Modules: Use hash of PCM content for SIGNATURE
Change ASTFileSignature from a random 32-bit number to the hash of the
PCM content.
- Move definition ASTFileSignature to Basic/Module.h so Module and
ASTSourceDescriptor can use it.
- Change the signature from uint64_t to std::array<uint32_t,5>.
- Stop using (saving/reading) the size and modification time of PCM
files when there is a valid SIGNATURE.
- Add UNHASHED_CONTROL_BLOCK, and use it to store the SIGNATURE record
and other records that shouldn't affect the hash. Because implicit
modules reuses the same file for multiple levels of -Werror, this
includes DIAGNOSTIC_OPTIONS and DIAG_PRAGMA_MAPPINGS.
This helps to solve a PCH + implicit Modules dependency issue: PCH files
are handled by the external build system, whereas implicit modules are
handled by internal compiler build system. This prevents invalidating a
PCH when the compiler overwrites a PCM file with the same content
(modulo the diagnostic differences).
Design and original patch by Manman Ren!
llvm-svn: 297655
diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index 2352974..d5ad3df 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -1434,6 +1434,7 @@
for (const Arg *A : Args.filtered(OPT_fprebuilt_module_path))
Opts.AddPrebuiltModulePath(A->getValue());
Opts.DisableModuleHash = Args.hasArg(OPT_fdisable_module_hash);
+ Opts.ModulesHashContent = Args.hasArg(OPT_fmodules_hash_content);
Opts.ModulesValidateDiagnosticOptions =
!Args.hasArg(OPT_fmodules_disable_diagnostic_validation);
Opts.ImplicitModuleMaps = Args.hasArg(OPT_fimplicit_module_maps);