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53fee0c665
One of the fast-math optimizations is to replace calls to standard double
functions with their float equivalents, e.g. exp -> expf. However, this can
cause infinite loops for the following:
float expf(float val) { return (float) exp((double) val); }
A similar inline declaration exists in the MinGW-w64 math.h header file which
when compiled with -O2/3 and fast-math generates infinite loops.
So this fix checks that the calling function to the standard double function
that is being replaced does not match the float equivalent.
Differential Revision: https://reviews.llvm.org/D31806
llvm-svn: 301304
61 lines
2.7 KiB
LLVM
61 lines
2.7 KiB
LLVM
; RUN: opt -S -instcombine -o - %s | FileCheck %s
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; Test that fast math lib call simplification of double math function to float
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; equivalent doesn't occur when the calling function matches the float
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; equivalent math function. Otherwise this can cause the generation of infinite
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; loops when compiled with -O2/3 and fast math.
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; Test case C source:
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;
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; extern double exp(double x);
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; inline float expf(float x) { return (float) exp((double) x); }
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; float fn(float f) { return expf(f); }
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;
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; IR generated with command:
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;
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; clang -cc1 -O2 -ffast-math -emit-llvm -disable-llvm-passes -triple x86_64-unknown-unknown -o - <srcfile>
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target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
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target triple = "x86_64-unknown-unknown"
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; Function Attrs: nounwind
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define float @fn(float %f) #0 {
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; CHECK: define float @fn(
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; CHECK: call fast float @expf(
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%f.addr = alloca float, align 4
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store float %f, float* %f.addr, align 4, !tbaa !1
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%1 = load float, float* %f.addr, align 4, !tbaa !1
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%call = call fast float @expf(float %1) #3
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ret float %call
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}
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; Function Attrs: inlinehint nounwind readnone
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define available_externally float @expf(float %x) #1 {
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; CHECK: define available_externally float @expf(
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; CHECK: fpext float
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; CHECK: call fast double @exp(
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; CHECK: fptrunc double
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%x.addr = alloca float, align 4
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store float %x, float* %x.addr, align 4, !tbaa !1
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%1 = load float, float* %x.addr, align 4, !tbaa !1
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%conv = fpext float %1 to double
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%call = call fast double @exp(double %conv) #3
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%conv1 = fptrunc double %call to float
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ret float %conv1
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}
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; Function Attrs: nounwind readnone
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declare double @exp(double) #2
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attributes #0 = { nounwind "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "target-features"="+mmx,+sse,+sse2,+x87" "unsafe-fp-math"="false" "use-soft-float"="false" }
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attributes #1 = { inlinehint nounwind readnone "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "target-features"="+mmx,+sse,+sse2,+x87" "unsafe-fp-math"="false" "use-soft-float"="false" }
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attributes #2 = { nounwind readnone }
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!llvm.ident = !{!0}
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!0 = !{!"clang version 5.0.0"}
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!1 = !{!2, !2, i64 0}
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!2 = !{!"float", !3, i64 0}
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!3 = !{!"omnipotent char", !4, i64 0}
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!4 = !{!"Simple C/C++ TBAA"}
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