[Mesa-dev] [PATCH 3/3] gallivm: Initialize LLVM Modules's DataLayout to an empty string.

[Roland Scheidegger]

Am 20.07.2015 um 19:35 schrieb Tom Stellard:
> This fixes crashes in some piglit tests on radeonsi that use the draw
> module, and llvmpipe is likely completely broken without this on LLVM
> 3.8.
Yes, see https://llvm.org/bugs/show_bug.cgi?id=24172


> 
> This is just a temporary solution.  The correct solution will require
> creating a TargetMachine during gallivm initialization and pulling the
> DataLayout from there.  This will be a somewhat invasive change, and it
> will need to be validatated on multiple LLVM versions.

Reviewed-by: Roland Scheidegger <sroland at vmware.com>
> ---
>  src/gallium/auxiliary/gallivm/lp_bld_init.c | 28 +++++++++++++++++++++++-----
>  1 file changed, 23 insertions(+), 5 deletions(-)
> 
> diff --git a/src/gallium/auxiliary/gallivm/lp_bld_init.c b/src/gallium/auxiliary/gallivm/lp_bld_init.c
> index 384ea86..017d075 100644
> --- a/src/gallium/auxiliary/gallivm/lp_bld_init.c
> +++ b/src/gallium/auxiliary/gallivm/lp_bld_init.c
> @@ -106,7 +106,6 @@ enum LLVM_CodeGenOpt_Level {
>  static boolean
>  create_pass_manager(struct gallivm_state *gallivm)
>  {
> -   char *td_str;
>     assert(!gallivm->passmgr);
>     assert(gallivm->target);
>  
> @@ -122,10 +121,29 @@ create_pass_manager(struct gallivm_state *gallivm)
>     // Old versions of LLVM get the DataLayout from the pass manager.
>     LLVMAddTargetData(gallivm->target, gallivm->passmgr);
>  
> -   // New ones from the Module.
> -   td_str = LLVMCopyStringRepOfTargetData(gallivm->target);
> -   LLVMSetDataLayout(gallivm->module, td_str);
> -   free(td_str);
> +   /* Setting the module's DataLayout to an empty string will cause the
> +    * ExecutionEngine to copy to the DataLayout string from its target
> +    * machine to the module.  As of LLVM 3.8 the module and the execution
> +    * engine are required to have the same DataLayout.
> +    *
> +    * TODO: This is just a temporary work-around.  The correct solution is
> +    * for gallivm_init_state() to create a TargetMachine and pull the
> +    * DataLayout from there.  Currently, the TargetMachine used by llvmpipe
> +    * is being implicitly created by the EngineBuilder in
> +    * lp_build_create_jit_compiler_for_module()
> +    */
> +
> +#if HAVE_LLVM < 0x0308
> +   {
> +      char *td_str;
> +      // New ones from the Module.
> +      td_str = LLVMCopyStringRepOfTargetData(gallivm->target);
> +      LLVMSetDataLayout(gallivm->module, td_str);
> +      free(td_str);
> +   }
> +#else
> +   LLVMSetDataLayout(gallivm->module, "");
> +#endif
>  
>     if ((gallivm_debug & GALLIVM_DEBUG_NO_OPT) == 0) {
>        /* These are the passes currently listed in llvm-c/Transforms/Scalar.h,
>