread-7.c
new file mode 100644
index 0000000..21474f0
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/ssa-dom-thread-7.c
@@ -0,0 +1,127 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-dom1-details" } */
+/* { dg-final { scan-tree-dump-times "FSM" 19 "dom1" } } */
+/* { dg-final { cleanup-tree-dump "dom1" } } */
+
+enum STATE {
+ S0=0,
+ SI,
+ S1,
+ S2,
+ S3,
+ S4,
+ S5,
+ S6
+};
+
+int bar (enum STATE s);
+
+enum STATE foo (unsigned char **y, unsigned *c)
+{
+ unsigned char *x = *y;
+ unsigned char n;
+ enum STATE s = S0;
+
+ for( ; *x && s != SI; x++ )
+ {
+ n = *x;
+ if (n == 'x')
+ {
+ x++;
+ break;
+ }
+ switch(s)
+ {
+ case S0:
+ if(bar(n))
+ s = S3;
+ else if( n == 'a' || n == 'b' )
+ s = S1;
+ else if( n == 'c' )
+ s = S4;
+ else
+ {
+ s = SI;
+ c[SI]++;
+ }
+ c[S0]++;
+ break;
+ case S1:
+ if(bar(n))
+ {
+ s = S3;
+ c[S1]++;
+ }
+ else if( n == 'c' )
+ {
+ s = S4;
+ c[S1]++;
+ }
+ else
+ {
+ s = SI;
+ c[S1]++;
+ }
+ break;
+ case S3:
+ if( n == 'c' )
+ {
+ s = S4;
+ c[S3]++;
+ }
+ else if(!bar(n))
+ {
+ s = SI;
+ c[S3]++;
+ }
+ break;
+ case S4:
+ if( n == 'E' || n == 'e' )
+ {
+ s = S2;
+ c[S4]++;
+ }
+ else if(!bar(n))
+ {
+ s = SI;
+ c[S4]++;
+ }
+ break;
+ case S2:
+ if( n == 'a' || n == 'b' )
+ {
+ s = S5;
+ c[S2]++;
+ }
+ else
+ {
+ s = SI;
+ c[S2]++;
+ }
+ break;
+ case S5:
+ if(bar(n))
+ {
+ s = S6;
+ c[S5]++;
+ }
+ else
+ {
+ s = SI;
+ c[S5]++;
+ }
+ break;
+ case S6:
+ if(!bar(n))
+ {
+ s = SI;
+ c[SI]++;
+ }
+ break;
+ default:
+ break;
+ }
+ }
+ *y=x;
+ return s;
+}
diff --git a/gcc/tree-cfg.c b/gcc/tree-cfg.c
index 0a8d7a9..a4ac9d8 100644
--- a/gcc/tree-cfg.c
+++ b/gcc/tree-cfg.c
@@ -2666,7 +2666,7 @@ reinstall_phi_args (edge new_edge, edge old_edge)
near its "logical" location. This is of most help to humans looking
at debugging dumps. */
-static basic_block
+basic_block
split_edge_bb_loc (edge edge_in)
{
basic_block dest = edge_in->dest;
diff --git a/gcc/tree-cfg.h b/gcc/tree-cfg.h
index d35e5ba..834fa71 100644
--- a/gcc/tree-cfg.h
+++ b/gcc/tree-cfg.h
@@ -67,6 +67,7 @@ extern void verify_gimple_in_cfg (struct function *, bool);
extern tree gimple_block_label (basic_block);
extern void add_phi_args_after_copy_bb (basic_block);
extern void add_phi_args_after_copy (basic_block *, unsigned, edge);
+extern basic_block split_edge_bb_loc (edge);
extern bool gimple_duplicate_sese_region (edge, edge, basic_block *, unsigned,
basic_block *, bool);
extern bool gimple_duplicate_sese_tail (edge, edge, basic_block *, unsigned,
diff --git a/gcc/tree-ssa-threadedge.c b/gcc/tree-ssa-threadedge.c
index 8b0b7b8..a6fb361 100644
--- a/gcc/tree-ssa-threadedge.c
+++ b/gcc/tree-ssa-threadedge.c
@@ -56,6 +56,8 @@ along with GCC; see the file COPYING3. If not see
#include "params.h"
#include "tree-ssa-threadedge.h"
#include "builtins.h"
+#include "cfg.h"
+#include "cfganal.h"
/* To avoid code explosion due to jump threading, we limit the
number of statements we are going to copy. This variable
@@ -661,6 +663,7 @@ simplify_control_stmt_condition (edge e,
rather than use a relational operator. These are simpler to handle. */
if (TREE_CODE (cond) == SSA_NAME)
{
+ tree original_lhs = cond;
cached_lhs = cond;
/* Get the variable's current value from the equivalence chains.
@@ -689,6 +692,12 @@ simplify_control_stmt_condition (edge e,
pass specific callback to try and simplify it further. */
if (cached_lhs && ! is_gimple_min_invariant (cached_lhs))
cached_lhs = (*simplify) (stmt, stmt);
+
+ /* We couldn't find an invariant. But, callers of this
+ function may be able to do something useful with the
+ unmodified destination. */
+ if (!cached_lhs)
+ cached_lhs = original_lhs;
}
else
cached_lhs = NULL;
@@ -948,6 +957,236 @@ thread_around_empty_blocks (edge taken_edge,
return false;
}
+/* Return true if the CFG contains at least one path from START_BB to END_BB.
+ When a path is found, record in PATH the blocks from END_BB to START_BB.
+ VISITED_BBS is used to make sure we don't fall into an infinite loop. */
+
+static bool
+fsm_find_thread_path (basic_block start_bb, basic_block end_bb,
+ vec<basic_block, va_gc> *&path,
+ hash_set<basic_block> *visited_bbs, int n_insns)
+{
+ if (start_bb == end_bb)
+ {
+ vec_safe_push (path, start_bb);
+ return true;
+ }
+
+ if (!visited_bbs->add (start_bb))
+ {
+ edge e;
+ edge_iterator ei;
+ FOR_EACH_EDGE (e, ei, start_bb->succs)
+ if (fsm_find_thread_path (e->dest, end_bb, path, visited_bbs, n_insns))
+ {
+ vec_safe_push (path, start_bb);
+ return true;
+ }
+ }
+
+ return false;
+}
+
+static int max_threaded_paths;
+
+/* We trace the value of the variable EXPR back through any phi nodes looking
+ for places where it gets a constant value and save the path. Stop after
+ having recorded MAX_PATHS jump threading paths. */
+
+static void
+fsm_find_control_statement_thread_paths (tree expr,
+ hash_set<gimple> *visited_phis,
+ vec<basic_block, va_gc> *&path)
+{
+ tree var = SSA_NAME_VAR (expr);
+ gimple def_stmt = SSA_NAME_DEF_STMT (expr);
+ basic_block var_bb = gimple_bb (def_stmt);
+
+ if (var == NULL || var_bb == NULL)
+ return;
+
+ /* For the moment we assume that an SSA chain only contains phi nodes, and
+ eventually one of the phi arguments will be an integer constant. In the
+ future, this could be extended to also handle simple assignments of
+ arithmetic operations. */
+ if (gimple_code (def_stmt) != GIMPLE_PHI)
+ return;
+
+ /* Avoid infinite recursion. */
+ if (visited_phis->add (def_stmt))
+ return;
+
+ gphi *phi = as_a <gphi *> (def_stmt);
+ int next_path_length = 0;
+ basic_block last_bb_in_path = path->last ();
+
+ /* Following the chain of SSA_NAME definitions, we jumped from a definition in
+ LAST_BB_IN_PATH to a definition in VAR_BB. When these basic blocks are
+ different, append to PATH the blocks from LAST_BB_IN_PATH to VAR_BB. */
+ if (var_bb != last_bb_in_path)
+ {
+ edge e;
+ int e_count = 0;
+ edge_iterator ei;
+ vec<basic_block, va_gc> *next_path;
+ vec_alloc (next_path, n_basic_blocks_for_fn (cfun));
+
+ FOR_EACH_EDGE (e, ei, last_bb_in_path->preds)
+ {
+ hash_set<basic_block> *visited_bbs = new hash_set<basic_block>;
+
+ if (fsm_find_thread_path (var_bb, e->src, next_path, visited_bbs, 0))
+ ++e_count;
+
+ delete visited_bbs;
+
+ /* If there is more than one path, stop. */
+ if (e_count > 1)
+ {
+ vec_free (next_path);
+ return;
+ }
+ }
+
+ /* Append all the nodes from NEXT_PATH to PATH. */
+ vec_safe_splice (path, next_path);
+ next_path_length = next_path->length ();
+ vec_free (next_path);
+ }
+
+ gcc_assert (path->last () == var_bb);
+
+ /* Iterate over the arguments of PHI. */
+ unsigned int i;
+ for (i = 0; i < gimple_phi_num_args (phi); i++)
+ {
+ tree arg = gimple_phi_arg_def (phi, i);
+ basic_block bbi = gimple_phi_arg_edge (phi, i)->src;
+
+ /* Skip edges pointing outside the current loop. */
+ if (!arg || var_bb->loop_father != bbi->loop_father)
+ continue;
+
+ if (TREE_CODE (arg) == SSA_NAME)
+ {
+ vec_safe_push (path, bbi);
+ /* Recursively follow SSA_NAMEs looking for a constant definition. */
+ fsm_find_control_statement_thread_paths (arg, visited_phis, path);
+ path->pop ();
+ continue;
+ }
+
+ if (TREE_CODE (arg) != INTEGER_CST)
+ continue;
+
+ int path_length = path->length ();
+ /* A path with less than 2 basic blocks should not be jump-threaded. */
+ if (path_length < 2)
+ continue;
+
+ if (path_length > PARAM_VALUE (PARAM_MAX_FSM_THREAD_LENGTH))
+ {
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ fprintf (dump_file, "FSM jump-thread path not considered: "
+ "the number of basic blocks on the path "
+ "exceeds PARAM_MAX_FSM_THREAD_LENGTH.\n");
+ continue;
+ }
+
+ if (max_threaded_paths <= 0)
+ {
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ fprintf (dump_file, "FSM jump-thread path not considered: "
+ "the number of previously recorded FSM paths to thread "
+ "exceeds PARAM_MAX_FSM_THREAD_PATHS.\n");
+ continue;
+ }
+
+ /* Add BBI to the path. */
+ vec_safe_push (path, bbi);
+ ++path_length;
+
+ int n_insns = 0;
+ gimple_stmt_iterator gsi;
+ int j;
+ loop_p loop = (*path)[0]->loop_father;
+ bool path_crosses_loops = false;
+
+ /* Count the number of instructions on the path: as these instructions
+ will have to be duplicated, we will not record the path if there are
+ too many instructions on the path. Also check that all the blocks in
+ the path belong to a single loop. */
+ for (j = 1; j < path_length - 1; j++)
+ {
+ basic_block bb = (*path)[j];
+
+ if (bb->loop_father != loop)
+ {
+ path_crosses_loops = true;
+ break;
+ }
+
+ for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
+ {
+ gimple stmt = gsi_stmt (gsi);
+ /* Do not count empty statements and labels. */
+ if (gimple_code (stmt) != GIMPLE_NOP
+ && gimple_code (stmt) != GIMPLE_LABEL
+ && !is_gimple_debug (stmt))
+ ++n_insns;
+ }
+ }
+
+ if (path_crosses_loops)
+ {
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ fprintf (dump_file, "FSM jump-thread path not considered: "
+ "the path crosses loops.\n");
+ path->pop ();
+ continue;
+ }
+
+ if (n_insns >= PARAM_VALUE (PARAM_MAX_FSM_THREAD_PATH_INSNS))
+ {
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ fprintf (dump_file, "FSM jump-thread path not considered: "
+ "the number of instructions on the path "
+ "exceeds PARAM_MAX_FSM_THREAD_PATH_INSNS.\n");
+ path->pop ();
+ continue;
+ }
+
+ vec<jump_thread_edge *> *jump_thread_path
+ = new vec<jump_thread_edge *> ();
+
+ /* Record the edges between the blocks in PATH. */
+ for (j = 0; j < path_length - 1; j++)
+ {
+ edge e = find_edge ((*path)[path_length - j - 1],
+ (*path)[path_length - j - 2]);
+ gcc_assert (e);
+ jump_thread_edge *x = new jump_thread_edge (e, EDGE_FSM_THREAD);
+ jump_thread_path->safe_push (x);
+ }
+
+ /* Add the edge taken when the control variable has value ARG. */
+ edge taken_edge = find_taken_edge ((*path)[0], arg);
+ jump_thread_edge *x
+ = new jump_thread_edge (taken_edge, EDGE_NO_COPY_SRC_BLOCK);
+ jump_thread_path->safe_push (x);
+
+ register_jump_thread (jump_thread_path);
+ --max_threaded_paths;
+
+ /* Remove BBI from the path. */
+ path->pop ();
+ }
+
+ /* Remove all the nodes that we added from NEXT_PATH. */
+ if (next_path_length)
+ vec_safe_truncate (path, (path->length () - next_path_length));
+}
+
/* We are exiting E->src, see if E->dest ends with a conditional
jump which has a known value when reached via E.
@@ -1033,7 +1272,10 @@ thread_through_normal_block (edge e,
cond = simplify_control_stmt_condition (e, stmt, dummy_cond, simplify,
handle_dominating_asserts);
- if (cond && is_gimple_min_invariant (cond))
+ if (!cond)
+ return 0;
+
+ if (is_gimple_min_invariant (cond))
{
edge taken_edge = find_taken_edge (e->dest, cond);
basic_block dest = (taken_edge ? taken_edge->dest : NULL);
@@ -1079,6 +1321,26 @@ thread_through_normal_block (edge e,
backedge_seen_p);
return 1;
}
+
+ if (!flag_expensive_optimizations
+ || TREE_CODE (cond) != SSA_NAME
+ || e->dest->loop_father != e->src->loop_father
+ || loop_depth (e->dest->loop_father) == 0)
+ return 0;
+
+ /* When COND cannot be simplified, try to find paths from a control
+ statement back through the PHI nodes which would affect that control
+ statement. */
+ vec<basic_block, va_gc> *bb_path;
+ vec_alloc (bb_path, n_basic_blocks_for_fn (cfun));
+ vec_safe_push (bb_path, e->dest);
+ hash_set<gimple> *visited_phis = new hash_set<gimple>;
+
+ max_threaded_paths = PARAM_VALUE (PARAM_MAX_FSM_THREAD_PATHS);
+ fsm_find_control_statement_thread_paths (cond, visited_phis, bb_path);
+
+ delete visited_phis;
+ vec_free (bb_path);
}
return 0;
}
diff --git a/gcc/tree-ssa-threadupdate.c b/gcc/tree-ssa-threadupdate.c
index ca0b8bf..1dbffee 100644
--- a/gcc/tree-ssa-threadupdate.c
+++ b/gcc/tree-ssa-threadupdate.c
@@ -167,8 +167,9 @@ dump_jump_thread_path (FILE *dump_file, vec<jump_thread_edge *> path,
bool registering)
{
fprintf (dump_file,
- " %s jump thread: (%d, %d) incoming edge; ",
+ " %s%s jump thread: (%d, %d) incoming edge; ",
(registering ? "Registering" : "Cancelling"),
+ (path[0]->type == EDGE_FSM_THREAD ? " FSM": ""),
path[0]->e->src->index, path[0]->e->dest->index);
for (unsigned int i = 1; i < path.length (); i++)
@@ -2317,6 +2318,155 @@ bb_ends_with_multiway_branch (basic_block bb ATTRIBUTE_UNUSED)
return false;
}
+/* Verify that the REGION is a Single Entry Multiple Exits region: make sure no
+ edge other than ENTRY is entering the REGION. */
+
+DEBUG_FUNCTION void
+verify_seme (edge entry, basic_block *region, unsigned n_region)
+{
+ bitmap bbs = BITMAP_ALLOC (NULL);
+
+ for (unsigned i = 0; i < n_region; i++)
+ bitmap_set_bit (bbs, region[i]->index);
+
+ for (unsigned i = 0; i < n_region; i++)
+ {
+ edge e;
+ edge_iterator ei;
+ basic_block bb = region[i];
+
+ /* All predecessors other than ENTRY->src should be in the region. */
+ for (ei = ei_start (bb->preds); (e = ei_safe_edge (ei)); ei_next (&ei))
+ if (e != entry)
+ gcc_assert (bitmap_bit_p (bbs, e->src->index));
+ }
+
+ BITMAP_FREE (bbs);
+}
+
+/* Duplicates a Single Entry Multiple Exit REGION (set of N_REGION basic
+ blocks). The ENTRY edge is redirected to the duplicate of the region. If
+ REGION is not a Single Entry region, ignore any incoming edges other than
+ ENTRY: this makes the copied region a Single Entry region.
+
+ Remove the last conditional statement in the last basic block in the REGION,
+ and create a single fallthru edge pointing to the same destination as the
+ EXIT edge.
+
+ The new basic blocks are stored to REGION_COPY in the same order as they had
+ in REGION, provided that REGION_COPY is not NULL.
+
+ Returns false if it is unable to copy the region, true otherwise. */
+
+static bool
+duplicate_seme_region (edge entry, edge exit,
+ basic_block *region, unsigned n_region,
+ basic_block *region_copy)
+{
+ unsigned i;
+ bool free_region_copy = false, copying_header = false;
+ struct loop *loop = entry->dest->loop_father;
+ edge exit_copy;
+ edge redirected;
+ int total_freq = 0, entry_freq = 0;
+ gcov_type total_count = 0, entry_count = 0;
+
+ if (!can_copy_bbs_p (region, n_region))
+ return false;
+
+ /* Some sanity checking. Note that we do not check for all possible
+ missuses of the functions. I.e. if you ask to copy something weird,
+ it will work, but the state of structures probably will not be
+ correct. */
+ for (i = 0; i < n_region; i++)
+ {
+ /* We do not handle subloops, i.e. all the blocks must belong to the
+ same loop. */
+ if (region[i]->loop_father != loop)
+ return false;
+ }
+
+ initialize_original_copy_tables ();
+
+ if (copying_header)
+ set_loop_copy (loop, loop_outer (loop));
+ else
+ set_loop_copy (loop, loop);
+
+ if (!region_copy)
+ {
+ region_copy = XNEWVEC (basic_block, n_region);
+ free_region_copy = true;
+ }
+
+ if (entry->dest->count)
+ {
+ total_count = entry->dest->count;
+ entry_count = entry->count;
+ /* Fix up corner cases, to avoid division by zero or creation of negative
+ frequencies. */
+ if (entry_count > total_count)
+ entry_count = total_count;
+ }
+ else
+ {
+ total_freq = entry->dest->frequency;
+ entry_freq = EDGE_FREQUENCY (entry);
+ /* Fix up corner cases, to avoid division by zero or creation of negative
+ frequencies. */
+ if (total_freq == 0)
+ total_freq = 1;
+ else if (entry_freq > total_freq)
+ entry_freq = total_freq;
+ }
+
+ copy_bbs (region, n_region, region_copy, &exit, 1, &exit_copy, loop,
+ split_edge_bb_loc (entry), 0);
+ if (total_count)
+ {
+ scale_bbs_frequencies_gcov_type (region, n_region,
+ total_count - entry_count,
+ total_count);
+ scale_bbs_frequencies_gcov_type (region_copy, n_region, entry_count,
+ total_count);
+ }
+ else
+ {
+ scale_bbs_frequencies_int (region, n_region, total_freq - entry_freq,
+ total_freq);
+ scale_bbs_frequencies_int (region_copy, n_region, entry_freq, total_freq);
+ }
+
+#ifdef ENABLE_CHECKING
+ /* Make sure no edge other than ENTRY is entering the copied region. */
+ verify_seme (entry, region_copy, n_region);
+#endif
+
+ /* Remove the last branch in the jump thread path. */
+ remove_ctrl_stmt_and_useless_edges (region_copy[n_region - 1], exit->dest);
+ edge e = make_edge (region_copy[n_region - 1], exit->dest, EDGE_FALLTHRU);
+
+ if (e) {
+ rescan_loop_exit (e, true, false);
+ e->probability = REG_BR_PROB_BASE;
+ e->count = region_copy[n_region - 1]->count;
+ }
+
+ /* Redirect the entry and add the phi node arguments. */
+ redirected = redirect_edge_and_branch (entry, get_bb_copy (entry->dest));
+ gcc_assert (redirected != NULL);
+ flush_pending_stmts (entry);
+
+ /* Add the other PHI node arguments. */
+ add_phi_args_after_copy (region_copy, n_region, NULL);
+
+ if (free_region_copy)
+ free (region_copy);
+
+ free_original_copy_tables ();
+ return true;
+}
+
/* Walk through all blocks and thread incoming edges to the appropriate
outgoing edge for each edge pair recorded in THREADED_EDGES.
@@ -2343,6 +2493,56 @@ thread_through_all_blocks (bool may_peel_loop_headers)
threaded_blocks = BITMAP_ALLOC (NULL);
memset (&thread_stats, 0, sizeof (thread_stats));
+ /* Jump-thread all FSM threads before other jump-threads. */
+ for (i = 0; i < paths.length ();)
+ {
+ vec<jump_thread_edge *> *path = paths[i];
+ edge entry = (*path)[0]->e;
+
+ if ((*path)[0]->type != EDGE_FSM_THREAD
+ /* Do not jump-thread twice from the same block. */
+ || bitmap_bit_p (threaded_blocks, entry->src->index)) {
+ i++;
+ continue;
+ }
+
+ unsigned len = path->length ();
+ edge exit = (*path)[len - 1]->e;
+ basic_block *region = XNEWVEC (basic_block, len - 1);
+
+ for (unsigned int j = 0; j < len - 1; j++)
+ region[j] = (*path)[j]->e->dest;
+
+ if (duplicate_seme_region (entry, exit, region, len - 1, NULL))
+ {
+ /* We do not update dominance info. */
+ free_dominance_info (CDI_DOMINATORS);
+ bitmap_set_bit (threaded_blocks, entry->src->index);
+ }
+
+ delete_jump_thread_path (path);
+ paths.unordered_remove (i);
+ }
+
+ /* Remove from PATHS all the jump-threads starting with an edge already
+ jump-threaded. */
+ for (i = 0; i < paths.length ();)
+ {
+ vec<jump_thread_edge *> *path = paths[i];
+ edge entry = (*path)[0]->e;
+
+ /* Do not jump-thread twice from the same block. */
+ if (bitmap_bit_p (threaded_blocks, entry->src->index))
+ {
+ delete_jump_thread_path (path);
+ paths.unordered_remove (i);
+ }
+ else
+ i++;
+ }
+
+ bitmap_clear (threaded_blocks);
+
mark_threaded_blocks (threaded_blocks);
initialize_original_copy_tables ();
diff --git a/gcc/tree-ssa-threadupdate.h b/gcc/tree-ssa-threadupdate.h
index 426aca5..22c5bce 100644
--- a/gcc/tree-ssa-threadupdate.h
+++ b/gcc/tree-ssa-threadupdate.h
@@ -26,6 +26,7 @@ extern bool thread_through_all_blocks (bool);
enum jump_thread_edge_type
{
EDGE_START_JUMP_THREAD,
+ EDGE_FSM_THREAD,
EDGE_COPY_SRC_BLOCK,
EDGE_COPY_SRC_JOINER_BLOCK,
EDGE_NO_COPY_SRC_BLOCK
--
1.7.10.4
