[Mesa-dev] [PATCH] glsl_to_tgsi: don't use the negate modifier in integer ops after bitcast

[Marek Olšák]

On Mon, Jul 11, 2016 at 7:55 PM, Ilia Mirkin <imirkin at alum.mit.edu> wrote:
> On Mon, Jul 11, 2016 at 1:48 PM, Marek Olšák <maraeo at gmail.com> wrote:
>> On Mon, Jul 11, 2016 at 7:31 PM, Ilia Mirkin <imirkin at alum.mit.edu> wrote:
>>> On Mon, Jul 11, 2016 at 1:28 PM, Marek Olšák <maraeo at gmail.com> wrote:
>>>> From: Marek Olšák <marek.olsak at amd.com>
>>>>
>>>> This bug is uncovered by glsl/lower_if_to_cond_assign.
>>>> I don't know if it can be reproduced in any other way.
>>>>
>>>> Cc: <mesa-stable at lists.freedesktop.org>
>>>> ---
>>>>  src/mesa/state_tracker/st_glsl_to_tgsi.cpp | 12 +++++++-----
>>>>  1 file changed, 7 insertions(+), 5 deletions(-)
>>>>
>>>> diff --git a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
>>>> index 76656f5..0b7feb7 100644
>>>> --- a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
>>>> +++ b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
>>>> @@ -1958,12 +1958,14 @@ glsl_to_tgsi_visitor::visit_expression(ir_expression* ir, st_src_reg *op)
>>>>           emit_asm(ir, TGSI_OPCODE_TRUNC, result_dst, op[0]);
>>>>        break;
>>>>     case ir_unop_bitcast_f2i:
>>>> -      result_src = op[0];
>>>> -      result_src.type = GLSL_TYPE_INT;
>>>> -      break;
>>>>     case ir_unop_bitcast_f2u:
>>>> -      result_src = op[0];
>>>> -      result_src.type = GLSL_TYPE_UINT;
>>>> +      /* Make sure we don't propagate the negate modifier to integer opcodes. */
>>>> +      if (op[0].negate)
>>>
>>> Or abs or saturate, presumably?
>>
>> glsl_to_tgsi doesn't use ureg_abs.
>
> I'd rather not rely on that... it's pretty cheap to throw in there.

I can't throw abs in there because st_src_reg doesn't have abs. :)

>
>>
>> saturate is a dst modifier and this patch operates on src operands.
>
> Er, right, of course. Ignore that.
>
> With abs thrown into the condition,
>
> Reviewed-by: Ilia Mirkin <imirkin at alum.mit.edu>

Thanks.

Marek