i965/vs: Keep track of indices into a per-register array for virtual GRFs.

Tracking virtual GRFs has tension between using a packed array per
virtual GRF (which is good for register allocation), and sparse arrays
where there's an element per actual register (so the first and second
column of a mat2 can be distinguished inside of an optimization pass).

The FS mostly avoided the need for this second sparse array by doing
virtual GRF splitting, but that meant that instances where virtual GRF
splitting didn't work, instructions using those registers got much
less optimized.

diff --git a/src/mesa/drivers/dri/i965/brw_vec4.h b/src/mesa/drivers/dri/i965/brw_vec4.h
index 1597f983f2faf205f94911a63f5fbcec533a39f8..f148ca62cd5bd897ef0fc895580d0cd151cca303 100644 (file)
--- a/src/mesa/drivers/dri/i965/brw_vec4.h
+++ b/src/mesa/drivers/dri/i965/brw_vec4.h
@@ -320,6 +320,15 @@ public:
    int first_non_payload_grf;
    int *virtual_grf_def;
    int *virtual_grf_use;
+
+   /**
+    * This is the size to be used for an array with an element per
+    * reg_offset
+    */
+   int virtual_grf_reg_count;
+   /** Per-virtual-grf indices into an array of size virtual_grf_reg_count */
+   int *virtual_grf_reg_map;
+
    bool live_intervals_valid;
 
    dst_reg *variable_storage(ir_variable *var);

diff --git a/src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp b/src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp
index c50a722b0f424c859662b41429764b57e70fe8c5..83f543f6f41bc2110a4398ad0fabc83766911c52 100644 (file)
--- a/src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp
+++ b/src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp
@@ -432,7 +432,11 @@ vec4_visitor::virtual_grf_alloc(int size)
         virtual_grf_array_size *= 2;
       virtual_grf_sizes = reralloc(mem_ctx, virtual_grf_sizes, int,
                                   virtual_grf_array_size);
+      virtual_grf_reg_map = reralloc(mem_ctx, virtual_grf_reg_map, int,
+                                    virtual_grf_array_size);
    }
+   virtual_grf_reg_map[virtual_grf_count] = virtual_grf_reg_count;
+   virtual_grf_reg_count += size;
    virtual_grf_sizes[virtual_grf_count] = size;
    return virtual_grf_count++;
 }
@@ -2272,6 +2276,8 @@ vec4_visitor::vec4_visitor(struct brw_vs_compile *c,
    this->virtual_grf_use = NULL;
    this->virtual_grf_sizes = NULL;
    this->virtual_grf_count = 0;
+   this->virtual_grf_reg_map = NULL;
+   this->virtual_grf_reg_count = 0;
    this->virtual_grf_array_size = 0;
    this->live_intervals_valid = false;