HLSL: Added support for tessellation

Emit HLSL hull (tesc) and domain (tese) shaders from Vulkan-style
SPIR-V where per-CP and patch-constant work share one entry point
gated by `if (gl_InvocationID == 0)` (the dxc/glslang pattern).

The hull entry is split into tesc_main + tesc_main_patch so
[patchconstantfunc] can point at the patch half. Done via in-place
block mutation: pre-scan for the gate header, OpControlBarrier and
per-CP OpFunctionCall; for each pass truncate the header's ops and
redirect its terminator to the merge block (per-CP) or the
then-block (patch), run emit_block_chain, restore state.

Also adds HS/DS I/O struct emission, builtin lowering for
SV_TessFactor / SV_InsideTessFactor / SV_DomainLocation /
SV_OutputControlPointID / InvocationId, a patch-constant wrapper
that marshals InputPatch/OutputPatch into globals, and [domain] /
[partitioning] / [outputtopology] attribute emission with sensible
defaults when execution modes are absent (e.g. TCS compiled without
a linked TES).

Includes shaders-hlsl/{tesc,tese}/basic.{tesc,tese} reference tests.

Author: xen2

reference/shaders-hlsl/tesc/basic.tesc

@@ -0,0 +1,63 @@
+static uint gl_InvocationID;
+static float gl_TessLevelOuter[4];
+static float gl_TessLevelInner[2];
+static float3 vtxColor[3];
+
+struct SPIRV_Cross_Input
+{
+};
+
+struct SPIRV_Cross_Output
+{
+    float3 vtxColor : TEXCOORD0;
+};
+
+struct SPIRV_Cross_PatchConstant
+{
+    float gl_TessLevelOuter[3] : SV_TessFactor;
+    float gl_TessLevelInner[1] : SV_InsideTessFactor;
+};
+
+void tesc_main()
+{
+    float _18 = float(gl_InvocationID);
+    float3 _19 = _18.xxx;
+    vtxColor[gl_InvocationID] = _19;
+}
+
+void tesc_main_patch()
+{
+    float _18 = float(gl_InvocationID);
+    float3 _19 = _18.xxx;
+    vtxColor[gl_InvocationID] = _19;
+    gl_TessLevelOuter[0] = 1.0f;
+    gl_TessLevelOuter[1] = 2.0f;
+    gl_TessLevelOuter[2] = 3.0f;
+    gl_TessLevelInner[0] = 4.0f;
+}
+
+[domain("tri")]
+[partitioning("integer")]
+[outputtopology("triangle_cw")]
+[outputcontrolpoints(3)]
+[patchconstantfunc("patch_constant")]
+SPIRV_Cross_Output main(InputPatch<SPIRV_Cross_Input, 3> patch, uint uCPID : SV_OutputControlPointID)
+{
+    gl_InvocationID = uCPID;
+    tesc_main();
+    SPIRV_Cross_Output stage_output;
+    stage_output.vtxColor = vtxColor[gl_InvocationID];
+    return stage_output;
+}
+
+SPIRV_Cross_PatchConstant patch_constant(InputPatch<SPIRV_Cross_Input, 3> patch)
+{
+    gl_InvocationID = 0u;
+    tesc_main_patch();
+    SPIRV_Cross_PatchConstant patch_output;
+    patch_output.gl_TessLevelOuter[0] = gl_TessLevelOuter[0];
+    patch_output.gl_TessLevelOuter[1] = gl_TessLevelOuter[1];
+    patch_output.gl_TessLevelOuter[2] = gl_TessLevelOuter[2];
+    patch_output.gl_TessLevelInner[0] = gl_TessLevelInner[0];
+    return patch_output;
+}

reference/shaders-hlsl/tese/basic.tese

@@ -0,0 +1,36 @@
+static float4 gl_Position;
+static float3 gl_TessCoord;
+static float3 outColor;
+
+struct SPIRV_Cross_Input
+{
+};
+
+struct SPIRV_Cross_Output
+{
+    float3 outColor : TEXCOORD0;
+    float4 gl_Position : SV_Position;
+};
+
+struct SPIRV_Cross_PatchConstant
+{
+    float gl_TessLevelOuter[3] : SV_TessFactor;
+    float gl_TessLevelInner[1] : SV_InsideTessFactor;
+};
+
+void tese_main()
+{
+    gl_Position = float4(gl_TessCoord, 1.0f);
+    outColor = gl_TessCoord;
+}
+
+[domain("tri")]
+SPIRV_Cross_Output main(SPIRV_Cross_PatchConstant pc, const OutputPatch<SPIRV_Cross_Input, 3> patch, float3 domain : SV_DomainLocation)
+{
+    gl_TessCoord = domain;
+    tese_main();
+    SPIRV_Cross_Output stage_output;
+    stage_output.gl_Position = gl_Position;
+    stage_output.outColor = outColor;
+    return stage_output;
+}

shaders-hlsl/tesc/basic.tesc

@@ -0,0 +1,20 @@
+#version 450
+
+layout(vertices = 3) out;
+
+layout(location = 0) out vec3 vtxColor[];
+
+void main()
+{
+    vtxColor[gl_InvocationID] = vec3(float(gl_InvocationID));
+
+    barrier();
+
+    if (gl_InvocationID == 0)
+    {
+        gl_TessLevelOuter[0] = 1.0;
+        gl_TessLevelOuter[1] = 2.0;
+        gl_TessLevelOuter[2] = 3.0;
+        gl_TessLevelInner[0] = 4.0;
+    }
+}

shaders-hlsl/tese/basic.tese

@@ -0,0 +1,11 @@
+#version 450
+
+layout(triangles, fractional_odd_spacing, cw) in;
+
+layout(location = 0) out vec3 outColor;
+
+void main()
+{
+    gl_Position = vec4(gl_TessCoord, 1.0);
+    outColor = gl_TessCoord;
+}