Fix assert in X86 backend.

When running combine on an extract_vector_elt, it wants to look through
a bitcast to check if the argument to the bitcast was itself an
extract_vector_elt with particular operands.

However, it called getOperand() on the argument to the bitcast *before*
checking that the opcode was EXTRACT_VECTOR_ELT, assert-failing if there
were zero operands for the actual opcode.

Fix, and add trivial test.

llvm-svn: 249891

1 files changed, 6 insertions, 0 deletions

diff --git a/llvm/test/CodeGen/Generic/vector.ll b/llvm/test/CodeGen/Generic/vector.ll
index 962b1295b5d..2d4dc501a53 100644
--- a/llvm/test/CodeGen/Generic/vector.ll
+++ b/llvm/test/CodeGen/Generic/vector.ll
@@ -156,3 +156,9 @@ define <2 x i32*> @vector_gep(<2 x [3 x {i32, i32}]*> %a) {
     %w = getelementptr [3 x {i32, i32}], <2 x [3 x {i32, i32}]*> %a, <2 x i32> <i32 1, i32 2>, <2 x i32> <i32 2, i32 3>, <2 x i32> <i32 1, i32 1>
       ret <2 x i32*> %w
 }
+
+define i32 @extractelt_constant_bitcast() {
+  %1 = bitcast i64 4 to <2 x i32>
+  %2 = extractelement <2 x i32> %1, i32 0
+  ret i32 %2
+}