3 files changed, 11 insertions, 1 deletions

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
index f5f3716..694b180 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -504,6 +504,11 @@ static Instruction *foldCttzCtlz(IntrinsicInst &II, InstCombinerImpl &IC) {
     return IC.replaceInstUsesWith(II, ConstantInt::getNullValue(II.getType()));
   }
 
+  // If ctlz/cttz is only used as a shift amount, set is_zero_poison to true.
+  if (II.hasOneUse() && match(Op1, m_Zero()) &&
+      match(II.user_back(), m_Shift(m_Value(), m_Specific(&II))))
+    return IC.replaceOperand(II, 1, IC.Builder.getTrue());
+
   Constant *C;
 
   if (IsTZ) {
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
index 45afa63..a9817f1 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
@@ -1121,6 +1121,10 @@ Instruction *InstCombinerImpl::visitZExt(ZExtInst &Zext) {
   Value *Src = Zext.getOperand(0);
   Type *SrcTy = Src->getType(), *DestTy = Zext.getType();
 
+  // zext nneg bool x -> 0
+  if (SrcTy->isIntOrIntVectorTy(1) && Zext.hasNonNeg())
+    return replaceInstUsesWith(Zext, Constant::getNullValue(Zext.getType()));
+
   // Try to extend the entire expression tree to the wide destination type.
   unsigned BitsToClear;
   if (shouldChangeType(SrcTy, DestTy) &&
diff --git a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
index 1688005..c9bbe43 100644
--- a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -5202,7 +5202,8 @@ static bool combineInstructionsOverFunction(
     if (Iteration > Opts.MaxIterations) {
       report_fatal_error(
           "Instruction Combining did not reach a fixpoint after " +
-          Twine(Opts.MaxIterations) + " iterations");
+              Twine(Opts.MaxIterations) + " iterations",
+          /*GenCrashDiag=*/false);
     }
   }