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[InstSimplify] Missed optimization in math expression: log10(pow(10.0,x)) == x, log2(pow(2.0,x)) == x

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Summary: This patch enables folding following instructions under -ffast-math flag: log10(pow(10.0,x)) -> x, log2(pow(2.0,x)) -> x

Reviewers: hfinkel, spatel, efriedma, craig.topper, zvi, majnemer, lebedev.ri

Reviewed By: spatel, lebedev.ri

Subscribers: lebedev.ri, llvm-commits

Differential Revision: https://reviews.llvm.org/D41940

llvm-svn: 352981
This commit is contained in:
Dmitry Venikov 2019-02-03 03:48:30 +00:00
parent eb50f27657
commit c1c4330b2a
3 changed files with 13 additions and 13 deletions
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10
lib/Analysis/InstructionSimplify.cpp
View File

@ -4940,7 +4940,15 @@ static Value *simplifyUnaryIntrinsic(Function *F, Value *Op0,
case Intrinsic::log2:
// log2(exp2(x)) -> x
if (Q.CxtI->hasAllowReassoc() &&
match(Op0, m_Intrinsic<Intrinsic::exp2>(m_Value(X)))) return X;
(match(Op0, m_Intrinsic<Intrinsic::exp2>(m_Value(X))) ||
match(Op0, m_Intrinsic<Intrinsic::pow>(m_SpecificFP(2.0),
m_Value(X))))) return X;
break;
case Intrinsic::log10:
// log10(pow(10.0, x)) -> x
if (Q.CxtI->hasAllowReassoc() &&
match(Op0, m_Intrinsic<Intrinsic::pow>(m_SpecificFP(10.0),
m_Value(X)))) return X;
break;
default:
break;

8
test/Transforms/InstSimplify/log10-pow10-intrinsic.ll
View File

@ -28,9 +28,7 @@ define double @log10_strict_pow10_reassoc(double %x) {
define double @log10_reassoc_pow10_strict(double %x) {
; CHECK-LABEL: @log10_reassoc_pow10_strict(
; CHECK-NEXT: [[TMP1:%.*]] = call double @llvm.pow.f64(double 1.000000e+01, double [[X:%.*]])
; CHECK-NEXT: [[TMP2:%.*]] = call reassoc double @llvm.log10.f64(double [[TMP1]])
; CHECK-NEXT: ret double [[TMP2]]
; CHECK-NEXT: ret double [[X:%.*]]
;
%tmp = call double @llvm.pow.f64(double 1.000000e+01, double %x)
%tmp1 = call reassoc double @llvm.log10.f64(double %tmp)
@ -39,9 +37,7 @@ define double @log10_reassoc_pow10_strict(double %x) {
define double @log10_pow10_reassoc(double %x) {
; CHECK-LABEL: @log10_pow10_reassoc(
; CHECK-NEXT: [[TMP1:%.*]] = call reassoc double @llvm.pow.f64(double 1.000000e+01, double [[X:%.*]])
; CHECK-NEXT: [[TMP2:%.*]] = call reassoc double @llvm.log10.f64(double [[TMP1]])
; CHECK-NEXT: ret double [[TMP2]]
; CHECK-NEXT: ret double [[X:%.*]]
;
%tmp = call reassoc double @llvm.pow.f64(double 1.000000e+01, double %x)
%tmp1 = call reassoc double @llvm.log10.f64(double %tmp)

8
test/Transforms/InstSimplify/log2-pow2-intrinsic.ll
View File

@ -28,9 +28,7 @@ define double @log2_strict_pow2_reassoc(double %x) {
define double @log2_reassoc_pow2_strict(double %x) {
; CHECK-LABEL: @log2_reassoc_pow2_strict(
; CHECK-NEXT: [[TMP:%.*]] = call double @llvm.pow.f64(double 2.000000e+00, double [[X:%.*]])
; CHECK-NEXT: [[TMP1:%.*]] = call reassoc double @llvm.log2.f64(double [[TMP]])
; CHECK-NEXT: ret double [[TMP1]]
; CHECK-NEXT: ret double [[X:%.*]]
;
%tmp = call double @llvm.pow.f64(double 2.000000e+00, double %x)
%tmp1 = call reassoc double @llvm.log2.f64(double %tmp)
@ -39,9 +37,7 @@ define double @log2_reassoc_pow2_strict(double %x) {
define double @log2_pow2_reassoc(double %x) {
; CHECK-LABEL: @log2_pow2_reassoc(
; CHECK-NEXT: [[TMP:%.*]] = call reassoc double @llvm.pow.f64(double 2.000000e+00, double [[X:%.*]])
; CHECK-NEXT: [[TMP1:%.*]] = call reassoc double @llvm.log2.f64(double [[TMP]])
; CHECK-NEXT: ret double [[TMP1]]
; CHECK-NEXT: ret double [[X:%.*]]
;
%tmp = call reassoc double @llvm.pow.f64(double 2.000000e+00, double %x)
%tmp1 = call reassoc double @llvm.log2.f64(double %tmp)