[SystemZ] Add CodeGen test cases

This adds all CodeGen tests for the SystemZ target.

This version of the patch incorporates feedback from a review by
Sean Silva.  Thanks to all reviewers!

Patch by Richard Sandiford.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@181204 91177308-0d34-0410-b5e6-96231b3b80d8

test/CodeGen/SystemZ/atomic-store-04.ll

@@ -0,0 +1,16 @@
+; Test 64-bit atomic stores.
+;
+; RUN: llc < %s -mtriple=s390x-linux-gnu | FileCheck %s
+
+; This is just a placeholder to make sure that stores are handled.
+; Using CS is probably too conservative.
+define void @f1(i64 %val, i64 *%src) {
+; CHECK: f1:
+; CHECK: lg %r0, 0(%r3)
+; CHECK: [[LABEL:\.[^:]*]]:
+; CHECK: csg %r0, %r2, 0(%r3)
+; CHECK: j{{g?}}lh [[LABEL]]
+; CHECK: br %r14
+  store atomic i64 %val, i64 *%src seq_cst, align 8
+  ret void
+}