From 60fa28882eda2a05576e94690a586940ba9ca43c Mon Sep 17 00:00:00 2001 From: "Duncan P. N. Exon Smith" Date: Mon, 13 Mar 2017 18:45:08 +0000 Subject: 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. - 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 --- clang/lib/CodeGen/ObjectFilePCHContainerOperations.cpp | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) (limited to 'clang/lib/CodeGen/ObjectFilePCHContainerOperations.cpp') diff --git a/clang/lib/CodeGen/ObjectFilePCHContainerOperations.cpp b/clang/lib/CodeGen/ObjectFilePCHContainerOperations.cpp index 754f996..37ecc05a 100644 --- a/clang/lib/CodeGen/ObjectFilePCHContainerOperations.cpp +++ b/clang/lib/CodeGen/ObjectFilePCHContainerOperations.cpp @@ -171,7 +171,8 @@ public: // Prepare CGDebugInfo to emit debug info for a clang module. auto *DI = Builder->getModuleDebugInfo(); StringRef ModuleName = llvm::sys::path::filename(MainFileName); - DI->setPCHDescriptor({ModuleName, "", OutputFileName, ~1ULL}); + DI->setPCHDescriptor({ModuleName, "", OutputFileName, + ASTFileSignature{{{~0U, ~0U, ~0U, ~0U, ~1U}}}}); DI->setModuleMap(MMap); } @@ -241,7 +242,11 @@ public: // PCH files don't have a signature field in the control block, // but LLVM detects DWO CUs by looking for a non-zero DWO id. - uint64_t Signature = Buffer->Signature ? Buffer->Signature : ~1ULL; + // We use the lower 64 bits for debug info. + uint64_t Signature = + Buffer->Signature + ? (uint64_t)Buffer->Signature[1] << 32 | Buffer->Signature[0] + : ~1ULL; Builder->getModuleDebugInfo()->setDwoId(Signature); // Finalize the Builder. -- cgit v1.1