[clang] [CodeGen] Add conditional to module cloning in bitcode linking (PR #72478)
Jacob Lambert via cfe-commits
cfe-commits at lists.llvm.org
Wed Nov 15 22:16:09 PST 2023
https://github.com/lamb-j created https://github.com/llvm/llvm-project/pull/72478
Now that we have a commandline option dictating a second link step, (-relink-builtin-bitcode-postop), we can condition the module creation when linking in bitcode modules. This aims to improve performance by avoiding unnecessary linking
>From 3a2a066eeadce6b8f3cd5645965ffe564e68fba3 Mon Sep 17 00:00:00 2001
From: Jacob Lambert <jacob.lambert at amd.com>
Date: Wed, 15 Nov 2023 22:06:46 -0800
Subject: [PATCH] [CodeGen] Add conditional to module cloning in bitcode
linking
Now that we have a commandline option dictating a second link step,
(-relink-builtin-bitcode-postop), we can condition the module
creation when linking in bitcode modules. This aims to improve
performance by avoiding unnecessary linking
---
clang/lib/CodeGen/BackendUtil.cpp | 2 +-
clang/lib/CodeGen/CodeGenAction.cpp | 56 ++++++++++++++++++++---------
2 files changed, 40 insertions(+), 18 deletions(-)
diff --git a/clang/lib/CodeGen/BackendUtil.cpp b/clang/lib/CodeGen/BackendUtil.cpp
index a7a47d17723cb73..f01a6514f6effb0 100644
--- a/clang/lib/CodeGen/BackendUtil.cpp
+++ b/clang/lib/CodeGen/BackendUtil.cpp
@@ -103,7 +103,7 @@ static cl::opt<bool> ClSanitizeOnOptimizerEarlyEP(
cl::desc("Insert sanitizers on OptimizerEarlyEP."), cl::init(false));
// Re-link builtin bitcodes after optimization
-static cl::opt<bool> ClRelinkBuiltinBitcodePostop(
+cl::opt<bool> ClRelinkBuiltinBitcodePostop(
"relink-builtin-bitcode-postop", cl::Optional,
cl::desc("Re-link builtin bitcodes after optimization."), cl::init(false));
}
diff --git a/clang/lib/CodeGen/CodeGenAction.cpp b/clang/lib/CodeGen/CodeGenAction.cpp
index a31a271ed77d1ca..e3ceb3adbcc93a8 100644
--- a/clang/lib/CodeGen/CodeGenAction.cpp
+++ b/clang/lib/CodeGen/CodeGenAction.cpp
@@ -57,6 +57,10 @@ using namespace llvm;
#define DEBUG_TYPE "codegenaction"
+namespace llvm {
+extern cl::opt<bool> ClRelinkBuiltinBitcodePostop;
+}
+
namespace clang {
class BackendConsumer;
class ClangDiagnosticHandler final : public DiagnosticHandler {
@@ -251,32 +255,50 @@ bool BackendConsumer::LinkInModules(llvm::Module *M, bool ShouldLinkFiles) {
}
CurLinkModule = LM.Module.get();
-
- // TODO: If CloneModule() is updated to support cloning of unmaterialized
- // modules, we can remove this
bool Err;
- if (Error E = CurLinkModule->materializeAll())
- return false;
// Create a Clone to move to the linker, which preserves the original
// linking modules, allowing them to be linked again in the future
- // TODO: Add a ShouldCleanup option to make Cloning optional. When
- // set, we can pass the original modules to the linker for cleanup
- std::unique_ptr<llvm::Module> Clone = llvm::CloneModule(*LM.Module);
+ if (ClRelinkBuiltinBitcodePostop) {
+ // TODO: If CloneModule() is updated to support cloning of unmaterialized
+ // modules, we can remove this
+ if (Error E = CurLinkModule->materializeAll())
+ return false;
- if (LM.Internalize) {
- Err = Linker::linkModules(
+ std::unique_ptr<llvm::Module> Clone = llvm::CloneModule(*LM.Module);
+
+ if (LM.Internalize) {
+ Err = Linker::linkModules(
*M, std::move(Clone), LM.LinkFlags,
[](llvm::Module &M, const llvm::StringSet<> &GVS) {
- internalizeModule(M, [&GVS](const llvm::GlobalValue &GV) {
- return !GV.hasName() || (GVS.count(GV.getName()) == 0);
- });
+ internalizeModule(M, [&GVS](const llvm::GlobalValue &GV) {
+ return !GV.hasName() ||
+ (GVS.count(GV.getName()) == 0);
+ });
});
- } else
- Err = Linker::linkModules(*M, std::move(Clone), LM.LinkFlags);
+ } else
+ Err = Linker::linkModules(*M, std::move(Clone), LM.LinkFlags);
- if (Err)
- return true;
+ if (Err)
+ return true;
+ }
+ // Otherwise we can link (and clean up) the original modules
+ else {
+ if (LM.Internalize) {
+ Err = Linker::linkModules(
+ *M, std::move(LM.Module), LM.LinkFlags,
+ [](llvm::Module &M, const llvm::StringSet<> &GVS) {
+ internalizeModule(M, [&GVS](const llvm::GlobalValue &GV) {
+ return !GV.hasName() ||
+ (GVS.count(GV.getName()) == 0);
+ });
+ });
+ } else
+ Err = Linker::linkModules(*M, std::move(LM.Module), LM.LinkFlags);
+
+ if (Err)
+ return true;
+ }
}
return false; // success
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