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/Transforms/IPO.h"
  21
  22 using namespace llvm;
  23
  24 #define DEBUG_TYPE "annotation2metadata"
  25
  26 static bool convertAnnotation2Metadata(Module &M) {
  27   // Only add !annotation metadata if the corresponding remarks pass is also
  28   // enabled.
  29   if (!OptimizationRemarkEmitter::allowExtraAnalysis(M.getContext(),
  30                                                      "annotation-remarks"))
  31     return false;
  32
  33   auto *Annotations = M.getGlobalVariable("llvm.global.annotations");
  34   auto *C = dyn_cast_or_null<Constant>(Annotations);
  35   if (!C || C->getNumOperands() != 1)
  36     return false;
  37
  38   C = cast<Constant>(C->getOperand(0));
  39
  40   // Iterate over all entries in C and attach !annotation metadata to suitable
  41   // entries.
  42   for (auto &Op : C->operands()) {
  43     // Look at the operands to check if we can use the entry to generate
  44     // !annotation metadata.
  45     auto *OpC = dyn_cast<ConstantStruct>(&Op);
  46     if (!OpC || OpC->getNumOperands() != 4)
  47       continue;
  48     auto *StrC = dyn_cast<GlobalValue>(OpC->getOperand(1)->stripPointerCasts());
  49     if (!StrC)
  50       continue;
  51     auto *StrData = dyn_cast<ConstantDataSequential>(StrC->getOperand(0));
  52     if (!StrData)
  53       continue;
  54     auto *Fn = dyn_cast<Function>(OpC->getOperand(0)->stripPointerCasts());
  55     if (!Fn)
  56       continue;
  57
  58     // Add annotation to all instructions in the function.
  59     for (auto &I : instructions(Fn))
  60       I.addAnnotationMetadata(StrData->getAsCString());
  61   }
  62   return true;
  63 }
  64
  65 PreservedAnalyses Annotation2MetadataPass::run(Module &M,
  66                                                ModuleAnalysisManager &AM) {
  67   return convertAnnotation2Metadata(M) ? PreservedAnalyses::none()
  68                                        : PreservedAnalyses::all();
  69 }