intel/fs/gen12: Fix Render Target Read header setup for new thread payload layout.

In Gen12 the Poly 0 Info DWORD containing the Viewport Index and
Render Target Index fields were moved from r0.0 to r1.1 in order to
make room for dual-polygon dispatch.  The render target message format
was updated to expect that information in the same location, so we
didn't need to make any changes for framebuffer fetch to work with
SIMD8 and SIMD16 dispatch.  Unfortunately that won't work with SIMD32,
since the render target message header is assembled from r0 and r2
instead of r1, and the r2 thread payload wasn't updated with an
additional copy of the same information.  We need to fix things up
manually instead.  This avoids a handful of
EXT_shader_framebuffer_fetch regressions in combination with SIMD32
fragment shaders.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>

1 files changed, 17 insertions, 0 deletions

diff --git a/src/intel/compiler/brw_fs.cpp b/src/intel/compiler/brw_fs.cpp
index 0c6fe0bbf3b..0f271b014f1 100644
--- a/src/intel/compiler/brw_fs.cpp
+++ b/src/intel/compiler/brw_fs.cpp
@@ -4499,6 +4499,9 @@ lower_fb_write_logical_send(const fs_builder &bld, fs_inst *inst,
             retype(brw_vec8_grf(2, 0), BRW_REGISTER_TYPE_UD),
          };
          ubld.LOAD_PAYLOAD(header, header_sources, 2, 0);
+
+         /* Gen12 will require additional fix-ups if we ever hit this path. */
+         assert(devinfo->gen < 12);
       }
 
       uint32_t g00_bits = 0;
@@ -4684,6 +4687,7 @@ lower_fb_write_logical_send(const fs_builder &bld, fs_inst *inst,
 static void
 lower_fb_read_logical_send(const fs_builder &bld, fs_inst *inst)
 {
+   const gen_device_info *devinfo = bld.shader->devinfo;
    const fs_builder &ubld = bld.exec_all().group(8, 0);
    const unsigned length = 2;
    const fs_reg header = ubld.vgrf(BRW_REGISTER_TYPE_UD, length);
@@ -4698,6 +4702,19 @@ lower_fb_read_logical_send(const fs_builder &bld, fs_inst *inst)
          retype(brw_vec8_grf(2, 0), BRW_REGISTER_TYPE_UD)
       };
       ubld.LOAD_PAYLOAD(header, header_sources, ARRAY_SIZE(header_sources), 0);
+
+      if (devinfo->gen >= 12) {
+         /* On Gen12 the Viewport and Render Target Array Index fields (AKA
+          * Poly 0 Info) are provided in r1.1 instead of r0.0, and the render
+          * target message header format was updated accordingly -- However
+          * the updated format only works for the lower 16 channels in a
+          * SIMD32 thread, since the higher 16 channels want the subspan data
+          * from r2 instead of r1, so we need to copy over the contents of
+          * r1.1 in order to fix things up.
+          */
+         ubld.group(1, 0).MOV(component(header, 9),
+                              retype(brw_vec1_grf(1, 1), BRW_REGISTER_TYPE_UD));
+      }
    }
 
    inst->resize_sources(1);