1 files changed, 27 insertions, 0 deletions
diff --git a/llvm/test/CodeGen/X86/overlap-add.ll b/llvm/test/CodeGen/X86/overlap-add.ll
new file mode 100644
index 00000000000..a7150d21e36
--- /dev/null
+++ b/llvm/test/CodeGen/X86/overlap-add.ll
@@ -0,0 +1,27 @@
+;; X's live range extends beyond the shift, so the register allocator
+;; cannot coalesce it with Y.  Because of this, a copy needs to be
+;; emitted before the shift to save the register value before it is
+;; clobbered.  However, this copy is not needed if the register
+;; allocator turns the shift into an LEA.  This also occurs for ADD.
+
+; Check that the shift gets turned into an LEA.
+
+; RUN: llvm-upgrade < %s | llvm-as | llc -march=x86 -x86-asm-syntax=intel | not grep 'mov E.X, E.X'
+
+; FIXME: We need live variable information about flags to do this xform safely. :(
+; XFAIL: *
+
+%G = external global int
+
+int %test1(int %X, int %Y) {
+	%Z = add int %X, %Y
+	volatile store int %Y, int* %G
+	volatile store int %Z, int* %G
+	ret int %X
+}
+
+int %test2(int %X) {
+	%Z = add int %X, 1  ;; inc
+	volatile store int %Z, int* %G
+	ret int %X
+}