[llvm] r300927 - [InstCombine] Remove the zextOrTrunc from ShrinkDemandedConstant.

[Craig Topper via llvm-commits]

Author: ctopper
Date: Thu Apr 20 18:58:27 2017
New Revision: 300927

URL: http://llvm.org/viewvc/llvm-project?rev=300927&view=rev
Log:
[InstCombine] Remove the zextOrTrunc from ShrinkDemandedConstant.

The demanded mask and the constant should always be the same width for all callers today.

Also stop copying the demanded mask as its passed in. We should avoid allocating memory unless we are going to do something. The final AND to create the new constant will take care of it.

Modified:
    llvm/trunk/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp

Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp?rev=300927&r1=300926&r2=300927&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp Thu Apr 20 18:58:27 2017
@@ -26,7 +26,7 @@ using namespace llvm::PatternMatch;
 /// constant integer. If so, check to see if there are any bits set in the
 /// constant that are not demanded. If so, shrink the constant and return true.
 static bool ShrinkDemandedConstant(Instruction *I, unsigned OpNo,
-                                   APInt Demanded) {
+                                   const APInt &Demanded) {
   assert(I && "No instruction?");
   assert(OpNo < I->getNumOperands() && "Operand index too large");
 
@@ -37,13 +37,11 @@ static bool ShrinkDemandedConstant(Instr
     return false;
 
   // If there are no bits set that aren't demanded, nothing to do.
-  Demanded = Demanded.zextOrTrunc(C->getBitWidth());
   if (C->isSubsetOf(Demanded))
     return false;
 
   // This instruction is producing bits that are not demanded. Shrink the RHS.
-  Demanded &= *C;
-  I->setOperand(OpNo, ConstantInt::get(Op->getType(), Demanded));
+  I->setOperand(OpNo, ConstantInt::get(Op->getType(), *C & Demanded));
 
   return true;
 }