[Mesa-dev] [PATCH] r600g/sb: Don't fold integer value into float CND

[Dave Airlie]

On 12 February 2015 at 23:49, Maarten Lankhorst
<maarten.lankhorst at canonical.com> wrote:
> Op 12-02-15 om 14:23 schreef Glenn Kennard:
>> Don't try to do float comparisons on signed integer values,
>> some of them look like NaNs.
>>
>> Fixes fs-temp-array-mat3-index-col-row-rd.shader_test regression
>> caused by 0d4272cd8e7c45157140dc8e283707714a8238d5.
>>
>> Signed-off-by: Glenn Kennard <glenn.kennard at gmail.com>
>>
> Cc: "10.5" <mesa-stable at lists.freedesktop.org>
> Reported-andTested-by: Maarten Lankhorst <maarten.lankhorst at canonical.com>

This is certinaly right and leads to a problem later on though,

tests/spec/glsl-1.10/execution/variable-indexing/fs-uniform-array-mat3-col-row-rd.shader_test
regresses as pointed out,

however the TGSI generated for this as an uninitialised variable in it

FRAG
PROPERTY FS_COLOR0_WRITES_ALL_CBUFS 1
DCL OUT[0], COLOR
DCL CONST[0..8]
DCL TEMP[0..2], LOCAL
DCL ADDR[0]
IMM[0] INT32 {0, 1, 2, 0}
IMM[1] FLT32 {    0.0000,     1.0000,     0.0000,     0.0000}
  0: UARL ADDR[0].x, CONST[0].xxxx
  1: MOV TEMP[0].xyz, CONST[ADDR[0].x+6].xyzx
  2: USEQ TEMP[1].xyz, CONST[1].xxxx, IMM[0].xyzz
  3: UCMP TEMP[2].x, TEMP[1].xxxx, TEMP[0].xxxx, TEMP[2].xxxx
  4: UCMP TEMP[2].x, TEMP[1].yyyy, TEMP[0].yyyy, TEMP[2].xxxx
  5: UCMP TEMP[2].x, TEMP[1].zzzz, TEMP[0].zzzz, TEMP[2].xxxx
  6: FSEQ TEMP[0].x, TEMP[2].xxxx, CONST[2].xxxx
  7: UIF TEMP[0].xxxx :0
  8:   MOV TEMP[0], IMM[1].xyxy
  9: ELSE :0
 10:   MOV TEMP[0], IMM[1].yxxy
 11: ENDIF
 12: MOV OUT[0], TEMP[0]
 13: END

note TEMP[2] is used a src before being used a dst

the GLSL for this
GLSL IR for linked fragment program 3:
(
(declare (shader_out ) vec4 gl_FragColor)
(declare (temporary ) vec4 gl_FragColor)
(declare (uniform ) int col)
(declare (uniform ) int row)
(declare (uniform ) float expect)
(declare (uniform ) (array mat3 2) m)
(function main
  (signature void
    (parameters
    )
    (
      (declare (temporary ) vec4 conditional_tmp)
      (declare (temporary ) vec3 vec_value_tmp)
      (assign  (xyz) (var_ref vec_value_tmp)  (array_ref (array_ref
(var_ref m) (constant int (1)) ) (var_ref col) ) )
      (declare (temporary ) float vec_index_tmp_v)
      (declare (temporary ) bvec3 dereference_condition)
      (assign  (xyz) (var_ref dereference_condition)  (expression
bvec3 == (swiz xxx (var_ref row) )(constant ivec3 (0 1 2)) ) )
      (assign (swiz x (var_ref dereference_condition) ) (x) (var_ref
vec_index_tmp_v)  (swiz x (var_ref vec_value_tmp) ))
      (assign (swiz y (var_ref dereference_condition) ) (x) (var_ref
vec_index_tmp_v)  (swiz y (var_ref vec_value_tmp) ))
      (assign (swiz z (var_ref dereference_condition) ) (x) (var_ref
vec_index_tmp_v)  (swiz z (var_ref vec_value_tmp) ))
      (if (expression bool == (var_ref vec_index_tmp_v) (var_ref expect) ) (
        (assign  (xyzw) (var_ref conditional_tmp)  (constant vec4
(0.000000 1.000000 0.000000 1.000000)) )
      )
      (
        (assign  (xyzw) (var_ref conditional_tmp)  (constant vec4
(1.000000 0.000000 0.000000 1.000000)) )
      ))

      (assign  (xyzw) (var_ref gl_FragColor)  (var_ref conditional_tmp) )
      (assign  (xyzw) (var_ref gl_FragColor at 3)  (var_ref gl_FragColor) )
    ))

)

I'm having trouble deciphering :-) and it comes from
lower_vec_index_to_cond_assign.cpp.

This is probably a glsl->tgsi convertor bug, any GLSL expert say if
the GLSL is okay?

Dave.