[PATCH] D20444: [OpenCL] Include opencl-c.h by default as a clang module

[Yaxun Liu via cfe-commits]

yaxunl marked an inline comment as done.

================
Comment at: include/clang/Basic/LangOptions.def:220
@@ -219,3 +219,3 @@
 ENUM_LANGOPT(AddressSpaceMapMangling , AddrSpaceMapMangling, 2, ASMM_Target, "OpenCL address space map mangling mode")
-
+LANGOPT(IncludeDefaultHeader, 1, 0, "Include default header file for OpenCL")
 BENIGN_LANGOPT(DelayedTemplateParsing , 1, 0, "delayed template parsing")
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I agree and has made the change.

The module caches AST of the header file, which is essentially the same thing as PCH.

I checked a typical OpenCL progam. Without including header,

   ---User Time---   --System Time--   --User+System--   ---Wall Time---  --- Name ---
   0.0160 (100.0%)   0.0080 (100.0%)   0.0240 (100.0%)   0.0211 (100.0%)  Clang front-end timer
   0.0160 (100.0%)   0.0080 (100.0%)   0.0240 (100.0%)   0.0211 (100.0%)  Total


With header but without module caching,
   ---User Time---   --System Time--   --User+System--   ---Wall Time---  --- Name ---
   0.2160 (100.0%)   0.0120 (100.0%)   0.2280 (100.0%)   0.2271 (100.0%)  Clang front-end timer
   0.2160 (100.0%)   0.0120 (100.0%)   0.2280 (100.0%)   0.2271 (100.0%)  Total

With header and module caching,
   ---User Time---   --System Time--   --User+System--   ---Wall Time---  --- Name ---
   0.0160 (100.0%)   0.0080 (100.0%)   0.0240 (100.0%)   0.0222 ( 93.6%)  Clang front-end timer
   0.0000 (  0.0%)   0.0000 (  0.0%)   0.0000 (  0.0%)   0.0008 (  3.5%)  Reading modules
   0.0000 (  0.0%)   0.0000 (  0.0%)   0.0000 (  0.0%)   0.0007 (  2.9%)  Loading /home/yaxunl/llvm-tot/llvm/tools/clang/test/CodeGenOpenCL/./JJHF9CF78G8Z/opencl_c-3RXFI66A6CUM7.pcm
   0.0160 (100.0%)   0.0080 (100.0%)   0.0240 (100.0%)   0.0237 (100.0%)  Total

So the caching is very effective and essentially makes the header loading time to be ignored.


http://reviews.llvm.org/D20444