[PATCH] D31986: [coff] default to multiple parallel ThinLTO jobs

[Bob Haarman via Phabricator via llvm-commits]

inglorion created this revision.
Herald added subscribers: Prazek, mehdi_amini.

lld-link allows the number of parallel ThinLTO jobs to be specified
using /opt:lldltojobs=N. If left unspecified, the implementation
conservatively defaults to 1. This leads to very long link times. This
change makes it so that the default is to automatically set the
parallelism, as we do in the ELF linker.


https://reviews.llvm.org/D31986

Files:
  COFF/Config.h
  COFF/LTO.cpp


Index: COFF/LTO.cpp
===================================================================
--- COFF/LTO.cpp
+++ COFF/LTO.cpp
@@ -73,7 +73,7 @@
     checkError(Conf.addSaveTemps(std::string(Config->OutputFile) + ".",
                                  /*UseInputModulePath*/ true));
   lto::ThinBackend Backend;
-  if (Config->LTOJobs != -1u)
+  if (Config->LTOJobs != 0)
     Backend = lto::createInProcessThinBackend(Config->LTOJobs);
   return llvm::make_unique<lto::LTO>(std::move(Conf), Backend,
                                      Config->LTOPartitions);
Index: COFF/Config.h
===================================================================
--- COFF/Config.h
+++ COFF/Config.h
@@ -115,7 +115,7 @@
   unsigned LTOOptLevel = 2;
 
   // Used for /opt:lldltojobs=N
-  unsigned LTOJobs = 1;
+  unsigned LTOJobs = 0;
   // Used for /opt:lldltopartitions=N
   unsigned LTOPartitions = 1;
 


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