gallium: add PIPE_CAP_INVALIDATE_BUFFER

It makes sense to re-use pipe->invalidate_resource for the purpose of
glInvalidateBufferData, but this function is already implemented in vc4
where it doesn't have the expected behavior. So add a capability flag
to indicate that the driver supports the expected behavior.

Reviewed-by: Marek Olšák <marek.olsak@amd.com>

src/gallium/docs/source/screen.rst

@@ -301,6 +301,8 @@ The integer capabilities:
   alignment for pipe_shader_buffer::buffer_offset, in bytes. Maximum
   value allowed is 256 (for GL conformance). 0 is only allowed if
   shader buffers are not supported.
+* ``PIPE_CAP_INVALIDATE_BUFFER``: Whether the use of ``invalidate_resource``
+  for buffers is supported.
 
 
 .. _pipe_capf:

src/gallium/drivers/freedreno/freedreno_screen.c

@@ -245,6 +245,7 @@ fd_screen_get_param(struct pipe_screen *pscreen, enum pipe_cap param)
 	case PIPE_CAP_TGSI_FS_POSITION_IS_SYSVAL:
 	case PIPE_CAP_TGSI_FS_FACE_IS_INTEGER_SYSVAL:
 	case PIPE_CAP_SHADER_BUFFER_OFFSET_ALIGNMENT:
+	case PIPE_CAP_INVALIDATE_BUFFER:
 		return 0;
 
 	case PIPE_CAP_MAX_VIEWPORTS:

src/gallium/drivers/i915/i915_screen.c

@@ -259,6 +259,7 @@ i915_get_param(struct pipe_screen *screen, enum pipe_cap cap)
    case PIPE_CAP_TGSI_FS_POSITION_IS_SYSVAL:
    case PIPE_CAP_TGSI_FS_FACE_IS_INTEGER_SYSVAL:
    case PIPE_CAP_SHADER_BUFFER_OFFSET_ALIGNMENT:
+   case PIPE_CAP_INVALIDATE_BUFFER:
       return 0;
 
    case PIPE_CAP_MAX_DUAL_SOURCE_RENDER_TARGETS:

src/gallium/drivers/ilo/ilo_screen.c

@@ -483,6 +483,7 @@ ilo_get_param(struct pipe_screen *screen, enum pipe_cap param)
    case PIPE_CAP_TGSI_FS_POSITION_IS_SYSVAL:
    case PIPE_CAP_TGSI_FS_FACE_IS_INTEGER_SYSVAL:
    case PIPE_CAP_SHADER_BUFFER_OFFSET_ALIGNMENT:
+   case PIPE_CAP_INVALIDATE_BUFFER:
       return 0;
 
    case PIPE_CAP_VENDOR_ID:

src/gallium/drivers/llvmpipe/lp_screen.c

@@ -308,6 +308,7 @@ llvmpipe_get_param(struct pipe_screen *screen, enum pipe_cap param)
    case PIPE_CAP_TGSI_FS_POSITION_IS_SYSVAL:
    case PIPE_CAP_TGSI_FS_FACE_IS_INTEGER_SYSVAL:
    case PIPE_CAP_SHADER_BUFFER_OFFSET_ALIGNMENT:
+   case PIPE_CAP_INVALIDATE_BUFFER:
       return 0;
    }
    /* should only get here on unhandled cases */

src/gallium/drivers/nouveau/nv30/nv30_screen.c

@@ -181,6 +181,7 @@ nv30_screen_get_param(struct pipe_screen *pscreen, enum pipe_cap param)
    case PIPE_CAP_TGSI_FS_POSITION_IS_SYSVAL:
    case PIPE_CAP_TGSI_FS_FACE_IS_INTEGER_SYSVAL:
    case PIPE_CAP_SHADER_BUFFER_OFFSET_ALIGNMENT:
+   case PIPE_CAP_INVALIDATE_BUFFER:
       return 0;
 
    case PIPE_CAP_VENDOR_ID:

src/gallium/drivers/nouveau/nv50/nv50_screen.c

@@ -224,6 +224,7 @@ nv50_screen_get_param(struct pipe_screen *pscreen, enum pipe_cap param)
    case PIPE_CAP_TGSI_PACK_HALF_FLOAT:
    case PIPE_CAP_TGSI_FS_POSITION_IS_SYSVAL:
    case PIPE_CAP_SHADER_BUFFER_OFFSET_ALIGNMENT:
+   case PIPE_CAP_INVALIDATE_BUFFER:
       return 0;
 
    case PIPE_CAP_VENDOR_ID:

src/gallium/drivers/nouveau/nvc0/nvc0_screen.c

@@ -213,6 +213,7 @@ nvc0_screen_get_param(struct pipe_screen *pscreen, enum pipe_cap param)
    case PIPE_CAP_DEVICE_RESET_STATUS_QUERY:
    case PIPE_CAP_TGSI_FS_POSITION_IS_SYSVAL:
    case PIPE_CAP_SHADER_BUFFER_OFFSET_ALIGNMENT:
+   case PIPE_CAP_INVALIDATE_BUFFER:
       return 0;
 
    case PIPE_CAP_VENDOR_ID:

src/gallium/drivers/r300/r300_screen.c

@@ -207,6 +207,7 @@ static int r300_get_param(struct pipe_screen* pscreen, enum pipe_cap param)
         case PIPE_CAP_TGSI_FS_POSITION_IS_SYSVAL:
         case PIPE_CAP_TGSI_FS_FACE_IS_INTEGER_SYSVAL:
         case PIPE_CAP_SHADER_BUFFER_OFFSET_ALIGNMENT:
+        case PIPE_CAP_INVALIDATE_BUFFER:
             return 0;
 
         /* SWTCL-only features. */

src/gallium/drivers/r600/r600_pipe.c

@@ -355,6 +355,7 @@ static int r600_get_param(struct pipe_screen* pscreen, enum pipe_cap param)
 	case PIPE_CAP_TGSI_FS_POSITION_IS_SYSVAL:
 	case PIPE_CAP_TGSI_FS_FACE_IS_INTEGER_SYSVAL:
 	case PIPE_CAP_SHADER_BUFFER_OFFSET_ALIGNMENT:
+	case PIPE_CAP_INVALIDATE_BUFFER:
 		return 0;
 
 	case PIPE_CAP_MAX_SHADER_PATCH_VARYINGS:

src/gallium/drivers/radeonsi/si_pipe.c

@@ -347,6 +347,7 @@ static int si_get_param(struct pipe_screen* pscreen, enum pipe_cap param)
 	case PIPE_CAP_MULTI_DRAW_INDIRECT:
 	case PIPE_CAP_MULTI_DRAW_INDIRECT_PARAMS:
 	case PIPE_CAP_SHADER_BUFFER_OFFSET_ALIGNMENT:
+	case PIPE_CAP_INVALIDATE_BUFFER:
 		return 0;
 
 	case PIPE_CAP_MAX_SHADER_PATCH_VARYINGS:

src/gallium/drivers/softpipe/sp_screen.c

@@ -258,6 +258,7 @@ softpipe_get_param(struct pipe_screen *screen, enum pipe_cap param)
    case PIPE_CAP_TGSI_FS_POSITION_IS_SYSVAL:
    case PIPE_CAP_TGSI_FS_FACE_IS_INTEGER_SYSVAL:
    case PIPE_CAP_SHADER_BUFFER_OFFSET_ALIGNMENT:
+   case PIPE_CAP_INVALIDATE_BUFFER:
       return 0;
    }
    /* should only get here on unhandled cases */

src/gallium/drivers/svga/svga_screen.c

@@ -353,6 +353,7 @@ svga_get_param(struct pipe_screen *screen, enum pipe_cap param)
    case PIPE_CAP_MULTISAMPLE_Z_RESOLVE:
    case PIPE_CAP_TGSI_PACK_HALF_FLOAT:
    case PIPE_CAP_SHADER_BUFFER_OFFSET_ALIGNMENT:
+   case PIPE_CAP_INVALIDATE_BUFFER:
       return 0;
    case PIPE_CAP_MIN_MAP_BUFFER_ALIGNMENT:
       return 64;

src/gallium/drivers/vc4/vc4_screen.c

@@ -196,6 +196,7 @@ vc4_screen_get_param(struct pipe_screen *pscreen, enum pipe_cap param)
         case PIPE_CAP_TGSI_FS_POSITION_IS_SYSVAL:
         case PIPE_CAP_TGSI_FS_FACE_IS_INTEGER_SYSVAL:
         case PIPE_CAP_SHADER_BUFFER_OFFSET_ALIGNMENT:
+        case PIPE_CAP_INVALIDATE_BUFFER:
                 return 0;
 
                 /* Stream output. */

src/gallium/drivers/virgl/virgl_screen.c

@@ -226,6 +226,7 @@ virgl_get_param(struct pipe_screen *screen, enum pipe_cap param)
    case PIPE_CAP_TGSI_FS_POSITION_IS_SYSVAL:
    case PIPE_CAP_TGSI_FS_FACE_IS_INTEGER_SYSVAL:
    case PIPE_CAP_SHADER_BUFFER_OFFSET_ALIGNMENT:
+   case PIPE_CAP_INVALIDATE_BUFFER:
       return 0;
    case PIPE_CAP_VENDOR_ID:
       return 0x1af4;

src/gallium/include/pipe/p_context.h

@@ -649,11 +649,15 @@ struct pipe_context {
                           struct pipe_resource *resource);
 
    /**
-    * Invalidate the contents of the resource.
+    * Invalidate the contents of the resource. This is used to
     *
-    * This is used to implement EGL's semantic of undefined depth/stencil
+    * (1) implement EGL's semantic of undefined depth/stencil
     * contenst after a swapbuffers.  This allows a tiled renderer (for
     * example) to not store the depth buffer.
+    *
+    * (2) implement GL's InvalidateBufferData. For backwards compatibility,
+    * you must only rely on the usability for this purpose when
+    * PIPE_CAP_INVALIDATE_BUFFER is enabled.
     */
    void (*invalidate_resource)(struct pipe_context *ctx,
                                struct pipe_resource *resource);

src/gallium/include/pipe/p_defines.h

@@ -642,6 +642,7 @@ enum pipe_cap
    PIPE_CAP_TGSI_FS_POSITION_IS_SYSVAL,
    PIPE_CAP_TGSI_FS_FACE_IS_INTEGER_SYSVAL,
    PIPE_CAP_SHADER_BUFFER_OFFSET_ALIGNMENT,
+   PIPE_CAP_INVALIDATE_BUFFER,
 };
 
 #define PIPE_QUIRK_TEXTURE_BORDER_COLOR_SWIZZLE_NV50 (1 << 0)