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//===-- StripDeadPrototypes.cpp - Remove unused function declarations ----===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// This pass loops over all of the functions in the input module, looking for
// dead declarations and removes them. Dead declarations are declarations of
// functions for which no implementation is available (i.e., declarations for
// unused library functions).
//
//===----------------------------------------------------------------------===//
#include "llvm/Transforms/IPO/StripDeadPrototypes.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/IR/Module.h"
#include "llvm/Pass.h"
#include "llvm/Transforms/IPO.h"
using namespace llvm;
#define DEBUG_TYPE "strip-dead-prototypes"
STATISTIC(NumDeadPrototypes, "Number of dead prototypes removed");
static bool stripDeadPrototypes(Module &M) {
bool MadeChange = false;
// Erase dead function prototypes.
for (Module::iterator I = M.begin(), E = M.end(); I != E; ) {
Function *F = &*I++;
// Function must be a prototype and unused.
if (F->isDeclaration() && F->use_empty()) {
F->eraseFromParent();
++NumDeadPrototypes;
MadeChange = true;
}
}
// Erase dead global var prototypes.
for (Module::global_iterator I = M.global_begin(), E = M.global_end();
I != E; ) {
GlobalVariable *GV = &*I++;
// Global must be a prototype and unused.
if (GV->isDeclaration() && GV->use_empty())
GV->eraseFromParent();
}
// Return an indication of whether we changed anything or not.
return MadeChange;
}
PreservedAnalyses StripDeadPrototypesPass::run(Module &M,
ModuleAnalysisManager &) {
if (stripDeadPrototypes(M))
return PreservedAnalyses::none();
return PreservedAnalyses::all();
}
namespace {
class StripDeadPrototypesLegacyPass : public ModulePass {
public:
static char ID; // Pass identification, replacement for typeid
StripDeadPrototypesLegacyPass() : ModulePass(ID) {
initializeStripDeadPrototypesLegacyPassPass(
*PassRegistry::getPassRegistry());
}
bool runOnModule(Module &M) override {
if (skipModule(M))
return false;
return stripDeadPrototypes(M);
}
};
} // end anonymous namespace
char StripDeadPrototypesLegacyPass::ID = 0;
INITIALIZE_PASS(StripDeadPrototypesLegacyPass, "strip-dead-prototypes",
"Strip Unused Function Prototypes", false, false)
ModulePass *llvm::createStripDeadPrototypesPass() {
return new StripDeadPrototypesLegacyPass();
}
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