Fix misoptimization of: xor i1 (icmp eq (X, C1), icmp s[lg]t (X, C2))

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@56834 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp
index 9023db7d508fb7340a36d9ec5c2db6712ba4e8a9..6cac395405b75b7de721df9f76c0d3b0dc706851 100644 (file)
--- a/lib/Transforms/Scalar/InstructionCombining.cpp
+++ b/lib/Transforms/Scalar/InstructionCombining.cpp
@@ -3023,7 +3023,7 @@ Instruction *InstCombiner::visitSRem(BinaryOperator &I) {
       I.setOperand(1, RHSNeg);
       return &I;
     }
- 
+
   // If the sign bits of both operands are zero (i.e. we can prove they are
   // unsigned inputs), turn this into a urem.
   if (I.getType()->isInteger()) {
@@ -4205,7 +4205,8 @@ Instruction *InstCombiner::visitOr(BinaryOperator &I) {
           // Ensure that the larger constant is on the RHS.
           ICmpInst *LHS = cast<ICmpInst>(Op0);
           bool NeedsSwap;
-          if (ICmpInst::isSignedPredicate(LHSCC))
+          if (ICmpInst::isEquality(LHSCC) ? ICmpInst::isSignedPredicate(RHSCC)
+                                          : ICmpInst::isSignedPredicate(LHSCC))
             NeedsSwap = LHSCst->getValue().sgt(RHSCst->getValue());
           else
             NeedsSwap = LHSCst->getValue().ugt(RHSCst->getValue());

diff --git a/test/Transforms/InstCombine/2008-09-29-FoldingOr.ll b/test/Transforms/InstCombine/2008-09-29-FoldingOr.ll
new file mode 100644 (file)
index 0000000..e7a8ca9
--- /dev/null
+++ b/test/Transforms/InstCombine/2008-09-29-FoldingOr.ll
@@ -0,0 +1,10 @@
+; RUN: llvm-as < %s | opt -instcombine | llvm-dis | grep {or i1}
+; PR2844
+
+define i32 @test(i32 %p_74) {
+       %A = icmp eq i32 %p_74, 0               ; <i1> [#uses=1]
+       %B = icmp slt i32 %p_74, -638208501             ; <i1> [#uses=1]
+       %or.cond = or i1 %A, %B         ; <i1> [#uses=1]
+       %iftmp.10.0 = select i1 %or.cond, i32 0, i32 1          ; <i32> [#uses=1]
+       ret i32 %iftmp.10.0
+}