Uniuqe Names for Internal Linkage Symbols.
This is a standalone patch and this would help Propeller do a better job of code
layout as it can accurately attribute the profiles to the right internal linkage
function.
This also helps SampledFDO/AutoFDO correctly associate sampled profiles to the
right internal function. Currently, if there is more than one internal symbol
foo, their profiles are aggregated by SampledFDO.
This patch adds a new clang option, -funique-internal-funcnames, to generate
unique names for functions with internal linkage. This patch appends the md5
hash of the module name to the function symbol as a best effort to generate a
unique name for symbols with internal linkage.
Differential Revision: https://reviews.llvm.org/D73307
diff --git a/clang/lib/CodeGen/BackendUtil.cpp b/clang/lib/CodeGen/BackendUtil.cpp
index a125c96f..ba61a93 100644
--- a/clang/lib/CodeGen/BackendUtil.cpp
+++ b/clang/lib/CodeGen/BackendUtil.cpp
@@ -77,6 +77,7 @@
#include "llvm/Transforms/Utils/EntryExitInstrumenter.h"
#include "llvm/Transforms/Utils/NameAnonGlobals.h"
#include "llvm/Transforms/Utils/SymbolRewriter.h"
+#include "llvm/Transforms/Utils/UniqueInternalLinkageNames.h"
#include <memory>
using namespace clang;
using namespace llvm;
@@ -719,6 +720,12 @@
if (!CodeGenOpts.RewriteMapFiles.empty())
addSymbolRewriterPass(CodeGenOpts, &MPM);
+ // Add UniqueInternalLinkageNames Pass which renames internal linkage symbols
+ // with unique names.
+ if (CodeGenOpts.UniqueInternalLinkageNames) {
+ MPM.add(createUniqueInternalLinkageNamesPass());
+ }
+
if (Optional<GCOVOptions> Options = getGCOVOptions(CodeGenOpts)) {
MPM.add(createGCOVProfilerPass(*Options));
if (CodeGenOpts.getDebugInfo() == codegenoptions::NoDebugInfo)
@@ -1203,6 +1210,12 @@
if (LangOpts.Sanitize.has(SanitizerKind::LocalBounds))
MPM.addPass(createModuleToFunctionPassAdaptor(BoundsCheckingPass()));
+ // Add UniqueInternalLinkageNames Pass which renames internal linkage
+ // symbols with unique names.
+ if (CodeGenOpts.UniqueInternalLinkageNames) {
+ MPM.addPass(UniqueInternalLinkageNamesPass());
+ }
+
// Lastly, add semantically necessary passes for LTO.
if (IsLTO || IsThinLTO) {
MPM.addPass(CanonicalizeAliasesPass());
@@ -1292,6 +1305,12 @@
MPM.addPass(InstrProfiling(*Options, false));
});
+ // Add UniqueInternalLinkageNames Pass which renames internal linkage
+ // symbols with unique names.
+ if (CodeGenOpts.UniqueInternalLinkageNames) {
+ MPM.addPass(UniqueInternalLinkageNamesPass());
+ }
+
if (IsThinLTO) {
MPM = PB.buildThinLTOPreLinkDefaultPipeline(
Level, CodeGenOpts.DebugPassManager);