[Beignet] [V2 PATCH] Disable the PCH valid check to save a lot of compiling time.

[Zhigang Gong]

LGTM, pushed, thanks.

On Wed, Dec 11, 2013 at 11:09:27AM +0800, junyan.he at inbox.com wrote:
> From: Junyan He <junyan.he at linux.intel.com>
> 
> In clang, The PCH file will be used as an AST source, so
> the check is strict. The macro define is also checked,
> and if anything is different, the PCH is invalid and
> the build processing will start from scratch.
> Disable Clang's PCH valid check and do the compatible
> check by ourself.
> 
> This patch do not solve the clang version problems.
> Because the AST represent is an internal Clang's
> data struct and may change between two clang versions.
> So we will modify this issue later.
> 
> Signed-off-by: Junyan He <junyan.he at linux.intel.com>
> ---
>  backend/src/backend/program.cpp | 92 ++++++++++++++++++++++++++++++++++-------
>  1 file changed, 77 insertions(+), 15 deletions(-)
> 
> diff --git a/backend/src/backend/program.cpp b/backend/src/backend/program.cpp
> index 294bb16..fc9b03c 100644
> --- a/backend/src/backend/program.cpp
> +++ b/backend/src/backend/program.cpp
> @@ -569,6 +569,9 @@ namespace gbe {
>      clang::LangOptions & lang_opts = Clang.getLangOpts();
>      lang_opts.OpenCL = 1;
>  
> +    clang::PreprocessorOptions prep_opt = Clang.getPreprocessorOpts();
> +    prep_opt.DisablePCHValidation = 1;
> +
>      //llvm flags need command line parsing to take effect
>      if (!Clang.getFrontendOpts().LLVMArgs.empty()) {
>        unsigned NumArgs = Clang.getFrontendOpts().LLVMArgs.size();
> @@ -645,32 +648,91 @@ namespace gbe {
>      FILE *clFile = fopen(clName.c_str(), "w");
>      FATAL_IF(clFile == NULL, "Failed to open temporary file");
>  
> -    bool usePCH = false;
> +    bool usePCH = true;
> +    bool findPCH = false;
> +
> +    /* Because our header file is so big, we want to avoid recompile the header from
> +       scratch. We use the PCH support of Clang to save the huge compiling time.
> +       We just use the most general build opt to build the PCH header file, so if
> +       user pass new build options here, the PCH can not pass the Clang's compitable
> +       validating. Clang will do three kinds of compatible check: Language Option,
> +       Target Option and Preprocessing Option. Other kinds of options such as the
> +       CodeGen options will not affect the AST result, so no need to check.
> +
> +       According to OpenCL 1.1's spec, the CL build options:
> +       -D name=definition
> +       If the definition is not used in our header, it is compitable
> +
> +       -cl-single-precision-constant
> +       -cl-denorms-are-zero
> +       -cl-std=
> +       Language options, really affect.
> +
> +       -cl-opt-disable
> +       -cl-mad-enable
> +       -cl-no-signed-zeros
> +       -cl-unsafe-math-optimizations
> +       -cl-finite-math-only
> +       -cl-fast-relaxed-math
> +       CodeGen options, not affect
> +
> +       -Werror
> +       -w
> +       Our header should not block the compiling because of warning.
> +
> +       So we just disable the PCH validation of Clang and do the judgement by ourself. */
> +
> +    if(options) {
> +      char *p;
> +      const char * incompatible_opts[] = {
> +          "-cl-single-precision-constant",
> +//        "-cl-denorms-are-zero",
> +          "-cl-std=",
> +      };
> +      const char * incompatible_defs[] = {
> +          "GET_FLOAT_WORD",
> +          "__NV_CL_C_VERSION",
> +          "GEN7_SAMPLER_CLAMP_BORDER_WORKAROUND"
> +      };
> +
> +      for (unsigned int i = 0; i < sizeof(incompatible_opts)/sizeof(char *); i++ ) {
> +        p = strstr(const_cast<char *>(options), incompatible_opts[i]);
> +        if (p) {
> +          usePCH = false;
> +          break;
> +        }
> +      }
> +
> +      if (usePCH) {
> +        for (unsigned int i = 0; i < sizeof(incompatible_defs)/sizeof(char *); i++ ) {
> +          p = strstr(const_cast<char *>(options), incompatible_defs[i]);
> +          if (p) {
> +            usePCH = false;
> +            break;
> +          }
> +        }
> +      }
>  
> -    if(options)
>        clOpt += options;
> +    }
>  
> -    if (options || !OCL_USE_PCH) {
> -      /* Some building option may cause the prebuild pch header file
> -         not compatible with the XXX.cl source. We need rebuild all here.*/
> -      usePCH = false;
> -    } else {
> -      std::string dirs = PCH_OBJECT_DIR;
> -      std::istringstream idirs(dirs);
> +    std::string dirs = PCH_OBJECT_DIR;
> +    std::istringstream idirs(dirs);
>  
> -      while (getline(idirs, pchHeaderName, ';')) {
> -        if(access(pchHeaderName.c_str(), R_OK) == 0) {
> -          usePCH = true;
> -          break;
> -        }
> +    while (getline(idirs, pchHeaderName, ';')) {
> +      if(access(pchHeaderName.c_str(), R_OK) == 0) {
> +        findPCH = true;
> +        break;
>        }
>      }
> -    if (usePCH) {
> +
> +    if (usePCH && findPCH) {
>        clOpt += " -include-pch ";
>        clOpt += pchHeaderName;
>        clOpt += " ";
>      } else
>        fwrite(ocl_stdlib_str.c_str(), strlen(ocl_stdlib_str.c_str()), 1, clFile);
> +
>      // Write the source to the cl file
>      fwrite(source, strlen(source), 1, clFile);
>      fclose(clFile);
> -- 
> 1.8.3.2
> 
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