1//===--- RewriteMacros.cpp - Rewrite macros into their expansions ---------===//
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// This code rewrites macro invocations into their expansions. This gives you
10// a macro expanded file that retains comments and #includes.
11//
12//===----------------------------------------------------------------------===//
13
14#include "clang/Basic/SourceManager.h"
15#include "clang/Lex/Preprocessor.h"
16#include "clang/Rewrite/Core/Rewriter.h"
17#include "clang/Rewrite/Frontend/Rewriters.h"
18#include "llvm/ADT/RewriteBuffer.h"
19#include <cstdio>
20
21using namespace clang;
22using llvm::RewriteBuffer;
23
24/// isSameToken - Return true if the two specified tokens start have the same
25/// content.
26static bool isSameToken(Token &RawTok, Token &PPTok) {
27 // If two tokens have the same kind and the same identifier info, they are
28 // obviously the same.
29 if (PPTok.getKind() == RawTok.getKind() &&
30 PPTok.getIdentifierInfo() == RawTok.getIdentifierInfo())
31 return true;
32
33 // Otherwise, if they are different but have the same identifier info, they
34 // are also considered to be the same. This allows keywords and raw lexed
35 // identifiers with the same name to be treated the same.
36 if (PPTok.getIdentifierInfo() &&
37 PPTok.getIdentifierInfo() == RawTok.getIdentifierInfo())
38 return true;
39
40 return false;
41}
42
43
44/// GetNextRawTok - Return the next raw token in the stream, skipping over
45/// comments if ReturnComment is false.
46static const Token &GetNextRawTok(const std::vector<Token> &RawTokens,
47 unsigned &CurTok, bool ReturnComment) {
48 assert(CurTok < RawTokens.size() && "Overran eof!");
49
50 // If the client doesn't want comments and we have one, skip it.
51 if (!ReturnComment && RawTokens[CurTok].is(K: tok::comment))
52 ++CurTok;
53
54 return RawTokens[CurTok++];
55}
56
57
58/// LexRawTokensFromMainFile - Lets all the raw tokens from the main file into
59/// the specified vector.
60static void LexRawTokensFromMainFile(Preprocessor &PP,
61 std::vector<Token> &RawTokens) {
62 SourceManager &SM = PP.getSourceManager();
63
64 // Create a lexer to lex all the tokens of the main file in raw mode. Even
65 // though it is in raw mode, it will not return comments.
66 llvm::MemoryBufferRef FromFile = SM.getBufferOrFake(FID: SM.getMainFileID());
67 Lexer RawLex(SM.getMainFileID(), FromFile, SM, PP.getLangOpts());
68
69 // Switch on comment lexing because we really do want them.
70 RawLex.SetCommentRetentionState(true);
71
72 Token RawTok;
73 do {
74 RawLex.LexFromRawLexer(Result&: RawTok);
75
76 // If we have an identifier with no identifier info for our raw token, look
77 // up the identifier info. This is important for equality comparison of
78 // identifier tokens.
79 if (RawTok.is(K: tok::raw_identifier))
80 PP.LookUpIdentifierInfo(Identifier&: RawTok);
81
82 RawTokens.push_back(x: RawTok);
83 } while (RawTok.isNot(K: tok::eof));
84}
85
86
87/// RewriteMacrosInInput - Implement -rewrite-macros mode.
88void clang::RewriteMacrosInInput(Preprocessor &PP, raw_ostream *OS) {
89 SourceManager &SM = PP.getSourceManager();
90
91 Rewriter Rewrite;
92 Rewrite.setSourceMgr(SM, LO: PP.getLangOpts());
93 RewriteBuffer &RB = Rewrite.getEditBuffer(FID: SM.getMainFileID());
94
95 std::vector<Token> RawTokens;
96 LexRawTokensFromMainFile(PP, RawTokens);
97 unsigned CurRawTok = 0;
98 Token RawTok = GetNextRawTok(RawTokens, CurTok&: CurRawTok, ReturnComment: false);
99
100
101 // Get the first preprocessing token.
102 PP.EnterMainSourceFile();
103 Token PPTok;
104 PP.Lex(Result&: PPTok);
105
106 // Preprocess the input file in parallel with raw lexing the main file. Ignore
107 // all tokens that are preprocessed from a file other than the main file (e.g.
108 // a header). If we see tokens that are in the preprocessed file but not the
109 // lexed file, we have a macro expansion. If we see tokens in the lexed file
110 // that aren't in the preprocessed view, we have macros that expand to no
111 // tokens, or macro arguments etc.
112 while (RawTok.isNot(K: tok::eof) || PPTok.isNot(K: tok::eof)) {
113 SourceLocation PPLoc = SM.getExpansionLoc(Loc: PPTok.getLocation());
114
115 // If PPTok is from a different source file, ignore it.
116 if (!SM.isWrittenInMainFile(Loc: PPLoc)) {
117 PP.Lex(Result&: PPTok);
118 continue;
119 }
120
121 // If the raw file hits a preprocessor directive, they will be extra tokens
122 // in the raw file that don't exist in the preprocsesed file. However, we
123 // choose to preserve them in the output file and otherwise handle them
124 // specially.
125 if (RawTok.is(K: tok::hash) && RawTok.isAtStartOfLine()) {
126 // If this is a #warning directive or #pragma mark (GNU extensions),
127 // comment the line out.
128 if (RawTokens[CurRawTok].is(K: tok::identifier)) {
129 const IdentifierInfo *II = RawTokens[CurRawTok].getIdentifierInfo();
130 if (II->getName() == "warning") {
131 // Comment out #warning.
132 RB.InsertTextAfter(OrigOffset: SM.getFileOffset(SpellingLoc: RawTok.getLocation()), Str: "//");
133 } else if (II->getName() == "pragma" &&
134 RawTokens[CurRawTok+1].is(K: tok::identifier) &&
135 (RawTokens[CurRawTok+1].getIdentifierInfo()->getName() ==
136 "mark")) {
137 // Comment out #pragma mark.
138 RB.InsertTextAfter(OrigOffset: SM.getFileOffset(SpellingLoc: RawTok.getLocation()), Str: "//");
139 }
140 }
141
142 // Otherwise, if this is a #include or some other directive, just leave it
143 // in the file by skipping over the line.
144 RawTok = GetNextRawTok(RawTokens, CurTok&: CurRawTok, ReturnComment: false);
145 while (!RawTok.isAtStartOfLine() && RawTok.isNot(K: tok::eof))
146 RawTok = GetNextRawTok(RawTokens, CurTok&: CurRawTok, ReturnComment: false);
147 continue;
148 }
149
150 // Okay, both tokens are from the same file. Get their offsets from the
151 // start of the file.
152 unsigned PPOffs = SM.getFileOffset(SpellingLoc: PPLoc);
153 unsigned RawOffs = SM.getFileOffset(SpellingLoc: RawTok.getLocation());
154
155 // If the offsets are the same and the token kind is the same, ignore them.
156 if (PPOffs == RawOffs && isSameToken(RawTok, PPTok)) {
157 RawTok = GetNextRawTok(RawTokens, CurTok&: CurRawTok, ReturnComment: false);
158 PP.Lex(Result&: PPTok);
159 continue;
160 }
161
162 // If the PP token is farther along than the raw token, something was
163 // deleted. Comment out the raw token.
164 if (RawOffs <= PPOffs) {
165 // Comment out a whole run of tokens instead of bracketing each one with
166 // comments. Add a leading space if RawTok didn't have one.
167 bool HasSpace = RawTok.hasLeadingSpace();
168 RB.InsertTextAfter(OrigOffset: RawOffs, Str: &" /*"[HasSpace]);
169 unsigned EndPos;
170
171 do {
172 EndPos = RawOffs+RawTok.getLength();
173
174 RawTok = GetNextRawTok(RawTokens, CurTok&: CurRawTok, ReturnComment: true);
175 RawOffs = SM.getFileOffset(SpellingLoc: RawTok.getLocation());
176
177 if (RawTok.is(K: tok::comment)) {
178 // Skip past the comment.
179 RawTok = GetNextRawTok(RawTokens, CurTok&: CurRawTok, ReturnComment: false);
180 break;
181 }
182
183 } while (RawOffs <= PPOffs && !RawTok.isAtStartOfLine() &&
184 (PPOffs != RawOffs || !isSameToken(RawTok, PPTok)));
185
186 RB.InsertTextBefore(OrigOffset: EndPos, Str: "*/");
187 continue;
188 }
189
190 // Otherwise, there was a replacement an expansion. Insert the new token
191 // in the output buffer. Insert the whole run of new tokens at once to get
192 // them in the right order.
193 unsigned InsertPos = PPOffs;
194 std::string Expansion;
195 while (PPOffs < RawOffs) {
196 Expansion += ' ' + PP.getSpelling(Tok: PPTok);
197 PP.Lex(Result&: PPTok);
198 PPLoc = SM.getExpansionLoc(Loc: PPTok.getLocation());
199 PPOffs = SM.getFileOffset(SpellingLoc: PPLoc);
200 }
201 Expansion += ' ';
202 RB.InsertTextBefore(OrigOffset: InsertPos, Str: Expansion);
203 }
204
205 // Get the buffer corresponding to MainFileID. If we haven't changed it, then
206 // we are done.
207 if (const RewriteBuffer *RewriteBuf =
208 Rewrite.getRewriteBufferFor(FID: SM.getMainFileID())) {
209 //printf("Changed:\n");
210 *OS << std::string(RewriteBuf->begin(), RewriteBuf->end());
211 } else {
212 fprintf(stderr, format: "No changes\n");
213 }
214 OS->flush();
215}
216