[Mesa-dev] [PATCH v3 35/43] i965/fs: 16-bit source payloads always use 1 register

[Jose Maria Casanova Crespo]

Render Target Message's payloads for 16bit values fit in only one
register.

>From Intel PRM vol07, page 249 "Render Target Messages" / "Message
Data Payloads"

   "The half precision Render Target Write messages have data payloads
    that can pack a full SIMD16 payload into 1 register instead of
    two. The half-precision packed format is used for RGBA and Source
    0 Alpha, but Source Depth data payload is always supplied in full
    precision."

So when 16-bit data is uploaded to the payload it will use 1 register
independently of it is SIMD16 or SIMD8.

This change implies that we need to replicate the approach in the
copy propagation of the load_payload operations.

v2: By default 16-bit sources should be packed (Jason Ekstrand)
    Include changes in in copy_propagation of load_payload (Chema Casanova)
---
 src/intel/compiler/brw_fs.cpp                  | 5 ++++-
 src/intel/compiler/brw_fs_copy_propagation.cpp | 4 ++--
 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/src/intel/compiler/brw_fs.cpp b/src/intel/compiler/brw_fs.cpp
index 901e855c0b..1d6fbdd06a 100644
--- a/src/intel/compiler/brw_fs.cpp
+++ b/src/intel/compiler/brw_fs.cpp
@@ -3443,7 +3443,10 @@ fs_visitor::lower_load_payload()
       for (uint8_t i = inst->header_size; i < inst->sources; i++) {
          if (inst->src[i].file != BAD_FILE)
             ibld.MOV(retype(dst, inst->src[i].type), inst->src[i]);
-         dst = offset(dst, ibld, 1);
+         if (type_sz(inst->src[i].type) == 2)
+            dst = byte_offset(dst, REG_SIZE);
+         else
+            dst = offset(dst, ibld, 1);
       }
 
       inst->remove(block);
diff --git a/src/intel/compiler/brw_fs_copy_propagation.cpp b/src/intel/compiler/brw_fs_copy_propagation.cpp
index d4d01d783c..470eaeec4f 100644
--- a/src/intel/compiler/brw_fs_copy_propagation.cpp
+++ b/src/intel/compiler/brw_fs_copy_propagation.cpp
@@ -800,7 +800,7 @@ fs_visitor::opt_copy_propagation_local(void *copy_prop_ctx, bblock_t *block,
          int offset = 0;
          for (int i = 0; i < inst->sources; i++) {
             int effective_width = i < inst->header_size ? 8 : inst->exec_size;
-            assert(effective_width * type_sz(inst->src[i].type) % REG_SIZE == 0);
+            assert(effective_width * MAX2(4, type_sz(inst->src[i].type)) % REG_SIZE == 0);
             const unsigned size_written = effective_width *
                                           type_sz(inst->src[i].type);
             if (inst->src[i].file == VGRF) {
@@ -816,7 +816,7 @@ fs_visitor::opt_copy_propagation_local(void *copy_prop_ctx, bblock_t *block,
                   ralloc_free(entry);
                }
             }
-            offset += size_written;
+            offset += type_sz(inst->src[i].type) == 2 ? REG_SIZE : size_written;
          }
       }
    }
-- 
2.13.6