Add `ISession::getParameterBlockLayout()` (#1805)

3 files changed, 58 insertions, 0 deletions

diff --git a/slang.h b/slang.h
index df0a783be..673d93d1e 100644
--- a/slang.h
+++ b/slang.h
@@ -3933,6 +3933,12 @@ namespace slang
             LayoutRules     rules = LayoutRules::Default,
             ISlangBlob**    outDiagnostics = nullptr) = 0;
 
+        virtual SLANG_NO_THROW TypeLayoutReflection* SLANG_MCALL getParameterBlockLayout(
+            TypeReflection* elementType,
+            SlangInt        targetIndex = 0,
+            LayoutRules     rules = LayoutRules::Default,
+            ISlangBlob**    outDiagnostics = nullptr) = 0;
+
             /** Get the mangled name for a type RTTI object.
             */
         virtual SLANG_NO_THROW SlangResult SLANG_MCALL getTypeRTTIMangledName(
diff --git a/source/slang/slang-compiler.h b/source/slang/slang-compiler.h
index a3eac6fa6..e57c1683a 100755
--- a/source/slang/slang-compiler.h
+++ b/source/slang/slang-compiler.h
@@ -1198,10 +1198,14 @@ namespace Slang
         // TypeLayouts created on the fly by reflection API
         Dictionary<Type*, RefPtr<TypeLayout>> typeLayouts;
 
+        Dictionary<Type*, ParameterBlockType*> parameterBlockTypes;
+
         Dictionary<Type*, RefPtr<TypeLayout>>& getTypeLayouts() { return typeLayouts; }
 
         TypeLayout* getTypeLayout(Type* type);
 
+        TypeLayout* getParameterBlockLayout(Type* type);
+
     private:
         Linkage*                linkage = nullptr;
         CodeGenTarget           format = CodeGenTarget::Unknown;
@@ -1274,6 +1278,11 @@ namespace Slang
             SlangInt               targetIndex = 0,
             slang::LayoutRules     rules = slang::LayoutRules::Default,
             ISlangBlob**    outDiagnostics = nullptr) override;
+        SLANG_NO_THROW slang::TypeLayoutReflection* SLANG_MCALL getParameterBlockLayout(
+            slang::TypeReflection* elementType,
+            SlangInt targetIndex = 0,
+            slang::LayoutRules rules = slang::LayoutRules::Default,
+            ISlangBlob** outDiagnostics = nullptr) override;
         SLANG_NO_THROW SlangResult SLANG_MCALL getTypeRTTIMangledName(
             slang::TypeReflection* type,
             ISlangBlob** outNameBlob) override;
diff --git a/source/slang/slang.cpp b/source/slang/slang.cpp
index c48701575..d315570f5 100644
--- a/source/slang/slang.cpp
+++ b/source/slang/slang.cpp
@@ -897,6 +897,37 @@ SLANG_NO_THROW slang::TypeLayoutReflection* SLANG_MCALL Linkage::getTypeLayout(
     return asExternal(typeLayout);
 }
 
+SLANG_NO_THROW slang::TypeLayoutReflection* SLANG_MCALL Linkage::getParameterBlockLayout(
+    slang::TypeReflection* inType,
+    SlangInt targetIndex,
+    slang::LayoutRules rules,
+    ISlangBlob** outDiagnostics)
+{
+    auto type = asInternal(inType);
+
+    if (targetIndex < 0 || targetIndex >= targets.getCount())
+        return nullptr;
+
+    auto target = targets[targetIndex];
+
+    // TODO: We need a way to pass through the layout rules
+    // that the user requested (e.g., constant buffers vs.
+    // structured buffer rules). Right now the API only
+    // exposes a single case, so this isn't a big deal.
+    //
+    SLANG_UNUSED(rules);
+
+    auto typeLayout = target->getParameterBlockLayout(type);
+
+    // TODO: We currently don't have a path for capturing
+    // errors that occur during layout (e.g., types that
+    // are invalid because of target-specific layout constraints).
+    //
+    SLANG_UNUSED(outDiagnostics);
+
+    return asExternal(typeLayout);
+}
+
 SLANG_NO_THROW SlangResult SLANG_MCALL Linkage::getTypeRTTIMangledName(
     slang::TypeReflection* type, ISlangBlob** outNameBlob)
 {
@@ -1102,6 +1133,18 @@ TypeLayout* TargetRequest::getTypeLayout(Type* type)
     return result.Ptr();
 }
 
+TypeLayout* TargetRequest::getParameterBlockLayout(Type* type)
+{
+    ParameterBlockType* parameterBlockType = nullptr;
+    if (!parameterBlockTypes.TryGetValue(type, parameterBlockType))
+    {
+        parameterBlockType = getLinkage()->getASTBuilder()->create<ParameterBlockType>();
+        parameterBlockType->elementType = type;
+        parameterBlockTypes.Add(type, parameterBlockType);
+    }
+    return getTypeLayout(parameterBlockType);
+}
+
 
 //
 // TranslationUnitRequest