[Mesa-dev] [PATCH 27/57] i965/vec4: Drop backend_reg::in_range() in favor of regions_overlap().

Iago Toral itoral at igalia.com
Fri Sep 9 08:42:06 UTC 2016


On Wed, 2016-09-07 at 18:48 -0700, Francisco Jerez wrote:
> This makes sure that overlap checks are done correctly throughout the
> back-end when the '*this' register starts before the register/size
> pair provided as argument, and is actually less annoying to use than
> in_range() at this point since regions_overlap() takes its size
> arguments in bytes.
> ---
>  src/mesa/drivers/dri/i965/brw_shader.cpp                |  9 -----
> ----
>  src/mesa/drivers/dri/i965/brw_shader.h                  |  1 -
>  src/mesa/drivers/dri/i965/brw_vec4.cpp                  | 14
> ++++++++------
>  src/mesa/drivers/dri/i965/brw_vec4_cmod_propagation.cpp |  4 ++--
>  src/mesa/drivers/dri/i965/brw_vec4_copy_propagation.cpp |  4 ++--
>  5 files changed, 12 insertions(+), 20 deletions(-)
> 
> diff --git a/src/mesa/drivers/dri/i965/brw_shader.cpp
> b/src/mesa/drivers/dri/i965/brw_shader.cpp
> index e599235..951e6b2 100644
> --- a/src/mesa/drivers/dri/i965/brw_shader.cpp
> +++ b/src/mesa/drivers/dri/i965/brw_shader.cpp
> @@ -745,15 +745,6 @@ backend_reg::is_accumulator() const
>  }
>  
>  bool
> -backend_reg::in_range(const backend_reg &r, unsigned n) const
> -{
> -   return (file == r.file &&
> -           nr == r.nr &&
> -           offset >= r.offset &&
> -           offset < r.offset + n * REG_SIZE);
> -}
> -
> -bool
>  backend_instruction::is_commutative() const
>  {
>     switch (opcode) {
> diff --git a/src/mesa/drivers/dri/i965/brw_shader.h
> b/src/mesa/drivers/dri/i965/brw_shader.h
> index 0de0808..ba2404a 100644
> --- a/src/mesa/drivers/dri/i965/brw_shader.h
> +++ b/src/mesa/drivers/dri/i965/brw_shader.h
> @@ -62,7 +62,6 @@ struct backend_reg : private brw_reg
>     bool is_negative_one() const;
>     bool is_null() const;
>     bool is_accumulator() const;
> -   bool in_range(const backend_reg &r, unsigned n) const;
>  
>     /** Offset from the start of the (virtual) register in bytes. */
>     uint16_t offset;
> diff --git a/src/mesa/drivers/dri/i965/brw_vec4.cpp
> b/src/mesa/drivers/dri/i965/brw_vec4.cpp
> index 561170c..eb2888f 100644
> --- a/src/mesa/drivers/dri/i965/brw_vec4.cpp
> +++ b/src/mesa/drivers/dri/i965/brw_vec4.cpp
> @@ -1143,7 +1143,8 @@ vec4_visitor::opt_register_coalesce()
>                                                    inst) {
>           _scan_inst = scan_inst;
>  
> -         if (inst->src[0].in_range(scan_inst->dst,
> DIV_ROUND_UP(scan_inst->size_written, REG_SIZE))) {
> +         if (regions_overlap(inst->src[0], inst->size_read(0),
> +                             scan_inst->dst, scan_inst-
> >size_written)) {
>              /* Found something writing to the reg we want to
> coalesce away. */
>              if (to_mrf) {
>                 /* SEND instructions can't have MRF as a destination.
> */
> @@ -1197,8 +1198,8 @@ vec4_visitor::opt_register_coalesce()
>            */
>  	 bool interfered = false;
>  	 for (int i = 0; i < 3; i++) {
> -            if (inst->src[0].in_range(scan_inst->src[i],
> -                                      DIV_ROUND_UP(scan_inst-
> >size_read(i), REG_SIZE)))
> +            if (regions_overlap(inst->src[0], inst->size_read(0),
> +                                scan_inst->src[i], scan_inst-
> >size_read(i)))
>  	       interfered = true;
>  	 }
>  	 if (interfered)
> @@ -1207,7 +1208,8 @@ vec4_visitor::opt_register_coalesce()
>           /* If somebody else writes the same channels of our
> destination here,
>            * we can't coalesce before that.
>            */
> -         if (inst->dst.in_range(scan_inst->dst,
> DIV_ROUND_UP(scan_inst->size_written, REG_SIZE)) &&
> +         if (regions_overlap(inst->dst, inst->size_written,
> +                             scan_inst->dst, scan_inst-
> >size_written) &&
>               (inst->dst.writemask & scan_inst->dst.writemask) != 0)
> {
>              break;
>           }
> @@ -1223,8 +1225,8 @@ vec4_visitor::opt_register_coalesce()
>              }
>           } else {
>              for (int i = 0; i < 3; i++) {
> -               if (inst->dst.in_range(scan_inst->src[i],
> -                                      DIV_ROUND_UP(scan_inst-
> >size_read(i), REG_SIZE)))
> +               if (regions_overlap(inst->dst, inst->size_written,
> +                                   scan_inst->src[i], scan_inst-
> >size_read(i)))
>                    interfered = true;
>              }
>              if (interfered)
> diff --git a/src/mesa/drivers/dri/i965/brw_vec4_cmod_propagation.cpp
> b/src/mesa/drivers/dri/i965/brw_vec4_cmod_propagation.cpp
> index e74bc15..9977317 100644
> --- a/src/mesa/drivers/dri/i965/brw_vec4_cmod_propagation.cpp
> +++ b/src/mesa/drivers/dri/i965/brw_vec4_cmod_propagation.cpp
> @@ -68,8 +68,8 @@ opt_cmod_propagation_local(bblock_t *block)
>  
>        bool read_flag = false;
>        foreach_inst_in_block_reverse_starting_from(vec4_instruction,
> scan_inst, inst) {
> -         if (inst->src[0].in_range(scan_inst->dst,
> -                                   DIV_ROUND_UP(scan_inst-
> >size_written, REG_SIZE))) {
> +         if (regions_overlap(inst->src[0], inst->size_read(0),
> +                             scan_inst->dst, scan_inst-
> >size_written)) {
>              if ((scan_inst->predicate && scan_inst->opcode !=
> BRW_OPCODE_SEL) ||
>                  scan_inst->dst.offset / REG_SIZE != inst-
> >src[0].offset / REG_SIZE ||
>                  (scan_inst->dst.writemask != WRITEMASK_X &&
> diff --git a/src/mesa/drivers/dri/i965/brw_vec4_copy_propagation.cpp
> b/src/mesa/drivers/dri/i965/brw_vec4_copy_propagation.cpp
> index 777d252..fe76dea 100644
> --- a/src/mesa/drivers/dri/i965/brw_vec4_copy_propagation.cpp
> +++ b/src/mesa/drivers/dri/i965/brw_vec4_copy_propagation.cpp
> @@ -72,8 +72,8 @@ is_channel_updated(vec4_instruction *inst, src_reg
> *values[4], int ch)
>     if (!src || src->file != VGRF)
>        return false;
>  
> -   return (src->in_range(inst->dst, DIV_ROUND_UP(inst->size_written, 
> REG_SIZE)) &&
> -           inst->dst.writemask & (1 << BRW_GET_SWZ(src->swizzle,
> ch)));
> +   return regions_overlap(*src, REG_SIZE, inst->dst, inst-
> >size_written) &&
> +          inst->dst.writemask & (1 << BRW_GET_SWZ(src->swizzle,
> ch));

I suppose this (assuming that src always reads REG_SIZE) can be bogus,
at least for fp64 programs, right? In any case, this would not be a
problem introduced by this patch since the previous implementation
would fail in the same case.

If I am right, then I suppose that in order to fix this we would need
to store the real size read for each value in copy_entry.

>  }
>  
>  static bool


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