gallium: add PIPE_CAP_TGSI_CAN_READ_OUTPUTS

Drivers that support this benefit by saving one lowering pass in the
GLSL-to-TGSI conversion.

radeonsi already supports this because all outputs are stored in temporary
variables before the export (except for TCS outputs, which have always
been readable in TGSI anyway due to their special semantics).

Reviewed-by: Marek Olšák <[email protected]>

17 files changed, 18 insertions, 0 deletions

diff --git a/src/gallium/docs/source/screen.rst b/src/gallium/docs/source/screen.rst
index 33f233a4cb5..7ac39ffc44f 100644
--- a/src/gallium/docs/source/screen.rst
+++ b/src/gallium/docs/source/screen.rst
@@ -364,6 +364,8 @@ The integer capabilities:
 * ``PIPE_CAP_STREAM_OUTPUT_INTERLEAVE_BUFFERS``: Whether interleaved stream
   output mode is able to interleave across buffers. This is required for
   ARB_transform_feedback3.
+* ``PIPE_CAP_TGSI_CAN_READ_OUTPUTS``: Whether every TGSI shader stage can read
+  from the output file.
 
 
 .. _pipe_capf:
diff --git a/src/gallium/drivers/freedreno/freedreno_screen.c b/src/gallium/drivers/freedreno/freedreno_screen.c
index 4fe9a36fa1c..fb35742f2c0 100644
--- a/src/gallium/drivers/freedreno/freedreno_screen.c
+++ b/src/gallium/drivers/freedreno/freedreno_screen.c
@@ -288,6 +288,7 @@ fd_screen_get_param(struct pipe_screen *pscreen, enum pipe_cap param)
 	case PIPE_CAP_POLYGON_OFFSET_UNITS_UNSCALED:
 	case PIPE_CAP_VIEWPORT_SUBPIXEL_BITS:
 	case PIPE_CAP_TGSI_ARRAY_COMPONENTS:
+	case PIPE_CAP_TGSI_CAN_READ_OUTPUTS:
 		return 0;
 
 	case PIPE_CAP_MAX_VIEWPORTS:
diff --git a/src/gallium/drivers/i915/i915_screen.c b/src/gallium/drivers/i915/i915_screen.c
index bfadca32057..fa19b8bb0e7 100644
--- a/src/gallium/drivers/i915/i915_screen.c
+++ b/src/gallium/drivers/i915/i915_screen.c
@@ -294,6 +294,7 @@ i915_get_param(struct pipe_screen *screen, enum pipe_cap cap)
    case PIPE_CAP_TGSI_FS_FINE_DERIVATIVE:
    case PIPE_CAP_SAMPLER_VIEW_TARGET:
    case PIPE_CAP_VIEWPORT_SUBPIXEL_BITS:
+   case PIPE_CAP_TGSI_CAN_READ_OUTPUTS:
       return 0;
 
    case PIPE_CAP_MAX_VIEWPORTS:
diff --git a/src/gallium/drivers/ilo/ilo_screen.c b/src/gallium/drivers/ilo/ilo_screen.c
index f3f182cad5d..3fce936cde2 100644
--- a/src/gallium/drivers/ilo/ilo_screen.c
+++ b/src/gallium/drivers/ilo/ilo_screen.c
@@ -517,6 +517,7 @@ ilo_get_param(struct pipe_screen *screen, enum pipe_cap param)
    case PIPE_CAP_POLYGON_OFFSET_UNITS_UNSCALED:
    case PIPE_CAP_VIEWPORT_SUBPIXEL_BITS:
    case PIPE_CAP_TGSI_ARRAY_COMPONENTS:
+   case PIPE_CAP_TGSI_CAN_READ_OUTPUTS:
       return 0;
 
    case PIPE_CAP_VENDOR_ID:
diff --git a/src/gallium/drivers/llvmpipe/lp_screen.c b/src/gallium/drivers/llvmpipe/lp_screen.c
index 4b502f0631d..2d75f2d403c 100644
--- a/src/gallium/drivers/llvmpipe/lp_screen.c
+++ b/src/gallium/drivers/llvmpipe/lp_screen.c
@@ -338,6 +338,7 @@ llvmpipe_get_param(struct pipe_screen *screen, enum pipe_cap param)
    case PIPE_CAP_MAX_WINDOW_RECTANGLES:
    case PIPE_CAP_POLYGON_OFFSET_UNITS_UNSCALED:
    case PIPE_CAP_VIEWPORT_SUBPIXEL_BITS:
+   case PIPE_CAP_TGSI_CAN_READ_OUTPUTS:
       return 0;
    }
    /* should only get here on unhandled cases */
diff --git a/src/gallium/drivers/nouveau/nv30/nv30_screen.c b/src/gallium/drivers/nouveau/nv30/nv30_screen.c
index 126c2074bb6..b4b7a200b64 100644
--- a/src/gallium/drivers/nouveau/nv30/nv30_screen.c
+++ b/src/gallium/drivers/nouveau/nv30/nv30_screen.c
@@ -203,6 +203,7 @@ nv30_screen_get_param(struct pipe_screen *pscreen, enum pipe_cap param)
    case PIPE_CAP_VIEWPORT_SUBPIXEL_BITS:
    case PIPE_CAP_MIXED_COLOR_DEPTH_BITS:
    case PIPE_CAP_TGSI_ARRAY_COMPONENTS:
+   case PIPE_CAP_TGSI_CAN_READ_OUTPUTS:
       return 0;
 
    case PIPE_CAP_VENDOR_ID:
diff --git a/src/gallium/drivers/nouveau/nv50/nv50_screen.c b/src/gallium/drivers/nouveau/nv50/nv50_screen.c
index 4cf4d2ad933..60dfddc1552 100644
--- a/src/gallium/drivers/nouveau/nv50/nv50_screen.c
+++ b/src/gallium/drivers/nouveau/nv50/nv50_screen.c
@@ -255,6 +255,7 @@ nv50_screen_get_param(struct pipe_screen *pscreen, enum pipe_cap param)
    case PIPE_CAP_POLYGON_OFFSET_UNITS_UNSCALED:
    case PIPE_CAP_VIEWPORT_SUBPIXEL_BITS:
    case PIPE_CAP_STREAM_OUTPUT_INTERLEAVE_BUFFERS:
+   case PIPE_CAP_TGSI_CAN_READ_OUTPUTS:
       return 0;
 
    case PIPE_CAP_VENDOR_ID:
diff --git a/src/gallium/drivers/nouveau/nvc0/nvc0_screen.c b/src/gallium/drivers/nouveau/nvc0/nvc0_screen.c
index 68e3ab6851f..67f1d6b7a03 100644
--- a/src/gallium/drivers/nouveau/nvc0/nvc0_screen.c
+++ b/src/gallium/drivers/nouveau/nvc0/nvc0_screen.c
@@ -274,6 +274,7 @@ nvc0_screen_get_param(struct pipe_screen *pscreen, enum pipe_cap param)
    case PIPE_CAP_PCI_DEVICE:
    case PIPE_CAP_PCI_FUNCTION:
    case PIPE_CAP_VIEWPORT_SUBPIXEL_BITS:
+   case PIPE_CAP_TGSI_CAN_READ_OUTPUTS:
       return 0;
 
    case PIPE_CAP_VENDOR_ID:
diff --git a/src/gallium/drivers/r300/r300_screen.c b/src/gallium/drivers/r300/r300_screen.c
index 13fe7afd5e0..0cb817befc9 100644
--- a/src/gallium/drivers/r300/r300_screen.c
+++ b/src/gallium/drivers/r300/r300_screen.c
@@ -225,6 +225,7 @@ static int r300_get_param(struct pipe_screen* pscreen, enum pipe_cap param)
         case PIPE_CAP_POLYGON_OFFSET_UNITS_UNSCALED:
         case PIPE_CAP_VIEWPORT_SUBPIXEL_BITS:
         case PIPE_CAP_TGSI_ARRAY_COMPONENTS:
+        case PIPE_CAP_TGSI_CAN_READ_OUTPUTS:
             return 0;
 
         /* SWTCL-only features. */
diff --git a/src/gallium/drivers/r600/r600_pipe.c b/src/gallium/drivers/r600/r600_pipe.c
index adcb694f6d0..16c936f0905 100644
--- a/src/gallium/drivers/r600/r600_pipe.c
+++ b/src/gallium/drivers/r600/r600_pipe.c
@@ -374,6 +374,7 @@ static int r600_get_param(struct pipe_screen* pscreen, enum pipe_cap param)
 	case PIPE_CAP_TGSI_VOTE:
 	case PIPE_CAP_MAX_WINDOW_RECTANGLES:
 	case PIPE_CAP_TGSI_ARRAY_COMPONENTS:
+	case PIPE_CAP_TGSI_CAN_READ_OUTPUTS:
 		return 0;
 
 	case PIPE_CAP_MAX_SHADER_PATCH_VARYINGS:
diff --git a/src/gallium/drivers/radeonsi/si_pipe.c b/src/gallium/drivers/radeonsi/si_pipe.c
index c1442820a93..4297a4fa57f 100644
--- a/src/gallium/drivers/radeonsi/si_pipe.c
+++ b/src/gallium/drivers/radeonsi/si_pipe.c
@@ -409,6 +409,7 @@ static int si_get_param(struct pipe_screen* pscreen, enum pipe_cap param)
 	case PIPE_CAP_CLEAR_TEXTURE:
 	case PIPE_CAP_CULL_DISTANCE:
 	case PIPE_CAP_TGSI_ARRAY_COMPONENTS:
+	case PIPE_CAP_TGSI_CAN_READ_OUTPUTS:
 		return 1;
 
 	case PIPE_CAP_RESOURCE_FROM_USER_MEMORY:
diff --git a/src/gallium/drivers/softpipe/sp_screen.c b/src/gallium/drivers/softpipe/sp_screen.c
index 275adabb14d..4af1b00f83f 100644
--- a/src/gallium/drivers/softpipe/sp_screen.c
+++ b/src/gallium/drivers/softpipe/sp_screen.c
@@ -288,6 +288,7 @@ softpipe_get_param(struct pipe_screen *screen, enum pipe_cap param)
    case PIPE_CAP_MAX_WINDOW_RECTANGLES:
    case PIPE_CAP_POLYGON_OFFSET_UNITS_UNSCALED:
    case PIPE_CAP_VIEWPORT_SUBPIXEL_BITS:
+   case PIPE_CAP_TGSI_CAN_READ_OUTPUTS:
       return 0;
    case PIPE_CAP_SHADER_BUFFER_OFFSET_ALIGNMENT:
       return 4;
diff --git a/src/gallium/drivers/svga/svga_screen.c b/src/gallium/drivers/svga/svga_screen.c
index 677e6bf6a25..4e0ebc376de 100644
--- a/src/gallium/drivers/svga/svga_screen.c
+++ b/src/gallium/drivers/svga/svga_screen.c
@@ -419,6 +419,7 @@ svga_get_param(struct pipe_screen *screen, enum pipe_cap param)
    case PIPE_CAP_POLYGON_OFFSET_UNITS_UNSCALED:
    case PIPE_CAP_VIEWPORT_SUBPIXEL_BITS:
    case PIPE_CAP_TGSI_ARRAY_COMPONENTS:
+   case PIPE_CAP_TGSI_CAN_READ_OUTPUTS:
       return 0;
    }
 
diff --git a/src/gallium/drivers/swr/swr_screen.cpp b/src/gallium/drivers/swr/swr_screen.cpp
index 19bb102354e..6ee357ad761 100644
--- a/src/gallium/drivers/swr/swr_screen.cpp
+++ b/src/gallium/drivers/swr/swr_screen.cpp
@@ -311,6 +311,7 @@ swr_get_param(struct pipe_screen *screen, enum pipe_cap param)
    case PIPE_CAP_POLYGON_OFFSET_UNITS_UNSCALED:
    case PIPE_CAP_VIEWPORT_SUBPIXEL_BITS:
    case PIPE_CAP_TGSI_ARRAY_COMPONENTS:
+   case PIPE_CAP_TGSI_CAN_READ_OUTPUTS:
       return 0;
 
    case PIPE_CAP_VENDOR_ID:
diff --git a/src/gallium/drivers/vc4/vc4_screen.c b/src/gallium/drivers/vc4/vc4_screen.c
index 97510b621d4..5334453a18c 100644
--- a/src/gallium/drivers/vc4/vc4_screen.c
+++ b/src/gallium/drivers/vc4/vc4_screen.c
@@ -239,6 +239,7 @@ vc4_screen_get_param(struct pipe_screen *pscreen, enum pipe_cap param)
         case PIPE_CAP_POLYGON_OFFSET_UNITS_UNSCALED:
         case PIPE_CAP_VIEWPORT_SUBPIXEL_BITS:
         case PIPE_CAP_TGSI_ARRAY_COMPONENTS:
+        case PIPE_CAP_TGSI_CAN_READ_OUTPUTS:
                 return 0;
 
                 /* Stream output. */
diff --git a/src/gallium/drivers/virgl/virgl_screen.c b/src/gallium/drivers/virgl/virgl_screen.c
index 3d71d7dc935..87c4ce26bf2 100644
--- a/src/gallium/drivers/virgl/virgl_screen.c
+++ b/src/gallium/drivers/virgl/virgl_screen.c
@@ -250,6 +250,7 @@ virgl_get_param(struct pipe_screen *screen, enum pipe_cap param)
    case PIPE_CAP_POLYGON_OFFSET_UNITS_UNSCALED:
    case PIPE_CAP_VIEWPORT_SUBPIXEL_BITS:
    case PIPE_CAP_TGSI_ARRAY_COMPONENTS:
+   case PIPE_CAP_TGSI_CAN_READ_OUTPUTS:
       return 0;
    case PIPE_CAP_VENDOR_ID:
       return 0x1af4;
diff --git a/src/gallium/include/pipe/p_defines.h b/src/gallium/include/pipe/p_defines.h
index 6dd299e2120..46e9039a9ec 100644
--- a/src/gallium/include/pipe/p_defines.h
+++ b/src/gallium/include/pipe/p_defines.h
@@ -740,6 +740,7 @@ enum pipe_cap
    PIPE_CAP_MIXED_COLOR_DEPTH_BITS,
    PIPE_CAP_TGSI_ARRAY_COMPONENTS,
    PIPE_CAP_STREAM_OUTPUT_INTERLEAVE_BUFFERS,
+   PIPE_CAP_TGSI_CAN_READ_OUTPUTS,
 };
 
 #define PIPE_QUIRK_TEXTURE_BORDER_COLOR_SWIZZLE_NV50 (1 << 0)