[PATCH vkd3d 1/7] vkd3d-shader/hlsl: Use last_read for resource loads.

[Giovanni Mascellani]

Signed-off-by: Giovanni Mascellani <gmascellani at codeweavers.com>
---
I would suggest to write commit messages in a more terse way, though: 
they can be useful not only for future developers looking at the 
evolution of some feature, but also to people who try to learn about the 
code and might not know what "DCE" stands for (note that a search engine 
might not necessarily help a lot: "DCE" stands for many different 
things; knowing that it is "Dead Code Elimination" quickly leads to a 
useful Wikipedia article). In general, I think it's useful to err on the 
side of verbosity in commit messages.

Il 15/10/21 23:54, Zebediah Figura ha scritto:
> This fixes DCE.
> 
> Signed-off-by: Zebediah Figura <zfigura at codeweavers.com>
> ---
> I'm sure I had a reason for using a separate field here, but I can't remember
> it now, nor find any reason why it would matter.
> 
>   libs/vkd3d-shader/hlsl.h         |  1 -
>   libs/vkd3d-shader/hlsl_codegen.c | 14 +++++++-------
>   2 files changed, 7 insertions(+), 8 deletions(-)
> 
> diff --git a/libs/vkd3d-shader/hlsl.h b/libs/vkd3d-shader/hlsl.h
> index 31b7ddbb6..93191e56b 100644
> --- a/libs/vkd3d-shader/hlsl.h
> +++ b/libs/vkd3d-shader/hlsl.h
> @@ -240,7 +240,6 @@ struct hlsl_ir_var
>       uint32_t is_output_semantic : 1;
>       uint32_t is_uniform : 1;
>       uint32_t is_param : 1;
> -    uint32_t has_resource_access : 1;
>   };
>   
>   struct hlsl_ir_function
> diff --git a/libs/vkd3d-shader/hlsl_codegen.c b/libs/vkd3d-shader/hlsl_codegen.c
> index bf93a03df..b7b0cd1b8 100644
> --- a/libs/vkd3d-shader/hlsl_codegen.c
> +++ b/libs/vkd3d-shader/hlsl_codegen.c
> @@ -591,6 +591,8 @@ static void compute_liveness_recurse(struct list *instrs, unsigned int loop_firs
>   
>       LIST_FOR_EACH_ENTRY(instr, instrs, struct hlsl_ir_node, entry)
>       {
> +        const unsigned int var_last_read = loop_last ? max(instr->index, loop_last) : instr->index;
> +
>           switch (instr->type)
>           {
>           case HLSL_IR_STORE:
> @@ -628,7 +630,7 @@ static void compute_liveness_recurse(struct list *instrs, unsigned int loop_firs
>               struct hlsl_ir_load *load = hlsl_ir_load(instr);
>   
>               var = load->src.var;
> -            var->last_read = max(var->last_read, loop_last ? max(instr->index, loop_last) : instr->index);
> +            var->last_read = max(var->last_read, var_last_read);
>               if (load->src.offset.node)
>                   load->src.offset.node->last_read = instr->index;
>               break;
> @@ -645,7 +647,8 @@ static void compute_liveness_recurse(struct list *instrs, unsigned int loop_firs
>           {
>               struct hlsl_ir_resource_load *load = hlsl_ir_resource_load(instr);
>   
> -            load->resource.var->has_resource_access = 1;
> +            var = load->resource.var;
> +            var->last_read = max(var->last_read, var_last_read);
>               if (load->resource.offset.node)
>                   load->resource.offset.node->last_read = instr->index;
>               load->coords.node->last_read = instr->index;
> @@ -676,10 +679,7 @@ static void compute_liveness(struct hlsl_ctx *ctx, struct hlsl_ir_function_decl
>       LIST_FOR_EACH_ENTRY(scope, &ctx->scopes, struct hlsl_scope, entry)
>       {
>           LIST_FOR_EACH_ENTRY(var, &scope->vars, struct hlsl_ir_var, scope_entry)
> -        {
>               var->first_write = var->last_read = 0;
> -            var->has_resource_access = 0;
> -        }
>       }
>   
>       LIST_FOR_EACH_ENTRY(var, &ctx->extern_vars, struct hlsl_ir_var, extern_entry)
> @@ -1203,7 +1203,7 @@ static const struct hlsl_ir_var *get_reserved_texture(struct hlsl_ctx *ctx, uint
>   
>       LIST_FOR_EACH_ENTRY(var, &ctx->extern_vars, const struct hlsl_ir_var, extern_entry)
>       {
> -        if (var->has_resource_access && var->reg_reservation.type == 't' && var->reg_reservation.index == index)
> +        if (var->last_read && var->reg_reservation.type == 't' && var->reg_reservation.index == index)
>               return var;
>       }
>       return NULL;
> @@ -1216,7 +1216,7 @@ static void allocate_textures(struct hlsl_ctx *ctx)
>   
>       LIST_FOR_EACH_ENTRY(var, &ctx->extern_vars, struct hlsl_ir_var, extern_entry)
>       {
> -        if (!var->has_resource_access || var->data_type->type != HLSL_CLASS_OBJECT
> +        if (!var->last_read || var->data_type->type != HLSL_CLASS_OBJECT
>                   || var->data_type->base_type != HLSL_TYPE_TEXTURE)
>               continue;
>   
>