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fpu: Check for default_nan_mode before calling pickNaNMulAdd

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If the target sets default_nan_mode then we're always going to return
the default NaN, and pickNaNMulAdd() no longer has any side effects.
For consistency with pickNaN(), check for default_nan_mode before
calling pickNaNMulAdd().

When we convert pickNaNMulAdd() to allow runtime selection of the NaN
propagation rule, this means we won't have to make the targets which
use default_nan_mode also set a propagation rule.

Since RiscV always uses default_nan_mode, this allows us to remove
its ifdef case from pickNaNMulAdd().

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20241202131347.498124-3-peter.maydell@linaro.org
This commit is contained in:
Peter Maydell 2024-12-11 15:30:53 +00:00
parent 8adcff4ae7
commit ed885e3069
2 changed files with 13 additions and 4 deletions
Download patch file Download diff file Expand all files Collapse all files

8
fpu/softfloat-parts.c.inc
View file

@ -77,9 +77,13 @@ static FloatPartsN *partsN(pick_nan_muladd)(FloatPartsN *a, FloatPartsN *b,
float_raise(float_flag_invalid | float_flag_invalid_imz, s);
}
which = pickNaNMulAdd(a->cls, b->cls, c->cls, infzero, s);
if (s->default_nan_mode) {
which = 3;
} else {
which = pickNaNMulAdd(a->cls, b->cls, c->cls, infzero, s);
}
if (s->default_nan_mode || which == 3) {
if (which == 3) {
parts_default_nan(a, s);
return a;
}

9
fpu/softfloat-specialize.c.inc
View file

@ -475,6 +475,13 @@ static int pickNaN(FloatClass a_cls, FloatClass b_cls,
static int pickNaNMulAdd(FloatClass a_cls, FloatClass b_cls, FloatClass c_cls,
bool infzero, float_status *status)
{
/*
* We guarantee not to require the target to tell us how to
* pick a NaN if we're always returning the default NaN.
* But if we're not in default-NaN mode then the target must
* specify.
*/
assert(!status->default_nan_mode);
#if defined(TARGET_ARM)
/* For ARM, the (inf,zero,qnan) case sets InvalidOp and returns
* the default NaN
@ -578,8 +585,6 @@ static int pickNaNMulAdd(FloatClass a_cls, FloatClass b_cls, FloatClass c_cls,
} else {
return 1;
}
#elif defined(TARGET_RISCV)
return 3; /* default NaN */
#elif defined(TARGET_S390X)
if (infzero) {
return 3;