1 //===-- AnnotationRemarks.cpp - Generate remarks for annotated instrs. ----===//
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 // Generate remarks for instructions marked with !annotation.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #include "llvm/Transforms/Scalar/AnnotationRemarks.h"
14 #include "llvm/ADT/MapVector.h"
15 #include "llvm/Analysis/OptimizationRemarkEmitter.h"
16 #include "llvm/Analysis/TargetLibraryInfo.h"
17 #include "llvm/IR/Function.h"
18 #include "llvm/IR/InstIterator.h"
19 #include "llvm/InitializePasses.h"
20 #include "llvm/Pass.h"
21 #include "llvm/Support/Debug.h"
22 #include "llvm/Transforms/Scalar.h"
23 
24 using namespace llvm;
25 using namespace llvm::ore;
26 
27 #define DEBUG_TYPE "annotation-remarks"
28 #define REMARK_PASS DEBUG_TYPE
29 
30 static void tryEmitAutoInitRemark(ArrayRef<Instruction *> Instructions,
31                                   OptimizationRemarkEmitter &ORE) {
32   // For every auto-init annotation generate a separate remark.
33   for (Instruction *I : Instructions) {
34     if (!I->hasMetadata(LLVMContext::MD_annotation))
35       continue;
36     for (const MDOperand &Op :
37          I->getMetadata(LLVMContext::MD_annotation)->operands()) {
38       if (cast<MDString>(Op.get())->getString() != "auto-init")
39         continue;
40 
41       ORE.emit(
42           OptimizationRemarkMissed(REMARK_PASS, "AutoInitUnknownInstruction", I)
43           << "Initialization inserted by -ftrivial-auto-var-init.");
44     }
45   }
46 }
47 
48 static void runImpl(Function &F) {
49   if (!OptimizationRemarkEmitter::allowExtraAnalysis(F, REMARK_PASS))
50     return;
51 
52   // Track all annotated instructions aggregated based on their debug location.
53   DenseMap<MDNode *, SmallVector<Instruction *, 4>> DebugLoc2Annotated;
54 
55   OptimizationRemarkEmitter ORE(&F);
56   // First, generate a summary of the annotated instructions.
57   MapVector<StringRef, unsigned> Mapping;
58   for (Instruction &I : instructions(F)) {
59     if (!I.hasMetadata(LLVMContext::MD_annotation))
60       continue;
61     auto Iter = DebugLoc2Annotated.insert({I.getDebugLoc().getAsMDNode(), {}});
62     Iter.first->second.push_back(&I);
63 
64     for (const MDOperand &Op :
65          I.getMetadata(LLVMContext::MD_annotation)->operands()) {
66       auto Iter = Mapping.insert({cast<MDString>(Op.get())->getString(), 0});
67       Iter.first->second++;
68     }
69   }
70 
71   Instruction *IP = &*F.begin()->begin();
72   for (const auto &KV : Mapping)
73     ORE.emit(OptimizationRemarkAnalysis(REMARK_PASS, "AnnotationSummary", IP)
74              << "Annotated " << NV("count", KV.second) << " instructions with "
75              << NV("type", KV.first));
76 
77   // For each debug location, look for all the instructions with annotations and
78   // generate more detailed remarks to be displayed at that location.
79   for (auto &KV : DebugLoc2Annotated) {
80     // Don't generate remarks with no debug location.
81     if (!KV.first)
82       continue;
83 
84     tryEmitAutoInitRemark(KV.second, ORE);
85   }
86 }
87 
88 namespace {
89 
90 struct AnnotationRemarksLegacy : public FunctionPass {
91   static char ID;
92 
93   AnnotationRemarksLegacy() : FunctionPass(ID) {
94     initializeAnnotationRemarksLegacyPass(*PassRegistry::getPassRegistry());
95   }
96 
97   bool runOnFunction(Function &F) override {
98     runImpl(F);
99     return false;
100   }
101 
102   void getAnalysisUsage(AnalysisUsage &AU) const override {
103     AU.setPreservesAll();
104   }
105 };
106 
107 } // end anonymous namespace
108 
109 char AnnotationRemarksLegacy::ID = 0;
110 
111 INITIALIZE_PASS_BEGIN(AnnotationRemarksLegacy, "annotation-remarks",
112                       "Annotation Remarks", false, false)
113 INITIALIZE_PASS_END(AnnotationRemarksLegacy, "annotation-remarks",
114                     "Annotation Remarks", false, false)
115 
116 FunctionPass *llvm::createAnnotationRemarksLegacyPass() {
117   return new AnnotationRemarksLegacy();
118 }
119 
120 PreservedAnalyses AnnotationRemarksPass::run(Function &F,
121                                              FunctionAnalysisManager &AM) {
122   runImpl(F);
123   return PreservedAnalyses::all();
124 }
125