dblaikie created this revision.
dblaikie added reviewers: rnk, llunak, hans.
Herald added a project: clang.
Herald added a subscriber: cfe-commits.
I was trying to pick this up a bit when reviewing D48426
<https://reviews.llvm.org/D48426> (& perhaps D69778
<https://reviews.llvm.org/D69778>) - in any case, looks like D48426
<https://reviews.llvm.org/D48426> added a module level flag that might not be
needed.
The D48426 <https://reviews.llvm.org/D48426> implementation worked by setting a
module level flag, then code generating contents from the PCH a special case in
ASTContext::DeclMustBeEmitted would be used to delay emitting the definition of
these functions if they came from a Module with this flag.
This strategy is similar to the one initially implemented for modular codegen
that was removed in D29901 <https://reviews.llvm.org/D29901> in favor of the
modular decls list and a bit on each decl to specify whether it's homed to a
module.
One major difference between PCH object support and modular code generation,
other than the specific list of decls that are homed, is the compilation model:
MSVC PCH modules are built into the object file for some other source file
(when compiling that source file /Yc is specified to say "this compilation is
where the PCH is homed"), whereas modular code generation invokes a separate
compilation for the PCH alone. So the current modular code generation test of
to decide if a decl should be emitted "is the module where this decl is
serialized the current main file" has to be extended (as Lubos did in D69778
<https://reviews.llvm.org/D69778>) to also test the command line flag
-building-pch-with-obj.
Otherwise the whole thing is basically streamlined down to the modular code
generation path.
This even offers one extra material improvement compared to the existing
divergent implementation: Homed functions are not emitted into object files
that use the pch. Instead at -O0 they are not emitted into the IR at all, and
at -O1 they are emitted using available_externally (existing functionality
implemented for modular code generation). The pch-codegen test has been updated
to reflect this new behavior.
[If possible: I'd love it if we could not have the extra MSVC-style way of
accessing dllexport-pch-homing, and just do it the modular codegen way, but I
understand that it might be a limitation of existing build systems. @hans /
@thakis: Do either of you know if it'd be practical to move to something more
similar to .pcm handling, where the pch itself is passed to the compilation,
rather than homed as a side effect of compiling some other source file?]
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D83652
Files:
clang/include/clang/AST/ExternalASTSource.h
clang/include/clang/Sema/MultiplexExternalSemaSource.h
clang/include/clang/Serialization/ASTReader.h
clang/include/clang/Serialization/ModuleFile.h
clang/lib/Sema/MultiplexExternalSemaSource.cpp
clang/lib/Serialization/ASTReader.cpp
clang/lib/Serialization/ASTWriter.cpp
Index: clang/lib/Serialization/ASTWriter.cpp
===================================================================
--- clang/lib/Serialization/ASTWriter.cpp
+++ clang/lib/Serialization/ASTWriter.cpp
@@ -1119,7 +1119,6 @@
MetadataAbbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 16)); // Clang min.
MetadataAbbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // Relocatable
MetadataAbbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // Timestamps
- MetadataAbbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // PCHHasObjectFile
MetadataAbbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // Errors
MetadataAbbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob)); // SVN branch/tag
unsigned MetadataAbbrevCode = Stream.EmitAbbrev(std::move(MetadataAbbrev));
@@ -1134,7 +1133,6 @@
CLANG_VERSION_MINOR,
!isysroot.empty(),
IncludeTimestamps,
- false,
ASTHasCompilerErrors};
Stream.EmitRecordWithBlob(MetadataAbbrevCode, Record,
getClangFullRepositoryVersion());
Index: clang/lib/Serialization/ASTReader.cpp
===================================================================
--- clang/lib/Serialization/ASTReader.cpp
+++ clang/lib/Serialization/ASTReader.cpp
@@ -2747,7 +2747,7 @@
return VersionMismatch;
}
- bool hasErrors = Record[7];
+ bool hasErrors = Record[6];
if (hasErrors && !DisableValidation && !AllowASTWithCompilerErrors) {
Diag(diag::err_pch_with_compiler_errors);
return HadErrors;
@@ -2765,8 +2765,6 @@
F.HasTimestamps = Record[5];
- F.PCHHasObjectFile = Record[6];
-
const std::string &CurBranch = getClangFullRepositoryVersion();
StringRef ASTBranch = Blob;
if (StringRef(CurBranch) != ASTBranch && !DisableValidation) {
@@ -8590,11 +8588,6 @@
return getSubmodule(ID);
}
-bool ASTReader::DeclIsFromPCHWithObjectFile(const Decl *D) {
- ModuleFile *MF = getOwningModuleFile(D);
- return MF && MF->PCHHasObjectFile;
-}
-
ModuleFile *ASTReader::getLocalModuleFile(ModuleFile &F, unsigned ID) {
if (ID & 1) {
// It's a module, look it up by submodule ID.
Index: clang/lib/Sema/MultiplexExternalSemaSource.cpp
===================================================================
--- clang/lib/Sema/MultiplexExternalSemaSource.cpp
+++ clang/lib/Sema/MultiplexExternalSemaSource.cpp
@@ -172,13 +172,6 @@
return nullptr;
}
-bool MultiplexExternalSemaSource::DeclIsFromPCHWithObjectFile(const Decl *D) {
- for (auto *S : Sources)
- if (S->DeclIsFromPCHWithObjectFile(D))
- return true;
- return false;
-}
-
bool MultiplexExternalSemaSource::layoutRecordType(const RecordDecl *Record,
uint64_t &Size,
uint64_t &Alignment,
Index: clang/include/clang/Serialization/ModuleFile.h
===================================================================
--- clang/include/clang/Serialization/ModuleFile.h
+++ clang/include/clang/Serialization/ModuleFile.h
@@ -155,9 +155,6 @@
/// Whether timestamps are included in this module file.
bool HasTimestamps = false;
- /// Whether the PCH has a corresponding object file.
- bool PCHHasObjectFile = false;
-
/// Whether the top-level module has been read from the AST file.
bool DidReadTopLevelSubmodule = false;
Index: clang/include/clang/Serialization/ASTReader.h
===================================================================
--- clang/include/clang/Serialization/ASTReader.h
+++ clang/include/clang/Serialization/ASTReader.h
@@ -2085,8 +2085,6 @@
/// Note: overrides method in ExternalASTSource
Module *getModule(unsigned ID) override;
- bool DeclIsFromPCHWithObjectFile(const Decl *D) override;
-
/// Retrieve the module file with a given local ID within the specified
/// ModuleFile.
ModuleFile *getLocalModuleFile(ModuleFile &M, unsigned ID);
Index: clang/include/clang/Sema/MultiplexExternalSemaSource.h
===================================================================
--- clang/include/clang/Sema/MultiplexExternalSemaSource.h
+++ clang/include/clang/Sema/MultiplexExternalSemaSource.h
@@ -153,8 +153,6 @@
/// Retrieve the module that corresponds to the given module ID.
Module *getModule(unsigned ID) override;
- bool DeclIsFromPCHWithObjectFile(const Decl *D) override;
-
/// Perform layout on the given record.
///
/// This routine allows the external AST source to provide an specific
Index: clang/include/clang/AST/ExternalASTSource.h
===================================================================
--- clang/include/clang/AST/ExternalASTSource.h
+++ clang/include/clang/AST/ExternalASTSource.h
@@ -161,10 +161,6 @@
/// Retrieve the module that corresponds to the given module ID.
virtual Module *getModule(unsigned ID) { return nullptr; }
- /// Determine whether D comes from a PCH which was built with a corresponding
- /// object file.
- virtual bool DeclIsFromPCHWithObjectFile(const Decl *D) { return false; }
-
/// Return a descriptor for the corresponding module, if one exists.
virtual llvm::Optional<ASTSourceDescriptor> getSourceDescriptor(unsigned ID);
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