[llvm] 7b7940f - [InstSimplify] reduce code duplication for fmul folds; NFC

[Sanjay Patel via llvm-commits]

Author: Sanjay Patel
Date: 2022-10-03T10:36:02-04:00
New Revision: 7b7940f9da80de6aa0b8f28a0ef809dafe4cdffc

URL: https://github.com/llvm/llvm-project/commit/7b7940f9da80de6aa0b8f28a0ef809dafe4cdffc
DIFF: https://github.com/llvm/llvm-project/commit/7b7940f9da80de6aa0b8f28a0ef809dafe4cdffc.diff

LOG: [InstSimplify] reduce code duplication for fmul folds; NFC

The constant is already commuted for an fmul opcode,
but this code can be called more directly for fma,
so we have to swap for that caller. There are tests
in InstSimplify and InstCombine to verify that this
works as expected.

Added: 
    

Modified: 
    llvm/lib/Analysis/InstructionSimplify.cpp
    llvm/test/Transforms/InstSimplify/floating-point-arithmetic.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp
index c7a16562b901f..96b665e1c1f11 100644
--- a/llvm/lib/Analysis/InstructionSimplify.cpp
+++ b/llvm/lib/Analysis/InstructionSimplify.cpp
@@ -5325,22 +5325,18 @@ static Value *simplifyFMAFMul(Value *Op0, Value *Op1, FastMathFlags FMF,
   if (!isDefaultFPEnvironment(ExBehavior, Rounding))
     return nullptr;
 
-  // fmul X, 1.0 ==> X
+  // Canonicalize constant as operand 1.
+  if (match(Op0, m_ImmConstant()))
+    std::swap(Op0, Op1);
+
+  // X * 1.0 --> X
   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
+  // X * 0.0 --> 0.0 (with nnan and nsz)
   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/llvm/test/Transforms/InstSimplify/floating-point-arithmetic.ll b/llvm/test/Transforms/InstSimplify/floating-point-arithmetic.ll
index be84594e72027..1ba4045a4e308 100644
--- a/llvm/test/Transforms/InstSimplify/floating-point-arithmetic.ll
+++ b/llvm/test/Transforms/InstSimplify/floating-point-arithmetic.ll
@@ -161,9 +161,9 @@ define <2 x float> @fadd_x_n0_vec_undef_elt(<2 x float> %a) {
   ret <2 x float> %ret
 }
 
-; fmul X, 1.0 ==> X
-define double @fmul_X_1(double %a) {
-; CHECK-LABEL: @fmul_X_1(
+; fmul 1.0, X ==> X
+define double @fmul_1_X(double %a) {
+; CHECK-LABEL: @fmul_1_X(
 ; CHECK-NEXT:    ret double [[A:%.*]]
 ;
   %b = fmul double 1.0, %a