Add support for ConstBufferPointer on Vulkan. (#3089)

* Add support for `ConstBufferPointer` on Vulkan.

* Add spv compilation test.

* Fix.

* Fix code review issues.

---------

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

9 files changed, 118 insertions, 2 deletions

diff --git a/source/slang/hlsl.meta.slang b/source/slang/hlsl.meta.slang
index 56ad32326..434a8245a 100644
--- a/source/slang/hlsl.meta.slang
+++ b/source/slang/hlsl.meta.slang
@@ -7775,3 +7775,18 @@ ${{{{
 ${{{{
 }
 }}}}
+
+// Buffer Pointer
+
+__generic<T, let Alignment : int = 16>
+__intrinsic_type($(kIROp_HLSLConstBufferPointerType))
+__glsl_extension(GL_EXT_buffer_reference)
+__magic_type(ConstBufferPointerType)
+struct ConstBufferPointer
+{
+    __glsl_version(450)
+    __glsl_extension(GL_EXT_buffer_reference)
+    __target_intrinsic(glsl, "$0._data")
+    [__NoSideEffect]
+    T get();
+}
diff --git a/source/slang/slang-ast-type.h b/source/slang/slang-ast-type.h
index 8948f742c..f3dc975a3 100644
--- a/source/slang/slang-ast-type.h
+++ b/source/slang/slang-ast-type.h
@@ -519,6 +519,12 @@ class PtrType : public PtrTypeBase
     SLANG_AST_CLASS(PtrType)
 };
 
+// A GPU pointer type that for general readonly memory access.
+class ConstBufferPointerType : public PtrTypeBase
+{
+    SLANG_AST_CLASS(ConstBufferPointerType)
+};
+
 /// A pointer-like type used to represent a parameter "direction"
 class ParamDirectionType : public PtrTypeBase
 {
diff --git a/source/slang/slang-emit-c-like.cpp b/source/slang/slang-emit-c-like.cpp
index e2faba808..0cc3a196b 100644
--- a/source/slang/slang-emit-c-like.cpp
+++ b/source/slang/slang-emit-c-like.cpp
@@ -966,6 +966,19 @@ String CLikeSourceEmitter::generateName(IRInst* inst)
         return linkageDecoration->getMangledName();
     }
 
+    switch (inst->getOp())
+    {
+    case kIROp_HLSLConstBufferPointerType:
+        {
+            StringBuilder sb;
+            sb << "BufferPointer_";
+            sb << getName(inst->getOperand(0));
+            sb << "_" << Int32(getID(inst));
+            return sb.produceString();
+        }
+    default:
+        break;
+    }
     // Otherwise fall back to a construct temporary name
     // for the instruction.
     StringBuilder sb;
@@ -3743,7 +3756,6 @@ void CLikeSourceEmitter::emitGlobalInstImpl(IRInst* inst)
     case kIROp_InterfaceType:
         emitInterface(cast<IRInterfaceType>(inst));
         break;
-
     case kIROp_WitnessTable:
         emitWitnessTable(cast<IRWitnessTable>(inst));
         break;
diff --git a/source/slang/slang-emit-glsl.cpp b/source/slang/slang-emit-glsl.cpp
index 321f41d54..22a0c323b 100644
--- a/source/slang/slang-emit-glsl.cpp
+++ b/source/slang/slang-emit-glsl.cpp
@@ -1617,6 +1617,39 @@ bool GLSLSourceEmitter::_tryEmitBitBinOp(IRInst* inst, const EmitOpInfo& bitOp,
 
 }
 
+void GLSLSourceEmitter::emitBufferPointerTypeDefinition(IRInst* ptrType)
+{
+    _requireGLSLExtension(UnownedStringSlice("GL_EXT_buffer_reference"));
+
+    auto constPtrType = as<IRHLSLConstBufferPointerType>(ptrType);
+    auto ptrTypeName = getName(ptrType);
+    auto alignment = getIntVal(constPtrType->getBaseAlignment());
+    m_writer->emit("layout(buffer_reference, std430, buffer_reference_align = ");
+    m_writer->emitInt64(alignment);
+    m_writer->emit(") readonly buffer ");
+    m_writer->emit(ptrTypeName);
+    m_writer->emit("\n");
+    m_writer->emit("{\n");
+    m_writer->indent();
+    emitType((IRType*)constPtrType->getValueType(), "_data");
+    m_writer->emit(";\n");
+    m_writer->dedent();
+    m_writer->emit("};\n");
+}
+
+void GLSLSourceEmitter::emitGlobalInstImpl(IRInst* inst)
+{
+    switch (inst->getOp())
+    {
+    case kIROp_HLSLConstBufferPointerType:
+        emitBufferPointerTypeDefinition(inst);
+        break;
+    default:
+        Super::emitGlobalInstImpl(inst);
+        break;
+    }
+}
+
 bool GLSLSourceEmitter::tryEmitInstExprImpl(IRInst* inst, const EmitOpInfo& inOuterPrec)
 {
     switch (inst->getOp())
@@ -2228,6 +2261,7 @@ void GLSLSourceEmitter::emitSimpleTypeImpl(IRType* type)
             return;
         }
         case kIROp_StructType:
+        case kIROp_HLSLConstBufferPointerType:
             m_writer->emit(getName(type));
             return;
 
@@ -2629,3 +2663,4 @@ void GLSLSourceEmitter::emitMatrixLayoutModifiersImpl(IRVarLayout* layout)
 
 
 } // namespace Slang
+
diff --git a/source/slang/slang-emit-glsl.h b/source/slang/slang-emit-glsl.h
index c0f3336f0..d0cabfa94 100644
--- a/source/slang/slang-emit-glsl.h
+++ b/source/slang/slang-emit-glsl.h
@@ -48,6 +48,8 @@ protected:
 
     virtual bool tryEmitGlobalParamImpl(IRGlobalParam* varDecl, IRType* varType) SLANG_OVERRIDE;
     virtual bool tryEmitInstExprImpl(IRInst* inst, const EmitOpInfo& inOuterPrec) SLANG_OVERRIDE;
+    virtual void emitGlobalInstImpl(IRInst* inst) override;
+    void emitBufferPointerTypeDefinition(IRInst* ptrType);
 
     virtual void emitSimpleValueImpl(IRInst* inst) SLANG_OVERRIDE;
     virtual void emitLoopControlDecorationImpl(IRLoopControlDecoration* decl) SLANG_OVERRIDE;
diff --git a/source/slang/slang-ir-inst-defs.h b/source/slang/slang-ir-inst-defs.h
index c26d5fe53..062da75e8 100644
--- a/source/slang/slang-ir-inst-defs.h
+++ b/source/slang/slang-ir-inst-defs.h
@@ -119,6 +119,7 @@ INST(Nop, nop, 0, 0)
             INST(OutType, Out, 1, HOISTABLE)
             INST(InOutType, InOut, 1, HOISTABLE)
         INST_RANGE(OutTypeBase, OutType, InOutType)
+        INST(HLSLConstBufferPointerType, ConstBufferPointerType, 2, HOISTABLE)
     INST_RANGE(PtrTypeBase, PtrType, InOutType)
 
     // A ComPtr<T> type is treated as a opaque type that represents a reference-counted handle to a COM object.
diff --git a/source/slang/slang-ir.h b/source/slang/slang-ir.h
index 3cd8e9126..cdce11bbb 100644
--- a/source/slang/slang-ir.h
+++ b/source/slang/slang-ir.h
@@ -1641,6 +1641,12 @@ struct IRRTTIPointerType : IRRawPointerTypeBase
     IR_LEAF_ISA(RTTIPointerType)
 };
 
+struct IRHLSLConstBufferPointerType : IRPtrTypeBase
+{
+    IR_LEAF_ISA(HLSLConstBufferPointerType)
+    IRInst* getBaseAlignment() { return getOperand(1); }
+};
+
 struct IRGlobalHashedStringLiterals : IRInst
 {
     IR_LEAF_ISA(GlobalHashedStringLiterals)
diff --git a/source/slang/slang-type-layout.cpp b/source/slang/slang-type-layout.cpp
index f5e14366d..d075b12e2 100644
--- a/source/slang/slang-type-layout.cpp
+++ b/source/slang/slang-type-layout.cpp
@@ -3928,7 +3928,7 @@ static TypeLayoutResult _createTypeLayout(
     {
         return createArrayLikeTypeLayout(context, arrayType, arrayType->getElementType(), arrayType->getElementCount());
     }
-    else if (auto ptrType = as<PtrType>(type))
+    else if (auto ptrType = as<PtrTypeBase>(type))
     {
         RefPtr<PointerTypeLayout> ptrLayout = new PointerTypeLayout();
 
diff --git a/tests/hlsl-intrinsic/const-buffer-pointer.slang b/tests/hlsl-intrinsic/const-buffer-pointer.slang
new file mode 100644
index 000000000..33b538a60
--- /dev/null
+++ b/tests/hlsl-intrinsic/const-buffer-pointer.slang
@@ -0,0 +1,39 @@
+//TEST:SIMPLE(filecheck=CHECK):-target glsl -profile glsl_450 -entry main -stage compute
+//TEST:SIMPLE(filecheck=SPV):-target spirv -profile glsl_450 -entry main -stage compute
+
+// SPV: EntryPoint GLCompute {{.*}} "main" {{.*}}
+
+struct MyStruct
+{
+    float4 position;
+    float4x4 transform;
+}
+
+// CHECK: layout(buffer_reference, std430, buffer_reference_align = 16) readonly buffer BufferPointer_MyStruct
+// CHECK-NEXT: {
+// CHECK-NEXT: MyStruct{{.*}} _data;
+// CHECK-NEXT: }
+
+// CHECK: struct Globals
+// CHECK-NEXT: {
+// CHECK-NEXT: BufferPointer_MyStruct{{.*}} pStruct
+// CHECK-NEXT: }
+
+// CHECK: void main
+// CHECK: MyStruct{{.*}} s{{.*}} = ((gGlobals{{.*}}.pStruct{{.*}})._data);
+
+struct Globals
+{
+    ConstBufferPointer<MyStruct> pStruct;
+}
+
+ConstantBuffer<Globals> gGlobals;
+
+RWStructuredBuffer<uint> outputBuffer;
+
+[numthreads(1,1,1)]
+void main(int3 tid: SV_DispatchThreadID)
+{
+    MyStruct s = gGlobals.pStruct.get();
+    outputBuffer[tid.x] = uint(s.position.x);
+}
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