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Revert [InstCombine] Use SimplifyFMulInst to simplify multiply in fma. 

This introduces additional rounding error in some cases. See D67434.

This reverts r371518 (git commit 18a1f0818b)

llvm-svn: 371634
This commit is contained in:
Florian Hahn 2019-09-11 16:17:03 +00:00
parent 0c1257f517
commit 51de22c8ee
2 changed files with 13 additions and 10 deletions
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8
llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
View File

@ -2258,11 +2258,9 @@ Instruction *InstCombiner::visitCallInst(CallInst &CI) {
return II;
}
// Try to simplify the underlying FMul.
if (Value *V = SimplifyFMulInst(II->getArgOperand(0), II->getArgOperand(1),
II->getFastMathFlags(),
SQ.getWithInstruction(II))) {
auto *FAdd = BinaryOperator::CreateFAdd(V, II->getArgOperand(2));
// fma x, 1, z -> fadd x, z
if (match(Src1, m_FPOne())) {
auto *FAdd = BinaryOperator::CreateFAdd(Src0, II->getArgOperand(2));
FAdd->copyFastMathFlags(II);
return FAdd;
}

15
llvm/test/Transforms/InstCombine/fma.ll
View File

@ -372,7 +372,8 @@ define float @fmuladd_x_1_z_fast(float %x, float %z) {
define <2 x double> @fmuladd_a_0_b(<2 x double> %a, <2 x double> %b) {
; CHECK-LABEL: @fmuladd_a_0_b(
; CHECK-NEXT: entry:
; CHECK-NEXT: ret <2 x double> [[B:%.*]]
; CHECK-NEXT: [[RES:%.*]] = call nnan nsz <2 x double> @llvm.fmuladd.v2f64(<2 x double> [[A:%.*]], <2 x double> zeroinitializer, <2 x double> [[B:%.*]])
; CHECK-NEXT: ret <2 x double> [[RES]]
;
entry:
%res = call nnan nsz <2 x double> @llvm.fmuladd.v2f64(<2 x double> %a, <2 x double> zeroinitializer, <2 x double> %b)
@ -382,7 +383,8 @@ entry:
define <2 x double> @fmuladd_0_a_b(<2 x double> %a, <2 x double> %b) {
; CHECK-LABEL: @fmuladd_0_a_b(
; CHECK-NEXT: entry:
; CHECK-NEXT: ret <2 x double> [[B:%.*]]
; CHECK-NEXT: [[RES:%.*]] = call nnan nsz <2 x double> @llvm.fmuladd.v2f64(<2 x double> [[A:%.*]], <2 x double> zeroinitializer, <2 x double> [[B:%.*]])
; CHECK-NEXT: ret <2 x double> [[RES]]
;
entry:
%res = call nnan nsz <2 x double> @llvm.fmuladd.v2f64(<2 x double> zeroinitializer, <2 x double> %a, <2 x double> %b)
@ -405,7 +407,8 @@ declare <2 x double> @llvm.fmuladd.v2f64(<2 x double>, <2 x double>, <2 x double
define <2 x double> @fma_a_0_b(<2 x double> %a, <2 x double> %b) {
; CHECK-LABEL: @fma_a_0_b(
; CHECK-NEXT: entry:
; CHECK-NEXT: ret <2 x double> [[B:%.*]]
; CHECK-NEXT: [[RES:%.*]] = call nnan nsz <2 x double> @llvm.fma.v2f64(<2 x double> [[A:%.*]], <2 x double> zeroinitializer, <2 x double> [[B:%.*]])
; CHECK-NEXT: ret <2 x double> [[RES]]
;
entry:
%res = call nnan nsz <2 x double> @llvm.fma.v2f64(<2 x double> %a, <2 x double> zeroinitializer, <2 x double> %b)
@ -415,7 +418,8 @@ entry:
define <2 x double> @fma_0_a_b(<2 x double> %a, <2 x double> %b) {
; CHECK-LABEL: @fma_0_a_b(
; CHECK-NEXT: entry:
; CHECK-NEXT: ret <2 x double> [[B:%.*]]
; CHECK-NEXT: [[RES:%.*]] = call nnan nsz <2 x double> @llvm.fma.v2f64(<2 x double> [[A:%.*]], <2 x double> zeroinitializer, <2 x double> [[B:%.*]])
; CHECK-NEXT: ret <2 x double> [[RES]]
;
entry:
%res = call nnan nsz <2 x double> @llvm.fma.v2f64(<2 x double> zeroinitializer, <2 x double> %a, <2 x double> %b)
@ -436,7 +440,8 @@ entry:
define <2 x double> @fma_sqrt(<2 x double> %a, <2 x double> %b) {
; CHECK-LABEL: @fma_sqrt(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[RES:%.*]] = fadd fast <2 x double> [[A:%.*]], [[B:%.*]]
; CHECK-NEXT: [[SQRT:%.*]] = call fast <2 x double> @llvm.sqrt.v2f64(<2 x double> [[A:%.*]])
; CHECK-NEXT: [[RES:%.*]] = call fast <2 x double> @llvm.fma.v2f64(<2 x double> [[SQRT]], <2 x double> [[SQRT]], <2 x double> [[B:%.*]])
; CHECK-NEXT: ret <2 x double> [[RES]]
;
entry: