i965/fs/skl+: Use ld2dms_w instead of ld2dms

In order to support 16x MSAA, skl+ has a wider version of ld2dms that
takes two parameters for the MCS data. The MCS data retrieved from the
ld_mcs instruction already returns 4 or 8 registers and is documented
to return zeroes for the mcsh value when the sample count is less than
16.

v2: Use get_lowered_simd_width to fall back to SIMD8 instructions when
    the message length would be too long in SIMD16.
Reviewed-by: Ben Widawsky <ben@bwidawsk.net>

6 files changed, 60 insertions, 5 deletions

diff --git a/src/mesa/drivers/dri/i965/brw_defines.h b/src/mesa/drivers/dri/i965/brw_defines.h
index 6433cffc91..0396e13d0c 100644
--- a/src/mesa/drivers/dri/i965/brw_defines.h
+++ b/src/mesa/drivers/dri/i965/brw_defines.h
@@ -964,6 +964,8 @@ enum opcode {
    FS_OPCODE_TXB_LOGICAL,
    SHADER_OPCODE_TXF_CMS,
    SHADER_OPCODE_TXF_CMS_LOGICAL,
+   SHADER_OPCODE_TXF_CMS_W,
+   SHADER_OPCODE_TXF_CMS_W_LOGICAL,
    SHADER_OPCODE_TXF_UMS,
    SHADER_OPCODE_TXF_UMS_LOGICAL,
    SHADER_OPCODE_TXF_MCS,
@@ -1539,6 +1541,7 @@ enum brw_message_target {
 #define GEN7_SAMPLER_MESSAGE_SAMPLE_GATHER4_PO   17
 #define GEN7_SAMPLER_MESSAGE_SAMPLE_GATHER4_PO_C 18
 #define HSW_SAMPLER_MESSAGE_SAMPLE_DERIV_COMPARE 20
+#define GEN9_SAMPLER_MESSAGE_SAMPLE_LD2DMS_W     28
 #define GEN7_SAMPLER_MESSAGE_SAMPLE_LD_MCS       29
 #define GEN7_SAMPLER_MESSAGE_SAMPLE_LD2DMS       30
 #define GEN7_SAMPLER_MESSAGE_SAMPLE_LD2DSS       31
diff --git a/src/mesa/drivers/dri/i965/brw_disasm.c b/src/mesa/drivers/dri/i965/brw_disasm.c
index df74710718..fd93beaec1 100644
--- a/src/mesa/drivers/dri/i965/brw_disasm.c
+++ b/src/mesa/drivers/dri/i965/brw_disasm.c
@@ -622,6 +622,7 @@ static const char *const gen5_sampler_msg_type[] = {
    [GEN7_SAMPLER_MESSAGE_SAMPLE_GATHER4_PO]   = "gather4_po",
    [GEN7_SAMPLER_MESSAGE_SAMPLE_GATHER4_PO_C] = "gather4_po_c",
    [HSW_SAMPLER_MESSAGE_SAMPLE_DERIV_COMPARE] = "sample_d_c",
+   [GEN9_SAMPLER_MESSAGE_SAMPLE_LD2DMS_W]     = "ld2dms_w",
    [GEN7_SAMPLER_MESSAGE_SAMPLE_LD_MCS]       = "ld_mcs",
    [GEN7_SAMPLER_MESSAGE_SAMPLE_LD2DMS]       = "ld2dms",
    [GEN7_SAMPLER_MESSAGE_SAMPLE_LD2DSS]       = "ld2dss",
diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp b/src/mesa/drivers/dri/i965/brw_fs.cpp
index 4cc962613b..f529419565 100644
--- a/src/mesa/drivers/dri/i965/brw_fs.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs.cpp
@@ -717,6 +717,7 @@ fs_inst::components_read(unsigned i) const
    case SHADER_OPCODE_TXS_LOGICAL:
    case FS_OPCODE_TXB_LOGICAL:
    case SHADER_OPCODE_TXF_CMS_LOGICAL:
+   case SHADER_OPCODE_TXF_CMS_W_LOGICAL:
    case SHADER_OPCODE_TXF_UMS_LOGICAL:
    case SHADER_OPCODE_TXF_MCS_LOGICAL:
    case SHADER_OPCODE_LOD_LOGICAL:
@@ -732,6 +733,9 @@ fs_inst::components_read(unsigned i) const
       /* Texture offset. */
       else if (i == 7)
          return 2;
+      /* MCS */
+      else if (i == 5 && opcode == SHADER_OPCODE_TXF_CMS_W_LOGICAL)
+         return 2;
       else
          return 1;
 
@@ -896,6 +900,7 @@ fs_visitor::implied_mrf_writes(fs_inst *inst)
    case SHADER_OPCODE_TXD:
    case SHADER_OPCODE_TXF:
    case SHADER_OPCODE_TXF_CMS:
+   case SHADER_OPCODE_TXF_CMS_W:
    case SHADER_OPCODE_TXF_MCS:
    case SHADER_OPCODE_TG4:
    case SHADER_OPCODE_TG4_OFFSET:
@@ -3920,17 +3925,31 @@ lower_sampler_logical_send_gen7(const fs_builder &bld, fs_inst *inst, opcode op,
       coordinate_done = true;
       break;
    case SHADER_OPCODE_TXF_CMS:
+   case SHADER_OPCODE_TXF_CMS_W:
    case SHADER_OPCODE_TXF_UMS:
    case SHADER_OPCODE_TXF_MCS:
-      if (op == SHADER_OPCODE_TXF_UMS || op == SHADER_OPCODE_TXF_CMS) {
+      if (op == SHADER_OPCODE_TXF_UMS ||
+          op == SHADER_OPCODE_TXF_CMS ||
+          op == SHADER_OPCODE_TXF_CMS_W) {
          bld.MOV(retype(sources[length], BRW_REGISTER_TYPE_UD), sample_index);
          length++;
       }
 
-      if (op == SHADER_OPCODE_TXF_CMS) {
+      if (op == SHADER_OPCODE_TXF_CMS || op == SHADER_OPCODE_TXF_CMS_W) {
          /* Data from the multisample control surface. */
          bld.MOV(retype(sources[length], BRW_REGISTER_TYPE_UD), mcs);
          length++;
+
+         /* On Gen9+ we'll use ld2dms_w instead which has two registers for
+          * the MCS data.
+          */
+         if (op == SHADER_OPCODE_TXF_CMS_W) {
+            bld.MOV(retype(sources[length], BRW_REGISTER_TYPE_UD),
+                    mcs.file == IMM ?
+                    mcs :
+                    offset(mcs, bld, 1));
+            length++;
+         }
       }
 
       /* There is no offsetting for this message; just copy in the integer
@@ -4144,6 +4163,10 @@ fs_visitor::lower_logical_sends()
          lower_sampler_logical_send(ibld, inst, SHADER_OPCODE_TXF_CMS);
          break;
 
+      case SHADER_OPCODE_TXF_CMS_W_LOGICAL:
+         lower_sampler_logical_send(ibld, inst, SHADER_OPCODE_TXF_CMS_W);
+         break;
+
       case SHADER_OPCODE_TXF_UMS_LOGICAL:
          lower_sampler_logical_send(ibld, inst, SHADER_OPCODE_TXF_UMS);
          break;
@@ -4336,6 +4359,21 @@ get_lowered_simd_width(const struct brw_device_info *devinfo,
       else
          return inst->exec_size;
 
+   case SHADER_OPCODE_TXF_CMS_W_LOGICAL: {
+      /* This opcode can take up to 6 arguments which means that in some
+       * circumstances it can end up with a message that is too long in SIMD16
+       * mode.
+       */
+      const unsigned coord_components = inst->src[8].fixed_hw_reg.dw1.ud;
+      /* First three arguments are the sample index and the two arguments for
+       * the MCS data.
+       */
+      if ((coord_components + 3) * 2 > MAX_SAMPLER_MESSAGE_SIZE)
+         return 8;
+      else
+         return inst->exec_size;
+   }
+
    case SHADER_OPCODE_TYPED_ATOMIC_LOGICAL:
    case SHADER_OPCODE_TYPED_SURFACE_READ_LOGICAL:
    case SHADER_OPCODE_TYPED_SURFACE_WRITE_LOGICAL:
diff --git a/src/mesa/drivers/dri/i965/brw_fs_generator.cpp b/src/mesa/drivers/dri/i965/brw_fs_generator.cpp
index e207a77fdc..28fb620279 100644
--- a/src/mesa/drivers/dri/i965/brw_fs_generator.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs_generator.cpp
@@ -741,6 +741,10 @@ fs_generator::generate_tex(fs_inst *inst, struct brw_reg dst, struct brw_reg src
       case SHADER_OPCODE_TXF:
 	 msg_type = GEN5_SAMPLER_MESSAGE_SAMPLE_LD;
 	 break;
+      case SHADER_OPCODE_TXF_CMS_W:
+         assert(devinfo->gen >= 9);
+         msg_type = GEN9_SAMPLER_MESSAGE_SAMPLE_LD2DMS_W;
+         break;
       case SHADER_OPCODE_TXF_CMS:
          if (devinfo->gen >= 7)
             msg_type = GEN7_SAMPLER_MESSAGE_SAMPLE_LD2DMS;
@@ -2050,6 +2054,7 @@ fs_generator::generate_code(const cfg_t *cfg, int dispatch_width)
       case SHADER_OPCODE_TXD:
       case SHADER_OPCODE_TXF:
       case SHADER_OPCODE_TXF_CMS:
+      case SHADER_OPCODE_TXF_CMS_W:
       case SHADER_OPCODE_TXF_UMS:
       case SHADER_OPCODE_TXF_MCS:
       case SHADER_OPCODE_TXL:
diff --git a/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp b/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
index ef92098286..94a9c1b68f 100644
--- a/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
@@ -208,8 +208,8 @@ fs_visitor::emit_mcs_fetch(const fs_reg &coordinate, unsigned components,
    fs_inst *inst = bld.emit(SHADER_OPCODE_TXF_MCS_LOGICAL, dest, srcs,
                             ARRAY_SIZE(srcs));
 
-   /* We only care about one reg of response, but the sampler always writes
-    * 4/8.
+   /* We only care about one or two regs of response, but the sampler always
+    * writes 4/8.
     */
    inst->regs_written = 4 * dispatch_width / 8;
 
@@ -295,7 +295,10 @@ fs_visitor::emit_texture(ir_texture_opcode op,
       opcode = SHADER_OPCODE_TXF_LOGICAL;
       break;
    case ir_txf_ms:
-      opcode = SHADER_OPCODE_TXF_CMS_LOGICAL;
+      if (devinfo->gen >= 9)
+         opcode = SHADER_OPCODE_TXF_CMS_W_LOGICAL;
+      else
+         opcode = SHADER_OPCODE_TXF_CMS_LOGICAL;
       break;
    case ir_txs:
    case ir_query_levels:
diff --git a/src/mesa/drivers/dri/i965/brw_shader.cpp b/src/mesa/drivers/dri/i965/brw_shader.cpp
index 4ea297ade4..0312024ed1 100644
--- a/src/mesa/drivers/dri/i965/brw_shader.cpp
+++ b/src/mesa/drivers/dri/i965/brw_shader.cpp
@@ -351,6 +351,10 @@ brw_instruction_name(enum opcode op)
       return "txf_cms";
    case SHADER_OPCODE_TXF_CMS_LOGICAL:
       return "txf_cms_logical";
+   case SHADER_OPCODE_TXF_CMS_W:
+      return "txf_cms_w";
+   case SHADER_OPCODE_TXF_CMS_W_LOGICAL:
+      return "txf_cms_w_logical";
    case SHADER_OPCODE_TXF_UMS:
       return "txf_ums";
    case SHADER_OPCODE_TXF_UMS_LOGICAL:
@@ -787,6 +791,7 @@ backend_instruction::is_tex() const
            opcode == SHADER_OPCODE_TXD ||
            opcode == SHADER_OPCODE_TXF ||
            opcode == SHADER_OPCODE_TXF_CMS ||
+           opcode == SHADER_OPCODE_TXF_CMS_W ||
            opcode == SHADER_OPCODE_TXF_UMS ||
            opcode == SHADER_OPCODE_TXF_MCS ||
            opcode == SHADER_OPCODE_TXL ||