[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
diff --git a/llvm/test/CodeGen/X86/codegen-prepare-crash.ll b/llvm/test/CodeGen/X86/codegen-prepare-crash.ll
new file mode 100644
index 0000000..c3288170
--- /dev/null
+++ b/llvm/test/CodeGen/X86/codegen-prepare-crash.ll
@@ -0,0 +1,14 @@
+; RUN: llc < %s
+target triple = "x86_64-unknown-linux-gnu"
+
+@g = external global [10 x i32]
+
+define void @f(i32 %u) {
+ %1 = add i32 %u, 4
+ br label %P.Proc8.exit
+
+P.Proc8.exit:
+ %valueindex35.i = getelementptr [10 x i32]* @g, i32 0, i32 %1
+ store i32 %u, i32* %valueindex35.i
+ ret void
+}