[InstCombine] Don't insert instructions before a catch switch

CatchSwitches are not splittable, we cannot insert casts, etc. before
them.

This fixes PR26992.

llvm-svn: 263874

1 files changed, 3 insertions, 0 deletions

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
index 7401cb6034a..bbd118c67b8 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -661,6 +661,9 @@ static bool canRewriteGEPAsOffset(Value *Start, Value *Base,
       }
 
       if (auto *PN = dyn_cast<PHINode>(V)) {
+        // We cannot transform PHIs on unsplittable basic blocks.
+        if (isa<CatchSwitchInst>(PN->getParent()->getTerminator()))
+          return false;
         Explored.insert(PN);
         PHIs.insert(PN);
       }