[SCCP] Avoid computing range if the instructions are already refined.

Author: XChy

llvm/lib/Transforms/Utils/SCCPSolver.cpp

@@ -120,6 +120,9 @@ static bool refineInstruction(SCCPSolver &Solver,
   };
 
   if (isa<OverflowingBinaryOperator>(Inst)) {
+    if (Inst.hasNoSignedWrap() && Inst.hasNoUnsignedWrap())
+      return false;
+
     auto RangeA = GetRange(Inst.getOperand(0));
     auto RangeB = GetRange(Inst.getOperand(1));
     if (!Inst.hasNoUnsignedWrap()) {
@@ -147,6 +150,9 @@ static bool refineInstruction(SCCPSolver &Solver,
       Changed = true;
     }
   } else if (TruncInst *TI = dyn_cast<TruncInst>(&Inst)) {
+    if (TI->hasNoSignedWrap() && TI->hasNoUnsignedWrap())
+      return false;
+
     auto Range = GetRange(Inst.getOperand(0));
     uint64_t DestWidth = TI->getDestTy()->getScalarSizeInBits();
     if (!TI->hasNoUnsignedWrap()) {