gallium: add PIPE_CAP_FP16 for AMD_gpu_shader_half_float

Acked-by: Marek Olšák <marek.olsak@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/18540>

docs/gallium/screen.rst

@@ -426,6 +426,7 @@ The integer capabilities:
 * ``PIPE_CAP_LEGACY_MATH_RULES``: Whether NIR shaders support the
   ``shader_info.use_legacy_math_rules`` flag (see documentation there), and
   TGSI shaders support the corresponding ``TGSI_PROPERTY_LEGACY_MATH_RULES``.
+* ``PIPE_CAP_FP16``: Whether 16-bit float operations are supported.
 * ``PIPE_CAP_DOUBLES``: Whether double precision floating-point operations
   are supported.
 * ``PIPE_CAP_INT64``: Whether 64-bit integer operations are supported.

src/gallium/auxiliary/util/u_screen.c

@@ -332,6 +332,7 @@ u_pipe_screen_get_param_defaults(struct pipe_screen *pscreen,
    case PIPE_CAP_FBFETCH_ZS:
    case PIPE_CAP_BLEND_EQUATION_ADVANCED:
    case PIPE_CAP_LEGACY_MATH_RULES:
+   case PIPE_CAP_FP16:
    case PIPE_CAP_DOUBLES:
    case PIPE_CAP_INT64:
    case PIPE_CAP_TGSI_TEX_TXF_LZ:

src/gallium/include/pipe/p_defines.h

@@ -808,6 +808,7 @@ enum pipe_cap
    PIPE_CAP_GLSL_TESS_LEVELS_AS_INPUTS,
    PIPE_CAP_FBFETCH,
    PIPE_CAP_LEGACY_MATH_RULES,
+   PIPE_CAP_FP16,
    PIPE_CAP_DOUBLES,
    PIPE_CAP_INT64,
    PIPE_CAP_TGSI_TEX_TXF_LZ,

src/mesa/state_tracker/st_extensions.c

@@ -849,6 +849,7 @@ void st_init_extensions(struct pipe_screen *screen,
 
       { o(AMD_depth_clamp_separate),         PIPE_CAP_DEPTH_CLIP_DISABLE_SEPARATE      },
       { o(AMD_framebuffer_multisample_advanced), PIPE_CAP_FRAMEBUFFER_MSAA_CONSTRAINTS },
+      { o(AMD_gpu_shader_half_float),        PIPE_CAP_FP16                             },
       { o(AMD_performance_monitor),          PIPE_CAP_PERFORMANCE_MONITOR              },
       { o(AMD_pinned_memory),                PIPE_CAP_RESOURCE_FROM_USER_MEMORY        },
       { o(ATI_meminfo),                      PIPE_CAP_QUERY_MEMORY_INFO                },