ilya-biryukov created this revision.
ilya-biryukov added reviewers: bkramer, sammccall.
The new method 'OverridePreamble' allows to override the preamble of
any source file without checking if preamble bounds or dependencies
were changed.
This is used for completion in clangd.
Repository:
rC Clang
https://reviews.llvm.org/D41990
Files:
include/clang/Frontend/PrecompiledPreamble.h
lib/Frontend/PrecompiledPreamble.cpp
Index: lib/Frontend/PrecompiledPreamble.cpp
===================================================================
--- lib/Frontend/PrecompiledPreamble.cpp
+++ lib/Frontend/PrecompiledPreamble.cpp
@@ -485,20 +485,15 @@
void PrecompiledPreamble::AddImplicitPreamble(
CompilerInvocation &CI, IntrusiveRefCntPtr<vfs::FileSystem> &VFS,
llvm::MemoryBuffer *MainFileBuffer) const {
- assert(VFS && "VFS must not be null");
-
- auto &PreprocessorOpts = CI.getPreprocessorOpts();
-
- // Remap main file to point to MainFileBuffer.
- auto MainFilePath = CI.getFrontendOpts().Inputs[0].getFile();
- PreprocessorOpts.addRemappedFile(MainFilePath, MainFileBuffer);
-
- // Configure ImpicitPCHInclude.
- PreprocessorOpts.PrecompiledPreambleBytes.first = PreambleBytes.size();
- PreprocessorOpts.PrecompiledPreambleBytes.second = PreambleEndsAtStartOfLine;
- PreprocessorOpts.DisablePCHValidation = true;
+ PreambleBounds Bounds(PreambleBytes.size(), PreambleEndsAtStartOfLine);
+ configurePreamble(Bounds, CI, VFS, MainFileBuffer);
+}
- setupPreambleStorage(Storage, PreprocessorOpts, VFS);
+void PrecompiledPreamble::OverridePreamble(
+ CompilerInvocation &CI, IntrusiveRefCntPtr<vfs::FileSystem> &VFS,
+ llvm::MemoryBuffer *MainFileBuffer) const {
+ auto Bounds = ComputePreambleBounds(*CI.getLangOpts(), MainFileBuffer, 0);
+ configurePreamble(Bounds, CI, VFS, MainFileBuffer);
}
PrecompiledPreamble::PrecompiledPreamble(
@@ -681,6 +676,27 @@
return Result;
}
+void PrecompiledPreamble::configurePreamble(
+ PreambleBounds Bounds, CompilerInvocation &CI,
+ IntrusiveRefCntPtr<vfs::FileSystem> &VFS,
+ llvm::MemoryBuffer *MainFileBuffer) const {
+ assert(VFS && "VFS must not be null");
+
+ auto &PreprocessorOpts = CI.getPreprocessorOpts();
+
+ // Remap main file to point to MainFileBuffer.
+ auto MainFilePath = CI.getFrontendOpts().Inputs[0].getFile();
+ PreprocessorOpts.addRemappedFile(MainFilePath, MainFileBuffer);
+
+ // Configure ImpicitPCHInclude.
+ PreprocessorOpts.PrecompiledPreambleBytes.first = Bounds.Size;
+ PreprocessorOpts.PrecompiledPreambleBytes.second =
+ Bounds.PreambleEndsAtStartOfLine;
+ PreprocessorOpts.DisablePCHValidation = true;
+
+ setupPreambleStorage(Storage, PreprocessorOpts, VFS);
+}
+
void PrecompiledPreamble::setupPreambleStorage(
const PCHStorage &Storage, PreprocessorOptions &PreprocessorOpts,
IntrusiveRefCntPtr<vfs::FileSystem> &VFS) {
Index: include/clang/Frontend/PrecompiledPreamble.h
===================================================================
--- include/clang/Frontend/PrecompiledPreamble.h
+++ include/clang/Frontend/PrecompiledPreamble.h
@@ -104,14 +104,26 @@
/// Changes options inside \p CI to use PCH from this preamble. Also remaps
/// main file to \p MainFileBuffer and updates \p VFS to ensure the preamble
/// is accessible.
- /// For in-memory preambles, PrecompiledPreamble instance continues to own
- /// the MemoryBuffer with the Preamble after this method returns. The caller
- /// is reponsible for making sure the PrecompiledPreamble instance outlives
- /// the compiler run and the AST that will be using the PCH.
+ /// Callers of this function must ensure that that CanReuse() returns true for
+ /// the specified file before calling this function.
+ /// For in-memory preambles, PrecompiledPreamble instance continues to own the
+ /// MemoryBuffer with the Preamble after this method returns. The caller is
+ /// reponsible for making sure the PrecompiledPreamble instance outlives the
+ /// compiler run and the AST that will be using the PCH.
void AddImplicitPreamble(CompilerInvocation &CI,
IntrusiveRefCntPtr<vfs::FileSystem> &VFS,
llvm::MemoryBuffer *MainFileBuffer) const;
+ /// Configure \p CI to pretend \p MainFileBuffer has a preamble, identical to
+ /// the PCH stored by this instance. This function is similar to
+ /// AddImplicitPreamble, but does require checking that CanReuse() returns
+ /// true prior to calling this function. Using this function allows to avoid
+ /// the expensive CanReuse() call and rebuild of the preamble, but results of
+ /// parsing the file may be incorrect.
+ void OverridePreamble(CompilerInvocation &CI,
+ IntrusiveRefCntPtr<vfs::FileSystem> &VFS,
+ llvm::MemoryBuffer *MainFileBuffer) const;
+
private:
PrecompiledPreamble(PCHStorage Storage, std::vector<char> PreambleBytes,
bool PreambleEndsAtStartOfLine,
@@ -222,6 +234,12 @@
}
};
+ /// Helper function to set up PCH for the preamble into \p CI and \p VFS to
+ /// with the specified \p Bounds.
+ void configurePreamble(PreambleBounds Bounds, CompilerInvocation &CI,
+ IntrusiveRefCntPtr<vfs::FileSystem> &VFS,
+ llvm::MemoryBuffer *MainFileBuffer) const;
+
/// Sets up the PreprocessorOptions and changes VFS, so that PCH stored in \p
/// Storage is accessible to clang. This method is an implementation detail of
/// AddImplicitPreamble.
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