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https://github.com/c64scene-ar/llvm-6502.git
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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216351 91177308-0d34-0410-b5e6-96231b3b80d8
225 lines
7.8 KiB
C++
225 lines
7.8 KiB
C++
//===-- Internalize.cpp - Mark functions internal -------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This pass loops over all of the functions and variables in the input module.
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// If the function or variable is not in the list of external names given to
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// the pass it is marked as internal.
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//
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// This transformation would not be legal in a regular compilation, but it gets
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// extra information from the linker about what is safe.
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//
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// For example: Internalizing a function with external linkage. Only if we are
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// told it is only used from within this module, it is safe to do it.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Transforms/IPO.h"
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#include "llvm/ADT/SmallPtrSet.h"
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#include "llvm/ADT/Statistic.h"
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#include "llvm/Analysis/CallGraph.h"
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#include "llvm/IR/Module.h"
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#include "llvm/Pass.h"
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#include "llvm/Support/CommandLine.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/raw_ostream.h"
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#include "llvm/Transforms/Utils/GlobalStatus.h"
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#include "llvm/Transforms/Utils/ModuleUtils.h"
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#include <fstream>
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#include <set>
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using namespace llvm;
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#define DEBUG_TYPE "internalize"
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STATISTIC(NumAliases , "Number of aliases internalized");
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STATISTIC(NumFunctions, "Number of functions internalized");
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STATISTIC(NumGlobals , "Number of global vars internalized");
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// APIFile - A file which contains a list of symbols that should not be marked
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// external.
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static cl::opt<std::string>
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APIFile("internalize-public-api-file", cl::value_desc("filename"),
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cl::desc("A file containing list of symbol names to preserve"));
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// APIList - A list of symbols that should not be marked internal.
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static cl::list<std::string>
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APIList("internalize-public-api-list", cl::value_desc("list"),
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cl::desc("A list of symbol names to preserve"),
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cl::CommaSeparated);
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namespace {
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class InternalizePass : public ModulePass {
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std::set<std::string> ExternalNames;
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public:
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static char ID; // Pass identification, replacement for typeid
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explicit InternalizePass();
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explicit InternalizePass(ArrayRef<const char *> ExportList);
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void LoadFile(const char *Filename);
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bool runOnModule(Module &M) override;
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void getAnalysisUsage(AnalysisUsage &AU) const override {
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AU.setPreservesCFG();
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AU.addPreserved<CallGraphWrapperPass>();
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}
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};
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} // end anonymous namespace
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char InternalizePass::ID = 0;
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INITIALIZE_PASS(InternalizePass, "internalize",
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"Internalize Global Symbols", false, false)
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InternalizePass::InternalizePass() : ModulePass(ID) {
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initializeInternalizePassPass(*PassRegistry::getPassRegistry());
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if (!APIFile.empty()) // If a filename is specified, use it.
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LoadFile(APIFile.c_str());
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ExternalNames.insert(APIList.begin(), APIList.end());
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}
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InternalizePass::InternalizePass(ArrayRef<const char *> ExportList)
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: ModulePass(ID) {
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initializeInternalizePassPass(*PassRegistry::getPassRegistry());
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for(ArrayRef<const char *>::const_iterator itr = ExportList.begin();
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itr != ExportList.end(); itr++) {
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ExternalNames.insert(*itr);
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}
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}
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void InternalizePass::LoadFile(const char *Filename) {
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// Load the APIFile...
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std::ifstream In(Filename);
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if (!In.good()) {
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errs() << "WARNING: Internalize couldn't load file '" << Filename
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<< "'! Continuing as if it's empty.\n";
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return; // Just continue as if the file were empty
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}
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while (In) {
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std::string Symbol;
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In >> Symbol;
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if (!Symbol.empty())
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ExternalNames.insert(Symbol);
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}
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}
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static bool shouldInternalize(const GlobalValue &GV,
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const std::set<std::string> &ExternalNames) {
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// Function must be defined here
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if (GV.isDeclaration())
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return false;
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// Available externally is really just a "declaration with a body".
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if (GV.hasAvailableExternallyLinkage())
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return false;
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// Assume that dllexported symbols are referenced elsewhere
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if (GV.hasDLLExportStorageClass())
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return false;
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// Already has internal linkage
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if (GV.hasLocalLinkage())
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return false;
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// Marked to keep external?
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if (ExternalNames.count(GV.getName()))
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return false;
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return true;
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}
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bool InternalizePass::runOnModule(Module &M) {
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CallGraphWrapperPass *CGPass = getAnalysisIfAvailable<CallGraphWrapperPass>();
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CallGraph *CG = CGPass ? &CGPass->getCallGraph() : nullptr;
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CallGraphNode *ExternalNode = CG ? CG->getExternalCallingNode() : nullptr;
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bool Changed = false;
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SmallPtrSet<GlobalValue *, 8> Used;
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collectUsedGlobalVariables(M, Used, false);
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// We must assume that globals in llvm.used have a reference that not even
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// the linker can see, so we don't internalize them.
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// For llvm.compiler.used the situation is a bit fuzzy. The assembler and
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// linker can drop those symbols. If this pass is running as part of LTO,
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// one might think that it could just drop llvm.compiler.used. The problem
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// is that even in LTO llvm doesn't see every reference. For example,
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// we don't see references from function local inline assembly. To be
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// conservative, we internalize symbols in llvm.compiler.used, but we
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// keep llvm.compiler.used so that the symbol is not deleted by llvm.
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for (GlobalValue *V : Used) {
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ExternalNames.insert(V->getName());
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}
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// Mark all functions not in the api as internal.
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for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I) {
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if (!shouldInternalize(*I, ExternalNames))
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continue;
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I->setVisibility(GlobalValue::DefaultVisibility);
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I->setLinkage(GlobalValue::InternalLinkage);
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if (ExternalNode)
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// Remove a callgraph edge from the external node to this function.
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ExternalNode->removeOneAbstractEdgeTo((*CG)[I]);
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Changed = true;
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++NumFunctions;
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DEBUG(dbgs() << "Internalizing func " << I->getName() << "\n");
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}
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// Never internalize the llvm.used symbol. It is used to implement
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// attribute((used)).
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// FIXME: Shouldn't this just filter on llvm.metadata section??
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ExternalNames.insert("llvm.used");
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ExternalNames.insert("llvm.compiler.used");
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// Never internalize anchors used by the machine module info, else the info
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// won't find them. (see MachineModuleInfo.)
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ExternalNames.insert("llvm.global_ctors");
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ExternalNames.insert("llvm.global_dtors");
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ExternalNames.insert("llvm.global.annotations");
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// Never internalize symbols code-gen inserts.
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// FIXME: We should probably add this (and the __stack_chk_guard) via some
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// type of call-back in CodeGen.
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ExternalNames.insert("__stack_chk_fail");
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ExternalNames.insert("__stack_chk_guard");
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// Mark all global variables with initializers that are not in the api as
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// internal as well.
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for (Module::global_iterator I = M.global_begin(), E = M.global_end();
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I != E; ++I) {
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if (!shouldInternalize(*I, ExternalNames))
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continue;
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I->setVisibility(GlobalValue::DefaultVisibility);
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I->setLinkage(GlobalValue::InternalLinkage);
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Changed = true;
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++NumGlobals;
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DEBUG(dbgs() << "Internalized gvar " << I->getName() << "\n");
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}
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// Mark all aliases that are not in the api as internal as well.
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for (Module::alias_iterator I = M.alias_begin(), E = M.alias_end();
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I != E; ++I) {
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if (!shouldInternalize(*I, ExternalNames))
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continue;
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I->setVisibility(GlobalValue::DefaultVisibility);
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I->setLinkage(GlobalValue::InternalLinkage);
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Changed = true;
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++NumAliases;
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DEBUG(dbgs() << "Internalized alias " << I->getName() << "\n");
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}
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return Changed;
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}
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ModulePass *llvm::createInternalizePass() { return new InternalizePass(); }
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ModulePass *llvm::createInternalizePass(ArrayRef<const char *> ExportList) {
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return new InternalizePass(ExportList);
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}
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