[Mesa-dev] [PATCH] mesa: Replace the EmitNoIfs compiler flag with a MaxIfLevel flag.

[Ian Romanick]

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On 08/31/2011 03:30 PM, Bryan Cain wrote:
> This is a better, more fine-grained way of lowering if statements.  Fixes the
> game And Yet It Moves on nv50.

Other than the one comment below,

Reviewed-by: Ian Romanick <ian.d.romanick at intel.com>

> ---
>  src/mesa/drivers/dri/i915/i915_context.c   |    2 +-
>  src/mesa/main/mtypes.h                     |    6 +-----
>  src/mesa/program/ir_to_mesa.cpp            |    8 ++++----
>  src/mesa/state_tracker/st_extensions.c     |    2 +-
>  src/mesa/state_tracker/st_glsl_to_tgsi.cpp |    6 +++---
>  5 files changed, 10 insertions(+), 14 deletions(-)
> 
> diff --git a/src/mesa/drivers/dri/i915/i915_context.c b/src/mesa/drivers/dri/i915/i915_context.c
> index 11bee14..7a40ba1 100644
> --- a/src/mesa/drivers/dri/i915/i915_context.c
> +++ b/src/mesa/drivers/dri/i915/i915_context.c
> @@ -189,7 +189,7 @@ i915CreateContext(int api,
>  
>     struct gl_shader_compiler_options *const fs_options =
>        & ctx->ShaderCompilerOptions[MESA_SHADER_FRAGMENT];
> -   fs_options->EmitNoIfs = GL_TRUE;
> +   fs_options->MaxIfLevel = 0;
>     fs_options->EmitNoNoise = GL_TRUE;
>     fs_options->EmitNoPow = GL_TRUE;
>     fs_options->EmitNoMainReturn = GL_TRUE;
> diff --git a/src/mesa/main/mtypes.h b/src/mesa/main/mtypes.h
> index f2eb889..9f95bcd 100644
> --- a/src/mesa/main/mtypes.h
> +++ b/src/mesa/main/mtypes.h
> @@ -2266,11 +2266,6 @@ struct gl_shader_compiler_options
>     /** Driver-selectable options: */
>     GLboolean EmitCondCodes;             /**< Use condition codes? */
>     GLboolean EmitNVTempInitialization;  /**< 0-fill NV temp registers */
> -   /**
> -    * Attempts to flatten all ir_if (OPCODE_IF) for GPUs that can't
> -    * support control flow.
> -    */
> -   GLboolean EmitNoIfs;
>     GLboolean EmitNoLoops;
>     GLboolean EmitNoFunctions;
>     GLboolean EmitNoCont;                  /**< Emit CONT opcode? */
> @@ -2288,6 +2283,7 @@ struct gl_shader_compiler_options
>     GLboolean EmitNoIndirectUniform; /**< No indirect addressing of constants */
>     /*@}*/
>  
> +   GLuint MaxIfLevel;               /**< Maximum nested IF blocks */

I'd call this MaxIfDepth to match the lower_if_to_cond_assign parameter.

>     GLuint MaxUnrollIterations;
>  
>     struct gl_sl_pragmas DefaultPragmas; /**< Default #pragma settings */
> diff --git a/src/mesa/program/ir_to_mesa.cpp b/src/mesa/program/ir_to_mesa.cpp
> index dd154db..7fb286e 100644
> --- a/src/mesa/program/ir_to_mesa.cpp
> +++ b/src/mesa/program/ir_to_mesa.cpp
> @@ -3119,7 +3119,7 @@ get_mesa_program(struct gl_context *ctx,
>  
>        switch (mesa_inst->Opcode) {
>        case OPCODE_IF:
> -	 if (options->EmitNoIfs) {
> +	 if (options->MaxIfLevel == 0) {
>  	    linker_warning(shader_program,
>  			   "Couldn't flatten if-statement.  "
>  			   "This will likely result in software "
> @@ -3241,10 +3241,10 @@ _mesa_ir_link_shader(struct gl_context *ctx, struct gl_shader_program *prog)
>  
>  	 progress = lower_quadop_vector(ir, true) || progress;
>  
> -	 if (options->EmitNoIfs) {
> +	 if (options->MaxIfLevel == 0)
>  	    progress = lower_discard(ir) || progress;
> -	    progress = lower_if_to_cond_assign(ir) || progress;
> -	 }
> +	 
> +	 progress = lower_if_to_cond_assign(ir, options->MaxIfLevel) || progress;
>  
>  	 if (options->EmitNoNoise)
>  	    progress = lower_noise(ir) || progress;
> diff --git a/src/mesa/state_tracker/st_extensions.c b/src/mesa/state_tracker/st_extensions.c
> index 8e90093..9f429d9 100644
> --- a/src/mesa/state_tracker/st_extensions.c
> +++ b/src/mesa/state_tracker/st_extensions.c
> @@ -173,7 +173,7 @@ void st_init_limits(struct st_context *st)
>        options->EmitNoNoise = TRUE;
>  
>        /* TODO: make these more fine-grained if anyone needs it */
> -      options->EmitNoIfs = !screen->get_shader_param(screen, sh, PIPE_SHADER_CAP_MAX_CONTROL_FLOW_DEPTH);
> +      options->MaxIfLevel = screen->get_shader_param(screen, sh, PIPE_SHADER_CAP_MAX_CONTROL_FLOW_DEPTH);
>        options->EmitNoLoops = !screen->get_shader_param(screen, sh, PIPE_SHADER_CAP_MAX_CONTROL_FLOW_DEPTH);
>        options->EmitNoFunctions = !screen->get_shader_param(screen, sh, PIPE_SHADER_CAP_SUBROUTINES);
>        options->EmitNoMainReturn = !screen->get_shader_param(screen, sh, PIPE_SHADER_CAP_SUBROUTINES);
> diff --git a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
> index 98bea69..f5232af 100644
> --- a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
> +++ b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
> @@ -4991,10 +4991,10 @@ st_link_shader(struct gl_context *ctx, struct gl_shader_program *prog)
>  
>           progress = lower_quadop_vector(ir, false) || progress;
>  
> -         if (options->EmitNoIfs) {
> +         if (options->MaxIfLevel == 0)
>              progress = lower_discard(ir) || progress;
> -            progress = lower_if_to_cond_assign(ir) || progress;
> -         }
> +
> +         progress = lower_if_to_cond_assign(ir, options->MaxIfLevel) || progress;
>  
>           if (options->EmitNoNoise)
>              progress = lower_noise(ir) || progress;

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