Mesa (master): intel/compiler: fix derivative on y axis implementation

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Module: Mesa
Branch: master
Commit: 836225840c21dfb9ee77267e06e14bba781f69a1
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=836225840c21dfb9ee77267e06e14bba781f69a1

Author: Lionel Landwerlin <lionel.g.landwerlin at intel.com>
Date:   Tue Jun 25 11:10:14 2019 +0300

intel/compiler: fix derivative on y axis implementation

This rewrites the ddy in EXECUTE_4 mode with a loop to make it more
obvious what is going on and also sets the group each of the 4 threads
in the groups are supposed to execute.

Fixes the following CTS tests :

   dEQP-VK.glsl.derivate.dfdyfine.dynamic_*

Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin at intel.com>
Co-Authored-by: Jason Ekstrand <jason at jlekstrand.net>
Reviewed-by: Matt Turner <mattst88 at gmail.com>
Fixes: 2134ea380033d5 ("intel/compiler/fs: Implement ddy without using align16 for Gen11+")

---

 src/intel/compiler/brw_fs_generator.cpp | 26 +++++---------------------
 1 file changed, 5 insertions(+), 21 deletions(-)

diff --git a/src/intel/compiler/brw_fs_generator.cpp b/src/intel/compiler/brw_fs_generator.cpp
index 7adc8a7938b..14868baa009 100644
--- a/src/intel/compiler/brw_fs_generator.cpp
+++ b/src/intel/compiler/brw_fs_generator.cpp
@@ -1257,31 +1257,15 @@ fs_generator::generate_ddy(const fs_inst *inst,
       if (devinfo->gen >= 11 ||
           (devinfo->is_broadwell && src.type == BRW_REGISTER_TYPE_HF)) {
          src = stride(src, 0, 2, 1);
-         struct brw_reg src_0  = byte_offset(src,  0 * type_size);
-         struct brw_reg src_2  = byte_offset(src,  2 * type_size);
-         struct brw_reg src_4  = byte_offset(src,  4 * type_size);
-         struct brw_reg src_6  = byte_offset(src,  6 * type_size);
-         struct brw_reg src_8  = byte_offset(src,  8 * type_size);
-         struct brw_reg src_10 = byte_offset(src, 10 * type_size);
-         struct brw_reg src_12 = byte_offset(src, 12 * type_size);
-         struct brw_reg src_14 = byte_offset(src, 14 * type_size);
-
-         struct brw_reg dst_0  = byte_offset(dst,  0 * type_size);
-         struct brw_reg dst_4  = byte_offset(dst,  4 * type_size);
-         struct brw_reg dst_8  = byte_offset(dst,  8 * type_size);
-         struct brw_reg dst_12 = byte_offset(dst, 12 * type_size);
 
          brw_push_insn_state(p);
          brw_set_default_exec_size(p, BRW_EXECUTE_4);
-
-         brw_ADD(p, dst_0, negate(src_0), src_2);
-         brw_ADD(p, dst_4, negate(src_4), src_6);
-
-         if (inst->exec_size == 16) {
-            brw_ADD(p, dst_8,  negate(src_8),  src_10);
-            brw_ADD(p, dst_12, negate(src_12), src_14);
+         for (uint32_t g = 0; g < inst->exec_size; g += 4) {
+            brw_set_default_group(p, inst->group + g);
+            brw_ADD(p, byte_offset(dst, g * type_size),
+                       negate(byte_offset(src,  g * type_size)),
+                       byte_offset(src, (g + 2) * type_size));
          }
-
          brw_pop_insn_state(p);
       } else {
          struct brw_reg src0 = stride(src, 4, 4, 1);