intel/fs: Set up FB write message headers in the visitor

Doing instruction header setup in the generator is awful for a number
of reasons.  For one, we can't schedule the header setup at all.  For
another, it means lots of implied writes which the instruction scheduler
and other passes can't properly read about.  The second isn't a huge
problem for FB writes since they always happen at the end.  We made a
similar change to sampler handling in ff4726077d86.

Reviewed-by: Matt Turner <[email protected]>

2 files changed, 86 insertions, 83 deletions

diff --git a/src/intel/compiler/brw_fs.cpp b/src/intel/compiler/brw_fs.cpp
index fdf2f9d7ac1..479e07f1dc5 100644
--- a/src/intel/compiler/brw_fs.cpp
+++ b/src/intel/compiler/brw_fs.cpp
@@ -3235,7 +3235,18 @@ fs_visitor::emit_repclear_shader()
       write->mlen = 1;
    } else {
       assume(key->nr_color_regions > 0);
+
+      struct brw_reg header =
+         retype(brw_message_reg(base_mrf), BRW_REGISTER_TYPE_UD);
+      bld.exec_all().group(16, 0)
+         .MOV(header, retype(brw_vec8_grf(0, 0), BRW_REGISTER_TYPE_UD));
+
       for (int i = 0; i < key->nr_color_regions; ++i) {
+         if (i > 0) {
+            bld.exec_all().group(1, 0)
+               .MOV(component(header, 2), brw_imm_ud(i));
+         }
+
          write = bld.emit(FS_OPCODE_REP_FB_WRITE);
          write->saturate = key->clamp_fragment_color;
          write->base_mrf = base_mrf;
@@ -3960,25 +3971,83 @@ lower_fb_write_logical_send(const fs_builder &bld, fs_inst *inst,
    int header_size = 2, payload_header_size;
    unsigned length = 0;
 
-   /* From the Sandy Bridge PRM, volume 4, page 198:
-    *
-    *     "Dispatched Pixel Enables. One bit per pixel indicating
-    *      which pixels were originally enabled when the thread was
-    *      dispatched. This field is only required for the end-of-
-    *      thread message and on all dual-source messages."
-    */
-   if (devinfo->gen >= 6 &&
-       (devinfo->is_haswell || devinfo->gen >= 8 || !prog_data->uses_kill) &&
-       color1.file == BAD_FILE &&
-       key->nr_color_regions == 1) {
-      header_size = 0;
-   }
+   if (devinfo->gen < 6) {
+      /* For gen4-5, we always have a header consisting of g0 and g1.  We have
+       * an implied MOV from g0,g1 to the start of the message.  The MOV from
+       * g0 is handled by the hardware and the MOV from g1 is provided by the
+       * generator.  This is required because, on gen4-5, the generator may
+       * generate two write messages with different message lengths in order
+       * to handle AA data properly.
+       *
+       * Also, since the pixel mask goes in the g0 portion of the message and
+       * since render target writes are the last thing in the shader, we write
+       * the pixel mask directly into g0 and it will get copied as part of the
+       * implied write.
+       */
+      if (prog_data->uses_kill) {
+         bld.exec_all().group(1, 0)
+            .MOV(retype(brw_vec1_grf(0, 0), BRW_REGISTER_TYPE_UW),
+                 brw_flag_reg(0, 1));
+      }
+
+      assert(length == 0);
+      length = 2;
+   } else if ((devinfo->gen <= 7 && !devinfo->is_haswell &&
+               prog_data->uses_kill) ||
+              color1.file != BAD_FILE ||
+              key->nr_color_regions > 1) {
+      /* From the Sandy Bridge PRM, volume 4, page 198:
+       *
+       *     "Dispatched Pixel Enables. One bit per pixel indicating
+       *      which pixels were originally enabled when the thread was
+       *      dispatched. This field is only required for the end-of-
+       *      thread message and on all dual-source messages."
+       */
+      const fs_builder ubld = bld.exec_all().group(8, 0);
+
+      /* The header starts off as g0 and g1 */
+      fs_reg header = ubld.vgrf(BRW_REGISTER_TYPE_UD, 2);
+      ubld.group(16, 0).MOV(header, retype(brw_vec8_grf(0, 0),
+                                           BRW_REGISTER_TYPE_UD));
+
+      uint32_t g00_bits = 0;
+
+      /* Set "Source0 Alpha Present to RenderTarget" bit in message
+       * header.
+       */
+      if (inst->target > 0 && key->replicate_alpha)
+         g00_bits |= 1 << 11;
+
+      /* Set computes stencil to render target */
+      if (prog_data->computed_stencil)
+         g00_bits |= 1 << 14;
+
+      if (g00_bits) {
+         /* OR extra bits into g0.0 */
+         ubld.group(1, 0).OR(component(header, 0),
+                             retype(brw_vec1_grf(0, 0),
+                                    BRW_REGISTER_TYPE_UD),
+                             brw_imm_ud(g00_bits));
+      }
+
+      /* Set the render target index for choosing BLEND_STATE. */
+      if (inst->target > 0) {
+         ubld.group(1, 0).MOV(component(header, 2), brw_imm_ud(inst->target));
+      }
+
+      if (prog_data->uses_kill) {
+         ubld.group(1, 0).MOV(retype(component(header, 15),
+                                     BRW_REGISTER_TYPE_UW),
+                              brw_flag_reg(0, 1));
+      }
 
-   if (header_size != 0) {
-      assert(header_size == 2);
-      /* Allocate 2 registers for a header */
-      length += 2;
+      assert(length == 0);
+      sources[0] = header;
+      sources[1] = horiz_offset(header, 8);
+      length = 2;
    }
+   assert(length == 0 || length == 2);
+   header_size = length;
 
    if (payload.aa_dest_stencil_reg) {
       sources[length] = fs_reg(VGRF, bld.shader->alloc.allocate(1));
diff --git a/src/intel/compiler/brw_fs_generator.cpp b/src/intel/compiler/brw_fs_generator.cpp
index f72139d43c8..f00c07b1bc6 100644
--- a/src/intel/compiler/brw_fs_generator.cpp
+++ b/src/intel/compiler/brw_fs_generator.cpp
@@ -307,9 +307,6 @@ fs_generator::fire_fb_write(fs_inst *inst,
 void
 fs_generator::generate_fb_write(fs_inst *inst, struct brw_reg payload)
 {
-   struct brw_wm_prog_data *prog_data = brw_wm_prog_data(this->prog_data);
-   const brw_wm_prog_key * const key = (brw_wm_prog_key * const) this->key;
-
    if (devinfo->gen < 8 && !devinfo->is_haswell) {
       brw_set_default_predicate_control(p, BRW_PREDICATE_NONE);
    }
@@ -320,69 +317,6 @@ fs_generator::generate_fb_write(fs_inst *inst, struct brw_reg payload)
    if (inst->base_mrf >= 0)
       payload = brw_message_reg(inst->base_mrf);
 
-   /* Header is 2 regs, g0 and g1 are the contents. g0 will be implied
-    * move, here's g1.
-    */
-   if (inst->header_size != 0) {
-      brw_push_insn_state(p);
-      brw_set_default_mask_control(p, BRW_MASK_DISABLE);
-      brw_set_default_exec_size(p, BRW_EXECUTE_1);
-      brw_set_default_predicate_control(p, BRW_PREDICATE_NONE);
-      brw_set_default_compression_control(p, BRW_COMPRESSION_NONE);
-      brw_set_default_flag_reg(p, 0, 0);
-
-      /* On HSW, the GPU will use the predicate on SENDC, unless the header is
-       * present.
-       */
-      if (prog_data->uses_kill) {
-         struct brw_reg pixel_mask;
-
-         if (devinfo->gen >= 6)
-            pixel_mask = retype(brw_vec1_grf(1, 7), BRW_REGISTER_TYPE_UW);
-         else
-            pixel_mask = retype(brw_vec1_grf(0, 0), BRW_REGISTER_TYPE_UW);
-
-         brw_MOV(p, pixel_mask, brw_flag_reg(0, 1));
-      }
-
-      if (devinfo->gen >= 6) {
-         brw_push_insn_state(p);
-         brw_set_default_exec_size(p, BRW_EXECUTE_16);
-	 brw_set_default_compression_control(p, BRW_COMPRESSION_COMPRESSED);
-	 brw_MOV(p,
-		 retype(payload, BRW_REGISTER_TYPE_UD),
-		 retype(brw_vec8_grf(0, 0), BRW_REGISTER_TYPE_UD));
-         brw_pop_insn_state(p);
-
-         if (inst->target > 0 && key->replicate_alpha) {
-            /* Set "Source0 Alpha Present to RenderTarget" bit in message
-             * header.
-             */
-            brw_OR(p,
-		   vec1(retype(payload, BRW_REGISTER_TYPE_UD)),
-		   vec1(retype(brw_vec8_grf(0, 0), BRW_REGISTER_TYPE_UD)),
-		   brw_imm_ud(0x1 << 11));
-         }
-
-	 if (inst->target > 0) {
-	    /* Set the render target index for choosing BLEND_STATE. */
-	    brw_MOV(p, retype(vec1(suboffset(payload, 2)),
-                              BRW_REGISTER_TYPE_UD),
-		    brw_imm_ud(inst->target));
-	 }
-
-         /* Set computes stencil to render target */
-         if (prog_data->computed_stencil) {
-            brw_OR(p,
-                   vec1(retype(payload, BRW_REGISTER_TYPE_UD)),
-                   vec1(retype(brw_vec8_grf(0, 0), BRW_REGISTER_TYPE_UD)),
-                   brw_imm_ud(0x1 << 14));
-         }
-      }
-
-      brw_pop_insn_state(p);
-   }
-
    if (!runtime_check_aads_emit) {
       fire_fb_write(inst, payload, implied_header, inst->mlen);
    } else {