llvm/lib/Transforms/IPO/Annotation2Metadata.cpp

   1 //===-- Annotation2Metadata.cpp - Add !annotation metadata. ---------------===//
   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 // Add !annotation metadata for entries in @llvm.global.anotations, generated
  10 // using __attribute__((annotate("_name"))) on functions in Clang.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "llvm/Transforms/IPO/Annotation2Metadata.h"
  15 #include "llvm/Analysis/OptimizationRemarkEmitter.h"
  16 #include "llvm/IR/Constants.h"
  17 #include "llvm/IR/Function.h"
  18 #include "llvm/IR/InstIterator.h"
  19 #include "llvm/IR/Module.h"
  20 #include "llvm/InitializePasses.h"
  21 #include "llvm/Pass.h"
  22 #include "llvm/Transforms/IPO.h"
  23
  24 using namespace llvm;
  25
  26 #define DEBUG_TYPE "annotation2metadata"
  27
  28 static bool convertAnnotation2Metadata(Module &M) {
  29   // Only add !annotation metadata if the corresponding remarks pass is also
  30   // enabled.
  31   if (!OptimizationRemarkEmitter::allowExtraAnalysis(M.getContext(),
  32                                                      "annotation-remarks"))
  33     return false;
  34
  35   auto *Annotations = M.getGlobalVariable("llvm.global.annotations");
  36   auto *C = dyn_cast_or_null<Constant>(Annotations);
  37   if (!C || C->getNumOperands() != 1)
  38     return false;
  39
  40   C = cast<Constant>(C->getOperand(0));
  41
  42   // Iterate over all entries in C and attach !annotation metadata to suitable
  43   // entries.
  44   for (auto &Op : C->operands()) {
  45     // Look at the operands to check if we can use the entry to generate
  46     // !annotation metadata.
  47     auto *OpC = dyn_cast<ConstantStruct>(&Op);
  48     if (!OpC || OpC->getNumOperands() != 4)
  49       continue;
  50     auto *StrGEP = dyn_cast<ConstantExpr>(OpC->getOperand(1));
  51     if (!StrGEP || StrGEP->getNumOperands() < 2)
  52       continue;
  53     auto *StrC = dyn_cast<GlobalValue>(StrGEP->getOperand(0));
  54     if (!StrC)
  55       continue;
  56     auto *StrData = dyn_cast<ConstantDataSequential>(StrC->getOperand(0));
  57     if (!StrData)
  58       continue;
  59     // Look through bitcast.
  60     auto *Bitcast = dyn_cast<ConstantExpr>(OpC->getOperand(0));
  61     if (!Bitcast || Bitcast->getOpcode() != Instruction::BitCast)
  62       continue;
  63     auto *Fn = dyn_cast<Function>(Bitcast->getOperand(0));
  64     if (!Fn)
  65       continue;
  66
  67     // Add annotation to all instructions in the function.
  68     for (auto &I : instructions(Fn))
  69       I.addAnnotationMetadata(StrData->getAsCString());
  70   }
  71   return true;
  72 }
  73
  74 namespace {
  75 struct Annotation2MetadataLegacy : public ModulePass {
  76   static char ID;
  77
  78   Annotation2MetadataLegacy() : ModulePass(ID) {
  79     initializeAnnotation2MetadataLegacyPass(*PassRegistry::getPassRegistry());
  80   }
  81
  82   bool runOnModule(Module &M) override { return convertAnnotation2Metadata(M); }
  83
  84   void getAnalysisUsage(AnalysisUsage &AU) const override {
  85     AU.setPreservesAll();
  86   }
  87 };
  88
  89 } // end anonymous namespace
  90
  91 char Annotation2MetadataLegacy::ID = 0;
  92
  93 INITIALIZE_PASS_BEGIN(Annotation2MetadataLegacy, DEBUG_TYPE,
  94                       "Annotation2Metadata", false, false)
  95 INITIALIZE_PASS_END(Annotation2MetadataLegacy, DEBUG_TYPE,
  96                     "Annotation2Metadata", false, false)
  97
  98 ModulePass *llvm::createAnnotation2MetadataLegacyPass() {
  99   return new Annotation2MetadataLegacy();
 100 }
 101
 102 PreservedAnalyses Annotation2MetadataPass::run(Module &M,
 103                                                ModuleAnalysisManager &AM) {
 104   convertAnnotation2Metadata(M);
 105   return PreservedAnalyses::all();
 106 }