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authorJoseph Myers <joseph@codesourcery.com>2020-06-08 16:57:16 +0000
committerPaolo Bonzini <pbonzini@redhat.com>2020-06-26 09:39:38 -0400
commit445810ec915687d37b8ae0ef8d7340ab4a153efa (patch)
treebc84f9b462e85bf3340972ca57a14be6da92e233 /fpu
parent566601f1f9d972e44214696d3cb320e6c18880aa (diff)
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softfloat: return low bits of quotient from floatx80_modrem
Both x87 and m68k need the low parts of the quotient for their remainder operations. Arrange for floatx80_modrem to track those bits and return them via a pointer. The architectures using float32_rem and float64_rem do not appear to need this information, so the *_rem interface is left unchanged and the information returned only from floatx80_modrem. The logic used to determine the low 7 bits of the quotient for m68k (target/m68k/fpu_helper.c:make_quotient) appears completely bogus (it looks at the result of converting the remainder to integer, the quotient having been discarded by that point); this patch does not change that, but the m68k maintainers may wish to do so. Signed-off-by: Joseph Myers <joseph@codesourcery.com> Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Message-Id: <alpine.DEB.2.21.2006081656500.23637@digraph.polyomino.org.uk> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'fpu')
-rw-r--r--fpu/softfloat.c23
1 files changed, 18 insertions, 5 deletions
diff --git a/fpu/softfloat.c b/fpu/softfloat.c
index 1ee3342..79be4f5 100644
--- a/fpu/softfloat.c
+++ b/fpu/softfloat.c
@@ -5699,10 +5699,11 @@ floatx80 floatx80_div(floatx80 a, floatx80 b, float_status *status)
| `a' with respect to the corresponding value `b'. The operation is performed
| according to the IEC/IEEE Standard for Binary Floating-Point Arithmetic,
| if 'mod' is false; if 'mod' is true, return the remainder based on truncating
-| the quotient toward zero instead.
+| the quotient toward zero instead. '*quotient' is set to the low 64 bits of
+| the absolute value of the integer quotient.
*----------------------------------------------------------------------------*/
-floatx80 floatx80_modrem(floatx80 a, floatx80 b, bool mod,
+floatx80 floatx80_modrem(floatx80 a, floatx80 b, bool mod, uint64_t *quotient,
float_status *status)
{
bool aSign, zSign;
@@ -5710,6 +5711,7 @@ floatx80 floatx80_modrem(floatx80 a, floatx80 b, bool mod,
uint64_t aSig0, aSig1, bSig;
uint64_t q, term0, term1, alternateASig0, alternateASig1;
+ *quotient = 0;
if (floatx80_invalid_encoding(a) || floatx80_invalid_encoding(b)) {
float_raise(float_flag_invalid, status);
return floatx80_default_nan(status);
@@ -5768,7 +5770,7 @@ floatx80 floatx80_modrem(floatx80 a, floatx80 b, bool mod,
shift128Right( aSig0, 0, 1, &aSig0, &aSig1 );
expDiff = 0;
}
- q = ( bSig <= aSig0 );
+ *quotient = q = ( bSig <= aSig0 );
if ( q ) aSig0 -= bSig;
expDiff -= 64;
while ( 0 < expDiff ) {
@@ -5778,6 +5780,8 @@ floatx80 floatx80_modrem(floatx80 a, floatx80 b, bool mod,
sub128( aSig0, aSig1, term0, term1, &aSig0, &aSig1 );
shortShift128Left( aSig0, aSig1, 62, &aSig0, &aSig1 );
expDiff -= 62;
+ *quotient <<= 62;
+ *quotient += q;
}
expDiff += 64;
if ( 0 < expDiff ) {
@@ -5791,6 +5795,12 @@ floatx80 floatx80_modrem(floatx80 a, floatx80 b, bool mod,
++q;
sub128( aSig0, aSig1, term0, term1, &aSig0, &aSig1 );
}
+ if (expDiff < 64) {
+ *quotient <<= expDiff;
+ } else {
+ *quotient = 0;
+ }
+ *quotient += q;
}
else {
term1 = 0;
@@ -5805,6 +5815,7 @@ floatx80 floatx80_modrem(floatx80 a, floatx80 b, bool mod,
aSig0 = alternateASig0;
aSig1 = alternateASig1;
zSign = ! zSign;
+ ++*quotient;
}
}
return
@@ -5821,7 +5832,8 @@ floatx80 floatx80_modrem(floatx80 a, floatx80 b, bool mod,
floatx80 floatx80_rem(floatx80 a, floatx80 b, float_status *status)
{
- return floatx80_modrem(a, b, false, status);
+ uint64_t quotient;
+ return floatx80_modrem(a, b, false, &quotient, status);
}
/*----------------------------------------------------------------------------
@@ -5832,7 +5844,8 @@ floatx80 floatx80_rem(floatx80 a, floatx80 b, float_status *status)
floatx80 floatx80_mod(floatx80 a, floatx80 b, float_status *status)
{
- return floatx80_modrem(a, b, true, status);
+ uint64_t quotient;
+ return floatx80_modrem(a, b, true, &quotient, status);
}
/*----------------------------------------------------------------------------