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Optimize stringification a bit to avoid std::string thrashing and

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avoid the version of Preprocessor::getSpelling that returns an 
std::string.

llvm-svn: 61769
This commit is contained in:
Chris Lattner
2009-01-05 23:04:18 +00:00
parent 0479d7647f
commit 933d5ffc11
1 changed files with 24 additions and 10 deletions
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34
clang/lib/Lex/MacroArgs.cpp
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@@ -145,8 +145,9 @@ Token MacroArgs::StringifyArgument(const Token *ArgToks,
const Token *ArgTokStart = ArgToks;
// Stringify all the tokens.
std::string Result = "\"";
// FIXME: Optimize this loop to not use std::strings.
llvm::SmallString<128> Result;
Result += "\"";
bool isFirst = true;
for (; ArgToks->isNot(tok::eof); ++ArgToks) {
const Token &Tok = *ArgToks;
@@ -159,16 +160,30 @@ Token MacroArgs::StringifyArgument(const Token *ArgToks,
if (Tok.is(tok::string_literal) || // "foo"
Tok.is(tok::wide_string_literal) || // L"foo"
Tok.is(tok::char_constant)) { // 'x' and L'x'.
Result += Lexer::Stringify(PP.getSpelling(Tok));
std::string Str = Lexer::Stringify(PP.getSpelling(Tok));
Result.append(Str.begin(), Str.end());
} else {
// Otherwise, just append the token.
Result += PP.getSpelling(Tok);
// Otherwise, just append the token. Do some gymnastics to get the token
// in place and avoid copies where possible.
unsigned CurStrLen = Result.size();
Result.resize(CurStrLen+Tok.getLength());
const char *BufPtr = &Result[CurStrLen];
unsigned ActualTokLen = PP.getSpelling(Tok, BufPtr);
// If getSpelling returned a pointer to an already uniqued version of the
// string instead of filling in BufPtr, memcpy it onto our string.
if (BufPtr != &Result[CurStrLen])
memcpy(&Result[CurStrLen], BufPtr, ActualTokLen);
// If the token was dirty, the spelling may be shorter than the token.
if (ActualTokLen != Tok.getLength())
Result.resize(CurStrLen+ActualTokLen);
}
}
// If the last character of the string is a \, and if it isn't escaped, this
// is an invalid string literal, diagnose it as specified in C99.
if (Result[Result.size()-1] == '\\') {
if (Result.back() == '\\') {
// Count the number of consequtive \ characters. If even, then they are
// just escaped backslashes, otherwise it's an error.
unsigned FirstNonSlash = Result.size()-2;
@@ -178,7 +193,7 @@ Token MacroArgs::StringifyArgument(const Token *ArgToks,
if ((Result.size()-1-FirstNonSlash) & 1) {
// Diagnose errors for things like: #define F(X) #X / F(\)
PP.Diag(ArgToks[-1], diag::pp_invalid_string_literal);
Result.erase(Result.end()-1); // remove one of the \'s.
Result.pop_back(); // remove one of the \'s.
}
}
Result += '"';
@@ -192,11 +207,10 @@ Token MacroArgs::StringifyArgument(const Token *ArgToks,
// Check for bogus character.
bool isBad = false;
if (Result.size() == 3) {
if (Result.size() == 3)
isBad = Result[1] == '\''; // ''' is not legal. '\' already fixed above.
} else {
else
isBad = (Result.size() != 4 || Result[1] != '\\'); // Not '\x'
}
if (isBad) {
PP.Diag(ArgTokStart[0], diag::err_invalid_character_to_charify);