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62ad0a5cf3
As noted in the D44909 review, the transform from (fptosi+sitofp) to ftrunc
can produce -0.0 where the original code does not:
#include <stdio.h>
int main(int argc) {
float x;
x = -0.8 * argc;
printf("%f\n", (float)((int)x));
return 0;
}
$ clang -O0 -mavx fp.c ; ./a.out
0.000000
$ clang -O1 -mavx fp.c ; ./a.out
-0.000000
Ideally, we'd use IR/node flags to predicate the transform, but the IR parser
doesn't currently allow fast-math-flags on the cast instructions. So for now,
just use the function attribute that corresponds to clang's "-fno-signed-zeros"
option.
Differential Revision: https://reviews.llvm.org/D48085
llvm-svn: 335761
67 lines
1.4 KiB
LLVM
67 lines
1.4 KiB
LLVM
; RUN: llc -verify-machineinstrs -mcpu=a2 < %s | FileCheck %s -check-prefix=FPCVT
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; RUN: llc -verify-machineinstrs -mcpu=ppc64 < %s | FileCheck %s -check-prefix=PPC64
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target datalayout = "E-m:e-i64:64-n32:64"
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target triple = "powerpc64-unknown-linux-gnu"
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; Function Attrs: nounwind readnone
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define float @fool(float %X) #0 {
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entry:
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%conv = fptosi float %X to i64
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%conv1 = sitofp i64 %conv to float
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ret float %conv1
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; FPCVT-LABEL: @fool
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; FPCVT: friz 1, 1
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; FPCVT: blr
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; PPC64-LABEL: @fool
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; PPC64: fctidz [[REG1:[0-9]+]], 1
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; PPC64: fcfid [[REG2:[0-9]+]], [[REG1]]
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; PPC64: frsp 1, [[REG2]]
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; PPC64: blr
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}
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; Function Attrs: nounwind readnone
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define double @foodl(double %X) #0 {
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entry:
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%conv = fptosi double %X to i64
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%conv1 = sitofp i64 %conv to double
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ret double %conv1
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; FPCVT-LABEL: @foodl
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; FPCVT: friz 1, 1
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; FPCVT: blr
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; PPC64-LABEL: @foodl
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; PPC64: fctidz [[REG1:[0-9]+]], 1
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; PPC64: fcfid 1, [[REG1]]
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; PPC64: blr
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}
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; Function Attrs: nounwind readnone
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define float @fooul(float %X) #0 {
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entry:
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%conv = fptoui float %X to i64
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%conv1 = uitofp i64 %conv to float
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ret float %conv1
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; FPCVT-LABEL: @fooul
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; FPCVT: friz 1, 1
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; FPCVT: blr
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}
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; Function Attrs: nounwind readnone
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define double @fooudl(double %X) #0 {
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entry:
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%conv = fptoui double %X to i64
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%conv1 = uitofp i64 %conv to double
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ret double %conv1
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; FPCVT-LABEL: @fooudl
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; FPCVT: friz 1, 1
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; FPCVT: blr
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}
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attributes #0 = { nounwind readnone "no-signed-zeros-fp-math"="true" }
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