radeonsi: disable ReZ

This is a serious performance fix. Discovered by luck.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=94354

Cc: 12.0 <mesa-stable@lists.freedesktop.org>
Reviewed-by: Nicolai Hähnle <nicolai.haehnle@amd.com>

diff --git a/src/gallium/drivers/radeonsi/si_state_shaders.c b/src/gallium/drivers/radeonsi/si_state_shaders.c
index c41c519..be5c659 100644 (file)
--- a/src/gallium/drivers/radeonsi/si_state_shaders.c
+++ b/src/gallium/drivers/radeonsi/si_state_shaders.c
@@ -808,10 +808,10 @@ static void si_shader_ps(struct si_shader *shader)
                       S_00B02C_USER_SGPR(SI_PS_NUM_USER_SGPR) |
                       S_00B32C_SCRATCH_EN(shader->config.scratch_bytes_per_wave > 0));
 
-       /* Prefer RE_Z if the shader is complex enough. The requirement is either:
-        * - the shader uses at least 2 VMEM instructions, or
-        * - the code size is at least 50 2-dword instructions or 100 1-dword
-        *   instructions.
+       /* DON'T USE EARLY_Z_THEN_RE_Z !!!
+        *
+        * It decreases performance by 15% in DiRT: Showdown on Ultra settings.
+        * And it has pretty complex shaders.
         *
         * Shaders with side effects that must execute independently of the
         * depth test require LATE_Z.
@@ -819,9 +819,6 @@ static void si_shader_ps(struct si_shader *shader)
        if (info->writes_memory &&
            !info->properties[TGSI_PROPERTY_FS_EARLY_DEPTH_STENCIL])
                shader->z_order = V_02880C_LATE_Z;
-       else if (info->num_memory_instructions >= 2 ||
-                shader->binary.code_size > 100*4)
-               shader->z_order = V_02880C_EARLY_Z_THEN_RE_Z;
        else
                shader->z_order = V_02880C_EARLY_Z_THEN_LATE_Z;
 }