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Teach VRP to register assertions along default switch labels (PR18046) 

gcc/ChangeLog:

	PR tree-optimization/18046
	* genmodes.c (emit_mode_size_inline): Emit an assert that
	verifies that mode is a valid array index.
	(emit_mode_nuinits_inline): Likewise.
	(emit_mode_inner_inline): Likewise.
	(emit_mode_unit_size_inline): Likewise.
	(emit_mode_unit_precision_inline): Likewise.
	* tree-vrp.c: Include params.h.
	(find_switch_asserts): Register edge assertions for the default
	label which correspond to the anti-ranges of each case label.
	* params.def (PARAM_MAX_VRP_SWITCH_ASSERTIONS): New.
	* doc/invoke.texi: Document it.

gcc/testsuite/ChangeLog:

	PR tree-optimization/18046
	* gcc.dg/tree-ssa/ssa-dom-thread-6.c: Bump FSM count to 5.
	* gcc.dg/tree-ssa/vrp103.c: New test.
	* gcc.dg/tree-ssa/vrp104.c: New test.

From-SVN: r238761
This commit is contained in:
Patrick Palka 2016-07-26 15:19:58 +00:00
parent 100665d8d7
commit 524cf1e47a
9 changed files with 164 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

15
gcc/ChangeLog
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@ -1,3 +1,18 @@
2016-07-26 Patrick Palka <ppalka@gcc.gnu.org>
PR tree-optimization/18046
* genmodes.c (emit_mode_size_inline): Emit an assert that
verifies that mode is a valid array index.
(emit_mode_nuinits_inline): Likewise.
(emit_mode_inner_inline): Likewise.
(emit_mode_unit_size_inline): Likewise.
(emit_mode_unit_precision_inline): Likewise.
* tree-vrp.c: Include params.h.
(find_switch_asserts): Register edge assertions for the default
label which correspond to the anti-ranges of each case label.
* params.def (PARAM_MAX_VRP_SWITCH_ASSERTIONS): New.
* doc/invoke.texi: Document it.
2016-07-26 Bill Schmidt <wschmidt@linux.vnet.ibm.com>
* gimple-ssa-strength-reduction.c (slsr_process_phi): Remove dead

4
gcc/doc/invoke.texi
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@ -9781,6 +9781,10 @@ enable it.
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.
@item max-vrp-switch-assertions
The maximum number of assertions to add along the default edge of a switch
statement during VRP. The default is 10.
@end table
@end table

5
gcc/genmodes.c
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@ -976,6 +976,7 @@ unsigned char\n\
mode_size_inline (machine_mode mode)\n\
{\n\
extern %sunsigned char mode_size[NUM_MACHINE_MODES];\n\
gcc_assert (mode >= 0 && mode < NUM_MACHINE_MODES);\n\
switch (mode)\n\
{\n", adj_bytesize ? "" : "const ");
@ -1006,6 +1007,7 @@ unsigned char\n\
mode_nunits_inline (machine_mode mode)\n\
{\n\
extern const unsigned char mode_nunits[NUM_MACHINE_MODES];\n\
gcc_assert (mode >= 0 && mode < NUM_MACHINE_MODES);\n\
switch (mode)\n\
{");
@ -1035,6 +1037,7 @@ unsigned char\n\
mode_inner_inline (machine_mode mode)\n\
{\n\
extern const unsigned char mode_inner[NUM_MACHINE_MODES];\n\
gcc_assert (mode >= 0 && mode < NUM_MACHINE_MODES);\n\
switch (mode)\n\
{");
@ -1067,6 +1070,7 @@ mode_unit_size_inline (machine_mode mode)\n\
{\n\
extern CONST_MODE_UNIT_SIZE unsigned char mode_unit_size[NUM_MACHINE_MODES];\
\n\
gcc_assert (mode >= 0 && mode < NUM_MACHINE_MODES);\n\
switch (mode)\n\
{");
@ -1103,6 +1107,7 @@ unsigned short\n\
mode_unit_precision_inline (machine_mode mode)\n\
{\n\
extern const unsigned short mode_unit_precision[NUM_MACHINE_MODES];\n\
gcc_assert (mode >= 0 && mode < NUM_MACHINE_MODES);\n\
switch (mode)\n\
{");

6
gcc/params.def
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@ -1246,6 +1246,12 @@ DEFPARAM (PARAM_MAX_SPECULATIVE_DEVIRT_MAYDEFS,
"Maximum number of may-defs visited when devirtualizing "
"speculatively", 50, 0, 0)
DEFPARAM (PARAM_MAX_VRP_SWITCH_ASSERTIONS,
"max-vrp-switch-assertions",
"Maximum number of assertions to add along the default "
"edge of a switch statement during VRP",
10, 0, 0)
/*
Local variables:

7
gcc/testsuite/ChangeLog
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@ -1,3 +1,10 @@
2016-07-26 Patrick Palka <ppalka@gcc.gnu.org>
PR tree-optimization/18046
* gcc.dg/tree-ssa/ssa-dom-thread-6.c: Bump FSM count to 5.
* gcc.dg/tree-ssa/vrp103.c: New test.
* gcc.dg/tree-ssa/vrp104.c: New test.
2016-07-26 Bill Schmidt <wschmidt@linux.vnet.ibm.com>
* gcc.target/powerpc/pr63354.c: Require lp64 since

2
gcc/testsuite/gcc.dg/tree-ssa/ssa-dom-thread-6.c
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@ -1,7 +1,7 @@
/* { dg-do compile } */
/* { dg-options "-O2 -fdump-tree-thread1-details -fdump-tree-thread2-details" } */
/* { dg-final { scan-tree-dump-times "FSM" 3 "thread1" } } */
/* { dg-final { scan-tree-dump-times "FSM" 4 "thread2" } } */
/* { dg-final { scan-tree-dump-times "FSM" 5 "thread2" } } */
int sum0, sum1, sum2, sum3;
int foo (char *s, char **ret)

30
gcc/testsuite/gcc.dg/tree-ssa/vrp103.c Normal file
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@ -0,0 +1,30 @@
/* PR tree-optimization/18046 */
/* { dg-options "-O2 -fdump-tree-vrp" } */
/* { dg-final { scan-tree-dump-times "baz \\(0\\);" 4 "vrp1" } } */
void foo (void);
void bar (void);
void baz (int);
void
test (int i)
{
switch (i)
{
case 1:
case 2:
case 3:
foo ();
break;
case 5:
bar ();
break;
default:
/* These tests should be folded to 0, resulting in 4 calls of baz(0). */
baz (i == 1);
baz (i == 2);
baz (i == 3);
baz (i == 5);
break;
}
}

36
gcc/testsuite/gcc.dg/tree-ssa/vrp104.c Normal file
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@ -0,0 +1,36 @@
/* PR tree-optimization/18046 */
/* { dg-options "-O2 -fdump-tree-optimized" } */
/* { dg-final { scan-tree-dump-times "switch" 1 "optimized" } } */
void foo (void);
void bar (void);
void baz (void);
void
test (int i)
{
switch (i)
{
case 1:
foo ();
break;
case 2:
bar ();
break;
default:
break;
}
/* This switch should be gone after threading/VRP. */
switch (i)
{
case 1:
foo ();
break;
case 2:
baz ();
break;
default:
break;
}
}

62
gcc/tree-vrp.c
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@ -58,6 +58,7 @@ along with GCC; see the file COPYING3. If not see
#include "omp-low.h"
#include "target.h"
#include "case-cfn-macros.h"
#include "params.h"
/* Range of values that can be associated with an SSA_NAME after VRP
has executed. */
@ -5917,6 +5918,7 @@ find_switch_asserts (basic_block bb, gswitch *last)
ci[idx].expr = gimple_switch_label (last, idx);
ci[idx].bb = label_to_block (CASE_LABEL (ci[idx].expr));
}
edge default_edge = find_edge (bb, ci[0].bb);
qsort (ci, n, sizeof (struct case_info), compare_case_labels);
for (idx = 0; idx < n; ++idx)
@ -5945,8 +5947,8 @@ find_switch_asserts (basic_block bb, gswitch *last)
max = CASE_LOW (ci[idx].expr);
}
/* Nothing to do if the range includes the default label until we
can register anti-ranges. */
/* Can't extract a useful assertion out of a range that includes the
default label. */
if (min == NULL_TREE)
continue;
@ -5964,6 +5966,62 @@ find_switch_asserts (basic_block bb, gswitch *last)
}
XDELETEVEC (ci);
if (!live_on_edge (default_edge, op))
return;
/* Now register along the default label assertions that correspond to the
anti-range of each label. */
int insertion_limit = PARAM_VALUE (PARAM_MAX_VRP_SWITCH_ASSERTIONS);
for (idx = 1; idx < n; idx++)
{
tree min, max;
tree cl = gimple_switch_label (last, idx);
min = CASE_LOW (cl);
max = CASE_HIGH (cl);
/* Combine contiguous case ranges to reduce the number of assertions
to insert. */
for (idx = idx + 1; idx < n; idx++)
{
tree next_min, next_max;
tree next_cl = gimple_switch_label (last, idx);
next_min = CASE_LOW (next_cl);
next_max = CASE_HIGH (next_cl);
wide_int difference = wi::sub (next_min, max ? max : min);
if (wi::eq_p (difference, 1))
max = next_max ? next_max : next_min;
else
break;
}
idx--;
if (max == NULL_TREE)
{
/* Register the assertion OP != MIN. */
min = fold_convert (TREE_TYPE (op), min);
register_edge_assert_for (op, default_edge, bsi, NE_EXPR, op, min);
}
else
{
/* Register the assertion (unsigned)OP - MIN > (MAX - MIN),
which will give OP the anti-range ~[MIN,MAX]. */
tree uop = fold_convert (unsigned_type_for (TREE_TYPE (op)), op);
min = fold_convert (TREE_TYPE (uop), min);
max = fold_convert (TREE_TYPE (uop), max);
tree lhs = fold_build2 (MINUS_EXPR, TREE_TYPE (uop), uop, min);
tree rhs = int_const_binop (MINUS_EXPR, max, min);
register_new_assert_for (op, lhs, GT_EXPR, rhs,
NULL, default_edge, bsi);
}
if (--insertion_limit == 0)
break;
}
}