mesa: Add GL/GLSL plumbing for INTEL_fragment_shader_ordering

This extension provides new GLSL built-in function
beginFragmentShaderOrderingIntel() that guarantees
(taking wording of GL_INTEL_fragment_shader_ordering
extension) that any memory transactions issued by
shader invocations from previous primitives mapped to
same xy window coordinates (and same sample when
per-sample shading is active), complete and are visible
to the shader invocation that called
beginFragmentShaderOrderingINTEL().

One advantage of INTEL_fragment_shader_ordering over
ARB_fragment_shader_interlock is that it provides a
function that operates as a memory barrie (instead
of a defining a critcial section) that can be called
under arbitary control flow from any function (in
contrast the begin/end of ARB_fragment_shader_interlock
may only be called once, from main(), under no control
flow.

Signed-off-by: Kevin Rogovin <[email protected]>
Reviewed-by: Plamena Manolova <[email protected]>

1 files changed, 17 insertions, 0 deletions

diff --git a/src/compiler/glsl/builtin_functions.cpp b/src/compiler/glsl/builtin_functions.cpp
index b6018806865..5650365d1d5 100644
--- a/src/compiler/glsl/builtin_functions.cpp
+++ b/src/compiler/glsl/builtin_functions.cpp
@@ -526,6 +526,12 @@ supports_nv_fragment_shader_interlock(const _mesa_glsl_parse_state *state)
 }
 
 static bool
+supports_intel_fragment_shader_ordering(const _mesa_glsl_parse_state *state)
+{
+   return state->INTEL_fragment_shader_ordering_enable;
+}
+
+static bool
 shader_clock(const _mesa_glsl_parse_state *state)
 {
    return state->ARB_shader_clock_enable;
@@ -1305,6 +1311,11 @@ builtin_builder::create_intrinsics()
                    supports_arb_fragment_shader_interlock,
                    ir_intrinsic_end_invocation_interlock), NULL);
 
+   add_function("__intrinsic_begin_fragment_shader_ordering",
+                _invocation_interlock_intrinsic(
+                   supports_intel_fragment_shader_ordering,
+                   ir_intrinsic_begin_fragment_shader_ordering), NULL);
+
    add_function("__intrinsic_shader_clock",
                 _shader_clock_intrinsic(shader_clock,
                                         glsl_type::uvec2_type),
@@ -3419,6 +3430,12 @@ builtin_builder::create_builtins()
                    supports_nv_fragment_shader_interlock),
                 NULL);
 
+   add_function("beginFragmentShaderOrderingINTEL",
+                _invocation_interlock(
+                   "__intrinsic_begin_fragment_shader_ordering",
+                   supports_intel_fragment_shader_ordering),
+                NULL);
+
    add_function("anyInvocationARB",
                 _vote("__intrinsic_vote_any", vote),
                 NULL);