[InstCombine] Remove Duplicate Code in InstCombineShift

[suyog]

Summary

Remove duplicate code from "InstCombineShift".

This is already being handled in "SimplifyAShrInst".

No regression observed. No functionality change.

Please help in reviewing this code.

Thanks,
Suyog

[suyog]

Gentle Ping !!

[nicholas]

LGTM, good catch! Please commit!

[suyog]

Thanks Nick.
Please if you could commit it for me.

Thanks for reviewing all the patches.
Will shortly update the other 3 patches.

Thanks,
Suyog

[suyog]

Committed as r211250 by Nick.

Thanks!

lib/Transforms/InstCombine/InstCombineShifts.cpp

Instruction *InstCombiner::visitAShr(BinaryOperator &I) {
 
   if (ConstantInt *Op1C = dyn_cast<ConstantInt>(Op1)) {
     unsigned ShAmt = Op1C->getZExtValue();
 
     // If the input is a SHL by the same constant (ashr (shl X, C), C), then we
     // have a sign-extend idiom.
     Value *X;
     if (match(Op0, m_Shl(m_Value(X), m_Specific(Op1)))) {
-      // If the left shift is just shifting out partial signbits, delete the
-      // extension.
-      if (cast<OverflowingBinaryOperator>(Op0)->hasNoSignedWrap())
-        return ReplaceInstUsesWith(I, X);
-
       // If the input is an extension from the shifted amount value, e.g.
       //   %x = zext i8 %A to i32
       //   %y = shl i32 %x, 24
       //   %z = ashr %y, 24
       // then turn this into "z = sext i8 A to i32".
       if (ZExtInst *ZI = dyn_cast<ZExtInst>(X)) {
         uint32_t SrcBits = ZI->getOperand(0)->getType()->getScalarSizeInBits();
         uint32_t DestBits = ZI->getType()->getScalarSizeInBits();