[PATCH] D52193: RFC: [clang] Multithreaded compilation support

[Alexandre Ganea via Phabricator via cfe-commits]

aganea created this revision.
aganea added reviewers: rnk, hans, zturner.
Herald added a reviewer: JDevlieghere.
Herald added a subscriber: cfe-commits.

This is very preliminary change which adds support for (`clang-cl`) `/MP` (Build with multiple processes). Doc for `/MP` is here <https://msdn.microsoft.com/en-us/library/bb385193.aspx>.

Support for `-j` to the `clang` driver could also be added along the way.

I would simply like a general advice on this change. **I don't plan to commit this as it is**. If the general idea seems good, I'll cut it down in several smaller pieces.

The change about having explicit return codes (`Program.h / enum ProgramReturnCode`) should probably be discussed separately, although if you have an opinion about that, please do.

Some timings //(I ran each configuration several time to ensure the figures are stable)//

  Build LLVM + Clang + LLD (at r341847) inside VS2017:
  
  (Intel Xeon Haswell 6 cores / 12 HW threads, 3.5 GHz, 15M cache, 128 GB RAM, SSD 550 MB/s)
  
  - With VS2017 15.8.3: (56m 43 sec) 2 parallel msbuild
  - With Clang /MP + LLD (trunk r341847) [1]: (51m 8sec) 2 parallel msbuild
  
  
  (Intel Xeon Skylake 18 cores / 36 HW threads, x2 (Dual CPU), 72 HW threads total, 2.3 GHz, 24.75M cache, 128 GB RAM, NVMe 4.6 GB/s)
  
  - With VS2017 15.8.3: (12m 8sec) 32 parallel msbuild
  - With Clang /MP + LLD (trunk r341847) [1]: (9m 22sec) 32 parallel msbuild
  
  [1] running clang-cl.exe compiled with VS2017 15.8.3 at r341847

Please add anyone who might want to review this. Many thanks in advance!


Repository:
  rC Clang

https://reviews.llvm.org/D52193

Files:
  clang/trunk/include/clang/Driver/CLCompatOptions.td
  clang/trunk/include/clang/Driver/Compilation.h
  clang/trunk/include/clang/Driver/Driver.h
  clang/trunk/include/clang/Driver/Job.h
  clang/trunk/lib/Driver/Compilation.cpp
  clang/trunk/lib/Driver/Driver.cpp
  clang/trunk/lib/Driver/Job.cpp
  clang/trunk/tools/driver/cc1_main.cpp
  clang/trunk/tools/driver/cc1as_main.cpp
  clang/trunk/tools/driver/cc1gen_reproducer_main.cpp
  clang/trunk/tools/driver/driver.cpp
  llvm/trunk/include/llvm/Support/Program.h
  llvm/trunk/lib/Support/GraphWriter.cpp
  llvm/trunk/lib/Support/Program.cpp
  llvm/trunk/lib/Support/Windows/DynamicLibrary.inc
  llvm/trunk/lib/Support/Windows/Process.inc
  llvm/trunk/lib/Support/Windows/Program.inc
  llvm/trunk/lib/Support/Windows/WindowsSupport.h
  llvm/trunk/tools/bugpoint/ExecutionDriver.cpp
  llvm/trunk/tools/bugpoint/OptimizerDriver.cpp
  llvm/trunk/tools/bugpoint/ToolRunner.cpp
  llvm/trunk/tools/bugpoint/ToolRunner.h
  llvm/trunk/tools/dsymutil/MachOUtils.cpp
  llvm/trunk/tools/llvm-cov/CodeCoverage.cpp
  llvm/trunk/unittests/Support/ProgramTest.cpp
  llvm/trunk/utils/not/not.cpp

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