i965: Move PSCDEPTH calculations from draw time to compile time.

The "Pixel Shader Computed Depth Mode" value is entirely based on the
shader program, so we can easily do it at compile time.  This avoids the
if+switch on every 3DSTATE_WM (Gen7)/3DSTATE_PS_EXTRA (Gen8+) upload,
and shares a bit more code.

This also simplifies the PMA stall code, making it match the formula
more closely, and drops a BRW_NEW_FRAGMENT_PROGRAM dependency.  (Note
that the previous comment was wrong - the code and the documentation
have != PSCDEPTH_OFF, not ==.)

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Matt Turner <mattst88@gmail.com>

6 files changed, 40 insertions, 52 deletions

diff --git a/src/mesa/drivers/dri/i965/brw_context.h b/src/mesa/drivers/dri/i965/brw_context.h
index ec4b3dd..b4ddc17 100644
--- a/src/mesa/drivers/dri/i965/brw_context.h
+++ b/src/mesa/drivers/dri/i965/brw_context.h
@@ -390,6 +390,8 @@ struct brw_wm_prog_data {
       /** @} */
    } binding_table;
 
+   uint8_t computed_depth_mode;
+
    bool no_8;
    bool dual_src_blend;
    bool uses_pos_offset;
diff --git a/src/mesa/drivers/dri/i965/brw_defines.h b/src/mesa/drivers/dri/i965/brw_defines.h
index adcf1db..2acd0f8 100644
--- a/src/mesa/drivers/dri/i965/brw_defines.h
+++ b/src/mesa/drivers/dri/i965/brw_defines.h
@@ -2051,16 +2051,20 @@ enum brw_message_target {
 # define GEN9_WM_DS_BF_STENCIL_REF_MASK                 INTEL_MASK(7, 0)
 # define GEN9_WM_DS_BF_STENCIL_REF_SHIFT                0
 
+enum brw_pixel_shader_computed_depth_mode {
+   BRW_PSCDEPTH_OFF   = 0, /* PS does not compute depth */
+   BRW_PSCDEPTH_ON    = 1, /* PS computes depth; no guarantee about value */
+   BRW_PSCDEPTH_ON_GE = 2, /* PS guarantees output depth >= source depth */
+   BRW_PSCDEPTH_ON_LE = 3, /* PS guarantees output depth <= source depth */
+};
+
 #define _3DSTATE_PS_EXTRA                       0x784F /* GEN8+ */
 /* DW1 */
 # define GEN8_PSX_PIXEL_SHADER_VALID                    (1 << 31)
 # define GEN8_PSX_PIXEL_SHADER_NO_RT_WRITE              (1 << 30)
 # define GEN8_PSX_OMASK_TO_RENDER_TARGET                (1 << 29)
 # define GEN8_PSX_KILL_ENABLE                           (1 << 28)
-# define GEN8_PSX_PSCDEPTH_OFF                          (0 << 26)
-# define GEN8_PSX_PSCDEPTH_ON                           (1 << 26)
-# define GEN8_PSX_PSCDEPTH_ON_GE                        (2 << 26)
-# define GEN8_PSX_PSCDEPTH_ON_LE                        (3 << 26)
+# define GEN8_PSX_COMPUTED_DEPTH_MODE_SHIFT             26
 # define GEN8_PSX_FORCE_COMPUTED_DEPTH                  (1 << 25)
 # define GEN8_PSX_USES_SOURCE_DEPTH                     (1 << 24)
 # define GEN8_PSX_USES_SOURCE_W                         (1 << 23)
@@ -2202,10 +2206,7 @@ enum brw_wm_barycentric_interp_mode {
 # define GEN7_WM_DEPTH_RESOLVE				(1 << 28)
 # define GEN7_WM_HIERARCHICAL_DEPTH_RESOLVE		(1 << 27)
 # define GEN7_WM_KILL_ENABLE				(1 << 25)
-# define GEN7_WM_PSCDEPTH_OFF			        (0 << 23)
-# define GEN7_WM_PSCDEPTH_ON			        (1 << 23)
-# define GEN7_WM_PSCDEPTH_ON_GE			        (2 << 23)
-# define GEN7_WM_PSCDEPTH_ON_LE			        (3 << 23)
+# define GEN7_WM_COMPUTED_DEPTH_MODE_SHIFT              23
 # define GEN7_WM_USES_SOURCE_DEPTH			(1 << 20)
 # define GEN7_WM_USES_SOURCE_W			        (1 << 19)
 # define GEN7_WM_POSITION_ZW_PIXEL			(0 << 17)
diff --git a/src/mesa/drivers/dri/i965/brw_wm.c b/src/mesa/drivers/dri/i965/brw_wm.c
index fe36dd4..7badb23 100644
--- a/src/mesa/drivers/dri/i965/brw_wm.c
+++ b/src/mesa/drivers/dri/i965/brw_wm.c
@@ -116,6 +116,25 @@ brw_compute_barycentric_interp_modes(struct brw_context *brw,
    return barycentric_interp_modes;
 }
 
+static uint8_t
+computed_depth_mode(struct gl_fragment_program *fp)
+{
+   if (fp->Base.OutputsWritten & BITFIELD64_BIT(FRAG_RESULT_DEPTH)) {
+      switch (fp->FragDepthLayout) {
+      case FRAG_DEPTH_LAYOUT_NONE:
+      case FRAG_DEPTH_LAYOUT_ANY:
+         return BRW_PSCDEPTH_ON;
+      case FRAG_DEPTH_LAYOUT_GREATER:
+         return BRW_PSCDEPTH_ON_GE;
+      case FRAG_DEPTH_LAYOUT_LESS:
+         return BRW_PSCDEPTH_ON_LE;
+      case FRAG_DEPTH_LAYOUT_UNCHANGED:
+         return BRW_PSCDEPTH_OFF;
+      }
+   }
+   return BRW_PSCDEPTH_OFF;
+}
+
 bool
 brw_wm_prog_data_compare(const void *in_a, const void *in_b)
 {
@@ -161,6 +180,8 @@ bool do_wm_prog(struct brw_context *brw,
     */
    prog_data.uses_kill = fp->program.UsesKill || key->alpha_test_func;
 
+   prog_data.computed_depth_mode = computed_depth_mode(&fp->program);
+
    /* Allocate the references to the uniforms that will end up in the
     * prog_data associated with the compiled program, and which will be freed
     * by the state cache.
diff --git a/src/mesa/drivers/dri/i965/gen7_wm_state.c b/src/mesa/drivers/dri/i965/gen7_wm_state.c
index 575eaf5..5a5c726 100644
--- a/src/mesa/drivers/dri/i965/gen7_wm_state.c
+++ b/src/mesa/drivers/dri/i965/gen7_wm_state.c
@@ -41,7 +41,7 @@ upload_wm_state(struct brw_context *brw)
       brw_fragment_program_const(brw->fragment_program);
    /* BRW_NEW_FS_PROG_DATA */
    const struct brw_wm_prog_data *prog_data = brw->wm.prog_data;
-   bool writes_depth = false;
+   bool writes_depth = prog_data->computed_depth_mode != BRW_PSCDEPTH_OFF;
    uint32_t dw1, dw2;
 
    /* _NEW_BUFFERS */
@@ -62,24 +62,8 @@ upload_wm_state(struct brw_context *brw)
 
    if (fp->program.Base.InputsRead & VARYING_BIT_POS)
       dw1 |= GEN7_WM_USES_SOURCE_DEPTH | GEN7_WM_USES_SOURCE_W;
-   if (fp->program.Base.OutputsWritten & BITFIELD64_BIT(FRAG_RESULT_DEPTH)) {
-      writes_depth = fp->program.FragDepthLayout != FRAG_DEPTH_LAYOUT_UNCHANGED;
-
-      switch (fp->program.FragDepthLayout) {
-         case FRAG_DEPTH_LAYOUT_NONE:
-         case FRAG_DEPTH_LAYOUT_ANY:
-            dw1 |= GEN7_WM_PSCDEPTH_ON;
-            break;
-         case FRAG_DEPTH_LAYOUT_GREATER:
-            dw1 |= GEN7_WM_PSCDEPTH_ON_GE;
-            break;
-         case FRAG_DEPTH_LAYOUT_LESS:
-            dw1 |= GEN7_WM_PSCDEPTH_ON_LE;
-            break;
-         case FRAG_DEPTH_LAYOUT_UNCHANGED:
-            break;
-      }
-   }
+
+   dw1 |= prog_data->computed_depth_mode << GEN7_WM_COMPUTED_DEPTH_MODE_SHIFT;
    dw1 |= prog_data->barycentric_interp_modes <<
       GEN7_WM_BARYCENTRIC_INTERPOLATION_MODE_SHIFT;
 
diff --git a/src/mesa/drivers/dri/i965/gen8_depth_state.c b/src/mesa/drivers/dri/i965/gen8_depth_state.c
index fc0e3fd..e428089 100644
--- a/src/mesa/drivers/dri/i965/gen8_depth_state.c
+++ b/src/mesa/drivers/dri/i965/gen8_depth_state.c
@@ -225,8 +225,6 @@ static bool
 pma_fix_enable(const struct brw_context *brw)
 {
    const struct gl_context *ctx = &brw->ctx;
-   /* BRW_NEW_FRAGMENT_PROGRAM */
-   const struct gl_fragment_program *fp = brw->fragment_program;
    /* _NEW_BUFFERS */
    struct intel_renderbuffer *depth_irb =
       intel_get_renderbuffer(ctx->DrawBuffer, BUFFER_DEPTH);
@@ -279,12 +277,11 @@ pma_fix_enable(const struct brw_context *brw)
     */
    const bool stencil_writes_enabled = ctx->Stencil._WriteEnabled;
 
-   /* BRW_NEW_FRAGMENT_PROGRAM:
-    * 3DSTATE_PS_EXTRA::Pixel Shader Computed Depth Mode == PSCDEPTH_OFF
+   /* BRW_NEW_FS_PROG_DATA:
+    * 3DSTATE_PS_EXTRA::Pixel Shader Computed Depth Mode != PSCDEPTH_OFF
     */
    const bool ps_computes_depth =
-      (fp->Base.OutputsWritten & BITFIELD64_BIT(FRAG_RESULT_DEPTH)) &&
-      fp->FragDepthLayout != FRAG_DEPTH_LAYOUT_UNCHANGED;
+      brw->wm.prog_data->computed_depth_mode != BRW_PSCDEPTH_OFF;
 
    /* BRW_NEW_FS_PROG_DATA:        3DSTATE_PS_EXTRA::PixelShaderKillsPixels
     * BRW_NEW_FS_PROG_DATA:        3DSTATE_PS_EXTRA::oMask Present to RenderTarget
@@ -372,8 +369,7 @@ const struct brw_tracked_state gen8_pma_fix = {
               _NEW_DEPTH |
               _NEW_MULTISAMPLE |
               _NEW_STENCIL,
-      .brw = BRW_NEW_FRAGMENT_PROGRAM |
-             BRW_NEW_FS_PROG_DATA,
+      .brw = BRW_NEW_FS_PROG_DATA,
    },
    .emit = gen8_emit_pma_stall_workaround
 };
diff --git a/src/mesa/drivers/dri/i965/gen8_ps_state.c b/src/mesa/drivers/dri/i965/gen8_ps_state.c
index 4267bf2..3aa0ef3 100644
--- a/src/mesa/drivers/dri/i965/gen8_ps_state.c
+++ b/src/mesa/drivers/dri/i965/gen8_ps_state.c
@@ -39,6 +39,7 @@ upload_ps_extra(struct brw_context *brw)
    uint32_t dw1 = 0;
 
    dw1 |= GEN8_PSX_PIXEL_SHADER_VALID;
+   dw1 |= prog_data->computed_depth_mode << GEN8_PSX_COMPUTED_DEPTH_MODE_SHIFT;
 
    if (prog_data->uses_kill)
       dw1 |= GEN8_PSX_KILL_ENABLE;
@@ -46,23 +47,6 @@ upload_ps_extra(struct brw_context *brw)
    if (prog_data->num_varying_inputs != 0)
       dw1 |= GEN8_PSX_ATTRIBUTE_ENABLE;
 
-   if (fp->program.Base.OutputsWritten & BITFIELD64_BIT(FRAG_RESULT_DEPTH)) {
-      switch (fp->program.FragDepthLayout) {
-         case FRAG_DEPTH_LAYOUT_NONE:
-         case FRAG_DEPTH_LAYOUT_ANY:
-            dw1 |= GEN8_PSX_PSCDEPTH_ON;
-            break;
-         case FRAG_DEPTH_LAYOUT_GREATER:
-            dw1 |= GEN8_PSX_PSCDEPTH_ON_GE;
-            break;
-         case FRAG_DEPTH_LAYOUT_LESS:
-            dw1 |= GEN8_PSX_PSCDEPTH_ON_LE;
-            break;
-         case FRAG_DEPTH_LAYOUT_UNCHANGED:
-            break;
-      }
-   }
-
    if (fp->program.Base.InputsRead & VARYING_BIT_POS)
       dw1 |= GEN8_PSX_USES_SOURCE_DEPTH | GEN8_PSX_USES_SOURCE_W;