MSL: Support Invariant qualifier on position.

reference/opt/shaders-msl/asm/vert/invariant.msl21.asm.vert

@@ -0,0 +1,17 @@
+#include <metal_stdlib>
+#include <simd/simd.h>
+
+using namespace metal;
+
+struct main0_out
+{
+    float4 gl_Position [[position, invariant]];
+};
+
+vertex main0_out main0()
+{
+    main0_out out = {};
+    out.gl_Position = float4(1.0);
+    return out;
+}
+

reference/opt/shaders-msl/vert/invariant.msl21.vert

@@ -0,0 +1,26 @@
+#include <metal_stdlib>
+#include <simd/simd.h>
+
+using namespace metal;
+
+struct main0_out
+{
+    float4 gl_Position [[position, invariant]];
+};
+
+struct main0_in
+{
+    float4 vInput0 [[attribute(0)]];
+    float4 vInput1 [[attribute(1)]];
+    float4 vInput2 [[attribute(2)]];
+};
+
+vertex main0_out main0(main0_in in [[stage_in]])
+{
+    main0_out out = {};
+    float4 _20 = in.vInput1 * in.vInput2;
+    float4 _21 = in.vInput0 + _20;
+    out.gl_Position = _21;
+    return out;
+}
+

reference/shaders-msl/asm/vert/invariant.msl21.asm.vert

@@ -0,0 +1,25 @@
+#pragma clang diagnostic ignored "-Wmissing-prototypes"
+
+#include <metal_stdlib>
+#include <simd/simd.h>
+
+using namespace metal;
+
+struct main0_out
+{
+    float4 gl_Position [[position, invariant]];
+};
+
+float4 _main()
+{
+    return float4(1.0);
+}
+
+vertex main0_out main0()
+{
+    main0_out out = {};
+    float4 _14 = _main();
+    out.gl_Position = _14;
+    return out;
+}
+

reference/shaders-msl/vert/invariant.msl21.vert

@@ -0,0 +1,26 @@
+#include <metal_stdlib>
+#include <simd/simd.h>
+
+using namespace metal;
+
+struct main0_out
+{
+    float4 gl_Position [[position, invariant]];
+};
+
+struct main0_in
+{
+    float4 vInput0 [[attribute(0)]];
+    float4 vInput1 [[attribute(1)]];
+    float4 vInput2 [[attribute(2)]];
+};
+
+vertex main0_out main0(main0_in in [[stage_in]])
+{
+    main0_out out = {};
+    float4 _20 = in.vInput1 * in.vInput2;
+    float4 _21 = in.vInput0 + _20;
+    out.gl_Position = _21;
+    return out;
+}
+

shaders-msl/asm/vert/invariant.msl21.asm.vert

@@ -0,0 +1,34 @@
+; SPIR-V
+; Version: 1.0
+; Generator: Khronos Glslang Reference Front End; 3
+; Bound: 18
+; Schema: 0
+               OpCapability Shader
+          %1 = OpExtInstImport "GLSL.std.450"
+               OpMemoryModel Logical GLSL450
+               OpEntryPoint Vertex %main "main" %_entryPointOutput
+               OpSource HLSL 500
+               OpName %main "main"
+               OpName %_main_ "@main("
+               OpName %_entryPointOutput "@entryPointOutput"
+               OpDecorate %_entryPointOutput Invariant
+               OpDecorate %_entryPointOutput BuiltIn Position
+       %void = OpTypeVoid
+          %3 = OpTypeFunction %void
+      %float = OpTypeFloat 32
+    %v4float = OpTypeVector %float 4
+          %8 = OpTypeFunction %v4float
+    %float_1 = OpConstant %float 1
+         %12 = OpConstantComposite %v4float %float_1 %float_1 %float_1 %float_1
+%_ptr_Output_v4float = OpTypePointer Output %v4float
+%_entryPointOutput = OpVariable %_ptr_Output_v4float Output
+       %main = OpFunction %void None %3
+          %5 = OpLabel
+         %17 = OpFunctionCall %v4float %_main_
+               OpStore %_entryPointOutput %17
+               OpReturn
+               OpFunctionEnd
+     %_main_ = OpFunction %v4float None %8
+         %10 = OpLabel
+               OpReturnValue %12
+               OpFunctionEnd

shaders-msl/vert/invariant.msl21.vert

@@ -0,0 +1,11 @@
+#version 310 es
+
+invariant gl_Position;
+layout(location = 0) in vec4 vInput0;
+layout(location = 1) in vec4 vInput1;
+layout(location = 2) in vec4 vInput2;
+
+void main()
+{
+	gl_Position = vInput0 + vInput1 * vInput2;
+}

spirv_msl.cpp

@@ -7598,7 +7598,14 @@ string CompilerMSL::builtin_qualifier(BuiltIn builtin)
 	case BuiltInPointSize:
 		return "point_size";
 	case BuiltInPosition:
-		return "position";
+		if (position_invariant)
+		{
+			if (!msl_options.supports_msl_version(2, 1))
+				SPIRV_CROSS_THROW("Invariant position is only supported on MSL 2.1 and up.");
+			return "position, invariant";
+		}
+		else
+			return "position";
 	case BuiltInLayer:
 		return "render_target_array_index";
 	case BuiltInViewportIndex: