[Mesa-dev] [PATCH 2/3] i965/vec4: fix register width for DF VGRF and UNIFORM

[Samuel Iglesias Gonsálvez]

On gen7, the swizzles used in DF align16 instructions works for element
size of 32 bits, so we can address only 2 consecutive DFs. As we assumed that
in the rest of the code and prepare the instructions for this (scalarize_df()),
we need to set it to two again.

However, for DF align1 instructions, a width of 2 is wrong as we are not
reading the data we want. For example, an uniform would have a region of
<0, 2, 1> so it would repeat the first 2 DFs, when we wanted to access
to the first 4.

This patch sets the default one to 4 and then modifies the width of
align16 instruction's DF sources when we translate the logical swizzle
to the physical one.

Signed-off-by: Samuel Iglesias Gonsálvez <siglesias at igalia.com>
Cc: "17.1" <mesa-stable at lists.freedesktop.org>
---
 src/intel/compiler/brw_vec4.cpp | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/src/intel/compiler/brw_vec4.cpp b/src/intel/compiler/brw_vec4.cpp
index 95f96ea69c0..8b755e1b75e 100644
--- a/src/intel/compiler/brw_vec4.cpp
+++ b/src/intel/compiler/brw_vec4.cpp
@@ -2003,9 +2003,7 @@ vec4_visitor::convert_to_hw_regs()
          struct brw_reg reg;
          switch (src.file) {
          case VGRF: {
-            const unsigned type_size = type_sz(src.type);
-            const unsigned width = REG_SIZE / 2 / MAX2(4, type_size);
-            reg = byte_offset(brw_vecn_grf(width, src.nr, 0), src.offset);
+            reg = byte_offset(brw_vecn_grf(4, src.nr, 0), src.offset);
             reg.type = src.type;
             reg.abs = src.abs;
             reg.negate = src.negate;
@@ -2013,12 +2011,11 @@ vec4_visitor::convert_to_hw_regs()
          }
 
          case UNIFORM: {
-            const unsigned width = REG_SIZE / 2 / MAX2(4, type_sz(src.type));
             reg = stride(byte_offset(brw_vec4_grf(
                                         prog_data->base.dispatch_grf_start_reg +
                                         src.nr / 2, src.nr % 2 * 4),
                                      src.offset),
-                         0, width, 1);
+                         0, 4, 1);
             reg.type = src.type;
             reg.abs = src.abs;
             reg.negate = src.negate;
@@ -2576,6 +2573,12 @@ vec4_visitor::apply_logical_swizzle(struct brw_reg *hw_reg,
    assert(brw_is_single_value_swizzle(reg.swizzle) ||
           is_supported_64bit_region(inst, arg));
 
+   /* Apply the region <2, 2, 1> for GRF or <0, 2, 1> for uniforms, as align16
+    * HW can only do 32-bit swizzle channels.
+    */
+   if (reg.file == UNIFORM || reg.file == VGRF)
+      hw_reg->width = BRW_WIDTH_2;
+
    if (is_supported_64bit_region(inst, arg) &&
        !is_gen7_supported_64bit_swizzle(inst, arg)) {
       /* Supported 64-bit swizzles are those such that their first two
-- 
2.11.0