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Re: [PATCH] PR tree-optimization/102232 Adding a missing pattern to match.pd

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PR tree-optimization/102232

gcc/
	* match.pd (x * (1 + y / x) - y) -> (x - y % x): New optimization.

gcc/testsuite/

	* gcc.dg/tree-ssa/pr102232.c: Testcase for this optimization.
This commit is contained in:
Navid Rahimi 2021-11-22 22:07:35 -05:00 • committed by Jeff Law
parent 630686f93f
commit df1a0d526e
2 changed files with 58 additions and 0 deletions
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6
gcc/match.pd
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@ -651,6 +651,12 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
(if (INTEGRAL_TYPE_P (type) || VECTOR_INTEGER_TYPE_P (type))
(convert (trunc_mod @0 @1))))
/* x * (1 + y / x) - y -> x - y % x */
(simplify
(minus (mult:cs @0 (plus:s (trunc_div:s @1 @0) integer_onep)) @1)
(if (INTEGRAL_TYPE_P (type))
(minus @0 (trunc_mod @1 @0))))
/* Optimize TRUNC_MOD_EXPR by a power of two into a BIT_AND_EXPR,
i.e. "X % C" into "X & (C - 1)", if X and C are positive.
Also optimize A % (C << N) where C is a power of 2,

52
gcc/testsuite/gcc.dg/tree-ssa/pr102232.c Normal file
View file

@ -0,0 +1,52 @@
/* PR tree-optimization/102232 */
/* { dg-do run } */
/* { dg-options "-O -fdump-tree-optimized" } */
int __attribute__ ((noipa)) foo (int a, int b)
{
return b * (1 + a / b) - a;
}
int
main (void)
{
// few randomly generated test cases
if (foo (71856034, 238) != 212)
{
__builtin_abort ();
}
if (foo (71856034, 10909) != 1549)
{
__builtin_abort ();
}
if (foo (20350, 1744) != 578)
{
__builtin_abort ();
}
if (foo (444813, 88563) != 86565)
{
__builtin_abort ();
}
if (foo (112237, 63004) != 13771)
{
__builtin_abort ();
}
if (foo (68268386, 787116) != 210706)
{
__builtin_abort ();
}
if (foo (-444813, 88563) != 90561)
{
__builtin_abort ();
}
if (foo (-68268386, 787116) != 1363526)
{
__builtin_abort ();
}
return 0;
}
/* Verify that multiplication and division has been removed. */
/* { dg-final { scan-tree-dump-not " \\* " "optimized" } } */
/* { dg-final { scan-tree-dump-not " / " "optimized" } } */