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[PATCH] tree-scalar-evolution.c: Handle LSHIFT by constant 

gcc/:

	PR tree-optimization/65963
	* tree-scalar-evolution.c (interpret_rhs_expr): Try to handle
	LSHIFT_EXPRs as equivalent unsigned MULT_EXPRs.

gcc/testsuite/:

	* gcc.dg/pr68112.c: New.
	* gcc.dg/vect/vect-strided-shift-1.c: New.

From-SVN: r229825
This commit is contained in:
Alan Lawrence 2015-11-05 18:39:38 +00:00 committed by Alan Lawrence
parent bfcfbfa0d1
commit 60f2d2f36d
5 changed files with 72 additions and 0 deletions
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6
gcc/ChangeLog
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@ -1,3 +1,9 @@
2015-11-05 Alan Lawrence <alan.lawrence@arm.com>
PR tree-optimization/65963
* tree-scalar-evolution.c (interpret_rhs_expr): Try to handle
LSHIFT_EXPRs as equivalent unsigned MULT_EXPRs.
2015-11-05 James Greenhalgh <james.greenhalgh@arm.com>
* ifcvt.c (bb_ok_for_noce_convert_multiple_sets): New.

5
gcc/testsuite/ChangeLog
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@ -1,3 +1,8 @@
2015-11-05 Alan Lawrence <alan.lawrence@arm.com>
* gcc.dg/pr68112.c: New.
* gcc.dg/vect/vect-strided-shift-1.c: New.
2015-11-05 Marek Polacek <polacek@redhat.com>
PR c/68090

11
gcc/testsuite/gcc.dg/pr68112.c Normal file
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@ -0,0 +1,11 @@
/* { dg-do compile } */
/* { dg-options "-O2 -Waggressive-loop-optimizations" } */
int *a;
void
foo ()
{
for (int i = 0; i < 65536; i++)
*a = i << 24;
}

33
gcc/testsuite/gcc.dg/vect/vect-strided-shift-1.c Normal file
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@ -0,0 +1,33 @@
/* PR tree-optimization/65963. */
#include "tree-vect.h"
#define N 512
int in[2*N], out[N];
__attribute__ ((noinline)) void
loop (void)
{
for (int i = 0; i < N; i++)
out[i] = in[i << 1] + 7;
}
int
main (int argc, char **argv)
{
check_vect ();
for (int i = 0; i < 2*N; i++)
{
in[i] = i;
__asm__ volatile ("" : : : "memory");
}
loop ();
__asm__ volatile ("" : : : "memory");
for (int i = 0; i < N; i++)
{
if (out[i] != i*2 + 7)
abort ();
}
return 0;
}
/* { dg-final { scan-tree-dump-times "vectorized 1 loops in function" 1 "vect" { target { vect_strided2 } } } } */

17
gcc/tree-scalar-evolution.c
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@ -1827,6 +1827,23 @@ interpret_rhs_expr (struct loop *loop, gimple *at_stmt,
res = chrec_fold_multiply (type, chrec1, chrec2);
break;
case LSHIFT_EXPR:
{
/* Handle A<<B as A * (1<<B). */
tree uns = unsigned_type_for (type);
chrec1 = analyze_scalar_evolution (loop, rhs1);
chrec2 = analyze_scalar_evolution (loop, rhs2);
chrec1 = chrec_convert (uns, chrec1, at_stmt);
chrec1 = instantiate_parameters (loop, chrec1);
chrec2 = instantiate_parameters (loop, chrec2);
tree one = build_int_cst (uns, 1);
chrec2 = fold_build2 (LSHIFT_EXPR, uns, one, chrec2);
res = chrec_fold_multiply (uns, chrec1, chrec2);
res = chrec_convert (type, res, at_stmt);
}
break;
CASE_CONVERT:
/* In case we have a truncation of a widened operation that in
the truncated type has undefined overflow behavior analyze