Fix -fvk-u-shift not applying to global constant buffer. (#3033)

* Fix -fvk-u-shift not applying to global constant buffer.

* Fix test.

* Fix.

* Fix.

---------

Co-authored-by: Yong He <yhe@nvidia.com>

2 files changed, 18 insertions, 3 deletions

diff --git a/source/slang/slang-emit-glsl.cpp b/source/slang/slang-emit-glsl.cpp
index 37c38dd95..321f41d54 100644
--- a/source/slang/slang-emit-glsl.cpp
+++ b/source/slang/slang-emit-glsl.cpp
@@ -241,7 +241,10 @@ void GLSLSourceEmitter::_emitGLSLByteAddressBuffer(IRGlobalParam* varDecl, IRByt
     {
         // We can use ShaderResource/DescriptorSlot interchangably here. 
         // This is possible because vk-shift-*
-        const LayoutResourceKindFlags kinds = LayoutResourceKindFlag::ShaderResource | LayoutResourceKindFlag::DescriptorTableSlot;
+        bool isReadOnly = (as<IRHLSLByteAddressBufferType>(byteAddressBufferType) != nullptr);
+
+        const LayoutResourceKindFlags kinds = (isReadOnly ? LayoutResourceKindFlag::ShaderResource : LayoutResourceKindFlag::UnorderedAccess)
+            | LayoutResourceKindFlag::DescriptorTableSlot;
 
         EmitVarChain chain(layout);
 
diff --git a/source/slang/slang-parameter-binding.cpp b/source/slang/slang-parameter-binding.cpp
index 51279b605..47f370854 100644
--- a/source/slang/slang-parameter-binding.cpp
+++ b/source/slang/slang-parameter-binding.cpp
@@ -3634,7 +3634,8 @@ static void _appendRange(Index start, LayoutSize size, StringBuilder& ioBuf)
 }
 
 static void _maybeApplyHLSLToVulkanShifts(
-    ParameterBindingContext* paramContext, 
+    ParameterBindingContext* paramContext,
+    ParameterBindingAndKindInfo& globalConstantBinding,
     TargetRequest* targetReq,
     DiagnosticSink* sink)
 {
@@ -3655,6 +3656,17 @@ static void _maybeApplyHLSLToVulkanShifts(
         return;
     }
 
+    // If the user specified -fvk-b-shift for the default space but not -fvk-bind-global, we want to apply the shift
+    // to the global constant buffer.
+    if (!vulkanOptions->hasGlobalsBinding())
+    {
+        auto globalCBufferShift = vulkanOptions->getShift(HLSLToVulkanLayoutOptions::Kind::ConstantBuffer, globalConstantBinding.space);
+        if (globalCBufferShift != HLSLToVulkanLayoutOptions::kInvalidShift)
+        {
+            globalConstantBinding.index += globalCBufferShift;
+        }
+    }
+
     for (ParameterInfo* parameterInfo : sharedContext.parameters)
     {
         auto varLayout = parameterInfo->varLayout;
@@ -4035,7 +4047,7 @@ RefPtr<ProgramLayout> generateParameterBindings(
     _completeBindings(&context, program);
 
     // We may need to finally do any shifting if we have HLSLToVulkanLayoutOptions
-    _maybeApplyHLSLToVulkanShifts(&context, targetReq, sink);
+    _maybeApplyHLSLToVulkanShifts(&context, globalConstantBufferBinding, targetReq, sink);
 
     // Next we need to create a type layout to reflect the information
     // we have collected, and we will use the `ScopeLayoutBuilder`