intel/fs: Use the ATTR file for FS inputs

This replaces the special magic opcodes which implicitly read inputs
with explicit use of the ATTR file.

v2 (Jason Ekstrand):
 - Break into multiple patches
 - Change the units of the FS ATTR to be in logical scalars

Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
Reviewed-by: Matt Turner <mattst88@gmail.com>

src/intel/compiler/brw_fs.cpp

@@ -1079,8 +1079,8 @@ fs_visitor::emit_fragcoord_interpolation(fs_reg wpos)
       bld.MOV(wpos, fs_reg(brw_vec8_grf(payload.source_depth_reg, 0)));
    } else {
       bld.emit(FS_OPCODE_LINTERP, wpos,
-           this->delta_xy[BRW_BARYCENTRIC_PERSPECTIVE_PIXEL],
-           interp_reg(VARYING_SLOT_POS, 2));
+               this->delta_xy[BRW_BARYCENTRIC_PERSPECTIVE_PIXEL],
+               component(interp_reg(VARYING_SLOT_POS, 2), 0));
    }
    wpos = offset(wpos, bld, 1);
 
@@ -1609,14 +1609,26 @@ fs_visitor::assign_urb_setup()
     * setup regs, now that the location of the constants has been chosen.
     */
    foreach_block_and_inst(block, fs_inst, inst, cfg) {
-      if (inst->opcode == FS_OPCODE_LINTERP) {
-	 assert(inst->src[1].file == FIXED_GRF);
-         inst->src[1].nr += urb_start;
-      }
-
-      if (inst->opcode == FS_OPCODE_CINTERP) {
-	 assert(inst->src[0].file == FIXED_GRF);
-         inst->src[0].nr += urb_start;
+      for (int i = 0; i < inst->sources; i++) {
+         if (inst->src[i].file == ATTR) {
+            /* ATTR regs in the FS are in units of logical scalar inputs each
+             * of which consumes half of a GRF register.
+             */
+            assert(inst->src[i].offset < REG_SIZE / 2);
+            const unsigned grf = urb_start + inst->src[i].nr / 2;
+            const unsigned offset = (inst->src[i].nr % 2) * (REG_SIZE / 2) +
+                                    inst->src[i].offset;
+            const unsigned width = inst->src[i].stride == 0 ?
+                                   1 : MIN2(inst->exec_size, 8);
+            struct brw_reg reg = stride(
+               byte_offset(retype(brw_vec8_grf(grf, 0), inst->src[i].type),
+                           offset),
+               width * inst->src[i].stride,
+               width, inst->src[i].stride);
+            reg.abs = inst->src[i].abs;
+            reg.negate = inst->src[i].negate;
+            inst->src[i] = reg;
+         }
       }
    }
 

src/intel/compiler/brw_fs.h

@@ -276,7 +276,7 @@ public:
 
    fs_reg get_timestamp(const brw::fs_builder &bld);
 
-   struct brw_reg interp_reg(int location, int channel);
+   fs_reg interp_reg(int location, int channel);
 
    int implied_mrf_writes(fs_inst *inst) const;
 

src/intel/compiler/brw_fs_nir.cpp

@@ -3392,10 +3392,8 @@ fs_visitor::nir_emit_fs_intrinsic(const fs_builder &bld,
       }
 
       for (unsigned int i = 0; i < num_components; i++) {
-         struct brw_reg interp = interp_reg(base, comp + i);
-         interp = suboffset(interp, 3);
          bld.emit(FS_OPCODE_CINTERP, offset(retype(dest, type), bld, i),
-                  retype(fs_reg(interp), type));
+                  retype(component(interp_reg(base, comp + i), 3), type));
       }
 
       if (nir_dest_bit_size(instr->dest) == 64) {
@@ -3568,8 +3566,8 @@ fs_visitor::nir_emit_fs_intrinsic(const fs_builder &bld,
 
       for (unsigned int i = 0; i < instr->num_components; i++) {
          fs_reg interp =
-            fs_reg(interp_reg(nir_intrinsic_base(instr),
-                              nir_intrinsic_component(instr) + i));
+            component(interp_reg(nir_intrinsic_base(instr),
+                                 nir_intrinsic_component(instr) + i), 0);
          interp.type = BRW_REGISTER_TYPE_F;
          dest.type = BRW_REGISTER_TYPE_F;
 

src/intel/compiler/brw_fs_visitor.cpp

@@ -135,17 +135,15 @@ fs_visitor::emit_dummy_fs()
  * data.  It will get adjusted to be a real location before
  * generate_code() time.
  */
-struct brw_reg
+fs_reg
 fs_visitor::interp_reg(int location, int channel)
 {
    assert(stage == MESA_SHADER_FRAGMENT);
    struct brw_wm_prog_data *prog_data = brw_wm_prog_data(this->prog_data);
-   int regnr = prog_data->urb_setup[location] * 2 + channel / 2;
-   int stride = (channel & 1) * 4;
-
+   int regnr = prog_data->urb_setup[location] * 4 + channel;
    assert(prog_data->urb_setup[location] != -1);
 
-   return brw_vec1_grf(regnr, stride);
+   return fs_reg(ATTR, regnr, BRW_REGISTER_TYPE_F);
 }
 
 /** Emits the interpolation for the varying inputs. */
@@ -192,7 +190,7 @@ fs_visitor::emit_interpolation_setup_gen4()
     */
    this->wpos_w = vgrf(glsl_type::float_type);
    abld.emit(FS_OPCODE_LINTERP, wpos_w, delta_xy,
-             interp_reg(VARYING_SLOT_POS, 3));
+             component(interp_reg(VARYING_SLOT_POS, 3), 0));
    /* Compute the pixel 1/W value from wpos.w. */
    this->pixel_w = vgrf(glsl_type::float_type);
    abld.emit(SHADER_OPCODE_RCP, this->pixel_w, wpos_w);