[clang] [llvm] [PowerPC][AIX] Support #pragma comment copyright for AIX (PR #187985)
Tony Varghese via cfe-commits
cfe-commits at lists.llvm.org
Mon Mar 23 00:29:53 PDT 2026
https://github.com/tonykuttai created https://github.com/llvm/llvm-project/pull/187985
- Emit !aix.copyright.comment from Clang for the pragma.
- Lower it in LLVM to a TU-local string + llvm.used + !implicit.ref.
- Add module-import and backend relocation tests.
>From ed0f1ec37fa03d18518b59509bb77ea9693ae163 Mon Sep 17 00:00:00 2001
From: Tony Varghese <tony.varghese at ibm.com>
Date: Mon, 2 Feb 2026 23:19:10 -0500
Subject: [PATCH] [PowerPC][AIX] Support #pragma comment copyright for AIX
- Emit !aix.copyright.comment from Clang for the pragma.
- Lower it in LLVM to a TU-local string + llvm.used + !implicit.ref.
- Add module-import and backend relocation tests.
---
.../clang/Basic/DiagnosticParseKinds.td | 4 +
clang/include/clang/Basic/PragmaKinds.h | 3 +-
clang/lib/AST/TextNodeDumper.cpp | 3 +
clang/lib/CodeGen/CodeGenModule.cpp | 51 +++++-
clang/lib/CodeGen/CodeGenModule.h | 11 ++
clang/lib/Parse/ParsePragma.cpp | 53 +++++--
.../pragma-comment-copyright-modules.cpp | 30 ++++
clang/test/CodeGen/PowerPC/pragma-comment.c | 42 +++++
clang/test/CodeGen/lto-newpm-pipeline.c | 2 +
clang/test/Parser/pragma-comment.c | 11 ++
.../Transforms/Utils/LowerCommentStringPass.h | 24 +++
llvm/lib/Passes/PassBuilder.cpp | 1 +
llvm/lib/Passes/PassBuilderPipelines.cpp | 7 +
llvm/lib/Passes/PassRegistry.def | 1 +
llvm/lib/Transforms/Utils/CMakeLists.txt | 1 +
.../Utils/LowerCommentStringPass.cpp | 148 ++++++++++++++++++
.../CodeGen/AArch64/print-pipeline-passes.ll | 2 +-
.../CodeGen/Hexagon/print-pipeline-passes.ll | 2 +-
llvm/test/Other/new-pm-defaults.ll | 1 +
.../Other/new-pm-thinlto-postlink-defaults.ll | 1 +
.../new-pm-thinlto-postlink-pgo-defaults.ll | 1 +
...-pm-thinlto-postlink-samplepgo-defaults.ll | 1 +
.../lower-comment-string.ll | 59 +++++++
23 files changed, 444 insertions(+), 15 deletions(-)
create mode 100644 clang/test/CodeGen/PowerPC/pragma-comment-copyright-modules.cpp
create mode 100644 clang/test/CodeGen/PowerPC/pragma-comment.c
create mode 100644 clang/test/Parser/pragma-comment.c
create mode 100644 llvm/include/llvm/Transforms/Utils/LowerCommentStringPass.h
create mode 100644 llvm/lib/Transforms/Utils/LowerCommentStringPass.cpp
create mode 100644 llvm/test/Transforms/LowerCommentString/lower-comment-string.ll
diff --git a/clang/include/clang/Basic/DiagnosticParseKinds.td b/clang/include/clang/Basic/DiagnosticParseKinds.td
index 19edc7f7a3b23..964251bba9c41 100644
--- a/clang/include/clang/Basic/DiagnosticParseKinds.td
+++ b/clang/include/clang/Basic/DiagnosticParseKinds.td
@@ -1358,6 +1358,10 @@ def err_pragma_comment_unknown_kind : Error<"unknown kind of pragma comment">;
// PS4 recognizes only #pragma comment(lib)
def warn_pragma_comment_ignored : Warning<"'#pragma comment %0' ignored">,
InGroup<IgnoredPragmas>;
+def warn_pragma_comment_once
+ : Warning<"'#pragma comment %0' "
+ "ignored: it can be specified only once per translation unit">,
+ InGroup<IgnoredPragmas>;
// - #pragma detect_mismatch
def err_pragma_detect_mismatch_malformed : Error<
"pragma detect_mismatch is malformed; it requires two comma-separated "
diff --git a/clang/include/clang/Basic/PragmaKinds.h b/clang/include/clang/Basic/PragmaKinds.h
index 42f049f7323d2..52ca58855d460 100644
--- a/clang/include/clang/Basic/PragmaKinds.h
+++ b/clang/include/clang/Basic/PragmaKinds.h
@@ -17,7 +17,8 @@ enum PragmaMSCommentKind {
PCK_Lib, // #pragma comment(lib, ...)
PCK_Compiler, // #pragma comment(compiler, ...)
PCK_ExeStr, // #pragma comment(exestr, ...)
- PCK_User // #pragma comment(user, ...)
+ PCK_User, // #pragma comment(user, ...)
+ PCK_Copyright // #pragma comment(copyright, ...)
};
enum PragmaMSStructKind {
diff --git a/clang/lib/AST/TextNodeDumper.cpp b/clang/lib/AST/TextNodeDumper.cpp
index 250ec8b666e05..51c97e6700102 100644
--- a/clang/lib/AST/TextNodeDumper.cpp
+++ b/clang/lib/AST/TextNodeDumper.cpp
@@ -2560,6 +2560,9 @@ void TextNodeDumper::VisitPragmaCommentDecl(const PragmaCommentDecl *D) {
case PCK_User:
OS << "user";
break;
+ case PCK_Copyright:
+ OS << "copyright";
+ break;
}
StringRef Arg = D->getArg();
if (!Arg.empty())
diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index daaa846bf42bc..eaa64b10e2368 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -1632,6 +1632,8 @@ void CodeGenModule::Release() {
EmitBackendOptionsMetadata(getCodeGenOpts());
+ EmitLoadTimeComment();
+
// If there is device offloading code embed it in the host now.
EmbedObject(&getModule(), CodeGenOpts, *getFileSystem(), getDiags());
@@ -3541,6 +3543,39 @@ void CodeGenModule::AddDependentLib(StringRef Lib) {
LinkerOptionsMetadata.push_back(llvm::MDNode::get(C, MDOpts));
}
+/// Process copyright pragma and create LLVM metadata.
+/// #pragma comment(copyright, "string") embeds copyright information into a
+/// loadable program-data section of the object file for inclusion in the linked
+/// module.
+///
+/// Example: #pragma comment(copyright, "Copyright string")
+///
+/// This should only be called once per translation unit.
+void CodeGenModule::ProcessPragmaComment(PragmaMSCommentKind Kind,
+ StringRef Comment,
+ bool isFromASTFile) {
+ // Ensure we are only processing Copyright Pragmas
+ assert(Kind == PCK_Copyright &&
+ "Unexpected pragma comment kind, ProcessPragmaComment should only be "
+ "called for PCK_Copyright");
+ // Target Guard: Only AIX supports PCK_Copyright currently.
+ assert(getTriple().isOSAIX() &&
+ "pragma comment copyright is supported only when targeting AIX");
+
+ // Deserialization Guard: Only process if copyright originated in this TU.
+ if (isFromASTFile)
+ return;
+
+ // Only one copyright pragma allowed per translation unit
+ assert(!LoadTimeComment &&
+ "Only one copyright pragma allowed per translation unit");
+
+ // Create llvm metadata with the comment string
+ auto &C = getLLVMContext();
+ llvm::Metadata *Ops[] = {llvm::MDString::get(C, Comment)};
+ LoadTimeComment = llvm::MDNode::get(C, Ops);
+}
+
/// Add link options implied by the given module, including modules
/// it depends on, using a postorder walk.
static void addLinkOptionsPostorder(CodeGenModule &CGM, Module *Mod,
@@ -4061,6 +4096,16 @@ bool CodeGenModule::MustBeEmitted(const ValueDecl *Global) {
return getContext().DeclMustBeEmitted(Global);
}
+void CodeGenModule::EmitLoadTimeComment() {
+ // Emit copyright metadata for #pragma comment(copyright, ...).
+ // The LoadTimeComment is set during pragma processing and contains the
+ // copyright string that should be embedded in the executable.
+ if (LoadTimeComment) {
+ auto *NMD = getModule().getOrInsertNamedMetadata("comment_string.loadtime");
+ NMD->addOperand(LoadTimeComment);
+ }
+}
+
bool CodeGenModule::MayBeEmittedEagerly(const ValueDecl *Global) {
// In OpenMP 5.0 variables and function may be marked as
// device_type(host/nohost) and we should not emit them eagerly unless we sure
@@ -7793,7 +7838,11 @@ void CodeGenModule::EmitTopLevelDecl(Decl *D) {
AppendLinkerOptions(PCD->getArg());
break;
case PCK_Lib:
- AddDependentLib(PCD->getArg());
+ AddDependentLib(PCD->getArg());
+ break;
+ case PCK_Copyright:
+ ProcessPragmaComment(PCD->getCommentKind(), PCD->getArg(),
+ PCD->isFromASTFile());
break;
case PCK_Compiler:
case PCK_ExeStr:
diff --git a/clang/lib/CodeGen/CodeGenModule.h b/clang/lib/CodeGen/CodeGenModule.h
index 0a697c84b66a7..d859943ebfb78 100644
--- a/clang/lib/CodeGen/CodeGenModule.h
+++ b/clang/lib/CodeGen/CodeGenModule.h
@@ -592,6 +592,9 @@ class CodeGenModule : public CodeGenTypeCache {
/// A vector of metadata strings for dependent libraries for ELF.
SmallVector<llvm::MDNode *, 16> ELFDependentLibraries;
+ /// Metadata for copyright pragma comment (if present).
+ llvm::MDNode *LoadTimeComment = nullptr;
+
/// @name Cache for Objective-C runtime types
/// @{
@@ -1495,6 +1498,9 @@ class CodeGenModule : public CodeGenTypeCache {
/// Appends a dependent lib to the appropriate metadata value.
void AddDependentLib(StringRef Lib);
+ /// Process pragma comment
+ void ProcessPragmaComment(PragmaMSCommentKind Kind, StringRef Comment,
+ bool isFromASTFile);
llvm::GlobalVariable::LinkageTypes getFunctionLinkage(GlobalDecl GD);
@@ -2075,6 +2081,11 @@ class CodeGenModule : public CodeGenTypeCache {
/// false, the definition can be emitted lazily if it's used.
bool MustBeEmitted(const ValueDecl *D);
+ /// Emit load-time comment metadata for #pragma comment(copyright, ...).
+ /// This adds the copyright string to the module's named metadata, which will
+ /// be processed by the backend to include it in the generated executable.
+ void EmitLoadTimeComment();
+
/// Determine whether the definition can be emitted eagerly, or should be
/// delayed until the end of the translation unit. This is relevant for
/// definitions whose linkage can change, e.g. implicit function instantions
diff --git a/clang/lib/Parse/ParsePragma.cpp b/clang/lib/Parse/ParsePragma.cpp
index 734d095d74cdf..d87967042089a 100644
--- a/clang/lib/Parse/ParsePragma.cpp
+++ b/clang/lib/Parse/ParsePragma.cpp
@@ -237,6 +237,7 @@ struct PragmaCommentHandler : public PragmaHandler {
private:
Sema &Actions;
+ bool SeenCopyrightInTU = false; // TU-scoped
};
struct PragmaDetectMismatchHandler : public PragmaHandler {
@@ -480,7 +481,8 @@ void Parser::initializePragmaHandlers() {
PP.AddPragmaHandler(OpenACCHandler.get());
if (getLangOpts().MicrosoftExt ||
- getTargetInfo().getTriple().isOSBinFormatELF()) {
+ getTargetInfo().getTriple().isOSBinFormatELF() ||
+ getTargetInfo().getTriple().isOSAIX()) {
MSCommentHandler = std::make_unique<PragmaCommentHandler>(Actions);
PP.AddPragmaHandler(MSCommentHandler.get());
}
@@ -607,7 +609,8 @@ void Parser::resetPragmaHandlers() {
OpenACCHandler.reset();
if (getLangOpts().MicrosoftExt ||
- getTargetInfo().getTriple().isOSBinFormatELF()) {
+ getTargetInfo().getTriple().isOSBinFormatELF() ||
+ getTargetInfo().getTriple().isOSAIX()) {
PP.RemovePragmaHandler(MSCommentHandler.get());
MSCommentHandler.reset();
}
@@ -3265,7 +3268,9 @@ void PragmaDetectMismatchHandler::HandlePragma(Preprocessor &PP,
/// \code
/// #pragma comment(linker, "foo")
/// \endcode
-/// 'linker' is one of five identifiers: compiler, exestr, lib, linker, user.
+/// 'linker' is one of six identifiers: compiler, copyright, exestr, lib,
+/// linker, user.
+///
/// "foo" is a string, which is fully macro expanded, and permits string
/// concatenation, embedded escape characters etc. See MSDN for more details.
void PragmaCommentHandler::HandlePragma(Preprocessor &PP,
@@ -3285,27 +3290,49 @@ void PragmaCommentHandler::HandlePragma(Preprocessor &PP,
return;
}
- // Verify that this is one of the 5 explicitly listed options.
+ // Verify that this is one of the 6 explicitly listed options.
IdentifierInfo *II = Tok.getIdentifierInfo();
PragmaMSCommentKind Kind =
- llvm::StringSwitch<PragmaMSCommentKind>(II->getName())
- .Case("linker", PCK_Linker)
- .Case("lib", PCK_Lib)
- .Case("compiler", PCK_Compiler)
- .Case("exestr", PCK_ExeStr)
- .Case("user", PCK_User)
- .Default(PCK_Unknown);
+ llvm::StringSwitch<PragmaMSCommentKind>(II->getName())
+ .Case("linker", PCK_Linker)
+ .Case("lib", PCK_Lib)
+ .Case("compiler", PCK_Compiler)
+ .Case("exestr", PCK_ExeStr)
+ .Case("user", PCK_User)
+ .Case("copyright", PCK_Copyright)
+ .Default(PCK_Unknown);
+
if (Kind == PCK_Unknown) {
PP.Diag(Tok.getLocation(), diag::err_pragma_comment_unknown_kind);
return;
}
+ // Handle AIX Target restrictions (all non-copyright kinds)
+ if (PP.getTargetInfo().getTriple().isOSAIX() && Kind != PCK_Copyright) {
+ // pragma comment kinds linker, lib, compiler, exestr and user are
+ // ignored when targeting AIX.
+ PP.Diag(Tok.getLocation(), diag::warn_pragma_comment_ignored)
+ << II->getName();
+ return;
+ }
+
if (PP.getTargetInfo().getTriple().isOSBinFormatELF() && Kind != PCK_Lib) {
PP.Diag(Tok.getLocation(), diag::warn_pragma_comment_ignored)
<< II->getName();
return;
}
+ // Handle pragma comment copyright
+ if (Kind == PCK_Copyright) {
+ if (SeenCopyrightInTU) {
+ // On AIX, pragma comment copyright can each appear only once in a TU.
+ PP.Diag(Tok.getLocation(), diag::warn_pragma_comment_once)
+ << II->getName();
+ return;
+ }
+ SeenCopyrightInTU = true;
+ }
+
// Read the optional string if present.
PP.Lex(Tok);
std::string ArgumentString;
@@ -3332,6 +3359,10 @@ void PragmaCommentHandler::HandlePragma(Preprocessor &PP,
return;
}
+ // Skip further processing for well-formed copyright with an empty string
+ if (Kind == PCK_Copyright && ArgumentString.empty())
+ return;
+
// If the pragma is lexically sound, notify any interested PPCallbacks.
if (PP.getPPCallbacks())
PP.getPPCallbacks()->PragmaComment(CommentLoc, II, ArgumentString);
diff --git a/clang/test/CodeGen/PowerPC/pragma-comment-copyright-modules.cpp b/clang/test/CodeGen/PowerPC/pragma-comment-copyright-modules.cpp
new file mode 100644
index 0000000000000..b8641531177ac
--- /dev/null
+++ b/clang/test/CodeGen/PowerPC/pragma-comment-copyright-modules.cpp
@@ -0,0 +1,30 @@
+// 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 emits copyright global when compiled to IR
+
+// RUN: %clang_cc1 -std=c++20 -triple powerpc-ibm-aix -emit-llvm %t/copymod.cppm -o - \
+// RUN: | FileCheck %s --check-prefix=CHECK-MOD
+// CHECK-MOD: @__loadtime_comment_str = internal unnamed_addr constant [10 x i8] c"module me\00", section "__loadtime_comment"
+// CHECK-MOD: @llvm.used = appending global {{.*}} @__loadtime_comment_str
+
+// Compile an importing TU that uses the prebuilt module and verify that it
+// does NOT re-emit the module's copyright global.
+
+// RUN: %clang_cc1 -std=c++20 -triple powerpc-ibm-aix \
+// RUN: -fprebuilt-module-path=%t -emit-llvm %t/importmod.cc -o - \
+// RUN: | FileCheck %s --check-prefix=CHECK-IMPORT
+// CHECK-IMPORT-NOT: @__loadtime_comment_str
+// CHECK-IMPORT-NOT: c"module me\00"
+
+//--- copymod.cppm
+export module copymod;
+#pragma comment(copyright, "module me")
+export inline void f() {}
+
+//--- importmod.cc
+import copymod;
+void g() { f(); }
diff --git a/clang/test/CodeGen/PowerPC/pragma-comment.c b/clang/test/CodeGen/PowerPC/pragma-comment.c
new file mode 100644
index 0000000000000..a8eb71b558180
--- /dev/null
+++ b/clang/test/CodeGen/PowerPC/pragma-comment.c
@@ -0,0 +1,42 @@
+// RUN: %clang_cc1 %s -DTEST_EMPTY_COPYRIGHT -triple powerpc-ibm-aix -verify
+// RUN: %clang_cc1 %s -DTEST_OTHER_COMMENT_KINDS -triple powerpc-ibm-aix -verify
+// RUN: %clang_cc1 %s -triple powerpc-ibm-aix -emit-llvm -disable-llvm-passes -o - | FileCheck %s
+// RUN: %clang_cc1 %s -triple powerpc-ibm-aix -verify
+
+// RUN: %clang_cc1 %s -DTEST_EMPTY_COPYRIGHT -triple powerpc64-ibm-aix -verify
+// RUN: %clang_cc1 %s -DTEST_OTHER_COMMENT_KINDS -triple powerpc64-ibm-aix -verify
+// RUN: %clang_cc1 %s -triple powerpc64-ibm-aix -emit-llvm -disable-llvm-passes -o - | FileCheck %s
+// RUN: %clang_cc1 %s -triple powerpc64-ibm-aix -verify
+
+#ifdef TEST_EMPTY_COPYRIGHT
+
+// 1. Verify no diagnostics for empty copyright string
+#pragma comment(copyright, "") // expected-no-diagnostics
+int main() {return 0; }
+
+#elif defined(TEST_OTHER_COMMENT_KINDS)
+
+// 2. Verify warnings for lib/linker and silent ignore for others
+#pragma comment(lib, "m") // expected-warning {{'#pragma comment lib' ignored}}
+#pragma comment(linker, "foo") // expected-warning {{'#pragma comment linker' ignored}}
+
+// These are recognized but ignored in CodeGen
+#pragma comment(compiler) // expected-warning {{'#pragma comment compiler' ignored}}
+#pragma comment(exestr, "foo") // expected-warning {{'#pragma comment exestr' ignored}}
+#pragma comment(user, "foo\abar\nbaz\tsomething") // expected-warning {{'#pragma comment user' ignored}}
+int main() {return 0; }
+
+#else
+
+// 3. Default Path: Verify metadata generation and duplicate warning
+#pragma comment(copyright, "@(#) Copyright")
+#pragma comment(copyright, "Duplicate Copyright") // expected-warning {{'#pragma comment copyright' ignored: it can be specified only once per translation unit}}
+
+int main() { return 0; }
+// Check that both metadata sections are present
+// CHECK: !comment_string.loadtime = !{![[copyright:[0-9]+]]}
+
+// Check individual metadata content
+// CHECK: ![[copyright]] = !{!"@(#) Copyright"}
+
+#endif
diff --git a/clang/test/CodeGen/lto-newpm-pipeline.c b/clang/test/CodeGen/lto-newpm-pipeline.c
index ea9784a76f923..b9466b9558b06 100644
--- a/clang/test/CodeGen/lto-newpm-pipeline.c
+++ b/clang/test/CodeGen/lto-newpm-pipeline.c
@@ -27,6 +27,7 @@
// CHECK-FULL-O0: Running pass: VerifierPass
// CHECK-FULL-O0-NEXT: Running analysis: VerifierAnalysis
+// CHECK-FULL-O0-NEXT: Running pass: LowerCommentStringPass
// CHECK-FULL-O0-NEXT: Running analysis: InnerAnalysisManagerProxy
// CHECK-FULL-O0-NEXT: Running pass: EntryExitInstrumenterPass
// CHECK-FULL-O0-NEXT: Running pass: AlwaysInlinerPass
@@ -41,6 +42,7 @@
// CHECK-THIN-O0: Running pass: VerifierPass
// CHECK-THIN-O0-NEXT: Running analysis: VerifierAnalysis
+// CHECK-THIN-O0-NEXT: Running pass: LowerCommentStringPass
// CHECK-THIN-O0-NEXT: Running analysis: InnerAnalysisManagerProxy
// CHECK-THIN-O0-NEXT: Running pass: EntryExitInstrumenterPass
// CHECK-THIN-O0-NEXT: Running pass: AlwaysInlinerPass
diff --git a/clang/test/Parser/pragma-comment.c b/clang/test/Parser/pragma-comment.c
new file mode 100644
index 0000000000000..c9618d44c0f2e
--- /dev/null
+++ b/clang/test/Parser/pragma-comment.c
@@ -0,0 +1,11 @@
+// RUN: %clang_cc1 -triple aarch64-none-linux-gnu -fsyntax-only -verify %s
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fsyntax-only -verify %s
+// RUN: %clang_cc1 -triple systemz -fsyntax-only -verify %s
+// RUN: %clang_cc1 -triple powerpc64-linux-gnu -fsyntax-only -verify %s
+// RUN: %clang_cc1 -DEXPOK -triple powerpc-ibm-aix -fsyntax-only -verify %s
+
+#ifdef EXPOK
+#pragma comment(copyright,"copyright") // expected-no-diagnostics
+#else
+#pragma comment(copyright,"copyright") // expected-warning {{'#pragma comment copyright' ignored}}
+#endif
diff --git a/llvm/include/llvm/Transforms/Utils/LowerCommentStringPass.h b/llvm/include/llvm/Transforms/Utils/LowerCommentStringPass.h
new file mode 100644
index 0000000000000..4c6109e1176d3
--- /dev/null
+++ b/llvm/include/llvm/Transforms/Utils/LowerCommentStringPass.h
@@ -0,0 +1,24 @@
+//===-- LowerCommentStringPass.h - Lower Comment string metadata --===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===---------------------------------------------------------------------===//
+
+#ifndef LLVM_TRANSFORMS_UTILS_LOWERCOMMENTSTRINGPASS_H
+#define LLVM_TRANSFORMS_UTILS_LOWERCOMMENTSTRINGPASS_H
+
+#include "llvm/IR/PassManager.h"
+
+namespace llvm {
+class LowerCommentStringPass : public PassInfoMixin<LowerCommentStringPass> {
+public:
+ PreservedAnalyses run(Module &M, ModuleAnalysisManager &AM);
+
+ static bool isRequired() { return true; }
+};
+
+} // namespace llvm
+
+#endif // LLVM_TRANSFORMS_UTILS_LOWERCOMMENTSTRINGPASS_H
diff --git a/llvm/lib/Passes/PassBuilder.cpp b/llvm/lib/Passes/PassBuilder.cpp
index a23d64b491a79..9cc5aed7ab5b1 100644
--- a/llvm/lib/Passes/PassBuilder.cpp
+++ b/llvm/lib/Passes/PassBuilder.cpp
@@ -363,6 +363,7 @@
#include "llvm/Transforms/Utils/LibCallsShrinkWrap.h"
#include "llvm/Transforms/Utils/LoopSimplify.h"
#include "llvm/Transforms/Utils/LoopVersioning.h"
+#include "llvm/Transforms/Utils/LowerCommentStringPass.h"
#include "llvm/Transforms/Utils/LowerGlobalDtors.h"
#include "llvm/Transforms/Utils/LowerIFunc.h"
#include "llvm/Transforms/Utils/LowerInvoke.h"
diff --git a/llvm/lib/Passes/PassBuilderPipelines.cpp b/llvm/lib/Passes/PassBuilderPipelines.cpp
index 5e4688f4dd7ef..7a35efc6a9339 100644
--- a/llvm/lib/Passes/PassBuilderPipelines.cpp
+++ b/llvm/lib/Passes/PassBuilderPipelines.cpp
@@ -142,6 +142,7 @@
#include "llvm/Transforms/Utils/ExtraPassManager.h"
#include "llvm/Transforms/Utils/InjectTLIMappings.h"
#include "llvm/Transforms/Utils/LibCallsShrinkWrap.h"
+#include "llvm/Transforms/Utils/LowerCommentStringPass.h"
#include "llvm/Transforms/Utils/Mem2Reg.h"
#include "llvm/Transforms/Utils/MoveAutoInit.h"
#include "llvm/Transforms/Utils/NameAnonGlobals.h"
@@ -1480,6 +1481,9 @@ PassBuilder::buildModuleOptimizationPipeline(OptimizationLevel Level,
const bool LTOPreLink = isLTOPreLink(LTOPhase);
ModulePassManager MPM;
+ // Process copyright metadata early, before any optimizations
+ MPM.addPass(LowerCommentStringPass());
+
// Run partial inlining pass to partially inline functions that have
// large bodies.
if (RunPartialInlining)
@@ -2328,6 +2332,9 @@ PassBuilder::buildO0DefaultPipeline(OptimizationLevel Level,
ModulePassManager MPM;
+ // Process copyright metadata at O0 before any other transformations
+ MPM.addPass(LowerCommentStringPass());
+
// Perform pseudo probe instrumentation in O0 mode. This is for the
// consistency between different build modes. For example, a LTO build can be
// mixed with an O0 prelink and an O2 postlink. Loading a sample profile in
diff --git a/llvm/lib/Passes/PassRegistry.def b/llvm/lib/Passes/PassRegistry.def
index c92d93d7ae396..e5d180fcf9bfd 100644
--- a/llvm/lib/Passes/PassRegistry.def
+++ b/llvm/lib/Passes/PassRegistry.def
@@ -62,6 +62,7 @@ MODULE_PASS("check-debugify", NewPMCheckDebugifyPass())
MODULE_PASS("constmerge", ConstantMergePass())
MODULE_PASS("coro-cleanup", CoroCleanupPass())
MODULE_PASS("coro-early", CoroEarlyPass())
+MODULE_PASS("lower-comment-string", LowerCommentStringPass())
MODULE_PASS("cross-dso-cfi", CrossDSOCFIPass())
MODULE_PASS("ctx-instr-gen",
PGOInstrumentationGen(PGOInstrumentationType::CTXPROF))
diff --git a/llvm/lib/Transforms/Utils/CMakeLists.txt b/llvm/lib/Transforms/Utils/CMakeLists.txt
index 2b5f5cf344e60..28f86c5e96010 100644
--- a/llvm/lib/Transforms/Utils/CMakeLists.txt
+++ b/llvm/lib/Transforms/Utils/CMakeLists.txt
@@ -53,6 +53,7 @@ add_llvm_component_library(LLVMTransformUtils
LoopUtils.cpp
LoopVersioning.cpp
LowerAtomic.cpp
+ LowerCommentStringPass.cpp
LowerGlobalDtors.cpp
LowerIFunc.cpp
LowerInvoke.cpp
diff --git a/llvm/lib/Transforms/Utils/LowerCommentStringPass.cpp b/llvm/lib/Transforms/Utils/LowerCommentStringPass.cpp
new file mode 100644
index 0000000000000..6deef2f75e0a3
--- /dev/null
+++ b/llvm/lib/Transforms/Utils/LowerCommentStringPass.cpp
@@ -0,0 +1,148 @@
+//===-- LowerCommentStringPass.cpp - Lower Comment string metadata -------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===---------------------------------------------------------------------===//
+//
+// LowerCommentStringPass pass lowers module-level comment string metadata
+// emitted by Clang:
+//
+// !comment_string.loadtime = !{!"Copyright ..."}
+//
+// into concrete, translation-unit–local globals.
+// This Pass is enabled only for AIX.
+// For each module (translation unit), the pass performs the following:
+//
+// 1. Creates a null-terminated, internal constant string global
+// (`__loadtime_comment_str`) containing the copyright text in
+// `__loadtime_comment` section.
+//
+// 2. Marks the string in `llvm.used` so it cannot be dropped by
+// optimization or LTO.
+//
+// 3. Attaches `!implicit.ref` metadata referencing the string to every
+// 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 (as long as the referencing symbol is kept).
+//
+// Input IR:
+// !comment_string.loadtime = !{!"Copyright"}
+// Output IR:
+// @__loadtime_comment_str = internal constant [N x i8] c"Copyright\00",
+// section "__loadtime_comment"
+// @llvm.used = appending global [1 x ptr] [ptr @__loadtime_comment_str]
+//
+// define i32 @func() !implicit.ref !5 { ... }
+// !5 = !{ptr @__loadtime_comment_str}
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Transforms/Utils/LowerCommentStringPass.h"
+
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/IR/Attributes.h"
+#include "llvm/IR/Constants.h"
+#include "llvm/IR/DerivedTypes.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/GlobalValue.h"
+#include "llvm/IR/GlobalVariable.h"
+#include "llvm/IR/MDBuilder.h"
+#include "llvm/IR/Metadata.h"
+#include "llvm/IR/Module.h"
+#include "llvm/IR/Type.h"
+#include "llvm/IR/Value.h"
+#include "llvm/Passes/PassBuilder.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/TargetParser/Triple.h"
+#include "llvm/Transforms/Utils/ModuleUtils.h"
+
+#define DEBUG_TYPE "lower-comment-string"
+
+using namespace llvm;
+
+static cl::opt<bool>
+ DisableCopyrightMetadata("disable-lower-comment-string", cl::ReallyHidden,
+ cl::desc("Disable LowerCommentString pass."),
+ cl::init(false));
+
+static bool isAIXTriple(const Module &M) {
+ return Triple(M.getTargetTriple()).isOSAIX();
+}
+
+PreservedAnalyses LowerCommentStringPass::run(Module &M,
+ ModuleAnalysisManager &AM) {
+ if (DisableCopyrightMetadata || !isAIXTriple(M))
+ return PreservedAnalyses::all();
+
+ LLVMContext &Ctx = M.getContext();
+
+ // Single-metadata: !comment_string.loadtime = !{!0}
+ // Each operand node is expected to have one MDString operand.
+ NamedMDNode *MD = M.getNamedMetadata("comment_string.loadtime");
+ if (!MD || MD->getNumOperands() == 0)
+ return PreservedAnalyses::all();
+
+ // At this point we are guarateed that one TU contains a single copyright
+ // metadata entry. Create TU-local string global for that metadata entry.
+ MDNode *MdNode = MD->getOperand(0);
+ if (!MdNode || MdNode->getNumOperands() == 0)
+ return PreservedAnalyses::all();
+
+ auto *MdString = dyn_cast_or_null<MDString>(MdNode->getOperand(0));
+ if (!MdString)
+ return PreservedAnalyses::all();
+
+ StringRef Text = MdString->getString();
+ if (Text.empty())
+ return PreservedAnalyses::all();
+
+ // 1. Create a single NULL-terminated string global
+ Constant *StrInit = ConstantDataArray::getString(Ctx, Text, /*AddNull=*/true);
+
+ // Internal, constant, TU-local--avoids duplicate symbol issues across TUs.
+ auto *StrGV = new GlobalVariable(M, StrInit->getType(),
+ /*isConstant=*/true,
+ GlobalValue::InternalLinkage, StrInit,
+ /*Name=*/"__loadtime_comment_str");
+ // Set unnamed_addr to allow the linker to merge identical strings
+ StrGV->setUnnamedAddr(GlobalValue::UnnamedAddr::Global);
+ StrGV->setAlignment(Align(1));
+ // Place in the "__loadtime_comment" section.
+ // The GV is constant, so we expect a read-only section.
+ StrGV->setSection("__loadtime_comment");
+
+ // 2. Add the string to llvm.used to prevent LLVM optimization/LTO passes from
+ // removing it.
+ appendToUsed(M, {StrGV});
+
+ // 3. Attach !implicit ref to every defined function
+ // Create a metadata node pointing to the copyright string:
+ // !N = !{ptr @__loadtime_comment_str}
+ Metadata *Ops[] = {ConstantAsMetadata::get(StrGV)};
+ MDNode *ImplicitRefMD = MDNode::get(Ctx, Ops);
+
+ // Lambda to attach implicit.ref metadata to a function.
+ auto AddImplicitRef = [&](Function &F) {
+ if (F.isDeclaration())
+ return;
+ // Attach the implicit.ref metadata to the function
+ F.setMetadata("implicit.ref", ImplicitRefMD);
+ LLVM_DEBUG(dbgs() << "[copyright] attached implicit.ref to function: "
+ << F.getName() << "\n");
+ };
+
+ // Process all functions in the module
+ for (Function &F : M)
+ AddImplicitRef(F);
+
+ // Cleanup the processed metadata.
+ MD->eraseFromParent();
+ LLVM_DEBUG(dbgs() << "[copyright] created string and anchor for module\n");
+
+ return PreservedAnalyses::all();
+}
diff --git a/llvm/test/CodeGen/AArch64/print-pipeline-passes.ll b/llvm/test/CodeGen/AArch64/print-pipeline-passes.ll
index 86090324c770c..f2b2738b89416 100644
--- a/llvm/test/CodeGen/AArch64/print-pipeline-passes.ll
+++ b/llvm/test/CodeGen/AArch64/print-pipeline-passes.ll
@@ -2,7 +2,7 @@
; RUN: opt -mtriple=aarch64 -S -passes='default<O2>' -print-pipeline-passes < %s | FileCheck %s
; CHECK: loop-idiom-vectorize
-; O0: {{^}}function(ee-instrument<>),always-inline,coro-cond(coro-early,cgscc(coro-split),coro-cleanup,globaldce),alloc-token,function(annotation-remarks),verify,print{{$}}
+; O0: {{^}}lower-comment-string,function(ee-instrument<>),always-inline,coro-cond(coro-early,cgscc(coro-split),coro-cleanup,globaldce),alloc-token,function(annotation-remarks),verify,print{{$}}
define void @foo() {
entry:
diff --git a/llvm/test/CodeGen/Hexagon/print-pipeline-passes.ll b/llvm/test/CodeGen/Hexagon/print-pipeline-passes.ll
index 0f80e9c60c441..50476ae020d68 100644
--- a/llvm/test/CodeGen/Hexagon/print-pipeline-passes.ll
+++ b/llvm/test/CodeGen/Hexagon/print-pipeline-passes.ll
@@ -3,7 +3,7 @@
; CHECK: hexagon-loop-idiom
; CHECK: hexagon-vlcr
-; O0: {{^}}function(ee-instrument<>),always-inline,coro-cond(coro-early,cgscc(coro-split),coro-cleanup,globaldce),alloc-token,function(annotation-remarks),verify,print{{$}}
+; O0: {{^}}lower-comment-string,function(ee-instrument<>),always-inline,coro-cond(coro-early,cgscc(coro-split),coro-cleanup,globaldce),alloc-token,function(annotation-remarks),verify,print{{$}}
define void @test_hexagon_passes() {
entry:
diff --git a/llvm/test/Other/new-pm-defaults.ll b/llvm/test/Other/new-pm-defaults.ll
index f074b2fdd3ab8..979a7897b4c02 100644
--- a/llvm/test/Other/new-pm-defaults.ll
+++ b/llvm/test/Other/new-pm-defaults.ll
@@ -238,6 +238,7 @@
; CHECK-O-NEXT: Running pass: CoroCleanupPass
; CHECK-O-NEXT: Running pass: GlobalOptPass
; CHECK-O-NEXT: Running pass: GlobalDCEPass
+; CHECK-O-NEXT: Running pass: LowerCommentStringPass
; CHECK-DEFAULT-NEXT: Running pass: EliminateAvailableExternallyPass
; CHECK-LTO-NOT: Running pass: EliminateAvailableExternallyPass
; CHECK-O-NEXT: Running pass: ReversePostOrderFunctionAttrsPass
diff --git a/llvm/test/Other/new-pm-thinlto-postlink-defaults.ll b/llvm/test/Other/new-pm-thinlto-postlink-defaults.ll
index b0d08316de4f0..d03b15d276e0b 100644
--- a/llvm/test/Other/new-pm-thinlto-postlink-defaults.ll
+++ b/llvm/test/Other/new-pm-thinlto-postlink-defaults.ll
@@ -162,6 +162,7 @@
; CHECK-O-NEXT: Running pass: CoroCleanupPass
; CHECK-POSTLINK-O-NEXT: Running pass: GlobalOptPass
; CHECK-POSTLINK-O-NEXT: Running pass: GlobalDCEPass
+; CHECK-POSTLINK-O-NEXT: Running pass: LowerCommentStringPass
; CHECK-POSTLINK-O-NEXT: Running pass: EliminateAvailableExternallyPass
; CHECK-POSTLINK-O-NEXT: Running pass: ReversePostOrderFunctionAttrsPass
; CHECK-POSTLINK-O-NEXT: Running pass: RecomputeGlobalsAAPass
diff --git a/llvm/test/Other/new-pm-thinlto-postlink-pgo-defaults.ll b/llvm/test/Other/new-pm-thinlto-postlink-pgo-defaults.ll
index 6b3e82a752899..b5b0d55bf410c 100644
--- a/llvm/test/Other/new-pm-thinlto-postlink-pgo-defaults.ll
+++ b/llvm/test/Other/new-pm-thinlto-postlink-pgo-defaults.ll
@@ -146,6 +146,7 @@
; CHECK-O-NEXT: Running pass: CoroCleanupPass
; CHECK-O-NEXT: Running pass: GlobalOptPass
; CHECK-O-NEXT: Running pass: GlobalDCEPass
+; CHECK-O-NEXT: Running pass: LowerCommentStringPass
; CHECK-O-NEXT: Running pass: EliminateAvailableExternallyPass
; CHECK-O-NEXT: Running pass: ReversePostOrderFunctionAttrsPass
; CHECK-O-NEXT: Running pass: RecomputeGlobalsAAPass
diff --git a/llvm/test/Other/new-pm-thinlto-postlink-samplepgo-defaults.ll b/llvm/test/Other/new-pm-thinlto-postlink-samplepgo-defaults.ll
index 88dc18f605ce2..57561975769d0 100644
--- a/llvm/test/Other/new-pm-thinlto-postlink-samplepgo-defaults.ll
+++ b/llvm/test/Other/new-pm-thinlto-postlink-samplepgo-defaults.ll
@@ -155,6 +155,7 @@
; CHECK-O-NEXT: Running pass: CoroCleanupPass
; CHECK-O-NEXT: Running pass: GlobalOptPass
; CHECK-O-NEXT: Running pass: GlobalDCEPass
+; CHECK-O-NEXT: Running pass: LowerCommentStringPass
; CHECK-O-NEXT: Running pass: EliminateAvailableExternallyPass
; CHECK-O-NEXT: Running pass: ReversePostOrderFunctionAttrsPass
; CHECK-O-NEXT: Running pass: RecomputeGlobalsAAPass
diff --git a/llvm/test/Transforms/LowerCommentString/lower-comment-string.ll b/llvm/test/Transforms/LowerCommentString/lower-comment-string.ll
new file mode 100644
index 0000000000000..ba7ad17f4c4b7
--- /dev/null
+++ b/llvm/test/Transforms/LowerCommentString/lower-comment-string.ll
@@ -0,0 +1,59 @@
+; RUN: opt -passes=lower-comment-string -S %s -o - | FileCheck %s --check-prefixes=CHECK,CHECK-O0
+
+; Verify that lower-comment-string is enabled by default on all opt pipelines.
+; RUN: opt --O0 -S %s -o - | FileCheck %s --check-prefixes=CHECK,CHECK-O0
+; RUN: opt --O1 -S %s -o - | FileCheck %s --check-prefixes=CHECK,CHECK-ON
+; RUN: opt --O2 -S %s -o - | FileCheck %s --check-prefixes=CHECK,CHECK-ON
+; RUN: opt --O3 -S %s -o - | FileCheck %s --check-prefixes=CHECK,CHECK-ON
+
+; Verify that LowerCommentStringPass lowers !loadtime.copyright.comment
+; into concrete, translation-unit–local globals.
+;
+; For each module (translation unit), the pass performs the following:
+;
+; 1. Creates a null-terminated, internal constant string global
+; (`__loadtime_comment_str`) containing the copyright text in
+; `__loadtime_comment` section.
+;
+; 2. Marks the string in `llvm.used` so it cannot be dropped by
+; optimization or LTO.
+;
+; 3. Attaches `!implicit.ref` metadata referencing the string to every
+; 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 (as long as the referencing symbol is kept).
+
+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}
+
+!comment_string.loadtime = !{!1}
+!1 = !{!"@(#) Copyright IBM 2025"}
+
+
+; ---- Globals--------------------------------------------
+; CHECK: @__loadtime_comment_str = internal unnamed_addr constant [24 x i8] c"@(#) Copyright IBM 2025\00", section "__loadtime_comment", align 1
+; Preservation in llvm.used sets
+; CHECK-NEXT: @llvm.used = appending global [1 x ptr] [ptr @__loadtime_comment_str], section "llvm.metadata"
+; CHECK-NOT: ![[copyright:[0-9]+]] = !{!"@(#) Copyright IBM 2025"}
+
+; Function has an implicit ref MD pointing at the string:
+; CHECK-O0: define void @f0() !implicit.ref ![[MD:[0-9]+]]
+; CHECK-ON: define void @f0() local_unnamed_addr #0 !implicit.ref ![[MD:[0-9]+]]
+; CHECK-O0: define i32 @main() !implicit.ref ![[MD]]
+; CHECK-ON: define noundef i32 @main() local_unnamed_addr #0 !implicit.ref ![[MD]]
+
+; Verify metadata content
+; CHECK-O0: ![[MD]] = !{ptr @__loadtime_comment_str}
+; CHECK-ON: ![[MD]] = !{ptr @__loadtime_comment_str}
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