[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

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@372915 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Analysis/InstructionSimplify.cpp b/lib/Analysis/InstructionSimplify.cpp
index 4ae052eb14b21762b114246013af57b7ab20f2fb..dd477fe1c5d8fc4680d1c44b22ca0853a0bb88e8 100644 (file)
--- a/lib/Analysis/InstructionSimplify.cpp
+++ b/lib/Analysis/InstructionSimplify.cpp
@@ -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.

diff --git a/test/Transforms/InstCombine/fma.ll b/test/Transforms/InstCombine/fma.ll
index 29d372fca05f86278e26c8423a33dcbb1aa6c90c..33dc8100b581470566b824b5247bac51932372f3 100644 (file)
--- a/test/Transforms/InstCombine/fma.ll
+++ b/test/Transforms/InstCombine/fma.ll
@@ -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: