https://github.com/jansvoboda11 created
https://github.com/llvm/llvm-project/pull/135813
This PR introduces new single-module preprocessing mode. It is very similar to
single-file-parse mode, but has the following differences:
* Single-file mode skips over all inclusion directives, while the single-module
mode skips only over import directives and does resolve textual inclusion
directives.
* Single-file mode enters all branches of a conditional directive with an
undefined identifier, while the single-module enters none of them.
This will be used from the dependency scanner to quickly discover a subset of
modular dependencies of a TU/module. The dependencies aren't being imported in
this mode, but the file-inclusion preprocessor callback does get invoked.
>From 9f16dedd19b7dda4f751375ef57fd18fc0e86b33 Mon Sep 17 00:00:00 2001
From: Jan Svoboda <jan_svob...@apple.com>
Date: Wed, 9 Apr 2025 13:11:38 -0700
Subject: [PATCH] [clang][lex] Introduce new single-module-parse mode
---
clang/include/clang/Driver/Options.td | 4 +
clang/include/clang/Lex/PreprocessorOptions.h | 7 ++
clang/lib/Lex/PPDirectives.cpp | 28 +++++-
clang/lib/Lex/PPExpressions.cpp | 12 ++-
clang/test/Modules/single-module-parse-mode.c | 92 +++++++++++++++++++
5 files changed, 134 insertions(+), 9 deletions(-)
create mode 100644 clang/test/Modules/single-module-parse-mode.c
diff --git a/clang/include/clang/Driver/Options.td
b/clang/include/clang/Driver/Options.td
index c9d2bc5e81976..5afac8f752d04 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -3247,6 +3247,10 @@ def fno_modules_prune_non_affecting_module_map_files :
Group<f_Group>, Flags<[]>, Visibility<[CC1Option]>,
MarshallingInfoNegativeFlag<HeaderSearchOpts<"ModulesPruneNonAffectingModuleMaps">>,
HelpText<"Do not prune non-affecting module map files when writing module
files">;
+def fmodules_single_module_parse_mode :
+ Flag<["-"], "fmodules-single-module-parse-mode">,
+ Group<f_Group>, Flags<[]>, Visibility<[CC1Option]>,
+ MarshallingInfoFlag<PreprocessorOpts<"SingleModuleParseMode">>;
def fincremental_extensions :
Flag<["-"], "fincremental-extensions">,
diff --git a/clang/include/clang/Lex/PreprocessorOptions.h
b/clang/include/clang/Lex/PreprocessorOptions.h
index c2e3d68333024..83d5a821d07fa 100644
--- a/clang/include/clang/Lex/PreprocessorOptions.h
+++ b/clang/include/clang/Lex/PreprocessorOptions.h
@@ -152,6 +152,13 @@ class PreprocessorOptions {
/// that the client can get the maximum amount of information from the
parser.
bool SingleFileParseMode = false;
+ /// When enabled, preprocessor is in a mode for parsing a single module only.
+ ///
+ /// Disables imports of other modules and if there are any unresolved
+ /// identifiers in preprocessor directive conditions it causes all blocks to
+ /// be skipped so that the client can get a strict subset of the contents.
+ bool SingleModuleParseMode = false;
+
/// When enabled, the preprocessor will construct editor placeholder tokens.
bool LexEditorPlaceholders = true;
diff --git a/clang/lib/Lex/PPDirectives.cpp b/clang/lib/Lex/PPDirectives.cpp
index 8411526019f3e..18c04279184a1 100644
--- a/clang/lib/Lex/PPDirectives.cpp
+++ b/clang/lib/Lex/PPDirectives.cpp
@@ -2073,10 +2073,11 @@ void
Preprocessor::HandleIncludeDirective(SourceLocation HashLoc,
return;
if (FilenameTok.isNot(tok::header_name)) {
- if (FilenameTok.is(tok::identifier) && PPOpts.SingleFileParseMode) {
+ if (FilenameTok.is(tok::identifier) &&
+ (PPOpts.SingleFileParseMode || PPOpts.SingleModuleParseMode)) {
// If we saw #include IDENTIFIER and lexing didn't turn in into a header
- // name, it was undefined. In 'single-file-parse' mode, just skip the
- // directive without emitting diagnostics - the identifier might be
+ // name, it was undefined. In 'single-{file,module}-parse' mode, just
skip
+ // the directive without emitting diagnostics - the identifier might be
// normally defined in previously-skipped include directive.
DiscardUntilEndOfDirective();
return;
@@ -2384,10 +2385,15 @@ Preprocessor::ImportAction
Preprocessor::HandleHeaderIncludeOrImport(
(getLangOpts().CPlusPlusModules || getLangOpts().Modules) &&
ModuleToImport && !ModuleToImport->isHeaderUnit();
+ if (MaybeTranslateInclude && (UsableHeaderUnit || UsableClangHeaderModule) &&
+ PPOpts.SingleModuleParseMode) {
+ Action = IncludeLimitReached;
+ }
// Determine whether we should try to import the module for this #include, if
// there is one. Don't do so if precompiled module support is disabled or we
// are processing this module textually (because we're building the module).
- if (MaybeTranslateInclude && (UsableHeaderUnit || UsableClangHeaderModule)) {
+ else if (MaybeTranslateInclude &&
+ (UsableHeaderUnit || UsableClangHeaderModule)) {
// If this include corresponds to a module but that module is
// unavailable, diagnose the situation and bail out.
// FIXME: Remove this; loadModule does the same check (but produces
@@ -3439,6 +3445,13 @@ void Preprocessor::HandleIfdefDirective(Token &Result,
CurPPLexer->pushConditionalLevel(DirectiveTok.getLocation(),
/*wasskip*/false, /*foundnonskip*/false,
/*foundelse*/false);
+ } else if (PPOpts.SingleModuleParseMode && !MI) {
+ // In 'single-module-parse mode' undefined identifiers trigger skipping of
+ // all the directive blocks. We lie here and set FoundNonSkipPortion so
that
+ // even any \#else blocks get skipped.
+ SkipExcludedConditionalBlock(
+ HashToken.getLocation(), DirectiveTok.getLocation(),
+ /*FoundNonSkipPortion=*/true, /*FoundElse=*/false);
} else if (!MI == isIfndef || RetainExcludedCB) {
// Yes, remember that we are inside a conditional, then lex the next token.
CurPPLexer->pushConditionalLevel(DirectiveTok.getLocation(),
@@ -3493,6 +3506,13 @@ void Preprocessor::HandleIfDirective(Token &IfToken,
// the directive blocks.
CurPPLexer->pushConditionalLevel(IfToken.getLocation(), /*wasskip*/false,
/*foundnonskip*/false,
/*foundelse*/false);
+ } else if (PPOpts.SingleModuleParseMode && DER.IncludedUndefinedIds) {
+ // In 'single-module-parse mode' undefined identifiers trigger skipping of
+ // all the directive blocks. We lie here and set FoundNonSkipPortion so
that
+ // even any \#else blocks get skipped.
+ SkipExcludedConditionalBlock(HashToken.getLocation(),
IfToken.getLocation(),
+ /*FoundNonSkipPortion=*/true,
+ /*FoundElse=*/false);
} else if (ConditionalTrue || RetainExcludedCB) {
// Yes, remember that we are inside a conditional, then lex the next token.
CurPPLexer->pushConditionalLevel(IfToken.getLocation(), /*wasskip*/false,
diff --git a/clang/lib/Lex/PPExpressions.cpp b/clang/lib/Lex/PPExpressions.cpp
index a202af774256a..240522ba194d6 100644
--- a/clang/lib/Lex/PPExpressions.cpp
+++ b/clang/lib/Lex/PPExpressions.cpp
@@ -593,11 +593,13 @@ static bool EvaluateDirectiveSubExpr(PPValue &LHS,
unsigned MinPrec,
Token &PeekTok, bool ValueLive,
bool &IncludedUndefinedIds,
Preprocessor &PP) {
- if (PP.getPreprocessorOpts().SingleFileParseMode && IncludedUndefinedIds) {
- // The single-file parse mode behavior kicks in as soon as single
identifier
- // is undefined. If we've already seen one, there's no point in continuing
- // with the rest of the expression. Besides saving work, this also prevents
- // calling undefined function-like macros.
+ if ((PP.getPreprocessorOpts().SingleFileParseMode ||
+ PP.getPreprocessorOpts().SingleModuleParseMode) &&
+ IncludedUndefinedIds) {
+ // The single-{file,module}-parse mode behavior kicks in as soon as single
+ // identifier is undefined. If we've already seen one, there's no point in
+ // continuing with the rest of the expression. Besides saving work, this
+ // also prevents calling undefined function-like macros.
PP.DiscardUntilEndOfDirective(PeekTok);
return true;
}
diff --git a/clang/test/Modules/single-module-parse-mode.c
b/clang/test/Modules/single-module-parse-mode.c
new file mode 100644
index 0000000000000..947c0e3c1fa8b
--- /dev/null
+++ b/clang/test/Modules/single-module-parse-mode.c
@@ -0,0 +1,92 @@
+// RUN: rm -rf %t
+// RUN: split-file %s %t
+
+// RUN: %clang_cc1 -fmodules -fmodules-cache-path=%t/cache \
+// RUN: -emit-module %t/module.modulemap -fmodule-name=B -o %t/cache/B.pcm \
+// RUN: -fmodules-single-module-parse-mode 2>&1 | FileCheck %s
+
+// Modules are not imported.
+// CHECK-NOT: A.h:1:2: error: unreachable
+
+// Headers belonging to this module are included.
+// CHECK: B2.h:2:2: warning: success
+
+// Non-modular headers are included.
+// CHECK: T.h:2:2: warning: success
+
+// No branches are entered for #if UNDEFINED.
+// CHECK-NOT: B1.h:6:2: error: unreachable
+// CHECK-NOT: B1.h:8:2: error: unreachable
+// CHECK-NOT: B1.h:10:2: error: unreachable
+
+// No branches are entered for #ifdef UNDEFINED.
+// CHECK-NOT: B1.h:14:2: error: unreachable
+// CHECK-NOT: B1.h:16:2: error: unreachable
+
+// No branches are entered for #ifndef UNDEFINED.
+// CHECK-NOT: B1.h:20:2: error: unreachable
+// CHECK-NOT: B1.h:22:2: error: unreachable
+
+// No error messages are emitted for UNDEFINED_FUNCTION_LIKE().
+// CHECK-NOT: B1.h:25:2: error: unreachable
+
+// The correct branch is entered for #if DEFINED.
+// CHECK: B1.h:32:3: warning: success
+// CHECK-NOT: B1.h:34:3: error: unreachable
+// CHECK-NOT: B1.h:36:3: error: unreachable
+
+// Headers belonging to this module are included.
+// CHECK: B2.h:2:2: warning: success
+
+//--- module.modulemap
+module A { header "A.h" }
+module B {
+ header "B1.h"
+ header "B2.h"
+}
+//--- A.h
+#error unreachable
+//--- B1.h
+#include "A.h"
+#include "B2.h"
+#include "T.h"
+
+#if UNDEFINED
+# error unreachable
+#elif UNDEFINED2
+# error unreachable
+#else
+# error unreachable
+#endif
+
+#ifdef UNDEFINED
+# error unreachable
+#else
+# error unreachable
+#endif
+
+#ifndef UNDEFINED
+# error unreachable
+#else
+# error unreachable
+#endif
+
+#if UNDEFINED_FUNCTION_LIKE()
+#endif
+
+#define DEFINED_1 1
+#define DEFINED_2 1
+
+#if DEFINED_1
+# warning success
+#elif DEFINED_2
+# error unreachable
+#else
+# error unreachable
+#endif
+//--- B2.h
+// Headers belonging to this module are included.
+#warning success
+//--- T.h
+// Non-modular headers are included.
+#warning success
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