[Mesa-dev] [PATCH 1/3] gallivm: Emit vector selects.

[Brian Paul]

On 04/20/2013 02:57 AM, jfonseca at vmware.com wrote:
> From: José Fonseca<jfonseca at vmware.com>
>
> They are supported on LLVM 3.1, at least on x86. (I haven't tested on PPC
> though.)
>
> Actually lp_build_linear_mip_levels() already has been emitting them for
> some time.
>
> This avoids intrinsics, which tend to be an obstacle for certain
> optimization passes.
> ---
>   src/gallium/auxiliary/gallivm/lp_bld_logic.c |   14 ++------------
>   1 file changed, 2 insertions(+), 12 deletions(-)
>
> diff --git a/src/gallium/auxiliary/gallivm/lp_bld_logic.c b/src/gallium/auxiliary/gallivm/lp_bld_logic.c
> index f56b61b..cdb7e0a 100644
> --- a/src/gallium/auxiliary/gallivm/lp_bld_logic.c
> +++ b/src/gallium/auxiliary/gallivm/lp_bld_logic.c
> @@ -458,20 +458,10 @@ lp_build_select(struct lp_build_context *bld,
>         mask = LLVMBuildTrunc(builder, mask, LLVMInt1TypeInContext(lc), "");
>         res = LLVMBuildSelect(builder, mask, a, b, "");
>      }
> -   else if (0) {
> +   else if (HAVE_LLVM>= 0x301) {
>         /* Generate a vector select.
>          *
> -       * XXX: Using vector selects would avoid emitting intrinsics, but they aren't
> -       * properly supported yet.
> -       *
> -       * LLVM 3.0 includes experimental support provided the -promote-elements
> -       * options is passed to LLVM's command line (e.g., via
> -       * llvm::cl::ParseCommandLineOptions), but resulting code quality is much
> -       * worse, probably because some optimization passes don't know how to
> -       * handle vector selects.
> -       *
> -       * See also:
> -       * - http://lists.cs.uiuc.edu/pipermail/llvmdev/2011-October/043659.html
> +       * Only supported on LLVM 3.1 onwards
>          */
>
>         /* Convert the mask to a vector of booleans.

For the series, Reviewed-by: Brian Paul <brianp at vmware.com>