[NFC] [C++20] [Modules] Test if the functions in importee are generated

In O0, all the functions (except the always-inline-functions) in the importee
shouldn't be imported for compilation speeds.

But with optimizations, all the potentially called function in the
importee should be imported to not prevent any inter-procedural
optimizations (primarily inline), which is pretty important for runtime
performances.

This patch adds the tests for the feature.

diff --git a/clang/test/CodeGenCXX/module-funcs-from-imports.cppm b/clang/test/CodeGenCXX/module-funcs-from-imports.cppm
new file mode 100644 (file)
index 0000000..4d3e558
--- /dev/null
+++ b/clang/test/CodeGenCXX/module-funcs-from-imports.cppm
@@ -0,0 +1,74 @@
+// RUN: rm -rf %t
+// RUN: split-file %s %t
+//
+// RUN: %clang_cc1 -triple %itanium_abi_triple -std=c++20 %t/M.cppm \
+// RUN:    -emit-module-interface -o %t/M.pcm
+// RUN: %clang_cc1 -std=c++20 %t/Use.cpp -fprebuilt-module-path=%t \
+// RUN:    -S -emit-llvm -o - -disable-llvm-passes \
+// RUN:    | FileCheck %t/Use.cpp --check-prefix=CHECK-O0
+//
+// RUN: %clang_cc1 -triple %itanium_abi_triple -std=c++20 -O1 %t/M.cppm \
+// RUN:    -emit-module-interface -o %t/M.pcm
+// RUN: %clang_cc1 -std=c++20 %t/Use.cpp -fprebuilt-module-path=%t -O1 \
+// RUN:    -S -emit-llvm -o - -disable-llvm-passes | \
+// RUN:    FileCheck %t/Use.cpp --check-prefix=CHECK-O1
+
+//--- foo.h
+int func_in_gmf() {
+    return 43;
+}
+int func_in_gmf_not_called() {
+    return 44;
+}
+
+//--- M.cppm
+module;
+#include "foo.h"
+export module M;
+int non_exported_func() {
+    return 43 + func_in_gmf();
+}
+export int exported_func() {
+    return non_exported_func();
+}
+
+int non_exported_func_not_called() {
+    return 44;
+}
+export int func_not_called() {
+    return non_exported_func_not_called();
+}
+
+export 
+__attribute__((always_inline))
+int always_inline_func() {
+    return 45;
+}
+
+//--- Use.cpp
+import M;
+int use() {
+    return exported_func() + always_inline_func();
+}
+
+// Checks that none of the function (except the always_inline_func) in the importees
+// are generated in the importer's code.
+// CHECK-O0: define{{.*}}_Z3usev(
+// CHECK-O0: declare{{.*}}_ZW1M13exported_funcv(
+// CHECK-O0: define{{.*}}available_externally{{.*}}_ZW1M18always_inline_funcv(
+// CHECK-O0-NOT: func_in_gmf
+// CHECK-O0-NOT: func_in_gmf_not_called
+// CHECK-O0-NOT: non_exported_func
+// CHECK-O0-NOT: non_exported_func_not_called
+// CHECK-O0-NOT: func_not_called
+
+// Checks that all the potentially called function in the importees are generated in the importer's code
+// with available_externally attribute.
+// CHECK-O1: define{{.*}}_Z3usev(
+// CHECK-O1: define{{.*}}available_externally{{.*}}_ZW1M13exported_funcv(
+// CHECK-O1: define{{.*}}available_externally{{.*}}_ZW1M18always_inline_funcv(
+// CHECK-O1: define{{.*}}available_externally{{.*}}_ZW1M17non_exported_funcv(
+// CHECK-O1: define{{.*}}available_externally{{.*}}_Z11func_in_gmfv(
+// CHECK-O1-NOT: func_in_gmf_not_called
+// CHECK-O1-NOT: non_exported_func_not_called
+// CHECK-O1-NOT: func_not_called