Mesa (master): i965/vec4: Use the actual channels used in pack_uniform_registers

[Jason Ekstrand]

Module: Mesa
Branch: master
Commit: ea35fb0fbead2902b1ba37e7cdb1523853fabd8b
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=ea35fb0fbead2902b1ba37e7cdb1523853fabd8b

Author: Jason Ekstrand <jason.ekstrand at intel.com>
Date:   Wed Sep 30 10:31:03 2015 -0700

i965/vec4: Use the actual channels used in pack_uniform_registers

Previously, pack_uniform_registers worked based on the size of the uniform
as given to us when we initially set up the uniforms.  However, we have to
walk through the uniforms and figure out liveness anyway, so we migh as
well record the number of channels used as we go.  This may also allow us
to pack things tighter in a few cases.

Reviewed-by: Iago Toral Quiroga <itoral at igalia.com>

---

 src/mesa/drivers/dri/i965/brw_vec4.cpp |   51 +++++++++++++++++++++++---------
 1 file changed, 37 insertions(+), 14 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/brw_vec4.cpp b/src/mesa/drivers/dri/i965/brw_vec4.cpp
index 407698f..057537e 100644
--- a/src/mesa/drivers/dri/i965/brw_vec4.cpp
+++ b/src/mesa/drivers/dri/i965/brw_vec4.cpp
@@ -518,11 +518,11 @@ vec4_visitor::split_uniform_registers()
 void
 vec4_visitor::pack_uniform_registers()
 {
-   bool uniform_used[this->uniforms];
+   uint8_t chans_used[this->uniforms];
    int new_loc[this->uniforms];
    int new_chan[this->uniforms];
 
-   memset(uniform_used, 0, sizeof(uniform_used));
+   memset(chans_used, 0, sizeof(chans_used));
    memset(new_loc, 0, sizeof(new_loc));
    memset(new_chan, 0, sizeof(new_chan));
 
@@ -531,11 +531,36 @@ vec4_visitor::pack_uniform_registers()
     * to pull constants, and from some GLSL code generators like wine.
     */
    foreach_block_and_inst(block, vec4_instruction, inst, cfg) {
+      unsigned readmask;
+      switch (inst->opcode) {
+      case VEC4_OPCODE_PACK_BYTES:
+      case BRW_OPCODE_DP4:
+      case BRW_OPCODE_DPH:
+         readmask = 0xf;
+         break;
+      case BRW_OPCODE_DP3:
+         readmask = 0x7;
+         break;
+      case BRW_OPCODE_DP2:
+         readmask = 0x3;
+         break;
+      default:
+         readmask = inst->dst.writemask;
+         break;
+      }
+
       for (int i = 0 ; i < 3; i++) {
-	 if (inst->src[i].file != UNIFORM)
-	    continue;
+         if (inst->src[i].file != UNIFORM)
+            continue;
 
-	 uniform_used[inst->src[i].reg] = true;
+         int reg = inst->src[i].reg;
+         for (int c = 0; c < 4; c++) {
+            if (!(readmask & (1 << c)))
+               continue;
+
+            chans_used[reg] = MAX2(chans_used[reg],
+                                   BRW_GET_SWZ(inst->src[i].swizzle, c) + 1);
+         }
       }
    }
 
@@ -546,17 +571,15 @@ vec4_visitor::pack_uniform_registers()
     */
    for (int src = 0; src < uniforms; src++) {
       assert(src < uniform_array_size);
-      int size = this->uniform_vector_size[src];
+      int size = chans_used[src];
 
-      if (!uniform_used[src]) {
-	 this->uniform_vector_size[src] = 0;
-	 continue;
-      }
+      if (size == 0)
+         continue;
 
       int dst;
       /* Find the lowest place we can slot this uniform in. */
       for (dst = 0; dst < src; dst++) {
-	 if (this->uniform_vector_size[dst] + size <= 4)
+	 if (chans_used[dst] + size <= 4)
 	    break;
       }
 
@@ -565,7 +588,7 @@ vec4_visitor::pack_uniform_registers()
 	 new_chan[src] = 0;
       } else {
 	 new_loc[src] = dst;
-	 new_chan[src] = this->uniform_vector_size[dst];
+	 new_chan[src] = chans_used[dst];
 
 	 /* Move the references to the data */
 	 for (int j = 0; j < size; j++) {
@@ -573,8 +596,8 @@ vec4_visitor::pack_uniform_registers()
 	       stage_prog_data->param[src * 4 + j];
 	 }
 
-	 this->uniform_vector_size[dst] += size;
-	 this->uniform_vector_size[src] = 0;
+	 chans_used[dst] += size;
+	 chans_used[src] = 0;
       }
 
       new_uniform_count = MAX2(new_uniform_count, dst + 1);