From: Zhou Sheng <zhousheng00@gmail.com>
Date: Thu, 8 Mar 2007 05:42:00 +0000 (+0000)
Subject: Fix a bug in APIntified ComputeMaskedBits().
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=9a28daa86444bd5e68ca58d6ceebce961b03cb86;p=oota-llvm.git

Fix a bug in APIntified ComputeMaskedBits().


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@35022 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp
index 9d327c7883d..02336e59c4c 100644
--- a/lib/Transforms/Scalar/InstructionCombining.cpp
+++ b/lib/Transforms/Scalar/InstructionCombining.cpp
@@ -675,11 +675,9 @@ static void ComputeMaskedBits(Value *V, APInt Mask, APInt& KnownZero,
   case Instruction::ZExt:  {
     // Compute the bits in the result that are not present in the input.
     const IntegerType *SrcTy = cast<IntegerType>(I->getOperand(0)->getType());
-    APInt NotIn(~SrcTy->getMask());
-    APInt NewBits = APInt::getAllOnesValue(BitWidth) & 
-                    NotIn.zext(BitWidth);
+    APInt NewBits(APInt::getAllOnesValue(BitWidth).shl(SrcTy->getBitWidth()));
       
-    Mask &= ~NotIn;
+    Mask &= SrcTy->getMask().zext(BitWidth);
     ComputeMaskedBits(I->getOperand(0), Mask, KnownZero, KnownOne, Depth+1);
     assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); 
     // The top bits are known to be zero.
@@ -689,11 +687,9 @@ static void ComputeMaskedBits(Value *V, APInt Mask, APInt& KnownZero,
   case Instruction::SExt: {
     // Compute the bits in the result that are not present in the input.
     const IntegerType *SrcTy = cast<IntegerType>(I->getOperand(0)->getType());
-    APInt NotIn(~SrcTy->getMask());
-    APInt NewBits = APInt::getAllOnesValue(BitWidth) & 
-                    NotIn.zext(BitWidth);
+    APInt NewBits(APInt::getAllOnesValue(BitWidth).shl(SrcTy->getBitWidth()));
       
-    Mask &= ~NotIn;
+    Mask &= SrcTy->getMask().zext(BitWidth);
     ComputeMaskedBits(I->getOperand(0), Mask, KnownZero, KnownOne, Depth+1);
     assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");