[clang] Extension: allow recursive macros (PR #65851)
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Mon Sep 11 01:03:50 PDT 2023
https://github.com/kelbon updated https://github.com/llvm/llvm-project/pull/65851:
>From 2f807b312baef8c6038c2452b84232acb6d6d2c2 Mon Sep 17 00:00:00 2001
From: Kelbon Nik <kelbonage at gmail.com>
Date: Sat, 9 Sep 2023 17:51:15 +0400
Subject: [PATCH 1/3] add define2 pp directive
---
clang/include/clang/Basic/TokenKinds.def | 1 +
clang/include/clang/Lex/MacroInfo.h | 19 +++++++++----------
clang/include/clang/Lex/Preprocessor.h | 2 +-
clang/lib/Basic/IdentifierTable.cpp | 2 ++
clang/lib/Format/WhitespaceManager.cpp | 2 +-
clang/lib/Lex/MacroInfo.cpp | 3 ++-
clang/lib/Lex/PPDirectives.cpp | 16 +++++++++++-----
7 files changed, 27 insertions(+), 18 deletions(-)
diff --git a/clang/include/clang/Basic/TokenKinds.def b/clang/include/clang/Basic/TokenKinds.def
index 45ebc200b168986..f059d809823ab42 100644
--- a/clang/include/clang/Basic/TokenKinds.def
+++ b/clang/include/clang/Basic/TokenKinds.def
@@ -115,6 +115,7 @@ PPKEYWORD(__include_macros)
// C99 6.10.3 - Macro Replacement.
PPKEYWORD(define)
+PPKEYWORD(define2)
PPKEYWORD(undef)
// C99 6.10.4 - Line Control.
diff --git a/clang/include/clang/Lex/MacroInfo.h b/clang/include/clang/Lex/MacroInfo.h
index 00c1c3866bbd9ca..4f0c8e987610e50 100644
--- a/clang/include/clang/Lex/MacroInfo.h
+++ b/clang/include/clang/Lex/MacroInfo.h
@@ -102,6 +102,10 @@ class MacroInfo {
/// like \#define A A.
bool IsDisabled : 1;
+ // True if 'define2' used,
+ // ignores 'IsDisabled' and enables expansion anyway
+ bool AllowRecurse : 1;
+
/// True if this macro is either defined in the main file and has
/// been used, or if it is not defined in the main file.
///
@@ -278,18 +282,13 @@ class MacroInfo {
/// Return true if this macro is enabled.
///
/// In other words, that we are not currently in an expansion of this macro.
- bool isEnabled() const { return !IsDisabled; }
-
- void EnableMacro() {
- assert(IsDisabled && "Cannot enable an already-enabled macro!");
- IsDisabled = false;
- }
+ bool isEnabled() const { return AllowRecurse || !IsDisabled; }
+ void setAllowRecursive(bool Allow) { AllowRecurse = Allow; }
+ bool isAllowRecurse() const { return AllowRecurse; }
- void DisableMacro() {
- assert(!IsDisabled && "Cannot disable an already-disabled macro!");
- IsDisabled = true;
- }
+ void EnableMacro() { IsDisabled = false; }
+ void DisableMacro() { IsDisabled = true; }
/// Determine whether this macro was used for a header guard.
bool isUsedForHeaderGuard() const { return UsedForHeaderGuard; }
diff --git a/clang/include/clang/Lex/Preprocessor.h b/clang/include/clang/Lex/Preprocessor.h
index 9efe439bc5f2192..de121ce82fd1d7b 100644
--- a/clang/include/clang/Lex/Preprocessor.h
+++ b/clang/include/clang/Lex/Preprocessor.h
@@ -2754,7 +2754,7 @@ class Preprocessor {
void replayPreambleConditionalStack();
// Macro handling.
- void HandleDefineDirective(Token &Tok, bool ImmediatelyAfterHeaderGuard);
+ void HandleDefineDirective(Token &Tok, bool ImmediatelyAfterHeaderGuard, bool AllowRecurse);
void HandleUndefDirective();
// Conditional Inclusion.
diff --git a/clang/lib/Basic/IdentifierTable.cpp b/clang/lib/Basic/IdentifierTable.cpp
index afb30268f2973ce..4de3565c8c6d9a8 100644
--- a/clang/lib/Basic/IdentifierTable.cpp
+++ b/clang/lib/Basic/IdentifierTable.cpp
@@ -433,6 +433,8 @@ tok::PPKeywordKind IdentifierInfo::getPPKeywordID() const {
unsigned Len = getLength();
if (Len < 2) return tok::pp_not_keyword;
const char *Name = getNameStart();
+ if (std::string_view(Name, Len) == "define2")
+ return tok::pp_define2;
switch (HASH(Len, Name[0], Name[2])) {
default: return tok::pp_not_keyword;
CASE( 2, 'i', '\0', if);
diff --git a/clang/lib/Format/WhitespaceManager.cpp b/clang/lib/Format/WhitespaceManager.cpp
index b7bd8d27dc976b1..d8ab76d6761553e 100644
--- a/clang/lib/Format/WhitespaceManager.cpp
+++ b/clang/lib/Format/WhitespaceManager.cpp
@@ -743,7 +743,7 @@ void WhitespaceManager::alignConsecutiveMacros() {
if (!Current || Current->isNot(tok::identifier))
return false;
- if (!Current->Previous || Current->Previous->isNot(tok::pp_define))
+ if (!Current->Previous || !Current->Previous->isOneOf(tok::pp_define, tok::pp_define2))
return false;
// For a macro function, 0 spaces are required between the
diff --git a/clang/lib/Lex/MacroInfo.cpp b/clang/lib/Lex/MacroInfo.cpp
index 39bb0f44eff25ba..9c3619c7c909304 100644
--- a/clang/lib/Lex/MacroInfo.cpp
+++ b/clang/lib/Lex/MacroInfo.cpp
@@ -50,7 +50,7 @@ static_assert(MacroInfoSizeChecker<sizeof(void *)>::AsExpected,
MacroInfo::MacroInfo(SourceLocation DefLoc)
: Location(DefLoc), IsDefinitionLengthCached(false), IsFunctionLike(false),
IsC99Varargs(false), IsGNUVarargs(false), IsBuiltinMacro(false),
- HasCommaPasting(false), IsDisabled(false), IsUsed(false),
+ HasCommaPasting(false), IsDisabled(false), AllowRecurse(false), IsUsed(false),
IsAllowRedefinitionsWithoutWarning(false), IsWarnIfUnused(false),
UsedForHeaderGuard(false) {}
@@ -157,6 +157,7 @@ LLVM_DUMP_METHOD void MacroInfo::dump() const {
if (IsBuiltinMacro) Out << " builtin";
if (IsDisabled) Out << " disabled";
if (IsUsed) Out << " used";
+ if (AllowRecurse) Out << " allow_recurse";
if (IsAllowRedefinitionsWithoutWarning)
Out << " allow_redefinitions_without_warning";
if (IsWarnIfUnused) Out << " warn_if_unused";
diff --git a/clang/lib/Lex/PPDirectives.cpp b/clang/lib/Lex/PPDirectives.cpp
index a4db8e7a84c07d5..4605d331eba6801 100644
--- a/clang/lib/Lex/PPDirectives.cpp
+++ b/clang/lib/Lex/PPDirectives.cpp
@@ -1111,7 +1111,11 @@ void Preprocessor::HandleSkippedDirectiveWhileUsingPCH(Token &Result,
if (const IdentifierInfo *II = Result.getIdentifierInfo()) {
if (II->getPPKeywordID() == tok::pp_define) {
return HandleDefineDirective(Result,
- /*ImmediatelyAfterHeaderGuard=*/false);
+ /*ImmediatelyAfterHeaderGuard=*/false, /*AllowRecurse=*/false);
+ }
+ if (II->getPPKeywordID() == tok::pp_define2) {
+ return HandleDefineDirective(Result,
+ /*ImmediatelyAfterHeaderGuard=*/false, /*AllowRecurse=*/true);
}
if (SkippingUntilPCHThroughHeader &&
II->getPPKeywordID() == tok::pp_include) {
@@ -1250,7 +1254,9 @@ void Preprocessor::HandleDirective(Token &Result) {
// C99 6.10.3 - Macro Replacement.
case tok::pp_define:
- return HandleDefineDirective(Result, ImmediatelyAfterTopLevelIfndef);
+ return HandleDefineDirective(Result, ImmediatelyAfterTopLevelIfndef, false);
+ case tok::pp_define2:
+ return HandleDefineDirective(Result, ImmediatelyAfterTopLevelIfndef, true);
case tok::pp_undef:
return HandleUndefDirective();
@@ -3036,10 +3042,10 @@ static bool isObjCProtectedMacro(const IdentifierInfo *II) {
II->isStr("__unsafe_unretained") || II->isStr("__autoreleasing");
}
-/// HandleDefineDirective - Implements \#define. This consumes the entire macro
+/// HandleDefineDirective - Implements \#define and define2. This consumes the entire macro
/// line then lets the caller lex the next real token.
void Preprocessor::HandleDefineDirective(
- Token &DefineTok, const bool ImmediatelyAfterHeaderGuard) {
+ Token &DefineTok, const bool ImmediatelyAfterHeaderGuard, bool AllowRecurse) {
++NumDefined;
Token MacroNameTok;
@@ -3064,7 +3070,7 @@ void Preprocessor::HandleDefineDirective(
MacroNameTok, ImmediatelyAfterHeaderGuard);
if (!MI) return;
-
+ MI->setAllowRecursive(AllowRecurse);
if (MacroShadowsKeyword &&
!isConfigurationPattern(MacroNameTok, MI, getLangOpts())) {
Diag(MacroNameTok, diag::warn_pp_macro_hides_keyword);
>From 9705feebf64466c2d095d52c99fedcdc800b194c Mon Sep 17 00:00:00 2001
From: Kelbon Nik <kelbonage at gmail.com>
Date: Sun, 10 Sep 2023 16:00:45 +0400
Subject: [PATCH 2/3] add recursion depth limit and tests
---
.../include/clang/Basic/DiagnosticLexKinds.td | 2 ++
clang/include/clang/Lex/MacroInfo.h | 33 ++++++++++++-------
clang/lib/Lex/MacroInfo.cpp | 4 +--
clang/lib/Lex/TokenLexer.cpp | 3 +-
.../test/Preprocessor/macro_vaopt_expand.cpp | 20 +++++++++++
clang/test/Preprocessor/recursive_macro.cpp | 13 ++++++++
6 files changed, 60 insertions(+), 15 deletions(-)
create mode 100644 clang/test/Preprocessor/recursive_macro.cpp
diff --git a/clang/include/clang/Basic/DiagnosticLexKinds.td b/clang/include/clang/Basic/DiagnosticLexKinds.td
index 940cca67368492f..f940fa01a3d2f38 100644
--- a/clang/include/clang/Basic/DiagnosticLexKinds.td
+++ b/clang/include/clang/Basic/DiagnosticLexKinds.td
@@ -440,6 +440,8 @@ def err_pp_missing_lparen_in_vaopt_use : Error<
def err_pp_vaopt_nested_use : Error<
"__VA_OPT__ cannot be nested within its own replacement tokens">;
+def err_pp_macro_recursion_depth_limit_exceeded : Error<
+ "macro recursion depth limit exceeded">;
def err_vaopt_paste_at_start : Error<
"'##' cannot appear at start of __VA_OPT__ argument">;
diff --git a/clang/include/clang/Lex/MacroInfo.h b/clang/include/clang/Lex/MacroInfo.h
index 4f0c8e987610e50..267292083058645 100644
--- a/clang/include/clang/Lex/MacroInfo.h
+++ b/clang/include/clang/Lex/MacroInfo.h
@@ -65,6 +65,12 @@ class MacroInfo {
/// Length in characters of the macro definition.
mutable unsigned DefinitionLength;
+
+ enum : uint16_t { recursion_depth_limit = 16'000 };
+ /// recursion depth,
+ /// > 0 if we have started an expansion of this macro already.
+ /// for 'define' max is 1, for 'define2' max is depth limit
+ uint16_t Depth = 0;
mutable bool IsDefinitionLengthCached : 1;
/// True if this macro is function-like, false if it is object-like.
@@ -96,14 +102,7 @@ class MacroInfo {
//===--------------------------------------------------------------------===//
// State that changes as the macro is used.
- /// True if we have started an expansion of this macro already.
- ///
- /// This disables recursive expansion, which would be quite bad for things
- /// like \#define A A.
- bool IsDisabled : 1;
-
- // True if 'define2' used,
- // ignores 'IsDisabled' and enables expansion anyway
+ // True if 'define2' used, enables expansion anyway
bool AllowRecurse : 1;
/// True if this macro is either defined in the main file and has
@@ -282,13 +281,23 @@ class MacroInfo {
/// Return true if this macro is enabled.
///
/// In other words, that we are not currently in an expansion of this macro.
- bool isEnabled() const { return AllowRecurse || !IsDisabled; }
+ bool isEnabled() const {
+ // macro disabled if depth exceeds and stops infinite recursion
+ if (AllowRecurse)
+ return Depth < recursion_depth_limit;
+ return Depth == 0;
+ }
void setAllowRecursive(bool Allow) { AllowRecurse = Allow; }
bool isAllowRecurse() const { return AllowRecurse; }
- void EnableMacro() { IsDisabled = false; }
-
- void DisableMacro() { IsDisabled = true; }
+ void EnableMacro() {
+ assert(Depth != 0 && "Cannot enable not disabled macro");
+ --Depth;
+ }
+ // returns false if max recursion depth exceeded
+ [[nodiscard]] bool TryDisableMacro() {
+ return ++Depth < recursion_depth_limit;
+ }
/// Determine whether this macro was used for a header guard.
bool isUsedForHeaderGuard() const { return UsedForHeaderGuard; }
diff --git a/clang/lib/Lex/MacroInfo.cpp b/clang/lib/Lex/MacroInfo.cpp
index 9c3619c7c909304..110e3232b66dc14 100644
--- a/clang/lib/Lex/MacroInfo.cpp
+++ b/clang/lib/Lex/MacroInfo.cpp
@@ -50,7 +50,7 @@ static_assert(MacroInfoSizeChecker<sizeof(void *)>::AsExpected,
MacroInfo::MacroInfo(SourceLocation DefLoc)
: Location(DefLoc), IsDefinitionLengthCached(false), IsFunctionLike(false),
IsC99Varargs(false), IsGNUVarargs(false), IsBuiltinMacro(false),
- HasCommaPasting(false), IsDisabled(false), AllowRecurse(false), IsUsed(false),
+ HasCommaPasting(false), AllowRecurse(false), IsUsed(false),
IsAllowRedefinitionsWithoutWarning(false), IsWarnIfUnused(false),
UsedForHeaderGuard(false) {}
@@ -155,7 +155,7 @@ LLVM_DUMP_METHOD void MacroInfo::dump() const {
// FIXME: Dump locations.
Out << "MacroInfo " << this;
if (IsBuiltinMacro) Out << " builtin";
- if (IsDisabled) Out << " disabled";
+ if (!isEnabled()) Out << " disabled";
if (IsUsed) Out << " used";
if (AllowRecurse) Out << " allow_recurse";
if (IsAllowRedefinitionsWithoutWarning)
diff --git a/clang/lib/Lex/TokenLexer.cpp b/clang/lib/Lex/TokenLexer.cpp
index 856d5682727fe3d..c51aec4fc17110d 100644
--- a/clang/lib/Lex/TokenLexer.cpp
+++ b/clang/lib/Lex/TokenLexer.cpp
@@ -88,7 +88,8 @@ void TokenLexer::Init(Token &Tok, SourceLocation ELEnd, MacroInfo *MI,
// Mark the macro as currently disabled, so that it is not recursively
// expanded. The macro must be disabled only after argument pre-expansion of
// function-like macro arguments occurs.
- Macro->DisableMacro();
+ if (!Macro->TryDisableMacro())
+ PP.Diag(Tok, diag::err_pp_macro_recursion_depth_limit_exceeded);
}
/// Create a TokenLexer for the specified token stream. This does not
diff --git a/clang/test/Preprocessor/macro_vaopt_expand.cpp b/clang/test/Preprocessor/macro_vaopt_expand.cpp
index 5eb0facb83f7364..9766b081516fd09 100644
--- a/clang/test/Preprocessor/macro_vaopt_expand.cpp
+++ b/clang/test/Preprocessor/macro_vaopt_expand.cpp
@@ -148,3 +148,23 @@
#undef F
#undef G
+
+#define merge_all_expand2(a, b) a ## b
+#define merge_all_expand(a, b) merge_all_expand2(a, b)
+#define2 concat_all(head, ...) merge_all_expand(head, __VA_OPT__(concat_all(__VA_ARGS__)))
+29: concat_all(aa, bb, cc)
+30: [concat_all()]
+// CHECK: 29: aabbcc
+// CHECK: 30: []
+
+#undef merge_all_expand
+#undef merge_all_expand2
+#undef concat_all
+
+#define2 reverse(head, ...) __VA_OPT__(reverse(__VA_ARGS__) , ) head
+
+31: reverse(1, 2, 3)
+
+// CHECK: 31: 3, 2, 1
+
+#undef reverse
diff --git a/clang/test/Preprocessor/recursive_macro.cpp b/clang/test/Preprocessor/recursive_macro.cpp
new file mode 100644
index 000000000000000..0fee436bf4d9ce0
--- /dev/null
+++ b/clang/test/Preprocessor/recursive_macro.cpp
@@ -0,0 +1,13 @@
+// RUN: %clang_cc1 %s -Eonly -std=c++11 -pedantic -verify
+
+#define2 A A
+
+A //expected-error {{macro recursion depth limit exceeded}}
+
+#undef A
+
+#define2 boom(x) boom(x)
+
+boom(5) //expected-error {{macro recursion depth limit exceeded}}
+
+#undef boom
>From 224a84f6922bf862cc4c04e79e5ab2de996ed273 Mon Sep 17 00:00:00 2001
From: Kelbon Nik <kelbonage at gmail.com>
Date: Mon, 11 Sep 2023 12:03:36 +0400
Subject: [PATCH 3/3] rewrite Lexer recursion to loop
---
clang/lib/Lex/Lexer.cpp | 32 +++++++++----------
clang/lib/Lex/PPMacroExpansion.cpp | 2 ++
.../test/Preprocessor/macro_vaopt_expand.cpp | 4 +--
3 files changed, 20 insertions(+), 18 deletions(-)
diff --git a/clang/lib/Lex/Lexer.cpp b/clang/lib/Lex/Lexer.cpp
index 37c3e4175d4736e..178bcc08a72e208 100644
--- a/clang/lib/Lex/Lexer.cpp
+++ b/clang/lib/Lex/Lexer.cpp
@@ -847,26 +847,26 @@ bool Lexer::isAtEndOfMacroExpansion(SourceLocation loc,
const SourceManager &SM,
const LangOptions &LangOpts,
SourceLocation *MacroEnd) {
- assert(loc.isValid() && loc.isMacroID() && "Expected a valid macro loc");
+ for(SourceLocation expansionLoc; true;loc = expansionLoc) {
+ assert(loc.isValid() && loc.isMacroID() && "Expected a valid macro loc");
- SourceLocation spellLoc = SM.getSpellingLoc(loc);
- unsigned tokLen = MeasureTokenLength(spellLoc, SM, LangOpts);
- if (tokLen == 0)
- return false;
+ SourceLocation spellLoc = SM.getSpellingLoc(loc);
+ unsigned tokLen = MeasureTokenLength(spellLoc, SM, LangOpts);
+ if (tokLen == 0)
+ return false;
- SourceLocation afterLoc = loc.getLocWithOffset(tokLen);
- SourceLocation expansionLoc;
- if (!SM.isAtEndOfImmediateMacroExpansion(afterLoc, &expansionLoc))
- return false;
+ SourceLocation afterLoc = loc.getLocWithOffset(tokLen);
+ if (!SM.isAtEndOfImmediateMacroExpansion(afterLoc, &expansionLoc))
+ return false;
- if (expansionLoc.isFileID()) {
- // No other macro expansions.
- if (MacroEnd)
- *MacroEnd = expansionLoc;
- return true;
+ if (expansionLoc.isFileID()) {
+ // No other macro expansions.
+ if (MacroEnd)
+ *MacroEnd = expansionLoc;
+ return true;
+ }
}
-
- return isAtEndOfMacroExpansion(expansionLoc, SM, LangOpts, MacroEnd);
+ llvm_unreachable("");
}
static CharSourceRange makeRangeFromFileLocs(CharSourceRange Range,
diff --git a/clang/lib/Lex/PPMacroExpansion.cpp b/clang/lib/Lex/PPMacroExpansion.cpp
index 775cbfafa999602..a0093fca0ab0afc 100644
--- a/clang/lib/Lex/PPMacroExpansion.cpp
+++ b/clang/lib/Lex/PPMacroExpansion.cpp
@@ -614,6 +614,8 @@ bool Preprocessor::HandleMacroExpandedIdentifier(Token &Identifier,
if (IdentifierInfo *NewII = Identifier.getIdentifierInfo()) {
if (MacroInfo *NewMI = getMacroInfo(NewII))
if (!NewMI->isEnabled() || NewMI == MI) {
+ if (NewMI->isAllowRecurse() && NewMI == MI)
+ Diag(Identifier, diag::err_pp_macro_recursion_depth_limit_exceeded);
Identifier.setFlag(Token::DisableExpand);
// Don't warn for "#define X X" like "#define bool bool" from
// stdbool.h.
diff --git a/clang/test/Preprocessor/macro_vaopt_expand.cpp b/clang/test/Preprocessor/macro_vaopt_expand.cpp
index 9766b081516fd09..17be324fdd71392 100644
--- a/clang/test/Preprocessor/macro_vaopt_expand.cpp
+++ b/clang/test/Preprocessor/macro_vaopt_expand.cpp
@@ -163,8 +163,8 @@
#define2 reverse(head, ...) __VA_OPT__(reverse(__VA_ARGS__) , ) head
-31: reverse(1, 2, 3)
+31: reverse(1,2,3)
-// CHECK: 31: 3, 2, 1
+// CHECK: 31: 3,2,1
#undef reverse
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