[Mesa-dev] [PATCH] glsl/cse: Maintain a list of free ae_entry objects

[Kenneth Graunke]

On Thursday, March 26, 2015 08:52:33 PM Ian Romanick wrote:
> From: Ian Romanick <ian.d.romanick at intel.com>
> 
> The CSE algorithm will continuously allocate new ae_entry objects.  As
> each new basic block is exited, all of the previously allocated objects
> are dumped.  Instead, put them in a free list and re-use them in the
> next basic block.  Reduce, reuse, recycle!
> 
> Signed-off-by: Ian Romanick <ian.d.romanick at intel.com>
> Cc: Jordan Justen <jordan.l.justen at intel.com>
> 
> ---
>  src/glsl/opt_cse.cpp | 63 
+++++++++++++++++++++++++++++++++++++++++++++-------
>  1 file changed, 55 insertions(+), 8 deletions(-)
> 
> diff --git a/src/glsl/opt_cse.cpp b/src/glsl/opt_cse.cpp
> index 623268e..425eebc 100644
> --- a/src/glsl/opt_cse.cpp
> +++ b/src/glsl/opt_cse.cpp
> @@ -63,6 +63,17 @@ public:
>        var = NULL;
>     }
>  
> +   void init(ir_instruction *base_ir, ir_rvalue **val)
> +   {
> +      this->val = val;
> +      this->base_ir = base_ir;
> +      this->var = NULL;
> +
> +      assert(val);
> +      assert(*val);
> +      assert(base_ir);
> +   }
> +
>     /**
>      * The pointer to the expression that we might be able to reuse
>      *
> @@ -116,6 +127,18 @@ private:
>     ir_rvalue *try_cse(ir_rvalue *rvalue);
>     void add_to_ae(ir_rvalue **rvalue);
>  
> +   /**
> +    * Move all nodes from the ae list to the free list
> +    */
> +   void empty_ae_list();
> +
> +   /**
> +    * Get and initialize a new ae_entry
> +    *
> +    * This will either come from the free list or be freshly allocated.
> +    */
> +   ae_entry *get_ae_entry(ir_rvalue **rvalue);
> +
>     /** List of ae_entry: The available expressions to reuse */
>     exec_list *ae;
>  
> @@ -126,6 +149,11 @@ private:
>      * right.
>      */
>     exec_list *validate_instructions;
> +
> +   /**
> +    * List of available-for-use ae_entry objects.
> +    */
> +   exec_list free_ae_entries;
>  };
>  
>  /**
> @@ -322,6 +350,25 @@ cse_visitor::try_cse(ir_rvalue *rvalue)
>     return NULL;
>  }
>  
> +void
> +cse_visitor::empty_ae_list()
> +{
> +   free_ae_entries.append_list(ae);

If you're just trying to save memory...it sure looks like you can just
ralloc_free(mem_ctx); mem_ctx = ralloc_context(NULL) here.  Which would
be much simpler.

But I suppose this does reduce the number of malloc calls considerably,
so it's probably more efficient.

> +}
> +
> +ae_entry *
> +cse_visitor::get_ae_entry(ir_rvalue **rvalue)
> +{
> +   ae_entry *entry = (ae_entry *) free_ae_entries.pop_head();
> +   if (entry) {
> +      entry->init(base_ir, rvalue);
> +   } else {
> +      entry = new(mem_ctx) ae_entry(base_ir, rvalue);
> +   }
> +
> +   return entry;
> +}
> +
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