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https://github.com/RPCS3/llvm-mirror.git
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84bd343622
Summary:
In order to avoid calling pow function we generate repeated fmul when n is a
positive or negative whole number.
For each exponent we pre-compute Addition Chains in order to minimize the no.
of fmuls.
Refer: http://wwwhomes.uni-bielefeld.de/achim/addition_chain.html
We pre-compute addition chains for exponents upto 32 (which results in a max of
7 fmuls).
For eg:
4 = 2+2
5 = 2+3
6 = 3+3 and so on
Hence,
pow(x, 4.0) ==> y = fmul x, x
x = fmul y, y
ret x
For negative exponents, we simply compute the reciprocal of the final result.
Note: This transformation is only enabled under fast-math.
Patch by Mandeep Singh Grang <mgrang@codeaurora.org>
Reviewers: weimingz, majnemer, escha, davide, scanon, joerg
Subscribers: probinson, escha, llvm-commits
Differential Revision: http://reviews.llvm.org/D13994
llvm-svn: 254776
121 lines
3.8 KiB
LLVM
121 lines
3.8 KiB
LLVM
; Test that the pow library call simplifier works correctly.
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; RUN: opt -instcombine -S < %s | FileCheck %s
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; Function Attrs: nounwind readnone
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declare double @llvm.pow.f64(double, double)
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declare float @llvm.pow.f32(float, float)
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; pow(x, 4.0f)
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define float @test_simplify_4f(float %x) #0 {
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; CHECK-LABEL: @test_simplify_4f(
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; CHECK-NOT: pow
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; CHECK-NEXT: %1 = fmul float %x, %x
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; CHECK-NEXT: %2 = fmul float %1, %1
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; CHECK-NEXT: ret float %2
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%1 = call float @llvm.pow.f32(float %x, float 4.000000e+00)
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ret float %1
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}
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; pow(x, 3.0)
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define double @test_simplify_3(double %x) #0 {
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; CHECK-LABEL: @test_simplify_3(
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; CHECK-NOT: pow
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; CHECK-NEXT: %1 = fmul double %x, %x
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; CHECK-NEXT: %2 = fmul double %1, %x
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; CHECK-NEXT: ret double %2
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%1 = call double @llvm.pow.f64(double %x, double 3.000000e+00)
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ret double %1
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}
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; pow(x, 4.0)
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define double @test_simplify_4(double %x) #0 {
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; CHECK-LABEL: @test_simplify_4(
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; CHECK-NOT: pow
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; CHECK-NEXT: %1 = fmul double %x, %x
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; CHECK-NEXT: %2 = fmul double %1, %1
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; CHECK-NEXT: ret double %2
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%1 = call double @llvm.pow.f64(double %x, double 4.000000e+00)
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ret double %1
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}
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; pow(x, 15.0)
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define double @test_simplify_15(double %x) #0 {
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; CHECK-LABEL: @test_simplify_15(
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; CHECK-NOT: pow
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; CHECK-NEXT: %1 = fmul double %x, %x
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; CHECK-NEXT: %2 = fmul double %1, %x
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; CHECK-NEXT: %3 = fmul double %2, %2
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; CHECK-NEXT: %4 = fmul double %3, %3
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; CHECK-NEXT: %5 = fmul double %2, %4
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; CHECK-NEXT: ret double %5
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%1 = call double @llvm.pow.f64(double %x, double 1.500000e+01)
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ret double %1
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}
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; pow(x, -7.0)
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define double @test_simplify_neg_7(double %x) #0 {
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; CHECK-LABEL: @test_simplify_neg_7(
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; CHECK-NOT: pow
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; CHECK-NEXT: %1 = fmul double %x, %x
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; CHECK-NEXT: %2 = fmul double %1, %x
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; CHECK-NEXT: %3 = fmul double %1, %2
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; CHECK-NEXT: %4 = fmul double %1, %3
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; CHECK-NEXT: %5 = fdiv double 1.000000e+00, %4
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; CHECK-NEXT: ret double %5
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%1 = call double @llvm.pow.f64(double %x, double -7.000000e+00)
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ret double %1
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}
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; pow(x, -19.0)
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define double @test_simplify_neg_19(double %x) #0 {
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; CHECK-LABEL: @test_simplify_neg_19(
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; CHECK-NOT: pow
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; CHECK-NEXT: %1 = fmul double %x, %x
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; CHECK-NEXT: %2 = fmul double %1, %1
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; CHECK-NEXT: %3 = fmul double %2, %2
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; CHECK-NEXT: %4 = fmul double %3, %3
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; CHECK-NEXT: %5 = fmul double %1, %4
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; CHECK-NEXT: %6 = fmul double %5, %x
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; CHECK-NEXT: %7 = fdiv double 1.000000e+00, %6
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; CHECK-NEXT: ret double %7
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%1 = call double @llvm.pow.f64(double %x, double -1.900000e+01)
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ret double %1
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}
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; pow(x, 11.23)
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define double @test_simplify_11_23(double %x) #0 {
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; CHECK-LABEL: @test_simplify_11_23(
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; CHECK-NOT: fmul
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; CHECK-NEXT: %1 = call double @llvm.pow.f64(double %x, double 1.123000e+01)
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; CHECK-NEXT: ret double %1
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%1 = call double @llvm.pow.f64(double %x, double 1.123000e+01)
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ret double %1
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}
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; pow(x, 32.0)
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define double @test_simplify_32(double %x) #0 {
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; CHECK-LABEL: @test_simplify_32(
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; CHECK-NOT: pow
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; CHECK-NEXT: %1 = fmul double %x, %x
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; CHECK-NEXT: %2 = fmul double %1, %1
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; CHECK-NEXT: %3 = fmul double %2, %2
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; CHECK-NEXT: %4 = fmul double %3, %3
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; CHECK-NEXT: %5 = fmul double %4, %4
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; CHECK-NEXT: ret double %5
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%1 = call double @llvm.pow.f64(double %x, double 3.200000e+01)
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ret double %1
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}
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; pow(x, 33.0)
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define double @test_simplify_33(double %x) #0 {
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; CHECK-LABEL: @test_simplify_33(
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; CHECK-NOT: fmul
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; CHECK-NEXT: %1 = call double @llvm.pow.f64(double %x, double 3.300000e+01)
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; CHECK-NEXT: ret double %1
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%1 = call double @llvm.pow.f64(double %x, double 3.300000e+01)
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ret double %1
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}
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attributes #0 = { nounwind readnone "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="true" "no-nans-fp-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="generic" "target-features"="+neon" "unsafe-fp-math"="true" "use-soft-float"="false" }
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