[Mesa-dev] [PATCH v2 16/30] i965/fs: Add do_untyped_vector_read helper

[Samuel Iglesias Gonsálvez]

From: Iago Toral Quiroga <itoral at igalia.com>

We are going to need the same logic for anything that reads
doubles via untyped messages (CS shared variables and SSBOs). Add a
helper function with that logic so that we can reuse it.

Reviewed-by: Kenneth Graunke <kenneth at whitecape.org>
---
 src/mesa/drivers/dri/i965/brw_fs.h       |  6 +++
 src/mesa/drivers/dri/i965/brw_fs_nir.cpp | 64 ++++++++++++++++++++++++++++++++
 2 files changed, 70 insertions(+)

diff --git a/src/mesa/drivers/dri/i965/brw_fs.h b/src/mesa/drivers/dri/i965/brw_fs.h
index 1970ad0..1aeacae 100644
--- a/src/mesa/drivers/dri/i965/brw_fs.h
+++ b/src/mesa/drivers/dri/i965/brw_fs.h
@@ -110,6 +110,12 @@ public:
                                                 const fs_reg src,
                                                 uint32_t components);
 
+   void do_untyped_vector_read(const brw::fs_builder &bld,
+                               const fs_reg surf_index,
+                               const fs_reg offset_reg,
+                               const fs_reg dest,
+                               unsigned num_components);
+
    bool run_fs(bool do_rep_send);
    bool run_vs(gl_clip_plane *clip_planes);
    bool run_tcs_single_patch();
diff --git a/src/mesa/drivers/dri/i965/brw_fs_nir.cpp b/src/mesa/drivers/dri/i965/brw_fs_nir.cpp
index 02f1e81..4af5979 100644
--- a/src/mesa/drivers/dri/i965/brw_fs_nir.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs_nir.cpp
@@ -3106,6 +3106,70 @@ fs_visitor::nir_emit_cs_intrinsic(const fs_builder &bld,
 }
 
 void
+fs_visitor::do_untyped_vector_read(const fs_builder &bld,
+                                   const fs_reg surf_index,
+                                   const fs_reg offset_reg,
+                                   const fs_reg dest,
+                                   unsigned num_components)
+{
+   if (type_sz(dest.type) <= 4) {
+      fs_reg read_result = emit_untyped_read(bld, surf_index, offset_reg,
+                                             1 /* dims */,
+                                             num_components,
+                                             BRW_PREDICATE_NONE);
+      read_result.type = dest.type;
+      for (unsigned i = 0; i < num_components; i++)
+         bld.MOV(offset(dest, bld, i), offset(read_result, bld, i));
+   } else {
+      /* Reading a dvec, so we need to:
+       *
+       * 1. Multiply num_components by 2, to account for the fact that we
+       *    need to read 64-bit components.
+       * 2. Shuffle the result of the load to form valid 64-bit elements
+       * 3. Emit a second load (for components z/w) if needed.
+       */
+      fs_reg read_offset = vgrf(glsl_type::uint_type);
+      bld.MOV(read_offset, offset_reg);
+
+      int iters = num_components <= 2 ? 1 : 2;
+
+      /* Load the dvec, the first iteration loads components x/y, the second
+       * iteration, if needed, loads components z/w
+       */
+      for (int it = 0; it < iters; it++) {
+         /* Compute number of components to read in this iteration */
+         int iter_components = MIN2(2, num_components);
+         num_components -= iter_components;
+
+         /* Read. Since this message reads 32-bit components, we need to
+          * read twice as many components.
+          */
+         fs_reg read_result = emit_untyped_read(bld, surf_index, read_offset,
+                                                1 /* dims */,
+                                                iter_components * 2,
+                                                BRW_PREDICATE_NONE);
+
+         /* Shuffle the 32-bit load result into valid 64-bit data */
+         shuffle_32bit_load_result_to_64bit_data(
+            bld,
+            retype(read_result, BRW_REGISTER_TYPE_DF),
+            retype(read_result, BRW_REGISTER_TYPE_F),
+            iter_components);
+
+         /* Move each component to its destination */
+         read_result = retype(read_result, BRW_REGISTER_TYPE_DF);
+         for (int c = 0; c < iter_components; c++) {
+            bld.MOV(offset(dest, bld, it * 2 + c),
+                    offset(read_result, bld, c));
+         }
+
+         bld.ADD(read_offset, read_offset, brw_imm_ud(16));
+      }
+   }
+}
+
+
+void
 fs_visitor::nir_emit_intrinsic(const fs_builder &bld, nir_intrinsic_instr *instr)
 {
    fs_reg dest;
-- 
2.5.0