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simplify-rtx: Fix up last argument to simplify_gen_unary [PR113656]

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When simplifying e.g. (float_truncate:SF (float_truncate:DF (reg:XF))
or (float_truncate:SF (float_extend:XF (reg:DF)) etc. into
(float_truncate:SF (reg:XF)) or (float_truncate:SF (reg:DF)) we call
simplify_gen_unary with incorrect op_mode argument, it should be
the argument's mode, but we call it with the outer mode instead.
As these are all floating point operations, the argument always
has non-VOIDmode and so we can just use that mode (as done in similar
simplifications a few lines later), but neither FLOAT_TRUNCATE nor
FLOAT_EXTEND are operations that should have the same modes of operand
and result.  This bug hasn't been a problem for years because normally
op_mode is used only if the mode of op is VOIDmode, otherwise it is
redundant, but r10-2139 added an assertion in some spots that op_mode
is right even in such cases.

2024-01-31  Jakub Jelinek  <jakub@redhat.com>

	PR rtl-optimization/113656
	* simplify-rtx.cc (simplify_context::simplify_unary_operation_1)
	<case FLOAT_TRUNCATE>: Fix up last argument to simplify_gen_unary.

	* gcc.target/i386/pr113656.c: New test.
This commit is contained in:
Jakub Jelinek 2024-01-31 10:56:56 +01:00
parent 457d2b59b5
commit b59775b642
2 changed files with 13 additions and 1 deletions
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2
gcc/simplify-rtx.cc
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@ -1305,7 +1305,7 @@ simplify_context::simplify_unary_operation_1 (rtx_code code, machine_mode mode,
> GET_MODE_UNIT_SIZE (mode)
? FLOAT_TRUNCATE : FLOAT_EXTEND,
mode,
XEXP (op, 0), mode);
XEXP (op, 0), GET_MODE (XEXP (op, 0)));
/* (float_truncate (float x)) is (float x) */
if ((GET_CODE (op) == FLOAT || GET_CODE (op) == UNSIGNED_FLOAT)

12
gcc/testsuite/gcc.target/i386/pr113656.c Normal file
View file

@ -0,0 +1,12 @@
/* PR rtl-optimization/113656 */
/* { dg-do compile } */
/* { dg-options "-O3 -frounding-math -funsafe-math-optimizations -mavx512fp16 -mavx512vl" } */
_Float16 a[8];
void
foo ()
{
for (int i = 0; i < 8; i++)
a[i] = i - 8.4;
}