// If the function or variable is not in the list of external names given to
// the pass it is marked as internal.
//
+// This transformation would not be legal in a regular compilation, but it gets
+// extra information from the linker about what is safe.
+//
+// For example: Internalizing a function with external linkage. Only if we are
+// told it is only used from within this module, it is safe to do it.
+//
//===----------------------------------------------------------------------===//
-#define DEBUG_TYPE "internalize"
#include "llvm/Transforms/IPO.h"
+#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/CallGraph.h"
-#include "llvm/Module.h"
+#include "llvm/IR/Module.h"
#include "llvm/Pass.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
+#include "llvm/Transforms/Utils/GlobalStatus.h"
+#include "llvm/Transforms/Utils/ModuleUtils.h"
#include <fstream>
#include <set>
using namespace llvm;
+#define DEBUG_TYPE "internalize"
+
STATISTIC(NumAliases , "Number of aliases internalized");
STATISTIC(NumFunctions, "Number of functions internalized");
STATISTIC(NumGlobals , "Number of global vars internalized");
public:
static char ID; // Pass identification, replacement for typeid
explicit InternalizePass();
- explicit InternalizePass(const std::vector <const char *>& exportList);
+ explicit InternalizePass(ArrayRef<const char *> ExportList);
void LoadFile(const char *Filename);
- virtual bool runOnModule(Module &M);
+ bool runOnModule(Module &M) override;
- virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.setPreservesCFG();
- AU.addPreserved<CallGraph>();
+ AU.addPreserved<CallGraphWrapperPass>();
}
};
} // end anonymous namespace
INITIALIZE_PASS(InternalizePass, "internalize",
"Internalize Global Symbols", false, false)
-InternalizePass::InternalizePass()
- : ModulePass(ID) {
+InternalizePass::InternalizePass() : ModulePass(ID) {
initializeInternalizePassPass(*PassRegistry::getPassRegistry());
if (!APIFile.empty()) // If a filename is specified, use it.
LoadFile(APIFile.c_str());
- if (!APIList.empty()) // If a list is specified, use it as well.
- ExternalNames.insert(APIList.begin(), APIList.end());
+ ExternalNames.insert(APIList.begin(), APIList.end());
}
-InternalizePass::InternalizePass(const std::vector<const char *>&exportList)
- : ModulePass(ID){
+InternalizePass::InternalizePass(ArrayRef<const char *> ExportList)
+ : ModulePass(ID) {
initializeInternalizePassPass(*PassRegistry::getPassRegistry());
- for(std::vector<const char *>::const_iterator itr = exportList.begin();
- itr != exportList.end(); itr++) {
+ for(ArrayRef<const char *>::const_iterator itr = ExportList.begin();
+ itr != ExportList.end(); itr++) {
ExternalNames.insert(*itr);
}
}
}
}
+static bool shouldInternalize(const GlobalValue &GV,
+ const std::set<std::string> &ExternalNames) {
+ // Function must be defined here
+ if (GV.isDeclaration())
+ return false;
+
+ // Available externally is really just a "declaration with a body".
+ if (GV.hasAvailableExternallyLinkage())
+ return false;
+
+ // Assume that dllexported symbols are referenced elsewhere
+ if (GV.hasDLLExportStorageClass())
+ return false;
+
+ // Already has internal linkage
+ if (GV.hasLocalLinkage())
+ return false;
+
+ // Marked to keep external?
+ if (ExternalNames.count(GV.getName()))
+ return false;
+
+ return true;
+}
+
bool InternalizePass::runOnModule(Module &M) {
- CallGraph *CG = getAnalysisIfAvailable<CallGraph>();
- CallGraphNode *ExternalNode = CG ? CG->getExternalCallingNode() : 0;
+ CallGraphWrapperPass *CGPass = getAnalysisIfAvailable<CallGraphWrapperPass>();
+ CallGraph *CG = CGPass ? &CGPass->getCallGraph() : nullptr;
+ CallGraphNode *ExternalNode = CG ? CG->getExternalCallingNode() : nullptr;
bool Changed = false;
- // Never internalize functions which code-gen might insert.
- // FIXME: We should probably add this (and the __stack_chk_guard) via some
- // type of call-back in CodeGen.
- ExternalNames.insert("__stack_chk_fail");
+ SmallPtrSet<GlobalValue *, 8> Used;
+ collectUsedGlobalVariables(M, Used, false);
+
+ // We must assume that globals in llvm.used have a reference that not even
+ // the linker can see, so we don't internalize them.
+ // For llvm.compiler.used the situation is a bit fuzzy. The assembler and
+ // linker can drop those symbols. If this pass is running as part of LTO,
+ // one might think that it could just drop llvm.compiler.used. The problem
+ // is that even in LTO llvm doesn't see every reference. For example,
+ // we don't see references from function local inline assembly. To be
+ // conservative, we internalize symbols in llvm.compiler.used, but we
+ // keep llvm.compiler.used so that the symbol is not deleted by llvm.
+ for (SmallPtrSet<GlobalValue *, 8>::iterator I = Used.begin(), E = Used.end();
+ I != E; ++I) {
+ GlobalValue *V = *I;
+ ExternalNames.insert(V->getName());
+ }
// Mark all functions not in the api as internal.
- // FIXME: maybe use private linkage?
- for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
- if (!I->isDeclaration() && // Function must be defined here
- // Available externally is really just a "declaration with a body".
- !I->hasAvailableExternallyLinkage() &&
- !I->hasLocalLinkage() && // Can't already have internal linkage
- !ExternalNames.count(I->getName())) {// Not marked to keep external?
- I->setLinkage(GlobalValue::InternalLinkage);
+ for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I) {
+ if (!shouldInternalize(*I, ExternalNames))
+ continue;
+
+ I->setVisibility(GlobalValue::DefaultVisibility);
+ I->setLinkage(GlobalValue::InternalLinkage);
+
+ if (ExternalNode)
// Remove a callgraph edge from the external node to this function.
- if (ExternalNode) ExternalNode->removeOneAbstractEdgeTo((*CG)[I]);
- Changed = true;
- ++NumFunctions;
- DEBUG(dbgs() << "Internalizing func " << I->getName() << "\n");
- }
+ ExternalNode->removeOneAbstractEdgeTo((*CG)[I]);
+
+ Changed = true;
+ ++NumFunctions;
+ DEBUG(dbgs() << "Internalizing func " << I->getName() << "\n");
+ }
// Never internalize the llvm.used symbol. It is used to implement
// attribute((used)).
ExternalNames.insert("llvm.global.annotations");
// Never internalize symbols code-gen inserts.
+ // FIXME: We should probably add this (and the __stack_chk_guard) via some
+ // type of call-back in CodeGen.
+ ExternalNames.insert("__stack_chk_fail");
ExternalNames.insert("__stack_chk_guard");
// Mark all global variables with initializers that are not in the api as
// internal as well.
- // FIXME: maybe use private linkage?
for (Module::global_iterator I = M.global_begin(), E = M.global_end();
- I != E; ++I)
- if (!I->isDeclaration() && !I->hasLocalLinkage() &&
- // Available externally is really just a "declaration with a body".
- !I->hasAvailableExternallyLinkage() &&
- !ExternalNames.count(I->getName())) {
- I->setLinkage(GlobalValue::InternalLinkage);
- Changed = true;
- ++NumGlobals;
- DEBUG(dbgs() << "Internalized gvar " << I->getName() << "\n");
- }
+ I != E; ++I) {
+ if (!shouldInternalize(*I, ExternalNames))
+ continue;
+
+ I->setVisibility(GlobalValue::DefaultVisibility);
+ I->setLinkage(GlobalValue::InternalLinkage);
+ Changed = true;
+ ++NumGlobals;
+ DEBUG(dbgs() << "Internalized gvar " << I->getName() << "\n");
+ }
// Mark all aliases that are not in the api as internal as well.
for (Module::alias_iterator I = M.alias_begin(), E = M.alias_end();
- I != E; ++I)
- if (!I->isDeclaration() && !I->hasInternalLinkage() &&
- // Available externally is really just a "declaration with a body".
- !I->hasAvailableExternallyLinkage() &&
- !ExternalNames.count(I->getName())) {
- I->setLinkage(GlobalValue::InternalLinkage);
- Changed = true;
- ++NumAliases;
- DEBUG(dbgs() << "Internalized alias " << I->getName() << "\n");
- }
+ I != E; ++I) {
+ if (!shouldInternalize(*I, ExternalNames))
+ continue;
+
+ I->setVisibility(GlobalValue::DefaultVisibility);
+ I->setLinkage(GlobalValue::InternalLinkage);
+ Changed = true;
+ ++NumAliases;
+ DEBUG(dbgs() << "Internalized alias " << I->getName() << "\n");
+ }
return Changed;
}
-ModulePass *llvm::createInternalizePass() {
- return new InternalizePass();
-}
+ModulePass *llvm::createInternalizePass() { return new InternalizePass(); }
-ModulePass *llvm::createInternalizePass(const std::vector <const char *> &el) {
- return new InternalizePass(el);
+ModulePass *llvm::createInternalizePass(ArrayRef<const char *> ExportList) {
+ return new InternalizePass(ExportList);
}
projects / oota-llvm.git / blobdiff