r600: implement EXT_shader_image_load_store

Evergreen and cayman have the hardware support for this extension.
This is described by the manual as EXPORT_RAT_INST_INC_UINT_RTN
and EXPORT_RAT_INST_DEC_UINT_RTN.

This change was tested and passes the piglit tests (17/17)
on cypress, palm and cayman.

Signed-off-by: Patrick Lerda <patrick9876@free.fr>
Reviewed-by: Gert Wollny <gert.wollny@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/34501>

src/gallium/drivers/r600/r600_pipe.c

@@ -440,7 +440,8 @@ static void r600_init_screen_caps(struct r600_screen *rscreen)
 	caps->shader_array_components =
 	caps->query_buffer_object =
 	caps->image_store_formatted =
-	caps->alpha_to_coverage_dither_control = family >= CHIP_CEDAR;
+	caps->alpha_to_coverage_dither_control =
+	caps->image_atomic_inc_wrap = family >= CHIP_CEDAR;
 	caps->max_texture_gather_components = family >= CHIP_CEDAR ? 4 : 0;
 	/* kernel command checker support is also required */
 	caps->draw_indirect = family >= CHIP_CEDAR;

src/gallium/drivers/r600/sfn/sfn_instr_mem.cpp

@@ -457,6 +457,10 @@ get_rat_opcode(const nir_atomic_op opcode)
       return RatInstr::CMPXCHG_INT_RTN;
    case nir_atomic_op_xchg:
       return RatInstr::XCHG_RTN;
+   case nir_atomic_op_inc_wrap:
+      return RatInstr::WRAP_INC_RTN;
+   case nir_atomic_op_dec_wrap:
+      return RatInstr::WRAP_DEC_RTN;
    default:
       unreachable("Unsupported atomic");
    }

src/gallium/drivers/r600/sfn/sfn_instr_mem.h

@@ -98,7 +98,8 @@ public:
       OR_RTN,
       XOR_RTN,
       MSKOR_RTN,
-      UINT_RTN,
+      WRAP_INC_RTN,
+      WRAP_DEC_RTN,
       UNSUPPORTED
    };