1//===--- MacroArgs.cpp - Formal argument info for Macros ------------------===//
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 file implements the MacroArgs interface.
10//
11//===----------------------------------------------------------------------===//
12
13#include "clang/Lex/MacroArgs.h"
14#include "clang/Lex/LexDiagnostic.h"
15#include "clang/Lex/MacroInfo.h"
16#include "clang/Lex/Preprocessor.h"
17#include "llvm/Support/SaveAndRestore.h"
18#include <algorithm>
19
20using namespace clang;
21
22/// MacroArgs ctor function - This destroys the vector passed in.
23MacroArgs *MacroArgs::create(const MacroInfo *MI,
24 ArrayRef<Token> UnexpArgTokens,
25 bool VarargsElided, Preprocessor &PP) {
26 assert(MI->isFunctionLike() &&
27 "Can't have args for an object-like macro!");
28 MacroArgs **ResultEnt = nullptr;
29 unsigned ClosestMatch = ~0U;
30
31 // See if we have an entry with a big enough argument list to reuse on the
32 // free list. If so, reuse it.
33 for (MacroArgs **Entry = &PP.MacroArgCache; *Entry;
34 Entry = &(*Entry)->ArgCache) {
35 if ((*Entry)->NumUnexpArgTokens >= UnexpArgTokens.size() &&
36 (*Entry)->NumUnexpArgTokens < ClosestMatch) {
37 ResultEnt = Entry;
38
39 // If we have an exact match, use it.
40 if ((*Entry)->NumUnexpArgTokens == UnexpArgTokens.size())
41 break;
42 // Otherwise, use the best fit.
43 ClosestMatch = (*Entry)->NumUnexpArgTokens;
44 }
45 }
46 MacroArgs *Result;
47 if (!ResultEnt) {
48 // Allocate memory for a MacroArgs object with the lexer tokens at the end,
49 // and construct the MacroArgs object.
50 Result = new (
51 llvm::safe_malloc(Sz: totalSizeToAlloc<Token>(Counts: UnexpArgTokens.size())))
52 MacroArgs(UnexpArgTokens.size(), VarargsElided, MI->getNumParams());
53 } else {
54 Result = *ResultEnt;
55 // Unlink this node from the preprocessors singly linked list.
56 *ResultEnt = Result->ArgCache;
57 Result->NumUnexpArgTokens = UnexpArgTokens.size();
58 Result->VarargsElided = VarargsElided;
59 Result->NumMacroArgs = MI->getNumParams();
60 }
61
62 // Copy the actual unexpanded tokens to immediately after the result ptr.
63 if (!UnexpArgTokens.empty()) {
64 static_assert(std::is_trivial_v<Token>,
65 "assume trivial copyability if copying into the "
66 "uninitialized array (as opposed to reusing a cached "
67 "MacroArgs)");
68 std::copy(first: UnexpArgTokens.begin(), last: UnexpArgTokens.end(),
69 result: Result->getTrailingObjects());
70 }
71
72 return Result;
73}
74
75/// destroy - Destroy and deallocate the memory for this object.
76///
77void MacroArgs::destroy(Preprocessor &PP) {
78 // Don't clear PreExpArgTokens, just clear the entries. Clearing the entries
79 // would deallocate the element vectors.
80 for (unsigned i = 0, e = PreExpArgTokens.size(); i != e; ++i)
81 PreExpArgTokens[i].clear();
82
83 // Add this to the preprocessor's free list.
84 ArgCache = PP.MacroArgCache;
85 PP.MacroArgCache = this;
86}
87
88/// deallocate - This should only be called by the Preprocessor when managing
89/// its freelist.
90MacroArgs *MacroArgs::deallocate() {
91 MacroArgs *Next = ArgCache;
92
93 // Run the dtor to deallocate the vectors.
94 this->~MacroArgs();
95 // Release the memory for the object.
96 static_assert(std::is_trivially_destructible_v<Token>,
97 "assume trivially destructible and forego destructors");
98 free(ptr: this);
99
100 return Next;
101}
102
103
104/// getArgLength - Given a pointer to an expanded or unexpanded argument,
105/// return the number of tokens, not counting the EOF, that make up the
106/// argument.
107unsigned MacroArgs::getArgLength(const Token *ArgPtr) {
108 unsigned NumArgTokens = 0;
109 for (; ArgPtr->isNot(K: tok::eof); ++ArgPtr)
110 ++NumArgTokens;
111 return NumArgTokens;
112}
113
114
115/// getUnexpArgument - Return the unexpanded tokens for the specified formal.
116///
117const Token *MacroArgs::getUnexpArgument(unsigned Arg) const {
118
119 assert(Arg < getNumMacroArguments() && "Invalid arg #");
120 // The unexpanded argument tokens start immediately after the MacroArgs object
121 // in memory.
122 const Token *Start = getTrailingObjects();
123 const Token *Result = Start;
124
125 // Scan to find Arg.
126 for (; Arg; ++Result) {
127 assert(Result < Start+NumUnexpArgTokens && "Invalid arg #");
128 if (Result->is(K: tok::eof))
129 --Arg;
130 }
131 assert(Result < Start+NumUnexpArgTokens && "Invalid arg #");
132 return Result;
133}
134
135bool MacroArgs::invokedWithVariadicArgument(const MacroInfo *const MI,
136 Preprocessor &PP) {
137 if (!MI->isVariadic())
138 return false;
139 const int VariadicArgIndex = getNumMacroArguments() - 1;
140 return getPreExpArgument(Arg: VariadicArgIndex, PP).front().isNot(K: tok::eof);
141}
142
143/// ArgNeedsPreexpansion - If we can prove that the argument won't be affected
144/// by pre-expansion, return false. Otherwise, conservatively return true.
145bool MacroArgs::ArgNeedsPreexpansion(const Token *ArgTok,
146 Preprocessor &PP) const {
147 // If there are no identifiers in the argument list, or if the identifiers are
148 // known to not be macros, pre-expansion won't modify it.
149 for (; ArgTok->isNot(K: tok::eof); ++ArgTok)
150 if (IdentifierInfo *II = ArgTok->getIdentifierInfo())
151 if (II->hasMacroDefinition())
152 // Return true even though the macro could be a function-like macro
153 // without a following '(' token, or could be disabled, or not visible.
154 return true;
155 return false;
156}
157
158/// getPreExpArgument - Return the pre-expanded form of the specified
159/// argument.
160const std::vector<Token> &MacroArgs::getPreExpArgument(unsigned Arg,
161 Preprocessor &PP) {
162 assert(Arg < getNumMacroArguments() && "Invalid argument number!");
163
164 // If we have already computed this, return it.
165 if (PreExpArgTokens.size() < getNumMacroArguments())
166 PreExpArgTokens.resize(new_size: getNumMacroArguments());
167
168 std::vector<Token> &Result = PreExpArgTokens[Arg];
169 if (!Result.empty()) return Result;
170
171 SaveAndRestore PreExpandingMacroArgs(PP.InMacroArgPreExpansion, true);
172
173 const Token *AT = getUnexpArgument(Arg);
174 unsigned NumToks = getArgLength(ArgPtr: AT)+1; // Include the EOF.
175
176 // Otherwise, we have to pre-expand this argument, populating Result. To do
177 // this, we set up a fake TokenLexer to lex from the unexpanded argument
178 // list. With this installed, we lex expanded tokens until we hit the EOF
179 // token at the end of the unexp list.
180 PP.EnterTokenStream(Toks: AT, NumToks, DisableMacroExpansion: false /*disable expand*/,
181 OwnsTokens: false /*owns tokens*/, IsReinject: false /*is reinject*/);
182
183 // Lex all of the macro-expanded tokens into Result.
184 do {
185 Result.push_back(x: Token());
186 Token &Tok = Result.back();
187 PP.Lex(Result&: Tok);
188 } while (Result.back().isNot(K: tok::eof));
189
190 // Pop the token stream off the top of the stack. We know that the internal
191 // pointer inside of it is to the "end" of the token stream, but the stack
192 // will not otherwise be popped until the next token is lexed. The problem is
193 // that the token may be lexed sometime after the vector of tokens itself is
194 // destroyed, which would be badness.
195 if (PP.InCachingLexMode())
196 PP.ExitCachingLexMode();
197 PP.RemoveTopOfLexerStack();
198 return Result;
199}
200
201
202/// StringifyArgument - Implement C99 6.10.3.2p2, converting a sequence of
203/// tokens into the literal string token that should be produced by the C #
204/// preprocessor operator. If Charify is true, then it should be turned into
205/// a character literal for the Microsoft charize (#@) extension.
206///
207Token MacroArgs::StringifyArgument(const Token *ArgToks,
208 Preprocessor &PP, bool Charify,
209 SourceLocation ExpansionLocStart,
210 SourceLocation ExpansionLocEnd) {
211 Token Tok;
212 Tok.startToken();
213 Tok.setKind(Charify ? tok::char_constant : tok::string_literal);
214
215 const Token *ArgTokStart = ArgToks;
216
217 // Stringify all the tokens.
218 SmallString<128> Result;
219 Result += "\"";
220
221 bool isFirst = true;
222 for (; ArgToks->isNot(K: tok::eof); ++ArgToks) {
223 const Token &Tok = *ArgToks;
224 if (!isFirst && (Tok.hasLeadingSpace() || Tok.isAtStartOfLine()))
225 Result += ' ';
226 isFirst = false;
227
228 // If this is a string or character constant, escape the token as specified
229 // by 6.10.3.2p2.
230 if (tok::isStringLiteral(K: Tok.getKind()) || // "foo", u8R"x(foo)x"_bar, etc.
231 Tok.is(K: tok::char_constant) || // 'x'
232 Tok.is(K: tok::wide_char_constant) || // L'x'.
233 Tok.is(K: tok::utf8_char_constant) || // u8'x'.
234 Tok.is(K: tok::utf16_char_constant) || // u'x'.
235 Tok.is(K: tok::utf32_char_constant)) { // U'x'.
236 bool Invalid = false;
237 std::string TokStr = PP.getSpelling(Tok, Invalid: &Invalid);
238 if (!Invalid) {
239 std::string Str = Lexer::Stringify(Str: TokStr);
240 Result.append(in_start: Str.begin(), in_end: Str.end());
241 }
242 } else if (Tok.is(K: tok::code_completion)) {
243 PP.CodeCompleteNaturalLanguage();
244 } else {
245 // Otherwise, just append the token. Do some gymnastics to get the token
246 // in place and avoid copies where possible.
247 unsigned CurStrLen = Result.size();
248 Result.resize(N: CurStrLen+Tok.getLength());
249 const char *BufPtr = Result.data() + CurStrLen;
250 bool Invalid = false;
251 unsigned ActualTokLen = PP.getSpelling(Tok, Buffer&: BufPtr, Invalid: &Invalid);
252
253 if (!Invalid) {
254 // If getSpelling returned a pointer to an already uniqued version of
255 // the string instead of filling in BufPtr, memcpy it onto our string.
256 if (ActualTokLen && BufPtr != &Result[CurStrLen])
257 memcpy(dest: &Result[CurStrLen], src: BufPtr, n: ActualTokLen);
258
259 // If the token was dirty, the spelling may be shorter than the token.
260 if (ActualTokLen != Tok.getLength())
261 Result.resize(N: CurStrLen+ActualTokLen);
262 }
263 }
264 }
265
266 // If the last character of the string is a \, and if it isn't escaped, this
267 // is an invalid string literal, diagnose it as specified in C99.
268 if (Result.back() == '\\') {
269 // Count the number of consecutive \ characters. If even, then they are
270 // just escaped backslashes, otherwise it's an error.
271 unsigned FirstNonSlash = Result.size()-2;
272 // Guaranteed to find the starting " if nothing else.
273 while (Result[FirstNonSlash] == '\\')
274 --FirstNonSlash;
275 if ((Result.size()-1-FirstNonSlash) & 1) {
276 // Diagnose errors for things like: #define F(X) #X / F(\)
277 PP.Diag(Tok: ArgToks[-1], DiagID: diag::pp_invalid_string_literal);
278 Result.pop_back(); // remove one of the \'s.
279 }
280 }
281 Result += '"';
282
283 // If this is the charify operation and the result is not a legal character
284 // constant, diagnose it.
285 if (Charify) {
286 // First step, turn double quotes into single quotes:
287 Result[0] = '\'';
288 Result[Result.size()-1] = '\'';
289
290 // Check for bogus character.
291 bool isBad = false;
292 if (Result.size() == 3)
293 isBad = Result[1] == '\''; // ''' is not legal. '\' already fixed above.
294 else
295 isBad = (Result.size() != 4 || Result[1] != '\\'); // Not '\x'
296
297 if (isBad) {
298 PP.Diag(Tok: ArgTokStart[0], DiagID: diag::err_invalid_character_to_charify);
299 Result = "' '"; // Use something arbitrary, but legal.
300 }
301 }
302
303 PP.CreateString(Str: Result, Tok,
304 ExpansionLocStart, ExpansionLocEnd);
305 return Tok;
306}
307