[clang] 1ecbab5 - [C++20] [Modules] Don't import non-inline function bodies even if it is marked as always_inline

[Chuanqi Xu via cfe-commits]

Author: Chuanqi Xu
Date: 2024-02-18T15:15:28+08:00
New Revision: 1ecbab56dcbb78268c8d19af34a50591f90b12a0

URL: https://github.com/llvm/llvm-project/commit/1ecbab56dcbb78268c8d19af34a50591f90b12a0
DIFF: https://github.com/llvm/llvm-project/commit/1ecbab56dcbb78268c8d19af34a50591f90b12a0.diff

LOG: [C++20] [Modules] Don't import non-inline function bodies even if it is marked as always_inline

Close https://github.com/llvm/llvm-project/issues/80949

Previously, I thought the always-inline function can be an exception to
enable optimizations as much as possible. However, it looks like it
breaks the ABI requirement we discussed later. So it looks better to not
import non-inline function bodies at all even if the function bodies are
marked as always_inline.

It doesn't produce regressions in some degree since the always_inline
still works in the same TU.

Added: 
    

Modified: 
    clang/lib/CodeGen/CodeGenModule.cpp
    clang/test/CodeGenCXX/module-funcs-from-imports.cppm

Removed: 
    


################################################################################
diff  --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index c984260b082cd1..836cd34a16c0a1 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -3985,8 +3985,7 @@ bool CodeGenModule::shouldEmitFunction(GlobalDecl GD) {
   // behavior may break ABI compatibility of the current unit.
   if (const Module *M = F->getOwningModule();
       M && M->getTopLevelModule()->isNamedModule() &&
-      getContext().getCurrentNamedModule() != M->getTopLevelModule() &&
-      !F->hasAttr<AlwaysInlineAttr>())
+      getContext().getCurrentNamedModule() != M->getTopLevelModule())
     return false;
 
   if (F->hasAttr<NoInlineAttr>())

diff  --git a/clang/test/CodeGenCXX/module-funcs-from-imports.cppm b/clang/test/CodeGenCXX/module-funcs-from-imports.cppm
index 33cdf437110a9e..8d04328eaf3fea 100644
--- a/clang/test/CodeGenCXX/module-funcs-from-imports.cppm
+++ b/clang/test/CodeGenCXX/module-funcs-from-imports.cppm
@@ -53,11 +53,11 @@ int use() {
     return exported_func() + always_inline_func();
 }
 
-// Checks that none of the function (except the always_inline_func) in the importees
+// Checks that none of the function 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: declare{{.*}}_ZW1M18always_inline_funcv(
 // CHECK-O0-NOT: func_in_gmf
 // CHECK-O0-NOT: func_in_gmf_not_called
 // CHECK-O0-NOT: non_exported_func
@@ -68,7 +68,7 @@ int use() {
 // O0 to keep consistent ABI.
 // CHECK-O1: define{{.*}}_Z3usev(
 // CHECK-O1: declare{{.*}}_ZW1M13exported_funcv(
-// CHECK-O1: define{{.*}}available_externally{{.*}}_ZW1M18always_inline_funcv(
+// CHECK-O1: declare{{.*}}_ZW1M18always_inline_funcv(
 // CHECK-O1-NOT: func_in_gmf
 // CHECK-O1-NOT: func_in_gmf_not_called
 // CHECK-O1-NOT: non_exported_func