brw: Always use MEMORY_LOAD for load_ubo_uniform_block_intel intrinsics

Rather than emitting FS_OPCODE_UNIFORM_PULL_CONSTANT_LOAD to do block
loads that were cacheline aligned, loading entire cachelines at a time,
we now rely on NIR passes to group, CSE, and vectorize things into
appropriately sized blocks.  This means that we'll usually still load
a cacheline, but we may load only 32B if we don't actually need anything
from the full 64B.  Prior to Xe2, this saves us registers, and it ought
to save us some bandwidth as well as the response length can be lowered.

The cacheline-aligning hack was the main reason not to simply call
fs_nir_emit_memory_access(), so now we do that instead, porting yet
one more thing to the common memory opcode framework.

We unfortunately still emit the old FS_OPCODE_UNIFORM_PULL_CONSTANT_LOAD
opcode for non-block intrinsics.  We'd have to clean up 16-bit handling
among other things in order to eliminate this, but we should in the
future.

fossil-db results on Alchemist for this and the previous patch together:

   Instrs: 161481888 -> 161297588 (-0.11%); split: -0.12%, +0.01%
   Subgroup size: 8102976 -> 8103000 (+0.00%)
   Send messages: 7895489 -> 7846178 (-0.62%); split: -0.67%, +0.05%
   Cycle count: 16583127302 -> 16703162264 (+0.72%); split: -0.57%, +1.29%
   Spill count: 72316 -> 67212 (-7.06%); split: -7.25%, +0.19%
   Fill count: 134457 -> 125970 (-6.31%); split: -6.83%, +0.52%
   Scratch Memory Size: 4093952 -> 3787776 (-7.48%); split: -7.53%, +0.05%
   Max live registers: 33037765 -> 32947425 (-0.27%); split: -0.28%, +0.00%
   Max dispatch width: 5780288 -> 5778536 (-0.03%); split: +0.17%, -0.20%
   Non SSA regs after NIR: 177862542 -> 178816944 (+0.54%); split: -0.06%, +0.60%

In particular, several titles see incredible reductions in spill/fills:

   Shadow of the Tomb Raider: -65.96% / -65.44%
   Batman: Arkham City GOTY:  -53.49% / -28.57%
   Witcher 3:                 -16.33% / -14.29%
   Total War: Warhammer III:   -9.60% / -10.14%
   Assassins Creed Odyssey:    -6.50% /  -9.92%
   Red Dead Redemption 2:      -6.77% /  -8.88%
   Far Cry: New Dawn:          -7.97% /  -4.53%

Improves performance in many games on Arc A750:

   Cyberpunk 2077: 5.8%
   Witcher 3: 4%
   Shadow of the Tomb Raider: 3.3%
   Assassins Creed: Valhalla: 3%
   Spiderman Remastered: 2.75%

Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/32888>

src/intel/compiler/brw_fs_nir.cpp

@@ -6263,6 +6263,11 @@ fs_nir_emit_intrinsic(nir_to_brw_state &ntb,
 
          s.prog_data->has_ubo_pull = true;
 
+         if (instr->intrinsic == nir_intrinsic_load_ubo_uniform_block_intel) {
+            fs_nir_emit_memory_access(ntb, bld, xbld, instr);
+            break;
+         }
+
          const unsigned block_sz = 64; /* Fetch one cacheline at a time. */
          const fs_builder ubld = bld.exec_all().group(block_sz / 4, 0);