[C++20] [Modules] Don't emit function bodies which is noinline and av…

clang/lib/CodeGen/CodeGenModule.cpp

@@ -3847,6 +3847,9 @@ bool CodeGenModule::shouldEmitFunction(GlobalDecl GD) {
   if (CodeGenOpts.OptimizationLevel == 0 && !F->hasAttr<AlwaysInlineAttr>())
     return false;
 
+  if (F->hasAttr<NoInlineAttr>())
+    return false;
+
   if (F->hasAttr<DLLImportAttr>() && !F->hasAttr<AlwaysInlineAttr>()) {
     // Check whether it would be safe to inline this dllimport function.
     DLLImportFunctionVisitor Visitor;

clang/test/Modules/no-import-func-body.cppm

@@ -0,0 +1,45 @@
+// RUN: rm -rf %t
+// RUN: split-file %s %t
+// RUN: cd %t
+//
+// RUN: %clang_cc1 -std=c++20 -O1 -triple %itanium_abi_triple %t/a.cppm \
+// RUN:     -emit-module-interface -o %t/a.pcm
+// RUN: %clang_cc1 -std=c++20 -O1 -triple %itanium_abi_triple %t/b.cppm \
+// RUN:     -emit-module-interface -fprebuilt-module-path=%t -o %t/b.pcm
+// RUN: %clang_cc1 -std=c++20 -O1 -triple %itanium_abi_triple %t/c.cppm \
+// RUN:     -emit-module-interface -fprebuilt-module-path=%t -o %t/c.pcm
+// RUN: %clang_cc1 -std=c++20 -O1 -triple %itanium_abi_triple %t/c.pcm -S \
+// RUN:     -emit-llvm -disable-llvm-passes -o - | FileCheck %t/c.cppm
+
+//--- a.cppm
+export module a;
+export int a() {
+    return 43;
+}
+export __attribute__((noinline)) int a_noinline() {
+    return 44;
+}
+
+//--- b.cppm
+export module b;
+export import a;
+export int b() {
+    return 43 + a();
+}
+
+export __attribute__((noinline)) int b_noinline() {
+    return 43 + a();
+}
+
+//--- c.cppm
+export module c;
+export import b;
+export int c() {
+    return 43 + b() + a() + b_noinline() + a_noinline();
+}
+
+// CHECK: define{{.*}}available_externally{{.*}}@_ZW1b1bv(
+// CHECK: define{{.*}}available_externally{{.*}}@_ZW1a1av(
+
+// CHECK: declare{{.*}}@_ZW1b10b_noinlinev()
+// CHECK: declare{{.*}}@_ZW1a10a_noinlinev()