Make Preprocessor::Lex non-recursive.
Before this patch, Lex() would recurse whenever the current lexer changed (e.g.
upon entry into a macro). This patch turns the recursion into a loop: the
various lex routines now don't return a token when the current lexer changes,
and at the top level Preprocessor::Lex() now loops until it finds a token.
Normally, the recursion wouldn't end up being very deep, but the recursion depth
can explode in edge cases like a bunch of consecutive macros which expand to
nothing (like in the testcase test/Preprocessor/macro_expand_empty.c in this
patch).
<rdar://problem/14569770>
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@190980 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Lex/PTHLexer.cpp b/lib/Lex/PTHLexer.cpp
index 32da92a..e2629a3 100644
--- a/lib/Lex/PTHLexer.cpp
+++ b/lib/Lex/PTHLexer.cpp
@@ -43,9 +43,7 @@
FileStartLoc = PP.getSourceManager().getLocForStartOfFile(FID);
}
-void PTHLexer::Lex(Token& Tok) {
-LexNextToken:
-
+bool PTHLexer::Lex(Token& Tok) {
//===--------------------------------------==//
// Read the raw token data.
//===--------------------------------------==//
@@ -90,8 +88,9 @@
Tok.setKind(II->getTokenID());
if (II->isHandleIdentifierCase())
- PP->HandleIdentifier(Tok);
- return;
+ return PP->HandleIdentifier(Tok);
+
+ return true;
}
//===--------------------------------------==//
@@ -101,16 +100,10 @@
// Save the end-of-file token.
EofToken = Tok;
- // Save 'PP' to 'PPCache' as LexEndOfFile can delete 'this'.
- Preprocessor *PPCache = PP;
-
assert(!ParsingPreprocessorDirective);
assert(!LexingRawMode);
-
- if (LexEndOfFile(Tok))
- return;
- return PPCache->Lex(Tok);
+ return LexEndOfFile(Tok);
}
if (TKind == tok::hash && Tok.isAtStartOfLine()) {
@@ -118,19 +111,17 @@
assert(!LexingRawMode);
PP->HandleDirective(Tok);
- if (PP->isCurrentLexer(this))
- goto LexNextToken;
-
- return PP->Lex(Tok);
+ return false;
}
if (TKind == tok::eod) {
assert(ParsingPreprocessorDirective);
ParsingPreprocessorDirective = false;
- return;
+ return true;
}
MIOpt.ReadToken();
+ return true;
}
bool PTHLexer::LexEndOfFile(Token &Result) {