On Thu, Feb 11, 2016 at 4:41 PM, Matt Turner <matts...@gmail.com> wrote:
> Gen4/5's SEL instruction cannot use conditional modifiers, so min/max
> are implemented as CMP + SEL. Handling that after optimization lets us
> CSE more.
>
> On Ironlake:
>
> total instructions in shared programs: 6426035 -> 6422753 (-0.05%)
> instructions in affected programs: 326604 -> 323322 (-1.00%)
> helped: 1411
>
> total cycles in shared programs: 129184700 -> 129101586 (-0.06%)
> cycles in affected programs: 18950290 -> 18867176 (-0.44%)
> helped: 2419
> HURT: 328
> ---
> src/mesa/drivers/dri/i965/brw_fs.cpp | 37 +++++++++++++++++++++++++
> src/mesa/drivers/dri/i965/brw_fs.h | 1 +
> src/mesa/drivers/dri/i965/brw_fs_builder.h | 10 ++-----
> src/mesa/drivers/dri/i965/brw_fs_nir.cpp | 20 +++-----------
> src/mesa/drivers/dri/i965/brw_vec4.cpp | 38
> ++++++++++++++++++++++++++
> src/mesa/drivers/dri/i965/brw_vec4.h | 2 ++
> src/mesa/drivers/dri/i965/brw_vec4_builder.h | 10 ++-----
> src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp | 14 ++--------
> 8 files changed, 88 insertions(+), 44 deletions(-)
>
> diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp
> b/src/mesa/drivers/dri/i965/brw_fs.cpp
> index 0ce7ed1..e83f0ba 100644
> --- a/src/mesa/drivers/dri/i965/brw_fs.cpp
> +++ b/src/mesa/drivers/dri/i965/brw_fs.cpp
> @@ -3475,6 +3475,36 @@ fs_visitor::lower_integer_multiplication()
> return progress;
> }
>
> +bool
> +fs_visitor::lower_minmax()
> +{
> + assert(devinfo->gen < 6);
> +
> + bool progress = false;
> +
> + foreach_block_and_inst_safe(block, fs_inst, inst, cfg) {
> + const fs_builder ibld(this, block, inst);
> +
> + if (inst->opcode == BRW_OPCODE_SEL &&
> + inst->predicate == BRW_PREDICATE_NONE) {
> + assert(inst->conditional_mod == BRW_CONDITIONAL_GE ||
> + inst->conditional_mod == BRW_CONDITIONAL_L);
Ken asked at the office if this assertion is necessary. I think it is.
The PRM doesn't say anything about SEL with conditional modifiers
other than .ge or .l.
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