[Mesa-dev] [PATCH 08/18] radeonsi: don't use llvm.AMDIL.fraction for FRC and DFRAC

[Tom Stellard]

On Fri, Jul 31, 2015 at 04:59:19PM +0200, Marek Olšák wrote:
> On Fri, Jul 31, 2015 at 4:18 PM, Tom Stellard <tom at stellard.net> wrote:
> > On Tue, Jul 28, 2015 at 12:05:43PM +0200, Marek Olšák wrote:
> >> From: Marek Olšák <marek.olsak at amd.com>
> >>
> >> There are 2 reasons for this:
> >> - LLVM optimization passes can work with floor
> >> - there are patterns to select v_fract from floor anyway
> >>
> >> There is no change in the generated code.
> >> ---
> >>  src/gallium/drivers/radeon/radeon_setup_tgsi_llvm.c | 20 ++++++++++++++++----
> >>  1 file changed, 16 insertions(+), 4 deletions(-)
> >>
> >> diff --git a/src/gallium/drivers/radeon/radeon_setup_tgsi_llvm.c b/src/gallium/drivers/radeon/radeon_setup_tgsi_llvm.c
> >> index 319380f..5c08cf5 100644
> >> --- a/src/gallium/drivers/radeon/radeon_setup_tgsi_llvm.c
> >> +++ b/src/gallium/drivers/radeon/radeon_setup_tgsi_llvm.c
> >> @@ -1170,6 +1170,20 @@ static void emit_dneg(
> >>                       emit_data->args[0], "");
> >>  }
> >>
> >> +static void emit_frac(
> >> +             const struct lp_build_tgsi_action * action,
> >> +             struct lp_build_tgsi_context * bld_base,
> >> +             struct lp_build_emit_data * emit_data)
> >> +{
> >> +     LLVMBuilderRef builder = bld_base->base.gallivm->builder;
> >> +
> >> +     LLVMValueRef floor = lp_build_intrinsic(builder, "floor", emit_data->dst_type,
> >
> > The intrinsics name should be "llvm.floor.f32" for float and "llvm.floor.f64"
> > for double.
> >
> > With that fixed, this is:
> > Reviewed-by: Tom Stellard <thomas.stellard at amd.com>
> 
> Sorry, I have pushed this already. Is it really required to use
> "llvm.floor.f*"? We've been using "floor" for FLR forever. We've also
> been using "fabs" and "ceil". Are those wrong too?
> 

It is better to use the intrinsics: (i.e. llvm.*) functions, because
they don't have side-effects like the libm calls, so they can be optimized
better.

-Tom

> Marek