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[InstSimplify] Match 1.0 and 0.0 for both operands in SimplifyFMAMul 

Because we do not constant fold multiplications in SimplifyFMAMul,
we match 1.0 and 0.0 for both operands, as multiplying by them
is guaranteed to produce an exact result (if it is allowed to do so).

Note that it is not enough to just swap the operands to ensure a
constant is on the RHS, as we want to also cover the case with
2 constants.

Reviewers: lebedev.ri, spatel, reames, scanon

Reviewed By: lebedev.ri, reames

Differential Revision: https://reviews.llvm.org/D67553

llvm-svn: 372915
This commit is contained in:
Florian Hahn 2019-09-25 19:33:26 +00:00
parent 3a7da6a7df
commit d663efe23a
2 changed files with 10 additions and 3 deletions
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8
llvm/lib/Analysis/InstructionSimplify.cpp
View File

@ -4582,10 +4582,18 @@ static Value *SimplifyFMAFMul(Value *Op0, Value *Op1, FastMathFlags FMF,
if (match(Op1, m_FPOne()))
return Op0;
// fmul 1.0, X ==> X
if (match(Op0, m_FPOne()))
return Op1;
// fmul nnan nsz X, 0 ==> 0
if (FMF.noNaNs() && FMF.noSignedZeros() && match(Op1, m_AnyZeroFP()))
return ConstantFP::getNullValue(Op0->getType());
// fmul nnan nsz 0, X ==> 0
if (FMF.noNaNs() && FMF.noSignedZeros() && match(Op0, m_AnyZeroFP()))
return ConstantFP::getNullValue(Op1->getType());
// sqrt(X) * sqrt(X) --> X, if we can:
// 1. Remove the intermediate rounding (reassociate).
// 2. Ignore non-zero negative numbers because sqrt would produce NAN.

5
llvm/test/Transforms/InstCombine/fma.ll
View File

@ -460,8 +460,7 @@ entry:
define <2 x double> @fma_const_fmul_zero(<2 x double> %b) {
; CHECK-LABEL: @fma_const_fmul_zero(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[RES:%.*]] = call nnan nsz <2 x double> @llvm.fma.v2f64(<2 x double> zeroinitializer, <2 x double> <double 0x4131233302898702, double 0x40C387800000D6C0>, <2 x double> [[B:%.*]])
; CHECK-NEXT: ret <2 x double> [[RES]]
; CHECK-NEXT: ret <2 x double> [[B:%.*]]
;
entry:
%res = call nnan nsz <2 x double> @llvm.fma.v2f64(<2 x double> <double 0.0, double 0.0>, <2 x double> <double 1123123.0099110012314, double 9999.0000001>, <2 x double> %b)
@ -481,7 +480,7 @@ entry:
define <2 x double> @fma_const_fmul_one(<2 x double> %b) {
; CHECK-LABEL: @fma_const_fmul_one(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[RES:%.*]] = call nnan nsz <2 x double> @llvm.fma.v2f64(<2 x double> <double 1.000000e+00, double 1.000000e+00>, <2 x double> <double 0x4131233302898702, double 0x40C387800000D6C0>, <2 x double> [[B:%.*]])
; CHECK-NEXT: [[RES:%.*]] = fadd nnan nsz <2 x double> [[B:%.*]], <double 0x4131233302898702, double 0x40C387800000D6C0>
; CHECK-NEXT: ret <2 x double> [[RES]]
;
entry: