Imported Upstream version 6.10.0.49

Former-commit-id: 1d6753294b2993e1fbf92de9366bb9544db4189b

external/llvm-project/llvm/test/CodeGen/AArch64/bitcast.ll

@@ -0,0 +1,27 @@
+; RUN: llc < %s -mtriple=aarch64--linux-gnu | FileCheck %s
+
+; PR23065: SCALAR_TO_VECTOR implies the top elements 1 to N-1 of the N-element vector are undefined.
+
+define <4 x i16> @foo1(<2 x i32> %a) {
+; CHECK-LABEL: foo1:
+; CHECK:       movi	d0, #0000000000000000
+; CHECK-NEXT:  ret
+
+  %1 = shufflevector <2 x i32> <i32 58712, i32 undef>, <2 x i32> %a, <2 x i32> <i32 0, i32 2>
+; Can't optimize the following bitcast to scalar_to_vector.
+  %2 = bitcast <2 x i32> %1 to <4 x i16>
+  %3 = shufflevector <4 x i16> %2, <4 x i16> undef, <4 x i32> <i32 1, i32 undef, i32 undef, i32 undef>
+  ret <4 x i16> %3
+}
+
+define <4 x i16> @foo2(<2 x i32> %a) {
+; CHECK-LABEL: foo2:
+; CHECK:       movi	d0, #0000000000000000
+; CHECK-NEXT:  ret
+
+  %1 = shufflevector <2 x i32> <i32 712, i32 undef>, <2 x i32> %a, <2 x i32> <i32 0, i32 2>
+; Can't optimize the following bitcast to scalar_to_vector.
+  %2 = bitcast <2 x i32> %1 to <4 x i16>
+  %3 = shufflevector <4 x i16> %2, <4 x i16> undef, <4 x i32> <i32 1, i32 undef, i32 undef, i32 undef>
+  ret <4 x i16> %3
+}