Pragmas from imported C++20 modules are ignored in the importing translation unit, add backend tests

Author: Tony Varghese

clang/lib/CodeGen/CodeGenModule.cpp

@@ -7474,7 +7474,10 @@ void CodeGenModule::EmitTopLevelDecl(Decl *D) {
     case PCK_Lib:
         AddDependentLib(PCD->getArg());
       break;
-    case PCK_Copyright:      
+    case PCK_Copyright:
+      // Skip pragmas deserialized from modules/PCHs
+      if (PCD->isFromASTFile())
+        break;
       ProcessPragmaCommentCopyright(PCD->getArg());
       break;
     case PCK_Compiler:

clang/test/CodeGen/PowerPC/pragma-comment-copyright-aix-modules.cpp

@@ -0,0 +1,26 @@
+// RUN: split-file %s %t
+
+// Build the module interface to a PCM
+// RUN: %clang_cc1 -std=c++20 -triple powerpc-ibm-aix \
+// RUN:   -emit-module-interface %t/copymod.cppm -o %t/copymod.pcm
+
+// verify that module interface emit copyright string when compiled to assembly
+// RUN: %clang_cc1 -std=c++20 -triple powerpc-ibm-aix -S %t/copymod.cppm -o - \
+// RUN:   | FileCheck %s --check-prefix=CHECK-MOD
+// CHECK-MOD: .string "module me"
+
+// Compile an importing TU that uses the prebuilt module and verify that it
+// does NOT re-emit the module's copyright string.
+// RUN: %clang_cc1 -std=c++20 -triple powerpc-ibm-aix \
+// RUN:   -fprebuilt-module-path=%t -S %t/importmod.cc -o - \
+// RUN:   | FileCheck %s
+// CHECK-NOT: .string "module me"
+
+//--- copymod.cppm
+export module copymod;
+#pragma comment(copyright, "module me")
+export inline void f() {}
+
+//--- importmod.cc
+import copymod;
+void g() { f(); }

llvm/test/CodeGen/PowerPC/pragma-comment-copyright-aix.ll

@@ -0,0 +1,61 @@
+; REQUIRES: powerpc-registered-target, system-aix
+
+; This test verify that the CopyrightMetadataPass and the PowerPC AIX backend
+; correctly lower and preserve copyright metadata emitted by Clang
+; from `#pragma comment(copyright, "...")`.
+
+; Build IR with the pass:
+; RUN: opt -passes=copyright-metadata %s -o %t.bc
+
+; ---------------- 32-bit AIX ----------------
+; RUN: llc -mtriple=powerpc-ibm-aix -filetype=obj -o %t32.o %t.bc
+; RUN: llc -mtriple=powerpc-ibm-aix -filetype=asm %t.bc -o - | FileCheck %s --check-prefix=CHECK-ASM
+
+; Verify that TU-local symbols and relocations reference the string.
+; RUN: llvm-objdump -t %t32.o | FileCheck %s --check-prefix=CHECK-SYMS
+; RUN: llvm-objdump -r %t32.o | FileCheck %s --check-prefix=CHECK-REL
+
+; ---------------- 64-bit AIX ----------------
+; RUN: llc -mtriple=powerpc64-ibm-aix -filetype=obj -o %t64.o %t.bc
+; RUN: llc -mtriple=powerpc-ibm-aix -filetype=asm %t.bc -o - | FileCheck %s --check-prefix=CHECK-ASM
+; RUN: llvm-objdump -t %t64.o | FileCheck %s --check-prefix=CHECK-SYMS
+; RUN: llvm-objdump -r %t64.o | FileCheck %s --check-prefix=CHECK-REL
+
+target triple = "powerpc-ibm-aix"
+
+define void @f0() {
+entry:
+  ret void
+}
+
+define i32 @main() {
+entry:
+  ret i32 0
+}
+
+!llvm.module.flags = !{!0}
+!0 = !{i32 1, !"wchar_size", i32 2}
+
+!aix.copyright.comment = !{!1}
+!1 = !{!"Copyright IBM"}
+
+; ---------------- Assembly checks ----------------
+; Verify that the backend:
+;   - Emits a `.ref` directive to tie the string to the TU
+;   - Emits the string in a dedicated read-only csect
+;
+; CHECK-ASM:       .ref __aix_copyright_str
+; CHECK-ASM:       .csect __aix_copyright[RO],2
+; CHECK-ASM-NEXT:  .lglobl __aix_copyright_str
+; CHECK-ASM:       __aix_copyright_str
+; CHECK-ASM:       .string "Copyright IBM"
+
+; ---------------- Symbol table checks ----------------
+; TU-local globals/functions should be present in the symbol table
+; CHECK-SYMS: __aix_copyright_str
+
+; ---------------- Relocation checks ----------------
+; The object should contain a relocation in the text section
+; that references the copyright string.
+; CHECK-LABEL: RELOCATION RECORDS FOR [.text]
+; CHECK-REL: __aix_copyright_str

llvm/test/Transforms/CopyrightMetadata/copyright-metadata.ll

@@ -21,7 +21,7 @@
 ;      defined function in the module. The PowerPC AIX backend recognizes
 ;      this metadata and emits a `.ref` directive from the function to the
 ;      string, creating a concrete relocation that prevents the linker from
-;      discarding it.
+;      discarding it (as long as the referencing symbol is kept).
 
 target triple = "powerpc-ibm-aix"