Implicit register binding for hlsl to non-hlsl targets (#4338)

* implicit register binding for hlsl to non-hlsl targets

* fix regressions

only warn once with `_maybeDiagnoseMissingVulkanLayoutModifier`

remove unneeded else

* address review and change bindings

address review comments on testing to make the tests indiscriminate over order of code emitted.

Change bindings to 1:1 map to vulkan bindings

* don't set bindings 1:1 with vulkan if command line option was added

---------

Co-authored-by: Yong He <yonghe@outlook.com>

2 files changed, 28 insertions, 11 deletions

diff --git a/source/slang/slang-hlsl-to-vulkan-layout-options.h b/source/slang/slang-hlsl-to-vulkan-layout-options.h
index 1b7daf330..b8ae40da0 100644
--- a/source/slang/slang-hlsl-to-vulkan-layout-options.h
+++ b/source/slang/slang-hlsl-to-vulkan-layout-options.h
@@ -75,6 +75,7 @@ public:
     {
         enum Enum : KindFlags
         {
+            None            = 0,
             UnorderedAccess = KindFlags(1) << Index(Kind::UnorderedAccess),
             Sampler         = KindFlags(1) << Index(Kind::Sampler), 
             ShaderResource  = KindFlags(1) << Index(Kind::ShaderResource),
diff --git a/source/slang/slang-parameter-binding.cpp b/source/slang/slang-parameter-binding.cpp
index cfbd7f2c5..523ba9287 100644
--- a/source/slang/slang-parameter-binding.cpp
+++ b/source/slang/slang-parameter-binding.cpp
@@ -1048,7 +1048,7 @@ static void addExplicitParameterBindings_GLSL(
     RefPtr<VarLayout>           varLayout)
 {
     // We only want to apply GLSL-style layout modifers
-    // when compiling for a Khronos-related target.
+    // when compiling for a Khronos-related target. 
     //
     // TODO: This should have some finer granularity
     // so that we are able to distinguish between
@@ -1143,15 +1143,13 @@ static void addExplicitParameterBindings_GLSL(
         return;
     }
 
-    // See if we can infer vulkan binding from HLSL if we have such options set, we know 
-    // we can't map
     auto hlslToVulkanLayoutOptions = context->getTargetProgram()->getHLSLToVulkanLayoutOptions();
-
-    // If we have the options, but cannot infer bindings, we don't need to go further
+    bool warnedMissingVulkanLayoutModifier = false;
+    // If we are not told how to infer bindings with a compile option, we warn
     if (hlslToVulkanLayoutOptions == nullptr || !hlslToVulkanLayoutOptions->canInferBindings())
     {
+        warnedMissingVulkanLayoutModifier = true;
         _maybeDiagnoseMissingVulkanLayoutModifier(context, varDecl.as<VarDeclBase>());
-        return;
     }
 
     // We need an HLSL register semantic to to infer from
@@ -1188,20 +1186,38 @@ static void addExplicitParameterBindings_GLSL(
     }
 
     // If inference is not enabled for this kind, we can issue a warning
-    if (!hlslToVulkanLayoutOptions->canInfer(vulkanKind, hlslInfo.space))
+    if (hlslToVulkanLayoutOptions && !hlslToVulkanLayoutOptions->canInfer(vulkanKind, hlslInfo.space))
     {
-        _maybeDiagnoseMissingVulkanLayoutModifier(context, varDecl.as<VarDeclBase>());
-        return;
+        if(!warnedMissingVulkanLayoutModifier)
+        {
+            _maybeDiagnoseMissingVulkanLayoutModifier(context, varDecl.as<VarDeclBase>());
+            warnedMissingVulkanLayoutModifier = true;
+        }
     }
 
     // We use the HLSL binding directly (even though this notionally for GLSL/Vulkan)
     // We'll do the shifting at later later point in _maybeApplyHLSLToVulkanShifts
     resInfo = typeLayout->findOrAddResourceInfo(hlslInfo.kind);
-    
+
+    if (warnedMissingVulkanLayoutModifier)
+    {
+        // If we warn due to invalid bindings and user did not set how to interpret 'hlsl style bindings', we should map 
+        // `register` 1:1 with equivlent vulkan bindings.
+        if(!hlslToVulkanLayoutOptions
+            || hlslToVulkanLayoutOptions->getKindShiftEnabledFlags() == HLSLToVulkanLayoutOptions::KindFlag::None)
+        {
+            resInfo->kind = LayoutResourceKind::DescriptorTableSlot;
+            resInfo->count = 1;
+        }
+        else
+        {
+            return;
+        }
+    }
+
     semanticInfo.kind = resInfo->kind;
     semanticInfo.index = UInt(hlslInfo.index);
     semanticInfo.space = UInt(hlslInfo.space);
-
     const LayoutSize count = resInfo->count;
 
     addExplicitParameterBinding(context, parameterInfo, as<VarDeclBase>(varDecl.getDecl()), semanticInfo, count);