[llvm-commits] [llvm] r156600 - in /llvm/trunk: lib/Transforms/InstCombine/InstCombineCompares.cpp test/Transforms/InstCombine/cast.ll

[Eli Friedman]

Author: efriedma
Date: Thu May 10 20:32:59 2012
New Revision: 156600

URL: http://llvm.org/viewvc/llvm-project?rev=156600&view=rev
Log:
Fix a minor logic mistake transforming compares in instcombine.  PR12514.


Modified:
    llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp
    llvm/trunk/test/Transforms/InstCombine/cast.ll

Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp?rev=156600&r1=156599&r2=156600&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp Thu May 10 20:32:59 2012
@@ -1035,7 +1035,7 @@
       if ((KnownZero|KnownOne).countLeadingOnes() >= SrcBits-DstBits) {
         // Pull in the high bits from known-ones set.
         APInt NewRHS = RHS->getValue().zext(SrcBits);
-        NewRHS |= KnownOne;
+        NewRHS |= KnownOne & APInt::getHighBitsSet(SrcBits, SrcBits-DstBits);
         return new ICmpInst(ICI.getPredicate(), LHSI->getOperand(0),
                             ConstantInt::get(ICI.getContext(), NewRHS));
       }

Modified: llvm/trunk/test/Transforms/InstCombine/cast.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/cast.ll?rev=156600&r1=156599&r2=156600&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/cast.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/cast.ll Thu May 10 20:32:59 2012
@@ -679,3 +679,18 @@
 ; CHECK: @test_mmx_const
 ; CHECK-NOT: x86_mmx
 }
+
+; PR12514
+define i1 @test67(i1 %a, i32 %b) {
+  %tmp2 = zext i1 %a to i32
+  %conv6 = xor i32 %tmp2, 1
+  %and = and i32 %b, %conv6
+  %sext = shl nuw nsw i32 %and, 24
+  %neg.i = xor i32 %sext, -16777216
+  %conv.i.i = ashr exact i32 %neg.i, 24
+  %trunc = trunc i32 %conv.i.i to i8
+  %tobool.i = icmp eq i8 %trunc, 0
+  ret i1 %tobool.i
+; CHECK: @test67
+; CHECK: ret i1 false
+}