Fix to support properly cleaning up failed address sinking against constants

As it turns out the source of the sunkaddr can be a constant, in which case
there is not an instruction to delete, causing the cleanup code introduced in
r204833 to crash. This patch adds a dynamic check to ensure the deleted value is
in fact an instruction and not a constant.

Patch by Louis Gerbarg <lgg@apple.com>

llvm-svn: 205941

1 files changed, 3 insertions, 2 deletions

diff --git a/llvm/lib/CodeGen/CodeGenPrepare.cpp b/llvm/lib/CodeGen/CodeGenPrepare.cpp
index e82a30617d2..9765485b5d5 100644
--- a/llvm/lib/CodeGen/CodeGenPrepare.cpp
+++ b/llvm/lib/CodeGen/CodeGenPrepare.cpp
@@ -2459,8 +2459,9 @@ 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.
-        if (Result != AddrMode.BaseReg)
-            cast<Instruction>(Result)->eraseFromParent();
+        Instruction *I = dyn_cast<Instruction>(Result);
+        if (I && (Result != AddrMode.BaseReg))
+          I->eraseFromParent();
         return false;
       }
       if (AddrMode.Scale != 1)