2 files changed, 5 insertions, 8 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
index dc3f32d..c672456 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
@@ -987,9 +987,7 @@ Instruction *InstCombinerImpl::transformZExtICmp(ICmpInst *Cmp, ZExtInst &Zext)
   if (match(Cmp->getOperand(1), m_APInt(Op1CV))) {
 
     // zext (x <s  0) to i32 --> x>>u31      true if signbit set.
-    // zext (x >s -1) to i32 --> (x>>u31)^1  true if signbit clear.
-    if ((Cmp->getPredicate() == ICmpInst::ICMP_SLT && Op1CV->isZero()) ||
-        (Cmp->getPredicate() == ICmpInst::ICMP_SGT && Op1CV->isAllOnes())) {
+    if (Cmp->getPredicate() == ICmpInst::ICMP_SLT && Op1CV->isZero()) {
       Value *In = Cmp->getOperand(0);
       Value *Sh = ConstantInt::get(In->getType(),
                                    In->getType()->getScalarSizeInBits() - 1);
@@ -997,11 +995,6 @@ Instruction *InstCombinerImpl::transformZExtICmp(ICmpInst *Cmp, ZExtInst &Zext)
       if (In->getType() != Zext.getType())
         In = Builder.CreateIntCast(In, Zext.getType(), false /*ZExt*/);
 
-      if (Cmp->getPredicate() == ICmpInst::ICMP_SGT) {
-        Constant *One = ConstantInt::get(In->getType(), 1);
-        In = Builder.CreateXor(In, One, In->getName() + ".not");
-      }
-
       return replaceInstUsesWith(Zext, In);
     }
 
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineShifts.cpp b/llvm/lib/Transforms/InstCombine/InstCombineShifts.cpp
index e5b0e32..8453c9f 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineShifts.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineShifts.cpp
@@ -1158,6 +1158,10 @@ Instruction *InstCombinerImpl::visitLShr(BinaryOperator &I) {
     }
 
     if (ShAmtC == BitWidth - 1) {
+      // lshr i32 (~X), 31 --> zext (X > -1)
+      if (match(Op0, m_OneUse(m_Not(m_Value(X)))))
+        return new ZExtInst(Builder.CreateIsNotNeg(X), Ty);
+
       // lshr i32 or(X,-X), 31 --> zext (X != 0)
       if (match(Op0, m_OneUse(m_c_Or(m_Neg(m_Value(X)), m_Deferred(X)))))
         return new ZExtInst(Builder.CreateIsNotNull(X), Ty);