[PowerPC] Add a testcase for TCO on string rvo function

[timshen]

Summary

Seems good to add a test case to ensure the TCO.

[iteratee]

Small nit. Other than that looks good.

test/CodeGen/PowerPC/tailcall-string-rvo.ll

2

Can you put this near the function being checked, and add a CHECK-LABEL line?

[timshen]

Move checks closer to the function.

[echristo]

I know you've already committed, but a couple of small requests.

Thanks!

llvm/trunk/test/CodeGen/PowerPC/tailcall-string-rvo.ll

19–23 ↗

(On Diff #58017)

Can you move this to the top please? And add a comment of what you want to be testing here?

test/CodeGen/PowerPC/tailcall-string-rvo.ll

+; RUN: llc -O2 < %s | FileCheck %s
+; CHECK: #TC_RETURNd8 TestBar 0
+
+target triple = "powerpc64le-linux-gnu"
+
+%class.basic_string.11.42.73 = type { %"class.__gnu_cxx::__versa_string.10.41.72" }
+%"class.__gnu_cxx::__versa_string.10.41.72" = type { %"class.__gnu_cxx::__sso_string_base.9.40.71" }
+%"class.__gnu_cxx::__sso_string_base.9.40.71" = type { %"struct.__gnu_cxx::__vstring_utility<char, std::char_traits<char>, std::allocator<char> >::_Alloc_hider.7.38.69", i64, %union.anon.8.39.70 }
+%"struct.__gnu_cxx::__vstring_utility<char, std::char_traits<char>, std::allocator<char> >::_Alloc_hider.7.38.69" = type { i8* }
+%union.anon.8.39.70 = type { i64, [8 x i8] }
+
+declare void @TestBaz(%class.basic_string.11.42.73* noalias sret %arg)
+
+define void @TestBar(%class.basic_string.11.42.73* noalias sret %arg) {
+bb:
+  call void @TestBaz(%class.basic_string.11.42.73* noalias sret %arg)
+  ret void
+}
+
+; string TestFoo() {
+;   string ret = undef;
+;   TestBar(&ret);  // tail call optimized
+;   return ret;
+; }
+define void @TestFoo(%class.basic_string.11.42.73* noalias sret %arg) {
+bb:
+  %tmp = getelementptr inbounds %class.basic_string.11.42.73, %class.basic_string.11.42.73* %arg, i64 0, i32 0, i32 0, i32 2
+  %tmp1 = bitcast %class.basic_string.11.42.73* %arg to %union.anon.8.39.70**
+  store %union.anon.8.39.70* %tmp, %union.anon.8.39.70** %tmp1, align 8
+  %tmp2 = bitcast %union.anon.8.39.70* %tmp to i8*
+  tail call void @llvm.memcpy.p0i8.p0i8.i64(i8* %tmp2, i8* nonnull undef, i64 13, i32 1, i1 false)
+  %tmp3 = getelementptr inbounds %class.basic_string.11.42.73, %class.basic_string.11.42.73* %arg, i64 0, i32 0, i32 0, i32 1
+  store i64 13, i64* %tmp3, align 8
+  %tmp4 = getelementptr inbounds %class.basic_string.11.42.73, %class.basic_string.11.42.73* %arg, i64 0, i32 0, i32 0, i32 2, i32 1, i64 5
+  store i8 0, i8* %tmp4, align 1
+  tail call void @TestBar(%class.basic_string.11.42.73* noalias sret %arg)
+  ret void
+}
+
+; Function Attrs: argmemonly nounwind
+declare void @llvm.memcpy.p0i8.p0i8.i64(i8* nocapture, i8* nocapture readonly, i64, i32, i1) #0
+
+attributes #0 = { argmemonly nounwind }