[clang] [CIR] Forward caller storage for byref call arguments (PR #216499)

[Andy Kaylor via cfe-commits]

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@@ -0,0 +1,91 @@
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fclangir -emit-cir %s -o %t.cir
+// RUN: FileCheck --check-prefix=CIR --input-file=%t.cir %s
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fclangir -emit-llvm %s -o %t-cir.ll
+// RUN: FileCheck --check-prefixes=LLVM,LLVM-CIR --input-file=%t-cir.ll %s
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-llvm %s -o %t.ll
+// RUN: FileCheck --check-prefixes=LLVM,OGCG --input-file=%t.ll %s
+
+struct WithDtor {
+  int x;
+  ~WithDtor();
+};
+
+struct Big {
+  long a, b, c, d;
+};
+
+void takeByref(WithDtor t);
+void takeTwoByref(WithDtor a, WithDtor b);
+void takeByval(Big b);
+
+// The callee must receive the temporary the caller destroys, not a copy of it.
+void callByref() {
+  WithDtor t;
+  takeByref(t);
+}
+
+// CIR-LABEL: cir.func {{.*}}@_Z9callByrefv
+// CIR:         %[[T:.*]] = cir.alloca "t" align(4) : !cir.ptr<!rec_WithDtor>
+// CIR:         %[[TMP:.*]] = cir.alloca "agg.tmp0" align(4) : !cir.ptr<!rec_WithDtor>
+// CIR:         cir.copy %[[T]] align(4) to %[[TMP]] align(4) : !cir.ptr<!rec_WithDtor>
+// CIR-NOT:     cir.alloca "byref"
----------------
andykaylor wrote:

It's not clear to me that these checks are useful. You've removed the code that would have created this alloca.

https://github.com/llvm/llvm-project/pull/216499