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match.pd: Guard 2 simplifications on integral TYPE_OVERFLOW_UNDEFINED [PR114090]

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These 2 patterns are incorrect on floating point, or for -fwrapv, or
for -ftrapv, or the first one for unsigned types (the second one is
mathematically correct, but we ought to just fold that to 0 instead).

So, the following patch properly guards this.

I think we don't need && !TYPE_OVERFLOW_SANITIZED (type) because
in both simplifications there would be UB before and after on
signed integer minimum.

2024-02-26  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/114090
	* match.pd ((x >= 0 ? x : 0) + (x <= 0 ? -x : 0) -> abs x):
	Restrict pattern to ANY_INTEGRAL_TYPE_P and TYPE_OVERFLOW_UNDEFINED
	types.
	((x <= 0 ? -x : 0) -> max(-x, 0)): Likewise.

	* gcc.dg/pr114090.c: New test.
This commit is contained in:
Jakub Jelinek 2024-02-26 10:08:45 +01:00
parent f9d2a95be5
commit 24aa051af7
2 changed files with 44 additions and 4 deletions
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10
gcc/match.pd
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@ -453,8 +453,9 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
/* (x >= 0 ? x : 0) + (x <= 0 ? -x : 0) -> abs x. */
(simplify
(plus:c (max @0 integer_zerop) (max (negate @0) integer_zerop))
(abs @0))
(plus:c (max @0 integer_zerop) (max (negate @0) integer_zerop))
(if (ANY_INTEGRAL_TYPE_P (type) && TYPE_OVERFLOW_UNDEFINED (type))
(abs @0)))
/* X * 1, X / 1 -> X. */
(for op (mult trunc_div ceil_div floor_div round_div exact_div)
@ -4218,8 +4219,9 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
/* (x <= 0 ? -x : 0) -> max(-x, 0). */
(simplify
(cond (le @0 integer_zerop@1) (negate@2 @0) integer_zerop@1)
(max @2 @1))
(cond (le @0 integer_zerop@1) (negate@2 @0) integer_zerop@1)
(if (ANY_INTEGRAL_TYPE_P (type) && TYPE_OVERFLOW_UNDEFINED (type))
(max @2 @1)))
/* (zero_one == 0) ? y : z <op> y -> ((typeof(y))zero_one * z) <op> y */
(for op (bit_xor bit_ior plus)

38
gcc/testsuite/gcc.dg/pr114090.c Normal file
View file

@ -0,0 +1,38 @@
/* PR tree-optimization/114090 */
/* { dg-do run } */
/* { dg-options "-O2 -fwrapv" } */
__attribute__((noipa)) int
foo (int x)
{
int w = (x >= 0 ? x : 0);
int y = -x;
int z = (y >= 0 ? y : 0);
return w + z;
}
__attribute__((noipa)) int
bar (int x)
{
int w = (x >= 0 ? x : 0);
int z = (x <= 0 ? -x : 0);
return w + z;
}
__attribute__((noipa)) int
baz (int x)
{
return x <= 0 ? -x : 0;
}
int
main ()
{
int v = -__INT_MAX__ - 1;
if (foo (v) != 0)
__builtin_abort ();
if (bar (v) != v)
__builtin_abort ();
if (baz (v) != v)
__builtin_abort ();
}