From 9eb2bd6b8d6d31cee53f4f89dd9189da721ed4a8 Mon Sep 17 00:00:00 2001 From: Simon Pilgrim Date: Tue, 1 Oct 2019 13:39:43 +0000 Subject: [PATCH] Revert rL349624 : Let TableGen write output only if it changed, instead of doing so in cmake, attempt 2 Differential Revision: https://reviews.llvm.org/D55842 ----------------- As discussed on PR43385 this is causing Visual Studio msbuilds to perpetually rebuild all tablegen generated files llvm-svn: 373338 --- llvm/cmake/modules/TableGen.cmake | 20 +++++++++++--- llvm/lib/TableGen/Main.cpp | 32 ++++++---------------- .../gn/secondary/llvm/utils/TableGen/tablegen.gni | 5 ++++ 3 files changed, 29 insertions(+), 28 deletions(-) diff --git a/llvm/cmake/modules/TableGen.cmake b/llvm/cmake/modules/TableGen.cmake index ca9357e..71dfebb 100644 --- a/llvm/cmake/modules/TableGen.cmake +++ b/llvm/cmake/modules/TableGen.cmake @@ -23,7 +23,7 @@ function(tablegen project ofn) file(RELATIVE_PATH ofn_rel ${CMAKE_BINARY_DIR} ${CMAKE_CURRENT_BINARY_DIR}/${ofn}) set(additional_cmdline - -o ${ofn_rel} + -o ${ofn_rel}.tmp -d ${ofn_rel}.d WORKING_DIRECTORY ${CMAKE_BINARY_DIR} DEPFILE ${CMAKE_CURRENT_BINARY_DIR}/${ofn}.d @@ -34,7 +34,7 @@ function(tablegen project ofn) file(GLOB local_tds "*.td") file(GLOB_RECURSE global_tds "${LLVM_MAIN_INCLUDE_DIR}/llvm/*.td") set(additional_cmdline - -o ${CMAKE_CURRENT_BINARY_DIR}/${ofn} + -o ${CMAKE_CURRENT_BINARY_DIR}/${ofn}.tmp ) endif() @@ -67,7 +67,8 @@ function(tablegen project ofn) # dependency twice in the result file when # ("${${project}_TABLEGEN_TARGET}" STREQUAL "${${project}_TABLEGEN_EXE}") # but lets us having smaller and cleaner code here. - add_custom_command(OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/${ofn} + add_custom_command(OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/${ofn}.tmp + # Generate tablegen output in a temporary file. COMMAND ${${project}_TABLEGEN_EXE} ${ARGN} -I ${CMAKE_CURRENT_SOURCE_DIR} ${LLVM_TABLEGEN_FLAGS} ${LLVM_TARGET_DEFINITIONS_ABSOLUTE} @@ -80,9 +81,20 @@ function(tablegen project ofn) ${LLVM_TARGET_DEFINITIONS_ABSOLUTE} COMMENT "Building ${ofn}..." ) + add_custom_command(OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/${ofn} + # Only update the real output file if there are any differences. + # This prevents recompilation of all the files depending on it if there + # aren't any. + COMMAND ${CMAKE_COMMAND} -E copy_if_different + ${CMAKE_CURRENT_BINARY_DIR}/${ofn}.tmp + ${CMAKE_CURRENT_BINARY_DIR}/${ofn} + DEPENDS ${CMAKE_CURRENT_BINARY_DIR}/${ofn}.tmp + COMMENT "Updating ${ofn}..." + ) # `make clean' must remove all those generated files: - set_property(DIRECTORY APPEND PROPERTY ADDITIONAL_MAKE_CLEAN_FILES ${ofn}) + set_property(DIRECTORY APPEND + PROPERTY ADDITIONAL_MAKE_CLEAN_FILES ${ofn}.tmp ${ofn}) set(TABLEGEN_OUTPUT ${TABLEGEN_OUTPUT} ${CMAKE_CURRENT_BINARY_DIR}/${ofn} PARENT_SCOPE) set_source_files_properties(${CMAKE_CURRENT_BINARY_DIR}/${ofn} PROPERTIES diff --git a/llvm/lib/TableGen/Main.cpp b/llvm/lib/TableGen/Main.cpp index 34195c3..bf97e37 100644 --- a/llvm/lib/TableGen/Main.cpp +++ b/llvm/lib/TableGen/Main.cpp @@ -99,39 +99,23 @@ int llvm::TableGenMain(char *argv0, TableGenMainFn *MainFn) { if (Parser.ParseFile()) return 1; - // Write output to memory. - std::string OutString; - raw_string_ostream Out(OutString); - if (MainFn(Out, Records)) - return 1; - - // Always write the depfile, even if the main output hasn't changed. - // If it's missing, Ninja considers the output dirty. If this was below - // the early exit below and someone deleted the .inc.d file but not the .inc - // file, tablegen would never write the depfile. + std::error_code EC; + ToolOutputFile Out(OutputFilename, EC, sys::fs::OF_None); + if (EC) + return reportError(argv0, "error opening " + OutputFilename + ":" + + EC.message() + "\n"); if (!DependFilename.empty()) { if (int Ret = createDependencyFile(Parser, argv0)) return Ret; } - // Only updates the real output file if there are any differences. - // This prevents recompilation of all the files depending on it if there - // aren't any. - if (auto ExistingOrErr = MemoryBuffer::getFile(OutputFilename)) - if (std::move(ExistingOrErr.get())->getBuffer() == Out.str()) - return 0; - - std::error_code EC; - ToolOutputFile OutFile(OutputFilename, EC, sys::fs::OF_None); - if (EC) - return reportError(argv0, "error opening " + OutputFilename + ":" + - EC.message() + "\n"); - OutFile.os() << Out.str(); + if (MainFn(Out.os(), Records)) + return 1; if (ErrorsPrinted > 0) return reportError(argv0, Twine(ErrorsPrinted) + " errors.\n"); // Declare success. - OutFile.keep(); + Out.keep(); return 0; } diff --git a/llvm/utils/gn/secondary/llvm/utils/TableGen/tablegen.gni b/llvm/utils/gn/secondary/llvm/utils/TableGen/tablegen.gni index cb588ab..a0e2e79 100644 --- a/llvm/utils/gn/secondary/llvm/utils/TableGen/tablegen.gni +++ b/llvm/utils/gn/secondary/llvm/utils/TableGen/tablegen.gni @@ -64,6 +64,11 @@ template("tablegen") { depfile = "$gen_output.d" td_file = rebase_path(td_file, root_build_dir) + # FIXME: The cmake build lets tablegen write to a temp file and then copies + # it over the final output only if it has changed, for ninja's restat + # optimization. Instead of doing that in cmake, llvm-tblgen should do this + # itself. r330742 tried this, but it caused problems. Fix those and reland, + # so that the gn build has the optimization too. args = [ rebase_path(tblgen_executable, root_build_dir), "-I", -- 2.7.4