[Mesa-dev] mishandling of bool comparisons in GLSL->TGSI translator

[Brian Paul]

Jose found a problem in the GLSL->TGSI translater with respect to 
boolean array comparisions when PIPE_SHADER_CAP_INTEGERS=1.  I dug 
into it a bit.

The attached shader_runner case shows the issue.

Basically, the comparison of boolean values (which are unsigned 
integers) winds up being done with TGSI_OPCODE_SEQ instead of USEQ:

VERT
DCL IN[0]
DCL OUT[0], POSITION
DCL OUT[1], GENERIC[12]
DCL CONST[0..1]
DCL TEMP[0], LOCAL
DCL TEMP[1], LOCAL
IMM UINT32 {4294967295, 0, 0, 0}
IMM FLT32 {    1.0000,     0.0000,     0.0000,     0.0000}
   0: SEQ TEMP[0].x, CONST[0].xxxx, IMM[0].xxxx   <<< UINT operands!
   1: F2I TEMP[0].x, -TEMP[0]
   2: SEQ TEMP[1].x, CONST[1].xxxx, IMM[0].xxxx   <<< UINT operands!
   3: F2I TEMP[1].x, -TEMP[1]
   4: AND TEMP[0].x, TEMP[0].xxxx, TEMP[1].xxxx
   5: IF TEMP[0].xxxx :0
   6:   MOV TEMP[0], IMM[1].xyyx
   7: ELSE :0
   8:   MOV TEMP[0], IMM[1].yxyx
   9: ENDIF
  10: MOV OUT[1], TEMP[0]
  11: MOV OUT[0], IN[0]
  12: END

The correct code sequence should be:

   0: USEQ TEMP[0].x, CONST[0].xxxx, IMM[0].xxxx
   1: USEQ TEMP[1].x, CONST[1].xxxx, IMM[0].xxxx
   2: AND TEMP[0].x, TEMP[0].xxxx, TEMP[1].xxxx
   3: IF TEMP[0].xxxx :0
   4:   MOV TEMP[0], IMM[1].xyyx
   5: ELSE :0
   6:   MOV TEMP[0], IMM[1].yxyx
   7: ENDIF
   8: MOV OUT[1], TEMP[0]
   9: MOV OUT[0], IN[0]
  10: END

The attached patch for glsl_to_tgsi_visitor::get_opcode() fixes the 
issue but the first assert which I added fails if it's enabled. 
AFAICT, by time we get into glsl_to_tgsi_visitor::get_opcode() we 
should have scalar operands, not arrays.  It's not clear to me how to 
fix that.

I'm hoping someone who's spent more time on glsl_to_tgsi.cpp (is Bryan 
Cain still around?) can take a look at this.  Thanks.

-Brian
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