[llvm] r340947 - [InstCombine] Expand the simplification of pow() into exp2()
Reid Kleckner via llvm-commits
llvm-commits at lists.llvm.org
Wed Aug 29 15:50:19 PDT 2018
My bisection shows that this broke the clang stage 2 build:
http://lab.llvm.org:8011/builders/clang-x86-windows-msvc2015/builds/13525
We end up with references to __unnamed_1 globals that are unresolved. I'll
revert and get a reproducer.
On Wed, Aug 29, 2018 at 11:00 AM Evandro Menezes via llvm-commits <
llvm-commits at lists.llvm.org> wrote:
> Author: evandro
> Date: Wed Aug 29 10:59:34 2018
> New Revision: 340947
>
> URL: http://llvm.org/viewvc/llvm-project?rev=340947&view=rev
> Log:
> [InstCombine] Expand the simplification of pow() into exp2()
>
> Generalize the simplification of `pow(2.0, y)` to `pow(2.0 ** n, y)` for
> all
> scalar and vector types.
>
> This improvement helps some benchmarks in SPEC CPU2000 and CPU2006, such as
> 252.eon, 447.dealII, 453.povray. Otherwise, no significant regressions on
> x86-64 or A64.
>
> Differential revision: https://reviews.llvm.org/D49273
>
> Modified:
> llvm/trunk/lib/Transforms/Utils/SimplifyLibCalls.cpp
> llvm/trunk/test/Transforms/InstCombine/pow-1.ll
>
> Modified: llvm/trunk/lib/Transforms/Utils/SimplifyLibCalls.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/SimplifyLibCalls.cpp?rev=340947&r1=340946&r2=340947&view=diff
>
> ==============================================================================
> --- llvm/trunk/lib/Transforms/Utils/SimplifyLibCalls.cpp (original)
> +++ llvm/trunk/lib/Transforms/Utils/SimplifyLibCalls.cpp Wed Aug 29
> 10:59:34 2018
> @@ -13,6 +13,7 @@
>
> //===----------------------------------------------------------------------===//
>
> #include "llvm/Transforms/Utils/SimplifyLibCalls.h"
> +#include "llvm/ADT/APSInt.h"
> #include "llvm/ADT/SmallString.h"
> #include "llvm/ADT/StringMap.h"
> #include "llvm/ADT/Triple.h"
> @@ -1183,12 +1184,13 @@ static Value *getPow(Value *InnerChain[3
> }
>
> /// Use exp{,2}(x * y) for pow(exp{,2}(x), y);
> -/// exp2(x) for pow(2.0, x); exp10(x) for pow(10.0, x).
> +/// exp2(n * x) for pow(2.0 ** n, x); exp10(x) for pow(10.0, x).
> Value *LibCallSimplifier::replacePowWithExp(CallInst *Pow, IRBuilder<>
> &B) {
> Value *Base = Pow->getArgOperand(0), *Expo = Pow->getArgOperand(1);
> AttributeList Attrs = Pow->getCalledFunction()->getAttributes();
> Module *Mod = Pow->getModule();
> Type *Ty = Pow->getType();
> + bool Ignored;
>
> // Evaluate special cases related to a nested function as the base.
>
> @@ -1232,10 +1234,28 @@ Value *LibCallSimplifier::replacePowWith
>
> // Evaluate special cases related to a constant base.
>
> - // pow(2.0, x) -> exp2(x)
> - if (match(Base, m_SpecificFP(2.0))) {
> - Value *Exp2 = Intrinsic::getDeclaration(Mod, Intrinsic::exp2, Ty);
> - return B.CreateCall(Exp2, Expo, "exp2");
> + const APFloat *BaseF;
> + if (!match(Pow->getArgOperand(0), m_APFloat(BaseF)))
> + return nullptr;
> +
> + // pow(2.0 ** n, x) -> exp2(n * x)
> + APFloat BaseR = APFloat(1.0);
> + BaseR.convert(BaseF->getSemantics(), APFloat::rmTowardZero, &Ignored);
> + BaseR = BaseR / *BaseF;
> + bool IsInteger = BaseF->isInteger(),
> + IsReciprocal = BaseR.isInteger();
> + const APFloat *NF = IsReciprocal ? &BaseR : BaseF;
> + APSInt NI(64, false);
> + if ((IsInteger || IsReciprocal) &&
> + !NF->convertToInteger(NI, APFloat::rmTowardZero, &Ignored) &&
> + NI > 1 && NI.isPowerOf2()) {
> + double N = NI.logBase2() * (IsReciprocal ? -1.0 : 1.0);
> + Value *FMul = B.CreateFMul(Expo, ConstantFP::get(Ty, N), "mul");
> + if (Pow->doesNotAccessMemory())
> + return B.CreateCall(Intrinsic::getDeclaration(Mod, Intrinsic::exp2,
> Ty),
> + FMul, "exp2");
> + else
> + return emitUnaryFloatFnCall(FMul, TLI->getName(LibFunc_exp2), B,
> Attrs);
> }
>
> // pow(10.0, x) -> exp10(x)
>
> Modified: llvm/trunk/test/Transforms/InstCombine/pow-1.ll
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/pow-1.ll?rev=340947&r1=340946&r2=340947&view=diff
>
> ==============================================================================
> --- llvm/trunk/test/Transforms/InstCombine/pow-1.ll (original)
> +++ llvm/trunk/test/Transforms/InstCombine/pow-1.ll Wed Aug 29 10:59:34
> 2018
> @@ -16,6 +16,7 @@
>
> declare float @powf(float, float) nounwind readonly
> declare double @pow(double, double) nounwind readonly
> +declare double @llvm.pow.f64(double, double)
> declare <2 x float> @llvm.pow.v2f32(<2 x float>, <2 x float>) nounwind
> readonly
> declare <2 x double> @llvm.pow.v2f64(<2 x double>, <2 x double>) nounwind
> readonly
>
> @@ -57,18 +58,18 @@ define <2 x double> @test_simplify2v(<2
>
> define float @test_simplify3(float %x) {
> ; ANY-LABEL: @test_simplify3(
> -; ANY-NEXT: [[EXP2:%.*]] = call float @llvm.exp2.f32(float [[X:%.*]])
> -; ANY-NEXT: ret float [[EXP2]]
> +; ANY-NEXT: [[EXP2F:%.*]] = call float @exp2f(float [[X:%.*]])
> [[NUW_RO:#[0-9]+]]
> +; ANY-NEXT: ret float [[EXP2F]]
> ;
> %retval = call float @powf(float 2.0, float %x)
> ret float %retval
> }
>
> -; TODO: Should result in exp2(-2.0 * x).
> define double @test_simplify3n(double %x) {
> ; ANY-LABEL: @test_simplify3n(
> -; ANY-NEXT: [[RETVAL:%.*]] = call double @pow(double 2.500000e-01,
> double [[X:%.*]])
> -; ANY-NEXT: ret double [[RETVAL]]
> +; ANY-NEXT: [[MUL:%.*]] = fmul double [[X:%.*]], -2.000000e+00
> +; ANY-NEXT: [[EXP2:%.*]] = call double @exp2(double [[MUL]]) [[NUW_RO]]
> +; ANY-NEXT: ret double [[EXP2]]
> ;
> %retval = call double @pow(double 0.25, double %x)
> ret double %retval
> @@ -83,11 +84,11 @@ define <2 x float> @test_simplify3v(<2 x
> ret <2 x float> %retval
> }
>
> -; TODO: Should result in exp2(2.0 * x).
> define <2 x double> @test_simplify3vn(<2 x double> %x) {
> ; ANY-LABEL: @test_simplify3vn(
> -; ANY-NEXT: [[RETVAL:%.*]] = call <2 x double> @llvm.pow.v2f64(<2 x
> double> <double 4.000000e+00, double 4.000000e+00>, <2 x double> [[X:%.*]])
> -; ANY-NEXT: ret <2 x double> [[RETVAL]]
> +; ANY-NEXT: [[MUL:%.*]] = fmul <2 x double> [[X:%.*]], <double
> 2.000000e+00, double 2.000000e+00>
> +; ANY-NEXT: [[EXP2:%.*]] = call <2 x double> @llvm.exp2.v2f64(<2 x
> double> [[MUL]])
> +; ANY-NEXT: ret <2 x double> [[EXP2]]
> ;
> %retval = call <2 x double> @llvm.pow.v2f64(<2 x double> <double 4.0,
> double 4.0>, <2 x double> %x)
> ret <2 x double> %retval
> @@ -95,18 +96,18 @@ define <2 x double> @test_simplify3vn(<2
>
> define double @test_simplify4(double %x) {
> ; ANY-LABEL: @test_simplify4(
> -; ANY-NEXT: [[EXP2:%.*]] = call double @llvm.exp2.f64(double [[X:%.*]])
> +; ANY-NEXT: [[EXP2:%.*]] = call double @exp2(double [[X:%.*]])
> [[NUW_RO]]
> ; ANY-NEXT: ret double [[EXP2]]
> ;
> %retval = call double @pow(double 2.0, double %x)
> ret double %retval
> }
>
> -; TODO: Should result in exp2f(3.0 * x).
> define float @test_simplify4n(float %x) {
> ; ANY-LABEL: @test_simplify4n(
> -; ANY-NEXT: [[RETVAL:%.*]] = call float @powf(float 8.000000e+00,
> float [[X:%.*]])
> -; ANY-NEXT: ret float [[RETVAL]]
> +; ANY-NEXT: [[MUL:%.*]] = fmul float [[X:%.*]], 3.000000e+00
> +; ANY-NEXT: [[EXP2F:%.*]] = call float @exp2f(float [[MUL]]) [[NUW_RO]]
> +; ANY-NEXT: ret float [[EXP2F]]
> ;
> %retval = call float @powf(float 8.0, float %x)
> ret float %retval
> @@ -121,11 +122,11 @@ define <2 x double> @test_simplify4v(<2
> ret <2 x double> %retval
> }
>
> -; TODO: Should result in exp2f(-x).
> define <2 x float> @test_simplify4vn(<2 x float> %x) {
> ; ANY-LABEL: @test_simplify4vn(
> -; ANY-NEXT: [[RETVAL:%.*]] = call <2 x float> @llvm.pow.v2f32(<2 x
> float> <float 5.000000e-01, float 5.000000e-01>, <2 x float> [[X:%.*]])
> -; ANY-NEXT: ret <2 x float> [[RETVAL]]
> +; ANY-NEXT: [[MUL:%.*]] = fsub <2 x float> <float -0.000000e+00, float
> -0.000000e+00>, [[X:%.*]]
> +; ANY-NEXT: [[EXP2:%.*]] = call <2 x float> @llvm.exp2.v2f32(<2 x
> float> [[MUL]])
> +; ANY-NEXT: ret <2 x float> [[EXP2]]
> ;
> %retval = call <2 x float> @llvm.pow.v2f32(<2 x float> <float 0.5,
> float 0.5>, <2 x float> %x)
> ret <2 x float> %retval
> @@ -169,7 +170,7 @@ define <2 x double> @test_simplify6v(<2
>
> define float @test_simplify7(float %x) {
> ; ANY-LABEL: @test_simplify7(
> -; ANY-NEXT: [[SQRTF:%.*]] = call float @sqrtf(float [[X:%.*]])
> [[NUW_RO:#[0-9]+]]
> +; ANY-NEXT: [[SQRTF:%.*]] = call float @sqrtf(float [[X:%.*]])
> [[NUW_RO]]
> ; ANY-NEXT: [[ABS:%.*]] = call float @llvm.fabs.f32(float [[SQRTF]])
> ; ANY-NEXT: [[ISINF:%.*]] = fcmp oeq float [[X]], 0xFFF0000000000000
> ; ANY-NEXT: [[TMP1:%.*]] = select i1 [[ISINF]], float
> 0x7FF0000000000000, float [[ABS]]
> @@ -330,7 +331,6 @@ define <2 x double> @pow_neg1_double_fas
> ret <2 x double> %r
> }
>
> -declare double @llvm.pow.f64(double %Val, double %Power)
> define double @test_simplify17(double %x) {
> ; ANY-LABEL: @test_simplify17(
> ; ANY-NEXT: [[SQRT:%.*]] = call double @llvm.sqrt.f64(double [[X:%.*]])
>
>
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