[Mesa-dev] [PATCH 05/23] i965/disasm: Improve disassembly of jump targets on Gen6+.

[Kristian Høgsberg]

On Sat, Jun 28, 2014 at 09:33:44PM -0700, Kenneth Graunke wrote:
> Previously, flow control instructions generated output like:
> 
> (+f0) if(8) 12 8  null         0x000c0008UD { align16 WE_normal 1Q };
> 
> which included a dissasembly of the register fields, even though those
> are meaningless for flow control instructions---those bits are reused
> for another purpose.
> 
> It also wasn't immediately obvious which number was UIP and which was
> JIP.
> 
> With this patch, we instead output:
> 
> (+f0) if(8)       JIP: 8       UIP: 12      { align16 WE_normal 1Q };
> 
> which is much clearer.

Yeah, makes sense.  Ideally we'd pass a start address to the
disassembler and have it compute the absolute jump addresses too.

Reviewed-by: Kristian Høgsberg <krh at bitplanet.net>

> The patch also introduces has_uip/has_jip helper functions which clear
> up a some generation/opcode checking mess.
> 
> Signed-off-by: Kenneth Graunke <kenneth at whitecape.org>
> ---
>  src/mesa/drivers/dri/i965/brw_disasm.c | 59 +++++++++++++++++++++++-----------
>  1 file changed, 41 insertions(+), 18 deletions(-)
> 
> diff --git a/src/mesa/drivers/dri/i965/brw_disasm.c b/src/mesa/drivers/dri/i965/brw_disasm.c
> index 569dd68..8966eda 100644
> --- a/src/mesa/drivers/dri/i965/brw_disasm.c
> +++ b/src/mesa/drivers/dri/i965/brw_disasm.c
> @@ -100,6 +100,30 @@ const struct opcode_desc opcode_descs[128] = {
>     [BRW_OPCODE_ENDIF]    = { .name = "endif",   .nsrc = 2, .ndst = 0 },
>  };
>  
> +static bool
> +has_jip(struct brw_context *brw, enum opcode opcode)
> +{
> +   if (brw->gen < 6)
> +      return false;
> +
> +   return opcode == BRW_OPCODE_IF ||
> +          opcode == BRW_OPCODE_ELSE ||
> +          opcode == BRW_OPCODE_ENDIF ||
> +          opcode == BRW_OPCODE_WHILE;
> +}
> +
> +static bool
> +has_uip(struct brw_context *brw, enum opcode opcode)
> +{
> +   if (brw->gen < 6)
> +      return false;
> +
> +   return (brw->gen >= 7 && opcode == BRW_OPCODE_IF) ||
> +          opcode == BRW_OPCODE_BREAK ||
> +          opcode == BRW_OPCODE_CONTINUE ||
> +          opcode == BRW_OPCODE_HALT;
> +}
> +
>  const char *const conditional_modifier[16] = {
>     [BRW_CONDITIONAL_NONE] = "",
>     [BRW_CONDITIONAL_Z]    = ".e",
> @@ -1170,7 +1194,22 @@ brw_disassemble_inst(FILE *file, struct brw_context *brw, brw_inst *inst,
>     if (opcode == BRW_OPCODE_SEND && brw->gen < 6)
>        format(file, " %d", brw_inst_base_mrf(brw, inst));
>  
> -   if (opcode_descs[opcode].nsrc == 3) {
> +   if (has_uip(brw, opcode)) {
> +      /* Instructions that have UIP also have JIP. */
> +      pad(file, 16);
> +      format(file, "JIP: %d", brw_inst_jip(brw, inst));
> +      pad(file, 32);
> +      format(file, "UIP: %d", brw_inst_uip(brw, inst));
> +   } else if (has_jip(brw, opcode)) {
> +      pad(file, 16);
> +      if (brw->gen >= 7) {
> +         format(file, "JIP: %d", brw_inst_jip(brw, inst));
> +      } else {
> +         format(file, "JIP: %d", brw_inst_gen6_jump_count(brw, inst));
> +      }
> +   } else if (opcode == BRW_OPCODE_JMPI) {
> +      format(file, " %d", brw_inst_imm_d(brw, inst));
> +   } else if (opcode_descs[opcode].nsrc == 3) {
>        pad(file, 16);
>        err |= dest_3src(file, brw, inst);
>  
> @@ -1186,29 +1225,13 @@ brw_disassemble_inst(FILE *file, struct brw_context *brw, brw_inst *inst,
>        if (opcode_descs[opcode].ndst > 0) {
>           pad(file, 16);
>           err |= dest(file, brw, inst);
> -      } else if (brw->gen == 7 && (opcode == BRW_OPCODE_ELSE ||
> -                                   opcode == BRW_OPCODE_ENDIF ||
> -                                   opcode == BRW_OPCODE_WHILE)) {
> -         format(file, " %d", brw_inst_jip(brw, inst));
> -      } else if (brw->gen == 6 && (opcode == BRW_OPCODE_IF ||
> -                                   opcode == BRW_OPCODE_ELSE ||
> -                                   opcode == BRW_OPCODE_ENDIF ||
> -                                   opcode == BRW_OPCODE_WHILE)) {
> -         format(file, " %d", brw_inst_gen6_jump_count(brw, inst));
> -      } else if ((brw->gen >= 6 && (opcode == BRW_OPCODE_BREAK ||
> -                                    opcode == BRW_OPCODE_CONTINUE ||
> -                                    opcode == BRW_OPCODE_HALT)) ||
> -                 (brw->gen == 7 && opcode == BRW_OPCODE_IF)) {
> -         format(file, " %d %d", brw_inst_uip(brw, inst),
> -                brw_inst_jip(brw, inst));
> -      } else if (opcode == BRW_OPCODE_JMPI) {
> -         format(file, " %d", brw_inst_imm_d(brw, inst));
>        }
>  
>        if (opcode_descs[opcode].nsrc > 0) {
>           pad(file, 32);
>           err |= src0(file, brw, inst);
>        }
> +
>        if (opcode_descs[opcode].nsrc > 1) {
>           pad(file, 48);
>           err |= src1(file, brw, inst);
> -- 
> 2.0.0
> 
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