i965/vs: add support for ir_txf_ms on Gen6+

On Gen6, lower this to `ld` with lod=0 and an extra sample_index
parameter.

On Gen7, use `ld2dms`. This takes an additional MCS parameter to support
compressed multisample surfaces, but we're not enabling them for
multisample textures for now, so it's always ignored and can be safely
omitted.

V2: Reworked completely, added support for Gen7.
V3: - Use new sample_index, sample_index_type rather than reusing lod
    - Clarify commit message.
V4: - Fix comment style

Signed-off-by: Chris Forbes <[email protected]>
Reviewed-by: Eric Anholt <[email protected]>

1 files changed, 21 insertions, 4 deletions

diff --git a/src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp b/src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp
index a2bc9f50a74..32de82b11f3 100644
--- a/src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp
+++ b/src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp
@@ -2098,8 +2098,8 @@ vec4_visitor::visit(ir_texture *ir)
       shadow_comparitor = this->result;
    }
 
-   const glsl_type *lod_type;
-   src_reg lod, dPdx, dPdy;
+   const glsl_type *lod_type, *sample_index_type;
+   src_reg lod, dPdx, dPdy, sample_index;
    switch (ir->op) {
    case ir_tex:
       lod = src_reg(0.0f);
@@ -2112,6 +2112,11 @@ vec4_visitor::visit(ir_texture *ir)
       lod = this->result;
       lod_type = ir->lod_info.lod->type;
       break;
+   case ir_txf_ms:
+      ir->lod_info.sample_index->accept(this);
+      sample_index = this->result;
+      sample_index_type = ir->lod_info.sample_index->type;
+      break;
    case ir_txd:
       ir->lod_info.grad.dPdx->accept(this);
       dPdx = this->result;
@@ -2137,6 +2142,9 @@ vec4_visitor::visit(ir_texture *ir)
    case ir_txf:
       inst = new(mem_ctx) vec4_instruction(this, SHADER_OPCODE_TXF);
       break;
+   case ir_txf_ms:
+      inst = new(mem_ctx) vec4_instruction(this, SHADER_OPCODE_TXF_MS);
+      break;
    case ir_txs:
       inst = new(mem_ctx) vec4_instruction(this, SHADER_OPCODE_TXS);
       break;
@@ -2223,8 +2231,17 @@ vec4_visitor::visit(ir_texture *ir)
 	 }
 	 emit(MOV(dst_reg(MRF, mrf, lod_type, writemask), lod));
       } else if (ir->op == ir_txf) {
-	 emit(MOV(dst_reg(MRF, param_base, lod_type, WRITEMASK_W),
-		  lod));
+         emit(MOV(dst_reg(MRF, param_base, lod_type, WRITEMASK_W), lod));
+      } else if (ir->op == ir_txf_ms) {
+         emit(MOV(dst_reg(MRF, param_base + 1, sample_index_type, WRITEMASK_X),
+                  sample_index));
+         inst->mlen++;
+
+         /* on Gen7, there is an additional MCS parameter here after SI,
+          * but we don't bother to emit it since it's always zero. If
+          * we start supporting texturing from CMS surfaces, this will have
+          * to change
+          */
       } else if (ir->op == ir_txd) {
 	 const glsl_type *type = lod_type;