[llvm] r365637 - [InstCombine] pow(C,x) -> exp2(log2(C)*x)
David Bolvansky via llvm-commits
llvm-commits at lists.llvm.org
Wed Jul 10 07:43:28 PDT 2019
Author: xbolva00
Date: Wed Jul 10 07:43:27 2019
New Revision: 365637
URL: http://llvm.org/viewvc/llvm-project?rev=365637&view=rev
Log:
[InstCombine] pow(C,x) -> exp2(log2(C)*x)
Summary:
Transform
pow(C,x)
To
exp2(log2(C)*x)
if C > 0, C != inf, C != NaN (and C is not power of 2, since we have some fold for such case already).
log(C) is folded by the compiler and exp2 is much faster to compute than pow.
Reviewers: spatel, efriedma, evandro
Reviewed By: evandro
Subscribers: lebedev.ri, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D64099
Modified:
llvm/trunk/lib/Transforms/Utils/SimplifyLibCalls.cpp
llvm/trunk/test/Transforms/InstCombine/pow-exp.ll
llvm/trunk/test/Transforms/InstCombine/pow_fp_int.ll
Modified: llvm/trunk/lib/Transforms/Utils/SimplifyLibCalls.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/SimplifyLibCalls.cpp?rev=365637&r1=365636&r2=365637&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Utils/SimplifyLibCalls.cpp (original)
+++ llvm/trunk/lib/Transforms/Utils/SimplifyLibCalls.cpp Wed Jul 10 07:43:27 2019
@@ -1235,7 +1235,8 @@ static Value *getPow(Value *InnerChain[3
}
/// Use exp{,2}(x * y) for pow(exp{,2}(x), y);
-/// exp2(n * x) for pow(2.0 ** n, x); exp10(x) for pow(10.0, x).
+/// exp2(n * x) for pow(2.0 ** n, x); exp10(x) for pow(10.0, x);
+/// exp2(log2(C)*x) for pow(C,x).
Value *LibCallSimplifier::replacePowWithExp(CallInst *Pow, IRBuilder<> &B) {
Value *Base = Pow->getArgOperand(0), *Expo = Pow->getArgOperand(1);
AttributeList Attrs = Pow->getCalledFunction()->getAttributes();
@@ -1347,6 +1348,28 @@ Value *LibCallSimplifier::replacePowWith
return emitUnaryFloatFnCall(Expo, TLI, LibFunc_exp10, LibFunc_exp10f,
LibFunc_exp10l, B, Attrs);
+ // pow(C,x) -> exp2(log2(C)*x)
+ if (Pow->hasOneUse() && Pow->hasApproxFunc() && Pow->hasNoNaNs() &&
+ Pow->hasNoInfs() && BaseF->isNormal() && !BaseF->isNegative()) {
+ Value *Log = nullptr;
+ if (Ty->isFloatTy())
+ Log = ConstantFP::get(Ty, std::log2(BaseF->convertToFloat()));
+ else if (Ty->isDoubleTy())
+ Log = ConstantFP::get(Ty, std::log2(BaseF->convertToDouble()));
+
+ if (Log) {
+ Value *FMul = B.CreateFMul(Log, Expo, "mul");
+ if (Pow->doesNotAccessMemory()) {
+ return B.CreateCall(Intrinsic::getDeclaration(Mod, Intrinsic::exp2, Ty),
+ FMul, "exp2");
+ } else {
+ if (hasUnaryFloatFn(TLI, Ty, LibFunc_exp2, LibFunc_exp2f,
+ LibFunc_exp2l))
+ return emitUnaryFloatFnCall(FMul, TLI, LibFunc_exp2, LibFunc_exp2f,
+ LibFunc_exp2l, B, Attrs);
+ }
+ }
+ }
return nullptr;
}
Modified: llvm/trunk/test/Transforms/InstCombine/pow-exp.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/pow-exp.ll?rev=365637&r1=365636&r2=365637&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/pow-exp.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/pow-exp.ll Wed Jul 10 07:43:27 2019
@@ -205,13 +205,16 @@ define double @function_pointer(double (
ret double %pow
}
+; pow(C,x) -> exp2(log2(C)*x)
+
declare void @use_d(double)
declare void @use_f(float)
define double @pow_ok_base(double %e) {
; CHECK-LABEL: @pow_ok_base(
-; CHECK-NEXT: [[CALL:%.*]] = tail call nnan ninf afn double @pow(double 0x3FE6666666666666, double [[E:%.*]])
-; CHECK-NEXT: ret double [[CALL]]
+; CHECK-NEXT: [[MUL:%.*]] = fmul nnan ninf afn double [[E:%.*]], 0xBFE0776228967D13
+; CHECK-NEXT: [[EXP2:%.*]] = call nnan ninf afn double @exp2(double [[MUL]])
+; CHECK-NEXT: ret double [[EXP2]]
;
%call = tail call afn nnan ninf double @pow(double 0x3FE6666666666666, double %e)
ret double %call
@@ -219,8 +222,9 @@ define double @pow_ok_base(double %e) {
define double @pow_ok_base_fast(double %e) {
; CHECK-LABEL: @pow_ok_base_fast(
-; CHECK-NEXT: [[CALL:%.*]] = tail call fast double @pow(double 0x3FE6666666666666, double [[E:%.*]])
-; CHECK-NEXT: ret double [[CALL]]
+; CHECK-NEXT: [[MUL:%.*]] = fmul fast double [[E:%.*]], 0xBFE0776228967D13
+; CHECK-NEXT: [[EXP2:%.*]] = call fast double @exp2(double [[MUL]])
+; CHECK-NEXT: ret double [[EXP2]]
;
%call = tail call fast double @pow(double 0x3FE6666666666666, double %e)
ret double %call
@@ -228,8 +232,9 @@ define double @pow_ok_base_fast(double %
define double @pow_ok_base2(double %e) {
; CHECK-LABEL: @pow_ok_base2(
-; CHECK-NEXT: [[CALL:%.*]] = tail call nnan ninf afn double @pow(double 1.770000e+01, double [[E:%.*]])
-; CHECK-NEXT: ret double [[CALL]]
+; CHECK-NEXT: [[MUL:%.*]] = fmul nnan ninf afn double [[E:%.*]], 0x4010952C788751AC
+; CHECK-NEXT: [[EXP2:%.*]] = call nnan ninf afn double @exp2(double [[MUL]])
+; CHECK-NEXT: ret double [[EXP2]]
;
%call = tail call afn nnan ninf double @pow(double 1.770000e+01, double %e)
ret double %call
@@ -237,8 +242,9 @@ define double @pow_ok_base2(double %e) {
define double @pow_ok_base3(double %e) {
; CHECK-LABEL: @pow_ok_base3(
-; CHECK-NEXT: [[CALL:%.*]] = tail call nnan ninf afn double @pow(double 1.010000e+01, double [[E:%.*]])
-; CHECK-NEXT: ret double [[CALL]]
+; CHECK-NEXT: [[MUL:%.*]] = fmul nnan ninf afn double [[E:%.*]], 0x400AB0B5584886CD
+; CHECK-NEXT: [[EXP2:%.*]] = call nnan ninf afn double @exp2(double [[MUL]])
+; CHECK-NEXT: ret double [[EXP2]]
;
%call = tail call afn nnan ninf double @pow(double 1.010000e+01, double %e)
ret double %call
@@ -246,8 +252,9 @@ define double @pow_ok_base3(double %e) {
define double @pow_ok_ten_base(double %e) {
; CHECK-LABEL: @pow_ok_ten_base(
-; CHECK-NEXT: [[CALL:%.*]] = tail call nnan ninf afn double @pow(double 1.000000e+01, double [[E:%.*]])
-; CHECK-NEXT: ret double [[CALL]]
+; CHECK-NEXT: [[MUL:%.*]] = fmul nnan ninf afn double [[E:%.*]], 0x400A934F0979A371
+; CHECK-NEXT: [[EXP2:%.*]] = call nnan ninf afn double @exp2(double [[MUL]])
+; CHECK-NEXT: ret double [[EXP2]]
;
%call = tail call afn nnan ninf double @pow(double 1.000000e+01, double %e)
ret double %call
@@ -255,8 +262,9 @@ define double @pow_ok_ten_base(double %e
define float @powf_ok_base(float %e) {
; CHECK-LABEL: @powf_ok_base(
-; CHECK-NEXT: [[CALL:%.*]] = tail call nnan ninf afn float @powf(float 0x3FE6666660000000, float [[E:%.*]])
-; CHECK-NEXT: ret float [[CALL]]
+; CHECK-NEXT: [[MUL:%.*]] = fmul nnan ninf afn float [[E:%.*]], 0xBFE0776240000000
+; CHECK-NEXT: [[EXP2F:%.*]] = call nnan ninf afn float @exp2f(float [[MUL]])
+; CHECK-NEXT: ret float [[EXP2F]]
;
%call = tail call afn nnan ninf float @powf(float 0x3FE6666660000000, float %e)
ret float %call
@@ -264,8 +272,9 @@ define float @powf_ok_base(float %e) {
define float @powf_ok_base2(float %e) {
; CHECK-LABEL: @powf_ok_base2(
-; CHECK-NEXT: [[CALL:%.*]] = tail call nnan ninf afn float @powf(float 0x4031B33340000000, float [[E:%.*]])
-; CHECK-NEXT: ret float [[CALL]]
+; CHECK-NEXT: [[MUL:%.*]] = fmul nnan ninf afn float [[E:%.*]], 0x4010952C80000000
+; CHECK-NEXT: [[EXP2F:%.*]] = call nnan ninf afn float @exp2f(float [[MUL]])
+; CHECK-NEXT: ret float [[EXP2F]]
;
%call = tail call afn nnan ninf float @powf(float 0x4031B33340000000, float %e)
ret float %call
@@ -273,8 +282,9 @@ define float @powf_ok_base2(float %e) {
define float @powf_ok_base3(float %e) {
; CHECK-LABEL: @powf_ok_base3(
-; CHECK-NEXT: [[CALL:%.*]] = tail call nnan ninf afn float @powf(float 0x4024333340000000, float [[E:%.*]])
-; CHECK-NEXT: ret float [[CALL]]
+; CHECK-NEXT: [[MUL:%.*]] = fmul nnan ninf afn float [[E:%.*]], 0x400AB0B560000000
+; CHECK-NEXT: [[EXP2F:%.*]] = call nnan ninf afn float @exp2f(float [[MUL]])
+; CHECK-NEXT: ret float [[EXP2F]]
;
%call = tail call afn nnan ninf float @powf(float 0x4024333340000000, float %e)
ret float %call
@@ -282,13 +292,16 @@ define float @powf_ok_base3(float %e) {
define float @powf_ok_ten_base(float %e) {
; CHECK-LABEL: @powf_ok_ten_base(
-; CHECK-NEXT: [[CALL:%.*]] = tail call nnan ninf afn float @powf(float 1.000000e+01, float [[E:%.*]])
-; CHECK-NEXT: ret float [[CALL]]
+; CHECK-NEXT: [[MUL:%.*]] = fmul nnan ninf afn float [[E:%.*]], 0x400A934F00000000
+; CHECK-NEXT: [[EXP2F:%.*]] = call nnan ninf afn float @exp2f(float [[MUL]])
+; CHECK-NEXT: ret float [[EXP2F]]
;
%call = tail call afn nnan ninf float @powf(float 1.000000e+01, float %e)
ret float %call
}
+; Negative tests
+
define double @pow_zero_base(double %e) {
; CHECK-LABEL: @pow_zero_base(
; CHECK-NEXT: [[CALL:%.*]] = tail call nnan ninf afn double @pow(double 0.000000e+00, double [[E:%.*]])
Modified: llvm/trunk/test/Transforms/InstCombine/pow_fp_int.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/pow_fp_int.ll?rev=365637&r1=365636&r2=365637&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/pow_fp_int.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/pow_fp_int.ll Wed Jul 10 07:43:27 2019
@@ -196,8 +196,9 @@ define double @powf_exp_const2_int_fast(
define double @pow_uitofp_const_base_fast_i32(i32 %x) {
; CHECK-LABEL: @pow_uitofp_const_base_fast_i32(
; CHECK-NEXT: [[SUBFP:%.*]] = uitofp i32 [[X:%.*]] to float
-; CHECK-NEXT: [[POW:%.*]] = tail call fast float @llvm.pow.f32(float 7.000000e+00, float [[SUBFP]])
-; CHECK-NEXT: [[RES:%.*]] = fpext float [[POW]] to double
+; CHECK-NEXT: [[MUL:%.*]] = fmul fast float [[SUBFP]], 0x4006757680000000
+; CHECK-NEXT: [[EXP2:%.*]] = call fast float @llvm.exp2.f32(float [[MUL]])
+; CHECK-NEXT: [[RES:%.*]] = fpext float [[EXP2]] to double
; CHECK-NEXT: ret double [[RES]]
;
%subfp = uitofp i32 %x to float
@@ -247,8 +248,9 @@ define double @pow_uitofp_double_base_fa
define double @pow_sitofp_const_base_fast_i64(i64 %x) {
; CHECK-LABEL: @pow_sitofp_const_base_fast_i64(
; CHECK-NEXT: [[SUBFP:%.*]] = sitofp i64 [[X:%.*]] to float
-; CHECK-NEXT: [[POW:%.*]] = tail call fast float @llvm.pow.f32(float 7.000000e+00, float [[SUBFP]])
-; CHECK-NEXT: [[RES:%.*]] = fpext float [[POW]] to double
+; CHECK-NEXT: [[MUL:%.*]] = fmul fast float [[SUBFP]], 0x4006757680000000
+; CHECK-NEXT: [[EXP2:%.*]] = call fast float @llvm.exp2.f32(float [[MUL]])
+; CHECK-NEXT: [[RES:%.*]] = fpext float [[EXP2]] to double
; CHECK-NEXT: ret double [[RES]]
;
%subfp = sitofp i64 %x to float
@@ -260,8 +262,9 @@ define double @pow_sitofp_const_base_fas
define double @pow_uitofp_const_base_fast_i64(i64 %x) {
; CHECK-LABEL: @pow_uitofp_const_base_fast_i64(
; CHECK-NEXT: [[SUBFP:%.*]] = uitofp i64 [[X:%.*]] to float
-; CHECK-NEXT: [[POW:%.*]] = tail call fast float @llvm.pow.f32(float 7.000000e+00, float [[SUBFP]])
-; CHECK-NEXT: [[RES:%.*]] = fpext float [[POW]] to double
+; CHECK-NEXT: [[MUL:%.*]] = fmul fast float [[SUBFP]], 0x4006757680000000
+; CHECK-NEXT: [[EXP2:%.*]] = call fast float @llvm.exp2.f32(float [[MUL]])
+; CHECK-NEXT: [[RES:%.*]] = fpext float [[EXP2]] to double
; CHECK-NEXT: ret double [[RES]]
;
%subfp = uitofp i64 %x to float
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