| 1 | //===-- StripDeadPrototypes.cpp - Remove unused function declarations ----===// |
|---|---|
| 2 | // |
| 3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| 4 | // See https://llvm.org/LICENSE.txt for license information. |
| 5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| 6 | // |
| 7 | //===----------------------------------------------------------------------===// |
| 8 | // |
| 9 | // This pass loops over all of the functions in the input module, looking for |
| 10 | // dead declarations and removes them. Dead declarations are declarations of |
| 11 | // functions for which no implementation is available (i.e., declarations for |
| 12 | // unused library functions). |
| 13 | // |
| 14 | //===----------------------------------------------------------------------===// |
| 15 | |
| 16 | #include "llvm/Transforms/IPO/StripDeadPrototypes.h" |
| 17 | #include "llvm/ADT/Statistic.h" |
| 18 | #include "llvm/IR/Module.h" |
| 19 | #include "llvm/Transforms/IPO.h" |
| 20 | |
| 21 | using namespace llvm; |
| 22 | |
| 23 | #define DEBUG_TYPE "strip-dead-prototypes" |
| 24 | |
| 25 | STATISTIC(NumDeadPrototypes, "Number of dead prototypes removed"); |
| 26 | |
| 27 | static bool stripDeadPrototypes(Module &M) { |
| 28 | bool MadeChange = false; |
| 29 | |
| 30 | // Erase dead function prototypes. |
| 31 | for (Function &F : llvm::make_early_inc_range(Range&: M)) { |
| 32 | // Function must be a prototype and unused. |
| 33 | if (F.isDeclaration() && F.use_empty()) { |
| 34 | F.eraseFromParent(); |
| 35 | ++NumDeadPrototypes; |
| 36 | MadeChange = true; |
| 37 | } |
| 38 | } |
| 39 | |
| 40 | // Erase dead global var prototypes. |
| 41 | for (GlobalVariable &GV : llvm::make_early_inc_range(Range: M.globals())) { |
| 42 | // Global must be a prototype and unused. |
| 43 | if (GV.isDeclaration() && GV.use_empty()) |
| 44 | GV.eraseFromParent(); |
| 45 | } |
| 46 | |
| 47 | // Return an indication of whether we changed anything or not. |
| 48 | return MadeChange; |
| 49 | } |
| 50 | |
| 51 | PreservedAnalyses StripDeadPrototypesPass::run(Module &M, |
| 52 | ModuleAnalysisManager &) { |
| 53 | if (stripDeadPrototypes(M)) |
| 54 | return PreservedAnalyses::none(); |
| 55 | return PreservedAnalyses::all(); |
| 56 | } |
| 57 |