From 7700cb6cd2918afcab3531eb762afe0abd9a5de0 Mon Sep 17 00:00:00 2001 From: Chris Lattner Date: Fri, 1 Aug 2003 20:35:01 +0000 Subject: [PATCH] Tablegen should only replace the output if it changes llvm-svn: 7486 --- llvm/support/tools/TableGen/TableGen.cpp | 22 ++++++++++++++++++---- 1 file changed, 18 insertions(+), 4 deletions(-) diff --git a/llvm/support/tools/TableGen/TableGen.cpp b/llvm/support/tools/TableGen/TableGen.cpp index 088dcbe0e393..1d8b60bed35d 100644 --- a/llvm/support/tools/TableGen/TableGen.cpp +++ b/llvm/support/tools/TableGen/TableGen.cpp @@ -11,6 +11,7 @@ #include "Record.h" #include "Support/CommandLine.h" #include "Support/Signals.h" +#include "Support/FileUtilities.h" #include "CodeEmitterGen.h" #include "RegisterInfoEmitter.h" #include @@ -391,15 +392,18 @@ int main(int argc, char **argv) { std::ostream *Out = &std::cout; if (OutputFilename != "-") { - Out = new std::ofstream(OutputFilename.c_str()); + // Output to a .tmp file, because we don't actually want to overwrite the + // output file unless the generated file is different or the specified file + // does not exist. + Out = new std::ofstream((OutputFilename+".tmp").c_str()); if (!Out->good()) { - std::cerr << argv[0] << ": error opening " << OutputFilename << "!\n"; + std::cerr << argv[0] << ": error opening " << OutputFilename << ".tmp!\n"; return 1; } // Make sure the file gets removed if *gasp* tablegen crashes... - RemoveFileOnSignal(OutputFilename); + RemoveFileOnSignal(OutputFilename+".tmp"); } try { @@ -438,6 +442,16 @@ int main(int argc, char **argv) { return 1; } - if (Out != &std::cout) delete Out; + if (Out != &std::cout) { + delete Out; // Close the file + + // Now that we have generated the result, check to see if we either don't + // have the requested file, or if the requested file is different than the + // file we generated. If so, move the generated file over the requested + // file. Otherwise, just remove the file we just generated, so 'make' + // doesn't try to regenerate tons of dependencies. + // + MoveFileOverIfUpdated(OutputFilename+".tmp", OutputFilename); + } return 0; }