i965: check-point commit of new constant buffer support

Currently, shader constants are stored in the GRF (loaded from the CURBE
prior to shader execution).  This severly limits the number of constants
and temps that we can support.

This new code will support (practically) unlimited size constant buffers
and free up registers in the GRF.  We allocate a new buffer object for the
constants and read them with "Read" messages/instructions.  When only a
small number of constants are used, we can still use the old method.

The code works for fragment shaders only (and is actually disabled) for now.
Need to do the same thing for vertex shaders and need to add the necessary
code-gen to fetch the constants which are referenced by the shader
instructions.

1 files changed, 108 insertions, 25 deletions

diff --git a/src/mesa/drivers/dri/i965/brw_wm_glsl.c b/src/mesa/drivers/dri/i965/brw_wm_glsl.c
index 67ba59c3252..28ef84e4aac 100644
--- a/src/mesa/drivers/dri/i965/brw_wm_glsl.c
+++ b/src/mesa/drivers/dri/i965/brw_wm_glsl.c
@@ -192,28 +192,41 @@ static void prealloc_reg(struct brw_wm_compile *c)
     /* constants */
     {
         const int nr_params = c->fp->program.Base.Parameters->NumParameters;
-        const struct gl_program_parameter_list *plist = 
-	    c->fp->program.Base.Parameters;
-	int index = 0;
-
-        /* number of float constants */
-	c->prog_data.nr_params = 4 * nr_params;
-
-        /* loop over program constants (float[4]) */
-	for (i = 0; i < nr_params; i++) {
-            /* loop over XYZW channels */
-            for (j = 0; j < 4; j++, index++) {
-                reg = brw_vec1_grf(c->reg_index + index / 8, index % 8);
-                /* Save pointer to parameter/constant value.
-                 * Constants will be copied in prepare_constant_buffer()
-                 */
-                c->prog_data.param[index] = &plist->ParameterValues[i][j];
-                set_reg(c, PROGRAM_STATE_VAR, i, j, reg);
-	    }
-	}
-        /* number of constant regs used (each reg is float[8]) */
-	c->nr_creg = 2 * ((4 * nr_params + 15) / 16);
-	c->reg_index += c->nr_creg;
+
+        if (1 /* XXX threshold: nr_params <= 8 */) {
+           const struct gl_program_parameter_list *plist = 
+              c->fp->program.Base.Parameters;
+           int index = 0;
+
+           /* number of float constants in CURBE */
+           c->prog_data.nr_params = 4 * nr_params;
+
+           /* loop over program constants (float[4]) */
+           for (i = 0; i < nr_params; i++) {
+              /* loop over XYZW channels */
+              for (j = 0; j < 4; j++, index++) {
+                 reg = brw_vec1_grf(c->reg_index + index / 8, index % 8);
+                 /* Save pointer to parameter/constant value.
+                  * Constants will be copied in prepare_constant_buffer()
+                  */
+                 c->prog_data.param[index] = &plist->ParameterValues[i][j];
+                 set_reg(c, PROGRAM_STATE_VAR, i, j, reg);
+              }
+           }
+           /* number of constant regs used (each reg is float[8]) */
+           c->nr_creg = 2 * ((4 * nr_params + 15) / 16);
+           c->reg_index += c->nr_creg;
+        }
+        else {
+           /* number of float constants in CURBE */
+           c->prog_data.nr_params = 0;
+
+           /* When there's a lot of FP constanst we'll store them in a
+            * texture-like buffer instead of using the CURBE buffer.
+            * This means we won't use GRF registers for constants and we'll
+            * have to fetch constants with a dataport read.
+            */
+        }
     }
 
     /* fragment shader inputs */
@@ -892,6 +905,19 @@ static void emit_add(struct brw_wm_compile *c,
     brw_set_saturate(p, 0);
 }
 
+static void emit_arl(struct brw_wm_compile *c,
+                     struct prog_instruction *inst)
+{
+    struct brw_compile *p = &c->func;
+    struct brw_reg src0, addr_reg;
+    brw_set_saturate(p, (inst->SaturateMode != SATURATE_OFF) ? 1 : 0);
+    addr_reg = brw_uw8_reg(BRW_ARCHITECTURE_REGISTER_FILE, 
+                           BRW_ARF_ADDRESS, 0);
+    src0 = get_src_reg(c, &inst->SrcReg[0], 0); /* channel 0 */
+    brw_MOV(p, addr_reg, src0);
+    brw_set_saturate(p, 0);
+}
+
 static void emit_sub(struct brw_wm_compile *c,
 		struct prog_instruction *inst)
 {
@@ -2331,9 +2357,10 @@ static void emit_txb(struct brw_wm_compile *c,
     struct brw_compile *p = &c->func;
     struct brw_reg dst[4], src[4], payload_reg;
     GLuint unit = c->fp->program.Base.SamplerUnits[inst->TexSrcUnit];
-
     GLuint i;
+
     payload_reg = get_reg(c, PROGRAM_PAYLOAD, PAYLOAD_DEPTH, 0, 1, 0, 0);
+
     for (i = 0; i < 4; i++) 
 	dst[i] = get_dst_reg(c, inst, i);
     for (i = 0; i < 4; i++)
@@ -2372,13 +2399,13 @@ static void emit_txb(struct brw_wm_compile *c,
                0);                                          /* eot */
 }
 
+
 static void emit_tex(struct brw_wm_compile *c,
 		struct prog_instruction *inst)
 {
     struct brw_compile *p = &c->func;
     struct brw_reg dst[4], src[4], payload_reg;
     GLuint unit = c->fp->program.Base.SamplerUnits[inst->TexSrcUnit];
-
     GLuint msg_len;
     GLuint i, nr;
     GLuint emit;
@@ -2419,7 +2446,7 @@ static void emit_tex(struct brw_wm_compile *c,
     }
 
     if (shadow) {
-       brw_MOV(p, brw_message_reg(5), brw_imm_f(0));  /* lod / bais */
+       brw_MOV(p, brw_message_reg(5), brw_imm_f(0));  /* lod / bias */
        brw_MOV(p, brw_message_reg(6), src[2]);        /* ref value / R coord */
     }
 
@@ -2439,6 +2466,49 @@ static void emit_tex(struct brw_wm_compile *c,
 	brw_MOV(p, dst[3], brw_imm_f(1.0));
 }
 
+
+static void emit_get_constant(struct brw_context *brw,
+                              struct brw_wm_compile *c,
+                              struct prog_instruction *inst,
+                              GLuint constIndex)
+{
+   struct brw_compile *p = &c->func;
+   struct brw_reg dst[4];
+   GLuint i;
+   const int mark = mark_tmps( c );
+   struct brw_reg writeback_reg[4];
+
+   /* XXX only need 1 temp reg??? */
+   for (i = 0; i < 4; i++) {
+      writeback_reg[i] = alloc_tmp(c);
+   }
+
+   for (i = 0; i < 4; i++) {
+      dst[i] = get_dst_reg(c, inst, i);
+   }
+
+   /* Get float[4] vector from constant buffer */
+   brw_dp_READ_4(p,
+                 writeback_reg[0],     /* first writeback dest */
+                 1,                    /* msg_reg */
+                 GL_FALSE,             /* rel addr? */
+                 16 * constIndex,      /* byte offset */
+                 BRW_WM_MAX_SURF - 1   /* surface, binding table index */
+                 );
+
+   /* Extract the four channel values, smear across dest registers */
+   for (i = 0; i < 4; i++) {
+      /* extract 1 float from the writeback reg */
+      struct brw_reg new_src = stride(writeback_reg[0], 0, 1, 0);
+      new_src.subnr = i * 4;
+      /* and smear it into the dest register */
+      brw_MOV(p, dst[i], new_src);
+   }
+
+   release_tmps( c, mark );
+}
+
+
 /**
  * Resolve subroutine calls after code emit is done.
  */
@@ -2504,6 +2574,9 @@ static void brw_wm_emit_glsl(struct brw_context *brw, struct brw_wm_compile *c)
 	    case OPCODE_ADD:
 		emit_add(c, inst);
 		break;
+	    case OPCODE_ARL:
+		emit_arl(c, inst);
+		break;
 	    case OPCODE_SUB:
 		emit_sub(c, inst);
 		break;
@@ -2520,7 +2593,17 @@ static void brw_wm_emit_glsl(struct brw_context *brw, struct brw_wm_compile *c)
 		emit_trunc(c, inst);
 		break;
 	    case OPCODE_MOV:
+#if 0
+                /* test hook for new constant buffer code */
+                if (inst->SrcReg[0].File == PROGRAM_UNIFORM) {
+                   emit_get_constant(brw, c, inst, inst->SrcReg[0].Index);
+                }
+                else {
+                   emit_mov(c, inst);
+                }
+#else
 		emit_mov(c, inst);
+#endif
 		break;
 	    case OPCODE_DP3:
 		emit_dp3(c, inst);