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expansion: Use __trunchfbf2 calls rather than __extendhfbf2 [PR114907]

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The HF and BF modes have the same size/precision and neither is
a subset nor superset of the other.
So, using either __extendhfbf2 or __trunchfbf2 is weird.
The expansion apparently emits __extendhfbf2, but on the libgcc side
we apparently have __trunchfbf2 implemented.

I think it is easier to switch to using what is available rather than
adding new entrypoints to libgcc, even alias, because this is backportable.

2024-05-07  Jakub Jelinek  <jakub@redhat.com>

	PR middle-end/114907
	* expr.cc (convert_mode_scalar): Use trunc_optab rather than
	sext_optab for HF->BF conversions.
	* optabs-libfuncs.cc (gen_trunc_conv_libfunc): Likewise.

	* gcc.dg/pr114907.c: New test.

(cherry picked from commit 28ee13db2e9d995bd3728c4ff3a3545e24b39cd2)
This commit is contained in:
Jakub Jelinek 2024-05-07 21:30:21 +02:00
parent aca573ea64
commit f43f346f19
3 changed files with 40 additions and 3 deletions
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12
gcc/expr.cc
View file

@ -355,8 +355,16 @@ convert_mode_scalar (rtx to, rtx from, int unsignedp)
&& REAL_MODE_FORMAT (from_mode) == &ieee_half_format));
if (GET_MODE_PRECISION (from_mode) == GET_MODE_PRECISION (to_mode))
/* Conversion between decimal float and binary float, same size. */
tab = DECIMAL_FLOAT_MODE_P (from_mode) ? trunc_optab : sext_optab;
{
if (REAL_MODE_FORMAT (to_mode) == &arm_bfloat_half_format
&& REAL_MODE_FORMAT (from_mode) == &ieee_half_format)
/* libgcc implements just __trunchfbf2, not __extendhfbf2. */
tab = trunc_optab;
else
/* Conversion between decimal float and binary float, same
size. */
tab = DECIMAL_FLOAT_MODE_P (from_mode) ? trunc_optab : sext_optab;
}
else if (GET_MODE_PRECISION (from_mode) < GET_MODE_PRECISION (to_mode))
tab = sext_optab;
else

4
gcc/optabs-libfuncs.cc
View file

@ -589,7 +589,9 @@ gen_trunc_conv_libfunc (convert_optab tab,
if (GET_MODE_CLASS (float_tmode) != GET_MODE_CLASS (float_fmode))
gen_interclass_conv_libfunc (tab, opname, float_tmode, float_fmode);
if (GET_MODE_PRECISION (float_fmode) <= GET_MODE_PRECISION (float_tmode))
if (GET_MODE_PRECISION (float_fmode) <= GET_MODE_PRECISION (float_tmode)
&& (REAL_MODE_FORMAT (float_tmode) != &arm_bfloat_half_format
|| REAL_MODE_FORMAT (float_fmode) != &ieee_half_format))
return;
if (GET_MODE_CLASS (float_tmode) == GET_MODE_CLASS (float_fmode))

27
gcc/testsuite/gcc.dg/pr114907.c Normal file
View file

@ -0,0 +1,27 @@
/* PR middle-end/114907 */
/* { dg-do run } */
/* { dg-options "" } */
/* { dg-add-options float16 } */
/* { dg-require-effective-target float16_runtime } */
/* { dg-add-options bfloat16 } */
/* { dg-require-effective-target bfloat16_runtime } */
__attribute__((noipa)) _Float16
foo (__bf16 x)
{
return (_Float16) x;
}
__attribute__((noipa)) __bf16
bar (_Float16 x)
{
return (__bf16) x;
}
int
main ()
{
if (foo (11.125bf16) != 11.125f16
|| bar (11.125f16) != 11.125bf16)
__builtin_abort ();
}