[Mesa-dev] [PATCH 04/11] i965/vec4: Use the actual channels used in pack_uniform_registers

[Jason Ekstrand]

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.
---
 src/mesa/drivers/dri/i965/brw_vec4.cpp | 52 +++++++++++++++++++++++++---------
 1 file changed, 38 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..f0fa07e 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));
 
@@ -532,10 +532,36 @@ vec4_visitor::pack_uniform_registers()
     */
    foreach_block_and_inst(block, vec4_instruction, inst, cfg) {
       for (int i = 0 ; i < 3; i++) {
-	 if (inst->src[i].file != UNIFORM)
-	    continue;
+         if (inst->src[i].file != UNIFORM)
+            continue;
+
+         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;
+         }
+
+         int reg = inst->src[i].reg;
+
+         for (int c = 0; c < 4; c++) {
+            if (!(readmask & (1 << c)))
+               continue;
 
-	 uniform_used[inst->src[i].reg] = true;
+            chans_used[reg] = MAX2(chans_used[reg],
+                                   BRW_GET_SWZ(inst->src[i].swizzle, c) + 1);
+         }
       }
    }
 
@@ -546,17 +572,15 @@ 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 +589,7 @@ 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 +597,8 @@ 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);
-- 
2.5.0.400.gff86faf