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re PR middle-end/12392 (very long optimized compile)

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2016-03-30  Michael Matz  <matz@suse.de>
	Richard Biener  <rguenther@suse.de>

	PR ipa/12392
	* ipa-polymorphic-call.c (struct type_change_info): Change
	speculative to an unsigned allowing to limit the work we do.
	(csftc_abort_walking_p): New inline function..
	(check_stmt_for_type_change): Limit the number of may-defs
	skipped for speculative devirtualization to
	max-speculative-devirt-maydefs.
	* params.def (max-speculative-devirt-maydefs): New param.
	* doc/invoke.texi (--param max-speculative-devirt-maydefs): Document.

Co-Authored-By: Richard Biener <rguenther@suse.de>

From-SVN: r234546
This commit is contained in:
Michael Matz 2016-03-30 07:47:40 +00:00 committed by Richard Biener
parent ff734e26c2
commit 9c49362f03
4 changed files with 52 additions and 13 deletions
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13
gcc/ChangeLog
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@ -1,3 +1,16 @@
2016-03-30 Michael Matz <matz@suse.de>
Richard Biener <rguenther@suse.de>
PR ipa/12392
* ipa-polymorphic-call.c (struct type_change_info): Change
speculative to an unsigned allowing to limit the work we do.
(csftc_abort_walking_p): New inline function..
(check_stmt_for_type_change): Limit the number of may-defs
skipped for speculative devirtualization to
max-speculative-devirt-maydefs.
* params.def (max-speculative-devirt-maydefs): New param.
* doc/invoke.texi (--param max-speculative-devirt-maydefs): Document.
2016-03-30 Mike Stump <mrs@gcc.gnu.org>
PR target/63890

5
gcc/doc/invoke.texi
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@ -9601,6 +9601,11 @@ Enable emission of special debug stores within HSA kernels which are
then read and reported by libgomp plugin. Generation of these stores
is disabled by default, use @option{--param hsa-gen-debug-stores=1} to
enable it.
@item max-speculative-devirt-maydefs
The maximum number of may-defs we analyze when looking for a must-def
specifying the dynamic type of an object that invokes a virtual call
we may be able to devirtualize speculatively.
@end table
@end table

41
gcc/ipa-polymorphic-call.c
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@ -38,6 +38,7 @@ along with GCC; see the file COPYING3. If not see
#include "tree-dfa.h"
#include "gimple-pretty-print.h"
#include "tree-into-ssa.h"
#include "params.h"
/* Return true when TYPE contains an polymorphic type and thus is interesting
for devirtualization machinery. */
@ -1094,14 +1095,15 @@ struct type_change_info
tree known_current_type;
HOST_WIDE_INT known_current_offset;
/* Set to nonzero if we possibly missed some dynamic type changes and we
should consider the set to be speculative. */
unsigned speculative;
/* Set to true if dynamic type change has been detected. */
bool type_maybe_changed;
/* Set to true if multiple types have been encountered. known_current_type
must be disregarded in that case. */
bool multiple_types_encountered;
/* Set to true if we possibly missed some dynamic type changes and we should
consider the set to be speculative. */
bool speculative;
bool seen_unanalyzed_store;
};
@ -1338,6 +1340,19 @@ record_known_type (struct type_change_info *tci, tree type, HOST_WIDE_INT offset
tci->type_maybe_changed = true;
}
/* The maximum number of may-defs we visit when looking for a must-def
that changes the dynamic type in check_stmt_for_type_change. Tuned
after the PR12392 testcase which unlimited spends 40% time within
these alias walks and 8% with the following limit. */
static inline bool
csftc_abort_walking_p (unsigned speculative)
{
unsigned max = PARAM_VALUE (PARAM_MAX_SPECULATIVE_DEVIRT_MAYDEFS);
return speculative > max ? true : false;
}
/* Callback of walk_aliased_vdefs and a helper function for
detect_type_change to check whether a particular statement may modify
the virtual table pointer, and if possible also determine the new type of
@ -1384,15 +1399,15 @@ check_stmt_for_type_change (ao_ref *ao ATTRIBUTE_UNUSED, tree vdef, void *data)
&size, &max_size, &reverse);
if (size != max_size || max_size == -1)
{
tci->speculative = true;
return false;
tci->speculative++;
return csftc_abort_walking_p (tci->speculative);
}
if (op && TREE_CODE (op) == MEM_REF)
{
if (!tree_fits_shwi_p (TREE_OPERAND (op, 1)))
{
tci->speculative = true;
return false;
tci->speculative++;
return csftc_abort_walking_p (tci->speculative);
}
offset += tree_to_shwi (TREE_OPERAND (op, 1))
* BITS_PER_UNIT;
@ -1402,8 +1417,8 @@ check_stmt_for_type_change (ao_ref *ao ATTRIBUTE_UNUSED, tree vdef, void *data)
;
else
{
tci->speculative = true;
return false;
tci->speculative++;
return csftc_abort_walking_p (tci->speculative);
}
op = walk_ssa_copies (op);
}
@ -1438,8 +1453,8 @@ check_stmt_for_type_change (ao_ref *ao ATTRIBUTE_UNUSED, tree vdef, void *data)
fprintf (dump_file, " Function call may change dynamic type:");
print_gimple_stmt (dump_file, stmt, 0, 0);
}
tci->speculative = true;
return false;
tci->speculative++;
return csftc_abort_walking_p (tci->speculative);
}
/* Check for inlined virtual table store. */
else if (noncall_stmt_may_be_vtbl_ptr_store (stmt))
@ -1461,7 +1476,7 @@ check_stmt_for_type_change (ao_ref *ao ATTRIBUTE_UNUSED, tree vdef, void *data)
if (dump_file)
fprintf (dump_file, " Unanalyzed store may change type.\n");
tci->seen_unanalyzed_store = true;
tci->speculative = true;
tci->speculative++;
}
else
record_known_type (tci, type, offset);
@ -1646,7 +1661,7 @@ ipa_polymorphic_call_context::get_dynamic_type (tree instance,
tci.otr_type = otr_type;
tci.type_maybe_changed = false;
tci.multiple_types_encountered = false;
tci.speculative = false;
tci.speculative = 0;
tci.seen_unanalyzed_store = false;
walk_aliased_vdefs (&ao, gimple_vuse (stmt), check_stmt_for_type_change,

6
gcc/params.def
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@ -1203,6 +1203,12 @@ DEFPARAM (PARAM_HSA_GEN_DEBUG_STORES,
"hsa-gen-debug-stores",
"Level of hsa debug stores verbosity",
0, 0, 1)
DEFPARAM (PARAM_MAX_SPECULATIVE_DEVIRT_MAYDEFS,
"max-speculative-devirt-maydefs",
"Maximum number of may-defs visited when devirtualizing "
"speculatively", 50, 0, 0)
/*
Local variables: