[llvm] Unittests and usability for BitstreamWriter incremental flushing (PR #92983)

[Teresa Johnson via llvm-commits]

================
@@ -29,81 +29,81 @@ class BitstreamWriter;
 class Module;
 class raw_ostream;
 
-  class BitcodeWriter {
-    SmallVectorImpl<char> &Buffer;
-    std::unique_ptr<BitstreamWriter> Stream;
-
-    StringTableBuilder StrtabBuilder{StringTableBuilder::RAW};
-
-    // Owns any strings created by the irsymtab writer until we create the
-    // string table.
-    BumpPtrAllocator Alloc;
-
-    bool WroteStrtab = false, WroteSymtab = false;
-
-    void writeBlob(unsigned Block, unsigned Record, StringRef Blob);
-
-    std::vector<Module *> Mods;
-
-  public:
-    /// Create a BitcodeWriter that writes to Buffer.
-    BitcodeWriter(SmallVectorImpl<char> &Buffer, raw_fd_stream *FS = nullptr);
-
-    ~BitcodeWriter();
-
-    /// Attempt to write a symbol table to the bitcode file. This must be called
-    /// at most once after all modules have been written.
-    ///
-    /// A reader does not require a symbol table to interpret a bitcode file;
-    /// the symbol table is needed only to improve link-time performance. So
-    /// this function may decide not to write a symbol table. It may so decide
-    /// if, for example, the target is unregistered or the IR is malformed.
-    void writeSymtab();
-
-    /// Write the bitcode file's string table. This must be called exactly once
-    /// after all modules and the optional symbol table have been written.
-    void writeStrtab();
-
-    /// Copy the string table for another module into this bitcode file. This
-    /// should be called after copying the module itself into the bitcode file.
-    void copyStrtab(StringRef Strtab);
-
-    /// Write the specified module to the buffer specified at construction time.
-    ///
-    /// If \c ShouldPreserveUseListOrder, encode the use-list order for each \a
-    /// Value in \c M.  These will be reconstructed exactly when \a M is
-    /// deserialized.
-    ///
-    /// If \c Index is supplied, the bitcode will contain the summary index
-    /// (currently for use in ThinLTO optimization).
-    ///
-    /// \p GenerateHash enables hashing the Module and including the hash in the
-    /// bitcode (currently for use in ThinLTO incremental build).
-    ///
-    /// If \p ModHash is non-null, when GenerateHash is true, the resulting
-    /// hash is written into ModHash. When GenerateHash is false, that value
-    /// is used as the hash instead of computing from the generated bitcode.
-    /// Can be used to produce the same module hash for a minimized bitcode
-    /// used just for the thin link as in the regular full bitcode that will
-    /// be used in the backend.
-    void writeModule(const Module &M, bool ShouldPreserveUseListOrder = false,
-                     const ModuleSummaryIndex *Index = nullptr,
-                     bool GenerateHash = false, ModuleHash *ModHash = nullptr);
-
-    /// Write the specified thin link bitcode file (i.e., the minimized bitcode
-    /// file) to the buffer specified at construction time. The thin link
-    /// bitcode file is used for thin link, and it only contains the necessary
-    /// information for thin link.
-    ///
-    /// ModHash is for use in ThinLTO incremental build, generated while the
-    /// IR bitcode file writing.
-    void writeThinLinkBitcode(const Module &M, const ModuleSummaryIndex &Index,
-                              const ModuleHash &ModHash);
-
-    void writeIndex(
-        const ModuleSummaryIndex *Index,
-        const std::map<std::string, GVSummaryMapTy> *ModuleToSummariesForIndex);
-  };
+class BitcodeWriter {
----------------
teresajohnson wrote:

Ideally don't change the spacing in this PR, because it creates a lot of spurious diffs.

https://github.com/llvm/llvm-project/pull/92983