[SCCP] Add UnaryOperator visitor to SCCP for unary FNeg

Differential Revision: https://reviews.llvm.org/D62819

llvm-svn: 362449

1 files changed, 26 insertions, 0 deletions

diff --git a/llvm/lib/Transforms/Scalar/SCCP.cpp b/llvm/lib/Transforms/Scalar/SCCP.cpp
index 66885ed57e2..1d0354bd708 100644
--- a/llvm/lib/Transforms/Scalar/SCCP.cpp
+++ b/llvm/lib/Transforms/Scalar/SCCP.cpp
@@ -613,6 +613,7 @@ private:
 
   void visitCastInst(CastInst &I);
   void visitSelectInst(SelectInst &I);
+  void visitUnaryOperator(Instruction &I);
   void visitBinaryOperator(Instruction &I);
   void visitCmpInst(CmpInst &I);
   void visitExtractValueInst(ExtractValueInst &EVI);
@@ -969,6 +970,29 @@ void SCCPSolver::visitSelectInst(SelectInst &I) {
   markOverdefined(&I);
 }
 
+// Handle Unary Operators.
+void SCCPSolver::visitUnaryOperator(Instruction &I) {
+  LatticeVal V0State = getValueState(I.getOperand(0));
+
+  LatticeVal &IV = ValueState[&I];
+  if (IV.isOverdefined()) return;
+
+  if (V0State.isConstant()) {
+    Constant *C = ConstantExpr::get(I.getOpcode(), V0State.getConstant());
+
+    // op Y -> undef.
+    if (isa<UndefValue>(C))
+      return;
+    return (void)markConstant(IV, &I, C);
+  }
+
+  // If something is undef, wait for it to resolve.
+  if (!V0State.isOverdefined())
+    return;
+
+  markOverdefined(&I);
+}
+
 // Handle Binary Operators.
 void SCCPSolver::visitBinaryOperator(Instruction &I) {
   LatticeVal V1State = getValueState(I.getOperand(0));
@@ -1484,6 +1508,8 @@ bool SCCPSolver::ResolvedUndefsIn(Function &F) {
         else
           markOverdefined(&I);
         return true;
+      case Instruction::FNeg:
+        break; // fneg undef -> undef
       case Instruction::ZExt:
       case Instruction::SExt:
       case Instruction::FPToUI: