rdar://12329730 (2nd part, revised)

The type of shirt-right (logical or arithemetic) should remain unchanged when transforming "X << C1 >> C2" into "X << (C1-C2)" git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@169209 91177308-0d34-0410-b5e6-96231b3b80d8
darkbasic · Dec 4, 2012 · bba3eb0 · bba3eb0
1 parent b715b20
commit bba3eb0
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Showing 2 changed files with 3 additions and 2 deletions.
diff --git a/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp b/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
@@ -876,7 +876,8 @@ Value *InstCombiner::SimplifyShrShlDemandedBits(Instruction *Shr,
       New->setHasNoUnsignedWrap(Orig->hasNoUnsignedWrap());
     } else {
       Constant *Amt = ConstantInt::get(VarX->getType(), ShrAmt - ShlAmt);
-      New = BinaryOperator::CreateLShr(VarX, Amt);
+      New = isLshr ? BinaryOperator::CreateLShr(VarX, Amt) :
+                     BinaryOperator::CreateAShr(VarX, Amt);
     }
 
     return InsertNewInstWith(New, *Shl);

diff --git a/test/Transforms/InstCombine/shift.ll b/test/Transforms/InstCombine/shift.ll
@@ -723,7 +723,7 @@ define i32 @test60(i32 %x) {
   %or = or i32 %shl, 1
   ret i32 %or
 ; CHECK: @test60
-; CHECK: lshr i32 %x, 3
+; CHECK: ashr i32 %x, 3
 }