radv: do not enable VRS flat shading if the VRS builtin is read

When the fragment shader reads the VRS builtin, VRS flat shading
shouldn't be enabled, otherwise the value might not be what the FS
expects.

Fixes dEQP-VK.fragment_shading_rate.renderpass2.monolithic.multipass.*
on RDNA2 (VRS flat shading isn't yet enabled on RDNA3).

Cc: mesa-stable
Signed-off-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/23187>

diff --git a/src/amd/vulkan/radv_shader_info.c b/src/amd/vulkan/radv_shader_info.c
index 508b92f..2deb449 100644 (file)
--- a/src/amd/vulkan/radv_shader_info.c
+++ b/src/amd/vulkan/radv_shader_info.c
@@ -587,7 +587,8 @@ gather_shader_info_fs(const struct radv_device *device, const nir_shader *nir,
 
    info->ps.allow_flat_shading =
       !(uses_persp_or_linear_interp || info->ps.needs_sample_positions ||
-        info->ps.writes_memory || nir->info.fs.needs_quad_helper_invocations ||
+        info->ps.reads_frag_shading_rate || info->ps.writes_memory ||
+        nir->info.fs.needs_quad_helper_invocations ||
         BITSET_TEST(nir->info.system_values_read, SYSTEM_VALUE_FRAG_COORD) ||
         BITSET_TEST(nir->info.system_values_read, SYSTEM_VALUE_POINT_COORD) ||
         BITSET_TEST(nir->info.system_values_read, SYSTEM_VALUE_SAMPLE_ID) ||