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[InstSimplify] Missed optimization in math expression: squashing exp(…
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…log), log(exp)

Summary: This patch enables folding following expressions under -ffast-math flag: exp(log(x)) -> x, exp2(log2(x)) -> x, log(exp(x)) -> x, log2(exp2(x)) -> x

Reviewers: spatel, hfinkel, davide

Reviewed By: spatel, hfinkel, davide

Subscribers: scanon, llvm-commits

Differential Revision: https://reviews.llvm.org/D41381

llvm-svn: 321710
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@Quolyk
Quolyk committed Jan 3, 2018
1 parent 1d18713 commit 3d8cd34
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Showing 5 changed files with 317 additions and 6 deletions.
39 changes: 33 additions & 6 deletions llvm/lib/Analysis/InstructionSimplify.cpp
View file
Expand Up @@ -4493,28 +4493,55 @@ static Value *SimplifyIntrinsic(Function *F, IterTy ArgBegin, IterTy ArgEnd,
}
}

Value *IIOperand = *ArgBegin;
Value *X;
switch (IID) {
case Intrinsic::fabs: {
if (SignBitMustBeZero(*ArgBegin, Q.TLI))
return *ArgBegin;
if (SignBitMustBeZero(IIOperand, Q.TLI))
return IIOperand;
return nullptr;
}
case Intrinsic::bswap: {
Value *IIOperand = *ArgBegin;
Value *X = nullptr;
// bswap(bswap(x)) -> x
if (match(IIOperand, m_BSwap(m_Value(X))))
return X;
return nullptr;
}
case Intrinsic::bitreverse: {
Value *IIOperand = *ArgBegin;
Value *X = nullptr;
// bitreverse(bitreverse(x)) -> x
if (match(IIOperand, m_BitReverse(m_Value(X))))
return X;
return nullptr;
}
case Intrinsic::exp: {
// exp(log(x)) -> x
if (Q.CxtI->isFast() &&
match(IIOperand, m_Intrinsic<Intrinsic::log>(m_Value(X))))
return X;
return nullptr;
}
case Intrinsic::exp2: {
// exp2(log2(x)) -> x
if (Q.CxtI->isFast() &&
match(IIOperand, m_Intrinsic<Intrinsic::log2>(m_Value(X))))
return X;
return nullptr;
}
case Intrinsic::log: {
// log(exp(x)) -> x
if (Q.CxtI->isFast() &&
match(IIOperand, m_Intrinsic<Intrinsic::exp>(m_Value(X))))
return X;
return nullptr;
}
case Intrinsic::log2: {
// log2(exp2(x)) -> x
if (Q.CxtI->isFast() &&
match(IIOperand, m_Intrinsic<Intrinsic::exp2>(m_Value(X)))) {
return X;
}
return nullptr;
}
default:
return nullptr;
}
Expand Down
71 changes: 71 additions & 0 deletions llvm/test/Transforms/InstSimplify/exp-intrinsic.ll
View file
@@ -0,0 +1,71 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt < %s -instsimplify -S | FileCheck %s

declare double @llvm.exp.f64(double)
declare double @llvm.log.f64(double)

define double @exp_log(double %a) {
; CHECK-LABEL: @exp_log(
; CHECK-NEXT: [[TMP1:%.*]] = call double @llvm.log.f64(double [[A:%.*]])
; CHECK-NEXT: [[TMP2:%.*]] = call double @llvm.exp.f64(double [[TMP1]])
; CHECK-NEXT: ret double [[TMP2]]
;
%1 = call double @llvm.log.f64(double %a)
%2 = call double @llvm.exp.f64(double %1)
ret double %2
}

define double @exp_log_fast(double %a) {
; CHECK-LABEL: @exp_log_fast(
; CHECK-NEXT: ret double [[A:%.*]]
;
%1 = call fast double @llvm.log.f64(double %a)
%2 = call fast double @llvm.exp.f64(double %1)
ret double %2
}

define double @exp_fast_log_strict(double %a) {
; CHECK-LABEL: @exp_fast_log_strict(
; CHECK-NEXT: ret double [[A:%.*]]
;
%1 = call double @llvm.log.f64(double %a)
%2 = call fast double @llvm.exp.f64(double %1)
ret double %2
}

define double @exp_strict_log_fast(double %a) {
; CHECK-LABEL: @exp_strict_log_fast(
; CHECK-NEXT: [[TMP1:%.*]] = call fast double @llvm.log.f64(double [[A:%.*]])
; CHECK-NEXT: [[TMP2:%.*]] = call double @llvm.exp.f64(double [[TMP1]])
; CHECK-NEXT: ret double [[TMP2]]
;
%1 = call fast double @llvm.log.f64(double %a)
%2 = call double @llvm.exp.f64(double %1)
ret double %2
}

define double @exp_log_exp_log(double %a) {
; CHECK-LABEL: @exp_log_exp_log(
; CHECK-NEXT: [[TMP1:%.*]] = call double @llvm.log.f64(double [[A:%.*]])
; CHECK-NEXT: [[TMP2:%.*]] = call double @llvm.exp.f64(double [[TMP1]])
; CHECK-NEXT: [[TMP3:%.*]] = call double @llvm.log.f64(double [[TMP2]])
; CHECK-NEXT: [[TMP4:%.*]] = call double @llvm.exp.f64(double [[TMP3]])
; CHECK-NEXT: ret double [[TMP4]]
;
%1 = call double @llvm.log.f64(double %a)
%2 = call double @llvm.exp.f64(double %1)
%3 = call double @llvm.log.f64(double %2)
%4 = call double @llvm.exp.f64(double %3)
ret double %4
}

define double @exp_log_exp_log_fast(double %a) {
; CHECK-LABEL: @exp_log_exp_log_fast(
; CHECK-NEXT: ret double [[A:%.*]]
;
%1 = call fast double @llvm.log.f64(double %a)
%2 = call fast double @llvm.exp.f64(double %1)
%3 = call fast double @llvm.log.f64(double %2)
%4 = call fast double @llvm.exp.f64(double %3)
ret double %4
}
71 changes: 71 additions & 0 deletions llvm/test/Transforms/InstSimplify/exp2-intrinsic.ll
View file
@@ -0,0 +1,71 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt < %s -instsimplify -S | FileCheck %s

declare double @llvm.exp2.f64(double)
declare double @llvm.log2.f64(double)

define double @exp2_log2(double %a) {
; CHECK-LABEL: @exp2_log2(
; CHECK-NEXT: [[TMP1:%.*]] = call double @llvm.log2.f64(double [[A:%.*]])
; CHECK-NEXT: [[TMP2:%.*]] = call double @llvm.exp2.f64(double [[TMP1]])
; CHECK-NEXT: ret double [[TMP2]]
;
%1 = call double @llvm.log2.f64(double %a)
%2 = call double @llvm.exp2.f64(double %1)
ret double %2
}

define double @exp2_log2_fast(double %a) {
; CHECK-LABEL: @exp2_log2_fast(
; CHECK-NEXT: ret double [[A:%.*]]
;
%1 = call fast double @llvm.log2.f64(double %a)
%2 = call fast double @llvm.exp2.f64(double %1)
ret double %2
}

define double @exp2_fast_log2_strict(double %a) {
; CHECK-LABEL: @exp2_fast_log2_strict(
; CHECK-NEXT: ret double [[A:%.*]]
;
%1 = call double @llvm.log2.f64(double %a)
%2 = call fast double @llvm.exp2.f64(double %1)
ret double %2
}

define double @exp2_strict_log2_fast(double %a) {
; CHECK-LABEL: @exp2_strict_log2_fast(
; CHECK-NEXT: [[TMP1:%.*]] = call fast double @llvm.log2.f64(double [[A:%.*]])
; CHECK-NEXT: [[TMP2:%.*]] = call double @llvm.exp2.f64(double [[TMP1]])
; CHECK-NEXT: ret double [[TMP2]]
;
%1 = call fast double @llvm.log2.f64(double %a)
%2 = call double @llvm.exp2.f64(double %1)
ret double %2
}

define double @exp2_log2_exp2_log2(double %a) {
; CHECK-LABEL: @exp2_log2_exp2_log2(
; CHECK-NEXT: [[TMP1:%.*]] = call double @llvm.log2.f64(double [[A:%.*]])
; CHECK-NEXT: [[TMP2:%.*]] = call double @llvm.exp2.f64(double [[TMP1]])
; CHECK-NEXT: [[TMP3:%.*]] = call double @llvm.log2.f64(double [[TMP2]])
; CHECK-NEXT: [[TMP4:%.*]] = call double @llvm.exp2.f64(double [[TMP3]])
; CHECK-NEXT: ret double [[TMP4]]
;
%1 = call double @llvm.log2.f64(double %a)
%2 = call double @llvm.exp2.f64(double %1)
%3 = call double @llvm.log2.f64(double %2)
%4 = call double @llvm.exp2.f64(double %3)
ret double %4
}

define double @exp2_log2_exp2_log2_fast(double %a) {
; CHECK-LABEL: @exp2_log2_exp2_log2_fast(
; CHECK-NEXT: ret double [[A:%.*]]
;
%1 = call fast double @llvm.log2.f64(double %a)
%2 = call fast double @llvm.exp2.f64(double %1)
%3 = call fast double @llvm.log2.f64(double %2)
%4 = call fast double @llvm.exp2.f64(double %3)
ret double %4
}
71 changes: 71 additions & 0 deletions llvm/test/Transforms/InstSimplify/log-intrinsic.ll
View file
@@ -0,0 +1,71 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt < %s -instsimplify -S | FileCheck %s

declare double @llvm.log.f64(double)
declare double @llvm.exp.f64(double)

define double @log_exp(double %a) {
; CHECK-LABEL: @log_exp(
; CHECK-NEXT: [[TMP1:%.*]] = call double @llvm.exp.f64(double [[A:%.*]])
; CHECK-NEXT: [[TMP2:%.*]] = call double @llvm.log.f64(double [[TMP1]])
; CHECK-NEXT: ret double [[TMP2]]
;
%1 = call double @llvm.exp.f64(double %a)
%2 = call double @llvm.log.f64(double %1)
ret double %2
}

define double @log_exp_fast(double %a) {
; CHECK-LABEL: @log_exp_fast(
; CHECK-NEXT: ret double [[A:%.*]]
;
%1 = call fast double @llvm.exp.f64(double %a)
%2 = call fast double @llvm.log.f64(double %1)
ret double %2
}

define double @log_fast_exp_strict(double %a) {
; CHECK-LABEL: @log_fast_exp_strict(
; CHECK-NEXT: ret double [[A:%.*]]
;
%1 = call double @llvm.exp.f64(double %a)
%2 = call fast double @llvm.log.f64(double %1)
ret double %2
}

define double @log_strict_exp_fast(double %a) {
; CHECK-LABEL: @log_strict_exp_fast(
; CHECK-NEXT: [[TMP1:%.*]] = call fast double @llvm.exp.f64(double [[A:%.*]])
; CHECK-NEXT: [[TMP2:%.*]] = call double @llvm.log.f64(double [[TMP1]])
; CHECK-NEXT: ret double [[TMP2]]
;
%1 = call fast double @llvm.exp.f64(double %a)
%2 = call double @llvm.log.f64(double %1)
ret double %2
}

define double @log_exp_log_exp(double %a) {
; CHECK-LABEL: @log_exp_log_exp(
; CHECK-NEXT: [[TMP1:%.*]] = call double @llvm.exp.f64(double [[A:%.*]])
; CHECK-NEXT: [[TMP2:%.*]] = call double @llvm.log.f64(double [[TMP1]])
; CHECK-NEXT: [[TMP3:%.*]] = call double @llvm.exp.f64(double [[TMP2]])
; CHECK-NEXT: [[TMP4:%.*]] = call double @llvm.log.f64(double [[TMP3]])
; CHECK-NEXT: ret double [[TMP4]]
;
%1 = call double @llvm.exp.f64(double %a)
%2 = call double @llvm.log.f64(double %1)
%3 = call double @llvm.exp.f64(double %2)
%4 = call double @llvm.log.f64(double %3)
ret double %4
}

define double @log_exp_log_exp_fast(double %a) {
; CHECK-LABEL: @log_exp_log_exp_fast(
; CHECK-NEXT: ret double [[A:%.*]]
;
%1 = call fast double @llvm.exp.f64(double %a)
%2 = call fast double @llvm.log.f64(double %1)
%3 = call fast double @llvm.exp.f64(double %2)
%4 = call fast double @llvm.log.f64(double %3)
ret double %4
}
71 changes: 71 additions & 0 deletions llvm/test/Transforms/InstSimplify/log2-intrinsic.ll
View file
@@ -0,0 +1,71 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt < %s -instsimplify -S | FileCheck %s

declare double @llvm.log2.f64(double)
declare double @llvm.exp2.f64(double)

define double @log2_exp2(double %a) {
; CHECK-LABEL: @log2_exp2(
; CHECK-NEXT: [[TMP1:%.*]] = call double @llvm.exp2.f64(double [[A:%.*]])
; CHECK-NEXT: [[TMP2:%.*]] = call double @llvm.log2.f64(double [[TMP1]])
; CHECK-NEXT: ret double [[TMP2]]
;
%1 = call double @llvm.exp2.f64(double %a)
%2 = call double @llvm.log2.f64(double %1)
ret double %2
}

define double @log2_exp2_fast(double %a) {
; CHECK-LABEL: @log2_exp2_fast(
; CHECK-NEXT: ret double [[A:%.*]]
;
%1 = call fast double @llvm.exp2.f64(double %a)
%2 = call fast double @llvm.log2.f64(double %1)
ret double %2
}

define double @log2_fast_exp2_strict(double %a) {
; CHECK-LABEL: @log2_fast_exp2_strict(
; CHECK-NEXT: ret double [[A:%.*]]
;
%1 = call double @llvm.exp2.f64(double %a)
%2 = call fast double @llvm.log2.f64(double %1)
ret double %2
}

define double @log2_strict_exp2_fast(double %a) {
; CHECK-LABEL: @log2_strict_exp2_fast(
; CHECK-NEXT: [[TMP1:%.*]] = call fast double @llvm.exp2.f64(double [[A:%.*]])
; CHECK-NEXT: [[TMP2:%.*]] = call double @llvm.log2.f64(double [[TMP1]])
; CHECK-NEXT: ret double [[TMP2]]
;
%1 = call fast double @llvm.exp2.f64(double %a)
%2 = call double @llvm.log2.f64(double %1)
ret double %2
}

define double @log2_exp2_log2_exp2(double %a) {
; CHECK-LABEL: @log2_exp2_log2_exp2(
; CHECK-NEXT: [[TMP1:%.*]] = call double @llvm.exp2.f64(double [[A:%.*]])
; CHECK-NEXT: [[TMP2:%.*]] = call double @llvm.log2.f64(double [[TMP1]])
; CHECK-NEXT: [[TMP3:%.*]] = call double @llvm.exp2.f64(double [[TMP2]])
; CHECK-NEXT: [[TMP4:%.*]] = call double @llvm.log2.f64(double [[TMP3]])
; CHECK-NEXT: ret double [[TMP4]]
;
%1 = call double @llvm.exp2.f64(double %a)
%2 = call double @llvm.log2.f64(double %1)
%3 = call double @llvm.exp2.f64(double %2)
%4 = call double @llvm.log2.f64(double %3)
ret double %4
}

define double @log2_exp2_log2_exp2_fast(double %a) {
; CHECK-LABEL: @log2_exp2_log2_exp2_fast(
; CHECK-NEXT: ret double [[A:%.*]]
;
%1 = call fast double @llvm.exp2.f64(double %a)
%2 = call fast double @llvm.log2.f64(double %1)
%3 = call fast double @llvm.exp2.f64(double %2)
%4 = call fast double @llvm.log2.f64(double %3)
ret double %4
}

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