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