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Fix fmadd et al. to set FPSCR[VXISI] only if any of the multiply operands

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is an inifinity (2.1.5 -- don't set based on the intermediate result)
This commit is contained in:
gbeauche 2006-07-04 23:20:46 +00:00
parent e020d63591
commit 98dea63921
1 changed files with 16 additions and 5 deletions
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21
SheepShaver/src/kpx_cpu/src/cpu/ppc/ppc-execute.hpp
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@ -346,7 +346,7 @@ template<> struct fp_exception_condition<op_fdiv> : fp_divide_exception_conditio
template< class FP, bool negate >
struct fp_fma_exception_condition {
static inline uint32 apply(FP a, FP b, FP c) {
return
int exceptions =
fp_invalid_operation_condition<FP>::
apply(FPSCR_VXSNAN_field::mask(), a) |
fp_invalid_operation_condition<FP>::
@ -354,10 +354,21 @@ struct fp_fma_exception_condition {
fp_invalid_operation_condition<FP>::
apply(FPSCR_VXSNAN_field::mask(), c) |
fp_invalid_operation_condition<FP>::
apply(FPSCR_VXIMZ_field::mask(), a, b) |
fp_invalid_operation_condition<FP>::
apply(FPSCR_VXISI_field::mask(), a * b, c, negate)
;
apply(FPSCR_VXIMZ_field::mask(), a, b);
// 2.1.5 -- The XER bit definitions are based on the
// operation of an instruction considered as a whole,
// not on intermediate results
if ((isinf(a) || isinf(b)) && isinf(c)) {
FP m = a * b;
if (isinf(m)) {
// make sure the intermediate result is an infinity and not a NaN
// FIXME: it could be faster to use (exceptions & IMZ) == 0 instead of isinf()
if (( negate && (signbit(m) == signbit(c))) ||
(!negate && (signbit(m) != signbit(c))))
exceptions |= FPSCR_VXISI_field::mask();
}
}
return exceptions;
}
};