| Message ID | 20241128104310.3452934-3-peter.maydell@linaro.org (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | fpu: Make pickNaNMulAdd behaviour runtime selected | expand |
On 11/28/24 04:42, Peter Maydell wrote: > 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> > --- > fpu/softfloat-parts.c.inc | 8 ++++++-- > fpu/softfloat-specialize.c.inc | 9 +++++++-- > 2 files changed, 13 insertions(+), 4 deletions(-) Reviewed-by: Richard Henderson <richard.henderson@linaro.org> r~
diff --git a/fpu/softfloat-parts.c.inc b/fpu/softfloat-parts.c.inc index d63cd957a19..aac1f9cd28c 100644 --- a/fpu/softfloat-parts.c.inc +++ b/fpu/softfloat-parts.c.inc @@ -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; } diff --git a/fpu/softfloat-specialize.c.inc b/fpu/softfloat-specialize.c.inc index c557c41b2af..81a67eb67b5 100644 --- a/fpu/softfloat-specialize.c.inc +++ b/fpu/softfloat-specialize.c.inc @@ -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;
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> --- fpu/softfloat-parts.c.inc | 8 ++++++-- fpu/softfloat-specialize.c.inc | 9 +++++++-- 2 files changed, 13 insertions(+), 4 deletions(-)