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