[Mesa-dev] [PATCH 12/23] i965/fs: fix pull constant load component selection for doubles

[Samuel Iglesias Gonsálvez]

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

UNIFORM_PULL_CONSTANT_LOAD is used to load a contiguous vec4 starting at a
constant offset that is 16-byte aligned. If we need to access an unaligned
offset we emit a load with an aligned offset and use the remaining constant
offset to select the component into the vec4 result that we are interested
in. This component must be computed in units of the type size, since that
is what fs_reg::set_smear expects.

This patch does this change in the two places where we use this message:
In demote_pull_constants when we lower uniform access with constant offset
into the pull constant buffer and in UBO loads with constant offset.
---
 src/mesa/drivers/dri/i965/brw_fs.cpp     | 3 ++-
 src/mesa/drivers/dri/i965/brw_fs_nir.cpp | 4 +++-
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp b/src/mesa/drivers/dri/i965/brw_fs.cpp
index 0e69be8..dff13ea 100644
--- a/src/mesa/drivers/dri/i965/brw_fs.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs.cpp
@@ -2268,7 +2268,8 @@ fs_visitor::lower_constant_loads()
          inst->src[i].file = VGRF;
          inst->src[i].nr = dst.nr;
          inst->src[i].reg_offset = 0;
-         inst->src[i].set_smear(pull_index & 3);
+         unsigned type_slots = MAX2(1, type_sz(inst->dst.type) / 4);
+         inst->src[i].set_smear((pull_index & 3) / type_slots);
 
          brw_mark_surface_used(prog_data, index);
       }
diff --git a/src/mesa/drivers/dri/i965/brw_fs_nir.cpp b/src/mesa/drivers/dri/i965/brw_fs_nir.cpp
index 4cd219a..532ca65 100644
--- a/src/mesa/drivers/dri/i965/brw_fs_nir.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs_nir.cpp
@@ -2980,8 +2980,10 @@ fs_visitor::nir_emit_intrinsic(const fs_builder &bld, nir_intrinsic_instr *instr
          bld.emit(FS_OPCODE_UNIFORM_PULL_CONSTANT_LOAD, packed_consts,
                   surf_index, const_offset_reg);
 
+         unsigned component_base =
+            (const_offset->u32[0] % 16) / MAX2(1, type_sz(dest.type));
          for (unsigned i = 0; i < instr->num_components; i++) {
-            packed_consts.set_smear(const_offset->u32[0] % 16 / 4 + i);
+            packed_consts.set_smear(component_base + i);
 
             /* The std140 packing rules don't allow vectors to cross 16-byte
              * boundaries, and a reg is 32 bytes.
-- 
2.5.0