From 5d159645ec705a36d8318301208c892eac91601c Mon Sep 17 00:00:00 2001
From: Jamie Reece Wilson <me@reece.sx>
Date: Sat, 17 Aug 2024 18:54:44 +0100
Subject: [PATCH] [*] Dummy SM3.0 MSAA intrins

---
 spirv_hlsl.cpp | 56 +++++++++++++++++++++++++++++++++++++-------------
 1 file changed, 42 insertions(+), 14 deletions(-)

diff --git a/spirv_hlsl.cpp b/spirv_hlsl.cpp
index 784a6373..cc676f14 100644
--- a/spirv_hlsl.cpp
+++ b/spirv_hlsl.cpp
@@ -579,10 +579,13 @@ void CompilerHLSL::emit_builtin_outputs_in_struct()
             break;
 
         case BuiltInSampleMask:
-            if (hlsl_options.shader_model < 41 || execution.model != ExecutionModelFragment)
-                SPIRV_CROSS_THROW("Sample Mask output is only supported in PS 4.1 or higher.");
-            type = "uint";
-            semantic = "SV_Coverage";
+            if (hlsl_options.shader_model >= 41)
+            {
+                if (execution.model != ExecutionModelFragment)
+                    SPIRV_CROSS_THROW("Sample Mask output is only supported in PS 4.1 or higher.");
+                type = "uint";
+                semantic = "SV_Coverage";
+            }
             break;
 
         case BuiltInFragDepth:
@@ -799,17 +802,21 @@ void CompilerHLSL::emit_builtin_inputs_in_struct()
             break;
 
         case BuiltInSampleId:
-            if (legacy)
-                SPIRV_CROSS_THROW("Sample ID not supported in SM 3.0 or lower.");
-            type = "uint";
-            semantic = "SV_SampleIndex";
+            if (hlsl_options.shader_model > 30)
+            {
+                type = "uint";
+                semantic = "SV_SampleIndex";
+            }
             break;
 
         case BuiltInSampleMask:
-            if (hlsl_options.shader_model < 50 || get_entry_point().model != ExecutionModelFragment)
-                SPIRV_CROSS_THROW("Sample Mask input is only supported in PS 5.0 or higher.");
-            type = "uint";
-            semantic = "SV_Coverage";
+            if (hlsl_options.shader_model >= 50)
+            {
+                if (get_entry_point().model != ExecutionModelFragment)
+                    SPIRV_CROSS_THROW("Sample Mask input is only supported in PS 5.0 or higher.");
+                type = "uint";
+                semantic = "SV_Coverage";
+            }
             break;
 
         case BuiltInGlobalInvocationId:
@@ -3216,7 +3223,25 @@ void CompilerHLSL::emit_hlsl_entry_point()
             break;
 
         case BuiltInSampleMask:
-            statement(builtin, "[0] = stage_input.", builtin, ";");
+            if (hlsl_options.shader_model >= 50)
+            {
+                statement(builtin, "[0] = stage_input.", builtin, ";");
+            }
+            else
+            {
+                statement(builtin, "[0] = 0;");
+            }
+            break;
+
+        case BuiltInSampleId:
+            if (hlsl_options.shader_model > 30)
+            {
+                statement(builtin, " = stage_input.", builtin, ";");
+            }
+            else
+            {
+                statement(builtin, " = 0;");
+            }
             break;
 
         case BuiltInNumWorkgroups:
@@ -3394,7 +3419,10 @@ void CompilerHLSL::emit_hlsl_entry_point()
                 break;
 
             case BuiltInSampleMask:
-                statement("stage_output.gl_SampleMask = gl_SampleMask[0];");
+                if (hlsl_options.shader_model >= 50)
+                {
+                    statement("stage_output.gl_SampleMask = gl_SampleMask[0];");
+                }
                 break;
 
             default: