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      1 //===- InstructionNamer.cpp - Give anonymous instructions names -----------===//
      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 is a little utility pass that gives instructions names, this is mostly
     10 // useful when diffing the effect of an optimization because deleting an
     11 // unnamed instruction can change all other instruction numbering, making the
     12 // diff very noisy.
     13 //
     14 //===----------------------------------------------------------------------===//
     15 
     16 #include "llvm/Transforms/Utils/InstructionNamer.h"
     17 #include "llvm/IR/Function.h"
     18 #include "llvm/IR/PassManager.h"
     19 #include "llvm/IR/Type.h"
     20 #include "llvm/InitializePasses.h"
     21 #include "llvm/Pass.h"
     22 #include "llvm/Transforms/Utils.h"
     23 
     24 using namespace llvm;
     25 
     26 namespace {
     27 void nameInstructions(Function &F) {
     28   for (auto &Arg : F.args()) {
     29     if (!Arg.hasName())
     30       Arg.setName("arg");
     31   }
     32 
     33   for (BasicBlock &BB : F) {
     34     if (!BB.hasName())
     35       BB.setName("bb");
     36 
     37     for (Instruction &I : BB) {
     38       if (!I.hasName() && !I.getType()->isVoidTy())
     39         I.setName("i");
     40     }
     41   }
     42 }
     43 
     44 struct InstNamer : public FunctionPass {
     45   static char ID; // Pass identification, replacement for typeid
     46   InstNamer() : FunctionPass(ID) {
     47     initializeInstNamerPass(*PassRegistry::getPassRegistry());
     48   }
     49 
     50   void getAnalysisUsage(AnalysisUsage &Info) const override {
     51     Info.setPreservesAll();
     52   }
     53 
     54   bool runOnFunction(Function &F) override {
     55     nameInstructions(F);
     56     return true;
     57   }
     58 };
     59 
     60   char InstNamer::ID = 0;
     61   } // namespace
     62 
     63 INITIALIZE_PASS(InstNamer, "instnamer",
     64                 "Assign names to anonymous instructions", false, false)
     65 char &llvm::InstructionNamerID = InstNamer::ID;
     66 //===----------------------------------------------------------------------===//
     67 //
     68 // InstructionNamer - Give any unnamed non-void instructions "tmp" names.
     69 //
     70 FunctionPass *llvm::createInstructionNamerPass() {
     71   return new InstNamer();
     72 }
     73 
     74 PreservedAnalyses InstructionNamerPass::run(Function &F,
     75                                             FunctionAnalysisManager &FAM) {
     76   nameInstructions(F);
     77   return PreservedAnalyses::all();
     78 }
     79