1//===- ForceFunctionAttrs.cpp - Force function attrs for debugging --------===//
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#include "llvm/Transforms/IPO/ForceFunctionAttrs.h"
10#include "llvm/IR/Function.h"
11#include "llvm/IR/Module.h"
12#include "llvm/Support/CommandLine.h"
13#include "llvm/Support/Debug.h"
14#include "llvm/Support/LineIterator.h"
15#include "llvm/Support/MemoryBuffer.h"
16#include "llvm/Support/raw_ostream.h"
17using namespace llvm;
18
19#define DEBUG_TYPE "forceattrs"
20
21static cl::list<std::string> ForceAttributes(
22 "force-attribute", cl::Hidden,
23 cl::desc(
24 "Add an attribute to a function. This can be a "
25 "pair of 'function-name:attribute-name', to apply an attribute to a "
26 "specific function. For "
27 "example -force-attribute=foo:noinline. Specifying only an attribute "
28 "will apply the attribute to every function in the module. This "
29 "option can be specified multiple times."));
30
31static cl::list<std::string> ForceRemoveAttributes(
32 "force-remove-attribute", cl::Hidden,
33 cl::desc("Remove an attribute from a function. This can be a "
34 "pair of 'function-name:attribute-name' to remove an attribute "
35 "from a specific function. For "
36 "example -force-remove-attribute=foo:noinline. Specifying only an "
37 "attribute will remove the attribute from all functions in the "
38 "module. This "
39 "option can be specified multiple times."));
40
41static cl::opt<std::string> CSVFilePath(
42 "forceattrs-csv-path", cl::Hidden,
43 cl::desc(
44 "Path to CSV file containing lines of function names and attributes to "
45 "add to them in the form of `f1,attr1` or `f2,attr2=str`."));
46
47/// If F has any forced attributes given on the command line, add them.
48/// If F has any forced remove attributes given on the command line, remove
49/// them. When both force and force-remove are given to a function, the latter
50/// takes precedence.
51static void forceAttributes(Function &F) {
52 auto ParseFunctionAndAttr = [&](StringRef S) {
53 StringRef AttributeText;
54 if (S.contains(C: ':')) {
55 auto KV = StringRef(S).split(Separator: ':');
56 if (KV.first != F.getName())
57 return Attribute::None;
58 AttributeText = KV.second;
59 } else {
60 AttributeText = S;
61 }
62 auto Kind = Attribute::getAttrKindFromName(AttrName: AttributeText);
63 if (Kind == Attribute::None || !Attribute::canUseAsFnAttr(Kind)) {
64 LLVM_DEBUG(dbgs() << "ForcedAttribute: " << AttributeText
65 << " unknown or not a function attribute!\n");
66 }
67 return Kind;
68 };
69
70 for (const auto &S : ForceAttributes) {
71 auto Kind = ParseFunctionAndAttr(S);
72 if (Kind == Attribute::None || F.hasFnAttribute(Kind))
73 continue;
74 F.addFnAttr(Kind);
75 }
76
77 for (const auto &S : ForceRemoveAttributes) {
78 auto Kind = ParseFunctionAndAttr(S);
79 if (Kind == Attribute::None || !F.hasFnAttribute(Kind))
80 continue;
81 F.removeFnAttr(Kind);
82 }
83}
84
85static bool hasForceAttributes() {
86 return !ForceAttributes.empty() || !ForceRemoveAttributes.empty();
87}
88
89PreservedAnalyses ForceFunctionAttrsPass::run(Module &M,
90 ModuleAnalysisManager &) {
91 bool Changed = false;
92 if (!CSVFilePath.empty()) {
93 auto BufferOrError = MemoryBuffer::getFileOrSTDIN(Filename: CSVFilePath);
94 if (!BufferOrError) {
95 std::error_code EC = BufferOrError.getError();
96 M.getContext().emitError(ErrorStr: "cannot open CSV file: " + EC.message());
97 return PreservedAnalyses::all();
98 }
99
100 StringRef Buffer = BufferOrError.get()->getBuffer();
101 auto MemoryBuffer = MemoryBuffer::getMemBuffer(InputData: Buffer);
102 line_iterator It(*MemoryBuffer);
103 for (; !It.is_at_end(); ++It) {
104 auto SplitPair = It->split(Separator: ',');
105 if (SplitPair.second.empty())
106 continue;
107 Function *Func = M.getFunction(Name: SplitPair.first);
108 if (Func) {
109 if (Func->isDeclaration())
110 continue;
111 auto SecondSplitPair = SplitPair.second.split(Separator: '=');
112 if (!SecondSplitPair.second.empty()) {
113 Func->addFnAttr(Kind: SecondSplitPair.first, Val: SecondSplitPair.second);
114 Changed = true;
115 } else {
116 auto AttrKind = Attribute::getAttrKindFromName(AttrName: SplitPair.second);
117 if (AttrKind != Attribute::None &&
118 Attribute::canUseAsFnAttr(Kind: AttrKind)) {
119 // TODO: There could be string attributes without a value, we should
120 // support those, too.
121 Func->addFnAttr(Kind: AttrKind);
122 Changed = true;
123 } else
124 errs() << "Cannot add " << SplitPair.second
125 << " as an attribute name.\n";
126 }
127 } else {
128 errs() << "Function in CSV file at line " << It.line_number()
129 << " does not exist.\n";
130 // TODO: `report_fatal_error at end of pass for missing functions.
131 continue;
132 }
133 }
134 }
135 if (hasForceAttributes()) {
136 for (Function &F : M.functions())
137 forceAttributes(F);
138 Changed = true;
139 }
140 // Just conservatively invalidate analyses if we've made any changes, this
141 // isn't likely to be important.
142 return Changed ? PreservedAnalyses::none() : PreservedAnalyses::all();
143}
144