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8g: respect ullman numbers in float comparison

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Fixes #602.

R=ken2
CC=golang-dev
https://golang.org/cl/212045
This commit is contained in:
Russ Cox 2010-02-17 15:28:45 -08:00
parent 7b76175a1c
commit fb5506600f
2 changed files with 47 additions and 8 deletions
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22
src/cmd/8g/cgen.c
View File

@ -848,7 +848,7 @@ bgen(Node *n, int true, Prog *to)
} }
if(isslice(nl->type)) { if(isslice(nl->type)) {
// only valid to cmp darray to literal nil // front end should only leave cmp to literal nil
if((a != OEQ && a != ONE) || nr->op != OLITERAL) { if((a != OEQ && a != ONE) || nr->op != OLITERAL) {
yyerror("illegal array comparison"); yyerror("illegal array comparison");
break; break;
@ -867,7 +867,7 @@ bgen(Node *n, int true, Prog *to)
} }
if(isinter(nl->type)) { if(isinter(nl->type)) {
// front end shold only leave cmp to literal nil // front end should only leave cmp to literal nil
if((a != OEQ && a != ONE) || nr->op != OLITERAL) { if((a != OEQ && a != ONE) || nr->op != OLITERAL) {
yyerror("illegal interface comparison"); yyerror("illegal interface comparison");
break; break;
@ -899,10 +899,16 @@ bgen(Node *n, int true, Prog *to)
nodreg(&ax, types[TUINT16], D_AX); nodreg(&ax, types[TUINT16], D_AX);
et = simsimtype(nr->type); et = simsimtype(nr->type);
if(et == TFLOAT64) { if(et == TFLOAT64) {
// easy - do in FPU if(nl->ullman > nr->ullman) {
cgen(nr, &tmp); cgen(nl, &tmp);
cgen(nl, &tmp); cgen(nr, &tmp);
gins(AFUCOMPP, &tmp, &n2); gins(AFXCHD, &tmp, &n2);
} else {
cgen(nr, &tmp);
cgen(nl, &tmp);
}
gins(AFUCOMIP, &tmp, &n2);
gins(AFMOVDP, &tmp, &tmp); // annoying pop but still better than STSW+SAHF
} else { } else {
// TODO(rsc): The moves back and forth to memory // TODO(rsc): The moves back and forth to memory
// here are for truncating the value to 32 bits. // here are for truncating the value to 32 bits.
@ -916,9 +922,9 @@ bgen(Node *n, int true, Prog *to)
cgen(nl, &t2); cgen(nl, &t2);
gmove(&t2, &tmp); gmove(&t2, &tmp);
gins(AFCOMFP, &t1, &tmp); gins(AFCOMFP, &t1, &tmp);
gins(AFSTSW, N, &ax);
gins(ASAHF, N, N);
} }
gins(AFSTSW, N, &ax);
gins(ASAHF, N, N);
if(a == OEQ) { if(a == OEQ) {
// neither NE nor P // neither NE nor P
p1 = gbranch(AJNE, T); p1 = gbranch(AJNE, T);

33
test/fixedbugs/bug258.go Normal file
View File

@ -0,0 +1,33 @@
// $G $D/$F.go && $L $F.$A && ./$A.out
// Copyright 2010 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package main
import "math"
func f() float64 {
math.Pow(2, 2)
return 1
}
func main() {
for i := 0; i < 10; i++ {
// 386 float register bug used to load constant before call
if -5 < f() {
} else {
println("BUG 1")
return
}
if f() > -7 {
} else {
println("BUG 2")
}
if math.Pow(2, 3) != 8 {
println("BUG 3")
}
}
}