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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 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/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 (Function &F : llvm::make_early_inc_range(M)) {
// Function must be a prototype and unused.
if (F.isDeclaration() && F.use_empty()) {
MadeChange = true;
// Erase dead global var prototypes.
for (GlobalVariable &GV : llvm::make_early_inc_range(M.globals())) {
// Global must be a prototype and unused.
if (GV.isDeclaration() && GV.use_empty())
// 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();