[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.

llvm-svn: 181204
diff --git a/llvm/test/CodeGen/SystemZ/args-05.ll b/llvm/test/CodeGen/SystemZ/args-05.ll
new file mode 100644
index 0000000..9fa193a
--- /dev/null
+++ b/llvm/test/CodeGen/SystemZ/args-05.ll
@@ -0,0 +1,47 @@
+; Test that we take advantage of signext and zeroext annotations.
+;
+; RUN: llc < %s -mtriple=s390x-linux-gnu | FileCheck %s
+
+; Zero extension of something that is already zero-extended.
+define void @f1(i32 zeroext %r2, i64 *%r3) {
+; CHECK: f1:
+; CHECK-NOT: %r2
+; CHECK: stg %r2, 0(%r3)
+; CHECK: br %r14
+  %conv = zext i32 %r2 to i64
+  store i64 %conv, i64* %r3
+  ret void
+}
+
+; Sign extension of something that is already sign-extended.
+define void @f2(i32 signext %r2, i64 *%r3) {
+; CHECK: f2:
+; CHECK-NOT: %r2
+; CHECK: stg %r2, 0(%r3)
+; CHECK: br %r14
+  %conv = sext i32 %r2 to i64
+  store i64 %conv, i64* %r3
+  ret void
+}
+
+; Sign extension of something that is already zero-extended.
+define void @f3(i32 zeroext %r2, i64 *%r3) {
+; CHECK: f3:
+; CHECK: lgfr [[REGISTER:%r[0-5]+]], %r2
+; CHECK: stg [[REGISTER]], 0(%r3)
+; CHECK: br %r14
+  %conv = sext i32 %r2 to i64
+  store i64 %conv, i64* %r3
+  ret void
+}
+
+; Zero extension of something that is already sign-extended.
+define void @f4(i32 signext %r2, i64 *%r3) {
+; CHECK: f4:
+; CHECK: llgfr [[REGISTER:%r[0-5]+]], %r2
+; CHECK: stg [[REGISTER]], 0(%r3)
+; CHECK: br %r14
+  %conv = zext i32 %r2 to i64
+  store i64 %conv, i64* %r3
+  ret void
+}