[Mesa-dev] [PATCH 4/4] st/mesa: use new float comparison opcodes if native integers are supported

[Roland Scheidegger]

I tested this for llvmpipe, but it would be good if the respective
driver authors could verify it works for their drivers, I have no idea
if I got it right there, just guessed how it might work based mostly on
how other comparison instructions are handled (and I hope I caught all
drivers, those supporting integers), but if not glsl will probably break
quite badly I suppose.

Roland


Am 13.08.2013 19:04, schrieb sroland at vmware.com:
> From: Roland Scheidegger <sroland at vmware.com>
> 
> Should get rid of some float-to-int conversions (with negation).
> No piglit regressions (with llvmpipe).
> ---
>  src/mesa/state_tracker/st_glsl_to_tgsi.cpp |   45 ++++++++++------------------
>  1 file changed, 15 insertions(+), 30 deletions(-)
> 
> diff --git a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
> index d9b4ed2..65ba449 100644
> --- a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
> +++ b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
> @@ -420,8 +420,6 @@ public:
>     void emit_scalar(ir_instruction *ir, unsigned op,
>          	    st_dst_reg dst, st_src_reg src0, st_src_reg src1);
>  
> -   void try_emit_float_set(ir_instruction *ir, unsigned op, st_dst_reg dst);
> -
>     void emit_arl(ir_instruction *ir, st_dst_reg dst, st_src_reg src0);
>  
>     void emit_scs(ir_instruction *ir, unsigned op,
> @@ -594,9 +592,6 @@ glsl_to_tgsi_visitor::emit(ir_instruction *ir, unsigned op,
>  
>     this->instructions.push_tail(inst);
>  
> -   if (native_integers)
> -      try_emit_float_set(ir, op, dst);
> -
>     return inst;
>  }
>  
> @@ -622,25 +617,6 @@ glsl_to_tgsi_visitor::emit(ir_instruction *ir, unsigned op)
>     return emit(ir, op, undef_dst, undef_src, undef_src, undef_src);
>  }
>  
> - /**
> - * Emits the code to convert the result of float SET instructions to integers.
> - */
> -void
> -glsl_to_tgsi_visitor::try_emit_float_set(ir_instruction *ir, unsigned op,
> -        		 st_dst_reg dst)
> -{
> -   if ((op == TGSI_OPCODE_SEQ ||
> -        op == TGSI_OPCODE_SNE ||
> -        op == TGSI_OPCODE_SGE ||
> -        op == TGSI_OPCODE_SLT))
> -   {
> -      st_src_reg src = st_src_reg(dst);
> -      src.negate = ~src.negate;
> -      dst.type = GLSL_TYPE_FLOAT;
> -      emit(ir, TGSI_OPCODE_F2I, dst, src);
> -   }
> -}
> -
>  /**
>   * Determines whether to use an integer, unsigned integer, or float opcode 
>   * based on the operands and input opcode, then emits the result.
> @@ -672,6 +648,15 @@ glsl_to_tgsi_visitor::get_opcode(ir_instruction *ir, unsigned op,
>  #define case2fi(f, i)   case4(f, f, i, i)
>  #define case2iu(i, u)   case4(i, LAST, i, u)
>     
> +#define casecomp(c, f, i, u) \
> +   case TGSI_OPCODE_##c: \
> +      if (type == GLSL_TYPE_INT) op = TGSI_OPCODE_##i; \
> +      else if (type == GLSL_TYPE_UINT) op = TGSI_OPCODE_##u; \
> +      else if (native_integers) \
> +         op = TGSI_OPCODE_##f; \
> +      else op = TGSI_OPCODE_##c; \
> +      break;
> +
>     switch(op) {
>        case2fi(ADD, UADD);
>        case2fi(MUL, UMUL);
> @@ -680,12 +665,12 @@ glsl_to_tgsi_visitor::get_opcode(ir_instruction *ir, unsigned op,
>        case3(MAX, IMAX, UMAX);
>        case3(MIN, IMIN, UMIN);
>        case2iu(MOD, UMOD);
> -      
> -      case2fi(SEQ, USEQ);
> -      case2fi(SNE, USNE);
> -      case3(SGE, ISGE, USGE);
> -      case3(SLT, ISLT, USLT);
> -      
> +
> +      casecomp(SEQ, FSEQ, USEQ, USEQ);
> +      casecomp(SNE, FSNE, USNE, USNE);
> +      casecomp(SGE, FSGE, ISGE, USGE);
> +      casecomp(SLT, FSLT, ISLT, USLT);
> +
>        case2iu(ISHR, USHR);
>  
>        case2fi(SSG, ISSG);
>