MSL: Don't bother fixing up triangle tess coords.

Instead, I'm going to have MoltenVK reverse the winding order in the
lower-left case. This seems to be what the test suite expects to happen
anyhow.

reference/opt/shaders-msl/desktop-only/tese/triangle.desktop.sso.domain.tese

@@ -1,28 +0,0 @@
-#include <metal_stdlib>
-#include <simd/simd.h>
-
-using namespace metal;
-
-struct main0_out
-{
-    float4 gl_Position [[position]];
-};
-
-struct main0_in
-{
-    float4 gl_Position [[attribute(0)]];
-};
-
-struct main0_patchIn
-{
-    patch_control_point<main0_in> gl_in;
-};
-
-[[ patch(triangle, 0) ]] vertex main0_out main0(main0_patchIn patchIn [[stage_in]], float3 gl_TessCoord [[position_in_patch]])
-{
-    main0_out out = {};
-    gl_TessCoord.yz = float2(gl_TessCoord.y - gl_TessCoord.x, 1.0 - gl_TessCoord.y);
-    out.gl_Position = ((patchIn.gl_in[0].gl_Position * gl_TessCoord.x) + (patchIn.gl_in[1].gl_Position * gl_TessCoord.y)) + (patchIn.gl_in[2].gl_Position * gl_TessCoord.z);
-    return out;
-}
-

reference/shaders-msl/desktop-only/tese/triangle.desktop.sso.domain.tese

@@ -1,28 +0,0 @@
-#include <metal_stdlib>
-#include <simd/simd.h>
-
-using namespace metal;
-
-struct main0_out
-{
-    float4 gl_Position [[position]];
-};
-
-struct main0_in
-{
-    float4 gl_Position [[attribute(0)]];
-};
-
-struct main0_patchIn
-{
-    patch_control_point<main0_in> gl_in;
-};
-
-[[ patch(triangle, 0) ]] vertex main0_out main0(main0_patchIn patchIn [[stage_in]], float3 gl_TessCoord [[position_in_patch]])
-{
-    main0_out out = {};
-    gl_TessCoord.yz = float2(gl_TessCoord.y - gl_TessCoord.x, 1.0 - gl_TessCoord.y);
-    out.gl_Position = ((patchIn.gl_in[0].gl_Position * gl_TessCoord.x) + (patchIn.gl_in[1].gl_Position * gl_TessCoord.y)) + (patchIn.gl_in[2].gl_Position * gl_TessCoord.z);
-    return out;
-}
-

shaders-msl/desktop-only/tese/triangle.desktop.sso.domain.tese

@@ -1,22 +0,0 @@
-#version 450
-
-layout(cw, triangles, fractional_even_spacing) in;
-
-in gl_PerVertex
-{
-   vec4 gl_Position;
-} gl_in[gl_MaxPatchVertices];
-
-out gl_PerVertex
-{
-   vec4 gl_Position;
-};
-
-void main()
-{
-   gl_Position =
-      gl_in[0].gl_Position * gl_TessCoord.x +
-      gl_in[1].gl_Position * gl_TessCoord.y +
-      gl_in[2].gl_Position * gl_TessCoord.z;
-}
-

spirv_msl.cpp

@@ -5582,20 +5582,12 @@ void CompilerMSL::fix_up_shader_inputs_outputs()
 					});
 				break;
 			case BuiltInTessCoord:
-				// Emit a fixup to account for the shifted domain. The fixup for triangles can be derived
-				// thus:
-				// u' = u
-				// w' = 1 - v
-				// v' = 1 - u' - w' = 1 - u - (1 - v) = v - u
-				// v and w are swapped because the winding must be reversed in lower-left mode.
-				if (msl_options.tess_domain_origin_lower_left)
+				// Emit a fixup to account for the shifted domain. Don't do this for triangles;
+				// MoltenVK will just reverse the winding order instead.
+				if (msl_options.tess_domain_origin_lower_left && !get_entry_point().flags.get(ExecutionModeTriangles))
 				{
 					string tc = to_expression(var_id);
-					if (get_entry_point().flags.get(ExecutionModeTriangles))
-						entry_func.fixup_hooks_in.push_back(
-						    [=]() { statement(tc, ".yz = float2(", tc, ".y - ", tc, ".x, 1.0 - ", tc, ".y);"); });
-					else
-						entry_func.fixup_hooks_in.push_back([=]() { statement(tc, ".y = 1.0 - ", tc, ".y;"); });
+					entry_func.fixup_hooks_in.push_back([=]() { statement(tc, ".y = 1.0 - ", tc, ".y;"); });
 				}
 				break;
 			default: