[CGP] r205941 changed the logic, so that a cast happens *before* 'Result' is

compared to 'AddrMode.BaseReg'. In the case that 'AddrMode.BaseReg' is
nullptr, 'Result' will also be nullptr, so the cast causes an assertion. We
should use dyn_cast_or_null here to check 'Result' is not null and it is an
instruction.

Bug found by Mats Petersson, and I reduced his IR to get a test case.

llvm-svn: 208705

1 files changed, 1 insertions, 1 deletions

diff --git a/llvm/lib/CodeGen/CodeGenPrepare.cpp b/llvm/lib/CodeGen/CodeGenPrepare.cpp
index d2559cf53d2..a6d8a68588d 100644
--- a/llvm/lib/CodeGen/CodeGenPrepare.cpp
+++ b/llvm/lib/CodeGen/CodeGenPrepare.cpp
@@ -2759,7 +2759,7 @@ bool CodeGenPrepare::OptimizeMemoryInst(Instruction *MemoryInst, Value *Addr,
         // the original IR value was tossed in favor of a constant back when
         // the AddrMode was created we need to bail out gracefully if widths
         // do not match instead of extending it.
-        Instruction *I = dyn_cast<Instruction>(Result);
+        Instruction *I = dyn_cast_or_null<Instruction>(Result);
         if (I && (Result != AddrMode.BaseReg))
           I->eraseFromParent();
         return false;