[Mesa-dev] [PATCH] gallivm: fix issue with AtomicCmpXchg wrapper on llvm 3.5-3.8

[Brian Paul]

On 08/02/2019 10:36 AM, sroland at vmware.com wrote:
> From: Roland Scheidegger <sroland at vmware.com>
> 
> These versions still need wrapper but already have both success and
> failure ordering.
> (Compile tested on llvm 3.7, llvm 3.8.)
> 
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=111102
> ---
>   src/gallium/auxiliary/gallivm/lp_bld_misc.cpp | 16 +++++++++++++++-
>   1 file changed, 15 insertions(+), 1 deletion(-)
> 
> diff --git a/src/gallium/auxiliary/gallivm/lp_bld_misc.cpp b/src/gallium/auxiliary/gallivm/lp_bld_misc.cpp
> index 79d10293e80..723c84d57c2 100644
> --- a/src/gallium/auxiliary/gallivm/lp_bld_misc.cpp
> +++ b/src/gallium/auxiliary/gallivm/lp_bld_misc.cpp
> @@ -822,15 +822,29 @@ static llvm::AtomicOrdering mapFromLLVMOrdering(LLVMAtomicOrdering Ordering) {
>      llvm_unreachable("Invalid LLVMAtomicOrdering value!");
>   }
>   
> +#if HAVE_LLVM < 0x305
>   LLVMValueRef LLVMBuildAtomicCmpXchg(LLVMBuilderRef B, LLVMValueRef Ptr,
>                                       LLVMValueRef Cmp, LLVMValueRef New,
>                                       LLVMAtomicOrdering SuccessOrdering,
>                                       LLVMAtomicOrdering FailureOrdering,
>                                       LLVMBool SingleThread)
>   {
> -   /* LLVM 3.8 doesn't have a second ordering and uses old SynchronizationScope enum */
> +   /* LLVM < 3.5 doesn't have a second ordering and uses old SynchronizationScope enum */
>      return llvm::wrap(llvm::unwrap(B)->CreateAtomicCmpXchg(llvm::unwrap(Ptr), llvm::unwrap(Cmp),
>                                                             llvm::unwrap(New), mapFromLLVMOrdering(SuccessOrdering),
>                                                             SingleThread ? llvm::SynchronizationScope::SingleThread : llvm::SynchronizationScope::CrossThread));
>   }
> +#else
> +LLVMValueRef LLVMBuildAtomicCmpXchg(LLVMBuilderRef B, LLVMValueRef Ptr,
> +                                    LLVMValueRef Cmp, LLVMValueRef New,
> +                                    LLVMAtomicOrdering SuccessOrdering,
> +                                    LLVMAtomicOrdering FailureOrdering,
> +                                    LLVMBool SingleThread)
> +{
> +   return llvm::wrap(llvm::unwrap(B)->CreateAtomicCmpXchg(llvm::unwrap(Ptr), llvm::unwrap(Cmp),
> +                                                          llvm::unwrap(New), mapFromLLVMOrdering(SuccessOrdering),
> +                                                          mapFromLLVMOrdering(FailureOrdering),
> +                                                          SingleThread ? llvm::SynchronizationScope::SingleThread : llvm::SynchronizationScope::CrossThread));
> +}
> +#endif
>   #endif
> 

Could the #if / #endif logic be moved into the body of 
LLVMBuildAtomicCmpXchg() so the whole function isn't duplicated?

Other than that,
Reviewed-by: Brian Paul <brianp at vmware.com>