[clang] ed1cfff - [NFC] [C++20] [Modules] [Reduced BMI] Make sure the size of reduced BMI is not large than full BMI

[Chuanqi Xu via cfe-commits]

Author: Chuanqi Xu
Date: 2024-04-03T10:51:42+08:00
New Revision: ed1cfffe9b2b2d3cc9279ff83400ace156b317a2

URL: https://github.com/llvm/llvm-project/commit/ed1cfffe9b2b2d3cc9279ff83400ace156b317a2
DIFF: https://github.com/llvm/llvm-project/commit/ed1cfffe9b2b2d3cc9279ff83400ace156b317a2.diff

LOG: [NFC] [C++20] [Modules] [Reduced BMI] Make sure the size of reduced BMI is not large than full BMI

Before this patch, the size of the reduced BMI may be large than the
full BMI when the source codes is pretty small. This violates the design
principles. The root cause is an oversight that we skipped something
in full BMI but forgot to make it in reduced BMI.

Added: 
    clang/test/Modules/reduced-bmi-size.cppm

Modified: 
    clang/include/clang/Serialization/ASTWriter.h
    clang/lib/Frontend/PrecompiledPreamble.cpp
    clang/lib/Serialization/GeneratePCH.cpp

Removed: 
    


################################################################################
diff  --git a/clang/include/clang/Serialization/ASTWriter.h b/clang/include/clang/Serialization/ASTWriter.h
index 3ed9803fa3745b..bd310b6c7a5cdd 100644
--- a/clang/include/clang/Serialization/ASTWriter.h
+++ b/clang/include/clang/Serialization/ASTWriter.h
@@ -846,7 +846,7 @@ class ASTWriter : public ASTDeserializationListener,
 /// AST and semantic-analysis consumer that generates a
 /// precompiled header from the parsed source code.
 class PCHGenerator : public SemaConsumer {
-  const Preprocessor &PP;
+  Preprocessor &PP;
   std::string OutputFile;
   std::string isysroot;
   Sema *SemaPtr;
@@ -867,11 +867,12 @@ class PCHGenerator : public SemaConsumer {
   DiagnosticsEngine &getDiagnostics() const {
     return SemaPtr->getDiagnostics();
   }
+  Preprocessor &getPreprocessor() { return PP; }
 
   virtual Module *getEmittingModule(ASTContext &Ctx);
 
 public:
-  PCHGenerator(const Preprocessor &PP, InMemoryModuleCache &ModuleCache,
+  PCHGenerator(Preprocessor &PP, InMemoryModuleCache &ModuleCache,
                StringRef OutputFile, StringRef isysroot,
                std::shared_ptr<PCHBuffer> Buffer,
                ArrayRef<std::shared_ptr<ModuleFileExtension>> Extensions,
@@ -893,7 +894,7 @@ class ReducedBMIGenerator : public PCHGenerator {
   virtual Module *getEmittingModule(ASTContext &Ctx) override;
 
 public:
-  ReducedBMIGenerator(const Preprocessor &PP, InMemoryModuleCache &ModuleCache,
+  ReducedBMIGenerator(Preprocessor &PP, InMemoryModuleCache &ModuleCache,
                       StringRef OutputFile);
 
   void HandleTranslationUnit(ASTContext &Ctx) override;

diff  --git a/clang/lib/Frontend/PrecompiledPreamble.cpp b/clang/lib/Frontend/PrecompiledPreamble.cpp
index 9b0ef30a14121b..fdf05c3613c956 100644
--- a/clang/lib/Frontend/PrecompiledPreamble.cpp
+++ b/clang/lib/Frontend/PrecompiledPreamble.cpp
@@ -290,8 +290,7 @@ class PrecompilePreambleAction : public ASTFrontendAction {
 
 class PrecompilePreambleConsumer : public PCHGenerator {
 public:
-  PrecompilePreambleConsumer(PrecompilePreambleAction &Action,
-                             const Preprocessor &PP,
+  PrecompilePreambleConsumer(PrecompilePreambleAction &Action, Preprocessor &PP,
                              InMemoryModuleCache &ModuleCache,
                              StringRef isysroot,
                              std::shared_ptr<PCHBuffer> Buffer)

diff  --git a/clang/lib/Serialization/GeneratePCH.cpp b/clang/lib/Serialization/GeneratePCH.cpp
index f54db36d4a0199..fa712264d54a97 100644
--- a/clang/lib/Serialization/GeneratePCH.cpp
+++ b/clang/lib/Serialization/GeneratePCH.cpp
@@ -14,6 +14,7 @@
 #include "clang/AST/ASTContext.h"
 #include "clang/Frontend/FrontendDiagnostic.h"
 #include "clang/Lex/HeaderSearch.h"
+#include "clang/Lex/HeaderSearchOptions.h"
 #include "clang/Lex/Preprocessor.h"
 #include "clang/Sema/SemaConsumer.h"
 #include "clang/Serialization/ASTReader.h"
@@ -23,8 +24,8 @@
 using namespace clang;
 
 PCHGenerator::PCHGenerator(
-    const Preprocessor &PP, InMemoryModuleCache &ModuleCache,
-    StringRef OutputFile, StringRef isysroot, std::shared_ptr<PCHBuffer> Buffer,
+    Preprocessor &PP, InMemoryModuleCache &ModuleCache, StringRef OutputFile,
+    StringRef isysroot, std::shared_ptr<PCHBuffer> Buffer,
     ArrayRef<std::shared_ptr<ModuleFileExtension>> Extensions,
     bool AllowASTWithErrors, bool IncludeTimestamps,
     bool BuildingImplicitModule, bool ShouldCacheASTInMemory,
@@ -88,7 +89,7 @@ ASTDeserializationListener *PCHGenerator::GetASTDeserializationListener() {
   return &Writer;
 }
 
-ReducedBMIGenerator::ReducedBMIGenerator(const Preprocessor &PP,
+ReducedBMIGenerator::ReducedBMIGenerator(Preprocessor &PP,
                                          InMemoryModuleCache &ModuleCache,
                                          StringRef OutputFile)
     : PCHGenerator(
@@ -107,6 +108,18 @@ Module *ReducedBMIGenerator::getEmittingModule(ASTContext &Ctx) {
 }
 
 void ReducedBMIGenerator::HandleTranslationUnit(ASTContext &Ctx) {
+  // We need to do this to make sure the size of reduced BMI not to be larger
+  // than full BMI.
+  //
+  // FIMXE: We'd better to wrap such options to a new class ASTWriterOptions
+  // since this is not about searching header really.
+  // FIXME2: We'd better to move the class writing full BMI with reduced BMI.
+  HeaderSearchOptions &HSOpts =
+      getPreprocessor().getHeaderSearchInfo().getHeaderSearchOpts();
+  HSOpts.ModulesSkipDiagnosticOptions = true;
+  HSOpts.ModulesSkipHeaderSearchPaths = true;
+  HSOpts.ModulesSkipPragmaDiagnosticMappings = true;
+
   PCHGenerator::HandleTranslationUnit(Ctx);
 
   if (!isComplete())

diff  --git a/clang/test/Modules/reduced-bmi-size.cppm b/clang/test/Modules/reduced-bmi-size.cppm
new file mode 100644
index 00000000000000..664f45f5c6a5a7
--- /dev/null
+++ b/clang/test/Modules/reduced-bmi-size.cppm
@@ -0,0 +1,16 @@
+// Ensure that the size of the reduced BMI is not larger than the full BMI
+// in the most simple case. 
+
+// This test requires linux commands.
+// REQUIRES: system-linux
+
+// RUN: rm -fr %t
+// RUN: mkdir %t
+//
+// RUN: %clang_cc1 -std=c++20 -emit-module-interface %s -o %t/a.pcm
+// RUN: %clang_cc1 -std=c++20 -emit-reduced-module-interface %s -o %t/a.reduced.pcm
+//
+// %s implies the current source file. So we can't use it directly.
+// RUN: [ $(stat -c%\s "%t/a.pcm") -le $(stat -c%\s "%t/a.reduced.pcm") ]
+
+export module a;