moved opt to IC from InstSimplify

Author: VedantParanjape

llvm/lib/Analysis/InstructionSimplify.cpp

@@ -5710,9 +5710,7 @@ simplifyFAddInst(Value *Op0, Value *Op1, FastMathFlags FMF,
   // fadd X, 0 ==> X, when we know X is not -0
   if (canIgnoreSNaN(ExBehavior, FMF))
     if (match(Op1, m_PosZeroFP()) &&
-        (FMF.noSignedZeros() || cannotBeNegativeZero(Op0, Q) ||
-         (Q.CxtI && !Q.CxtI->use_empty() &&
-          canIgnoreSignBitOfZero(*(Q.CxtI->use_begin())))))
+        (FMF.noSignedZeros() || cannotBeNegativeZero(Op0, Q)))
       return Op0;
 
   if (!isDefaultFPEnvironment(ExBehavior, Rounding))

llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp

@@ -2002,6 +2002,16 @@ Instruction *InstCombinerImpl::visitFAdd(BinaryOperator &I) {
   if (Instruction *FoldedFAdd = foldBinOpIntoSelectOrPhi(I))
     return FoldedFAdd;
 
+  // B = fadd A, 0
+  // Z = Op B
+  // can be transformed into
+  // Z = Op A
+  // Where Op is such that we can ignore sign of 0 in fadd
+  Value *A;
+  if (match(&I, m_c_FAdd(m_Value(A), m_AnyZeroFP())) && !I.use_empty() &&
+      canIgnoreSignBitOfZero(*I.use_begin()))
+    return replaceInstUsesWith(I, A);
+
   // (-X) + Y --> Y - X
   Value *X, *Y;
   if (match(&I, m_c_FAdd(m_FNeg(m_Value(X)), m_Value(Y))))

llvm/test/Transforms/InstSimplify/fold-fadd-with-zero-gh154238.ll renamed to llvm/test/Transforms/InstCombine/fold-fadd-with-zero-gh154238.ll

@@ -1,5 +1,5 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
-; RUN: opt < %s -passes=instsimplify -S | FileCheck %s
+; RUN: opt < %s -passes=instcombine -S | FileCheck %s
 define float @src(float %arg1) {
 ; CHECK-LABEL: define float @src(
 ; CHECK-SAME: float [[ARG1:%.*]]) {