[CIR] Upstream DynamicCastOp (#161734)

This adds the dialect handling for CIR_DynamicCastOp and
CIR_DynamicCastInfoAttr. Support for generating these operations from
source will be added in a later change.

Author: andykaylor

clang/include/clang/CIR/Dialect/IR/CIRAttrs.td

@@ -601,6 +601,63 @@ def CIR_VTableAttr : CIR_Attr<"VTable", "vtable", [TypedAttrInterface]> {
   }];
 }
 
+//===----------------------------------------------------------------------===//
+// DynamicCastInfoAttr
+//===----------------------------------------------------------------------===//
+
+def CIR_DynamicCastInfoAttr : CIR_Attr<"DynamicCastInfo", "dyn_cast_info"> {
+  let summary = "ABI specific information about a dynamic cast";
+  let description = [{
+    Provide ABI specific information about a dynamic cast operation.
+
+    The `src_rtti` and the `dest_rtti` parameters give the RTTI of the source
+    record type and the destination record type, respectively.
+
+    The `runtime_func` parameter gives the `__dynamic_cast` function which is
+    provided by the runtime. The `bad_cast_func` parameter gives the
+    `__cxa_bad_cast` function which is also provided by the runtime.
+
+    The `offset_hint` parameter gives the hint value that should be passed to
+    the `__dynamic_cast` runtime function.
+  }];
+
+  let parameters = (ins
+    CIR_GlobalViewAttr:$src_rtti,
+    CIR_GlobalViewAttr:$dest_rtti,
+    "mlir::FlatSymbolRefAttr":$runtime_func,
+    "mlir::FlatSymbolRefAttr":$bad_cast_func,
+    CIR_IntAttr:$offset_hint
+  );
+
+  let builders = [
+    AttrBuilderWithInferredContext<(ins
+                                    "GlobalViewAttr":$src_rtti,
+                                    "GlobalViewAttr":$dest_rtti,
+                                    "mlir::FlatSymbolRefAttr":$runtime_func,
+                                    "mlir::FlatSymbolRefAttr":$bad_cast_func,
+                                    "IntAttr":$offset_hint), [{
+      return $_get(src_rtti.getContext(), src_rtti, dest_rtti, runtime_func,
+                   bad_cast_func, offset_hint);
+    }]>,
+  ];
+
+  let genVerifyDecl = 1;
+  let assemblyFormat = [{
+    `<`
+      struct(qualified($src_rtti),
+             qualified($dest_rtti),
+             $runtime_func,
+             $bad_cast_func,
+             qualified($offset_hint))
+    `>`
+  }];
+
+  let extraClassDeclaration = [{
+    /// Get attribute alias name for this attribute.
+    std::string getAlias() const;
+  }];
+}
+
 //===----------------------------------------------------------------------===//
 // TargetAddressSpaceAttr
 //===----------------------------------------------------------------------===//

clang/include/clang/CIR/Dialect/IR/CIROps.td

@@ -232,6 +232,100 @@ def CIR_CastOp : CIR_Op<"cast", [
   }];
 }
 
+//===----------------------------------------------------------------------===//
+// DynamicCastOp
+//===----------------------------------------------------------------------===//
+
+def CIR_DynamicCastKind : CIR_I32EnumAttr<
+  "DynamicCastKind", "dynamic cast kind", [
+    I32EnumAttrCase<"Ptr", 0, "ptr">,
+    I32EnumAttrCase<"Ref", 1, "ref">
+]>;
+
+def CIR_DynamicCastOp : CIR_Op<"dyn_cast"> {
+  let summary = "Perform dynamic cast on record pointers";
+  let description = [{
+    The `cir.dyn_cast` operation models part of the semantics of the
+    `dynamic_cast` operator in C++. It can be used to perform 3 kinds of casts
+    on record pointers:
+
+    - Down-cast, which casts a base class pointer to a derived class pointer;
+    - Side-cast, which casts a class pointer to a sibling class pointer;
+    - Cast-to-complete, which casts a class pointer to a void pointer.
+
+    The input of the operation must be a record pointer. The result of the
+    operation is either a record pointer or a void pointer.
+
+    The parameter `kind` specifies the semantics of this operation. If its value
+    is `ptr`, then the operation models dynamic casts on pointers. Otherwise, if
+    its value is `ref`, the operation models dynamic casts on references.
+    Specifically:
+
+    - When the input pointer is a null pointer value:
+      - If `kind` is `ref`, the operation will invoke undefined behavior. A
+        sanitizer check will be emitted if sanitizer is on.
+      - Otherwise, the operation will return a null pointer value as its result.
+    - When the runtime type check fails:
+      - If `kind` is `ref`, the operation will throw a `bad_cast` exception.
+      - Otherwise, the operation will return a null pointer value as its result.
+
+    The `info` argument gives detailed information about the requested dynamic
+    cast operation. It is an optional `#cir.dyn_cast_info` attribute that is
+    only present when the operation models a down-cast or a side-cast.
+
+    The `relative_layout` argument specifies whether the Itanium C++ ABI vtable
+    uses relative layout. It is only meaningful when the operation models a
+    cast-to-complete operation.
+
+    Examples:
+
+    ```mlir
+    %0 = cir.dyn_cast ptr %p : !cir.ptr<!rec_Base> -> !cir.ptr<!rec_Derived>
+    %1 = cir.dyn_cast ptr relative_layout %p : !cir.ptr<!rec_Base>
+              -> !cir.ptr<!rec_Derived>
+    %2 = cir.dyn_cast ref %r : !cir.ptr<!rec_Base> -> !cir.ptr<!rec_Derived>
+              #cir.dyn_cast_info<
+                srcRtti = #cir.global_view<@_ZTI4Base> : !cir.ptr<!u8i>,
+                destRtti = #cir.global_view<@_ZTI7Derived> : !cir.ptr<!u8i>,
+                runtimeFunc = @__dynamic_cast,
+                badCastFunc = @__cxa_bad_cast,
+                offsetHint = #cir.int<0> : !s64i
+              >
+    ```
+  }];
+
+  let arguments = (ins
+    CIR_DynamicCastKind:$kind,
+    CIR_PtrToRecordType:$src,
+    OptionalAttr<CIR_DynamicCastInfoAttr>:$info,
+    UnitAttr:$relative_layout
+  );
+
+  let results = (outs
+    CIR_PtrToAnyOf<[CIR_VoidType, CIR_RecordType]>:$result
+  );
+
+  let assemblyFormat = [{
+    $kind (`relative_layout` $relative_layout^)? $src
+    `:` qualified(type($src)) `->` qualified(type($result))
+    (qualified($info)^)? attr-dict
+  }];
+
+  let extraClassDeclaration = [{
+    /// Determine whether this operation models reference casting in C++.
+    bool isRefCast() {
+      return getKind() == ::cir::DynamicCastKind::Ref;
+    }
+
+    /// Determine whether this operation represents a dynamic cast to a void
+    /// pointer.
+    bool isCastToVoid() {
+      return getType().isVoidPtr();
+    }
+  }];
+
+  let hasLLVMLowering = false;
+}
 
 //===----------------------------------------------------------------------===//
 // PtrStrideOp

clang/include/clang/CIR/Dialect/IR/CIRTypeConstraints.td

@@ -177,6 +177,12 @@ def CIR_AnyComplexOrIntOrBoolOrFloatType
   let cppFunctionName = "isComplexOrIntegerOrBoolOrFloatingPointType";
 }
 
+//===----------------------------------------------------------------------===//
+// Record Type predicates
+//===----------------------------------------------------------------------===//
+
+def CIR_AnyRecordType : CIR_TypeBase<"::cir::RecordType", "record type">;
+
 //===----------------------------------------------------------------------===//
 // Array Type predicates
 //===----------------------------------------------------------------------===//
@@ -234,6 +240,8 @@ def CIR_PtrToIntOrFloatType : CIR_PtrToType<CIR_AnyIntOrFloatType>;
 
 def CIR_PtrToComplexType : CIR_PtrToType<CIR_AnyComplexType>;
 
+def CIR_PtrToRecordType : CIR_PtrToType<CIR_AnyRecordType>;
+
 def CIR_PtrToArray : CIR_PtrToType<CIR_AnyArrayType>;
 
 //===----------------------------------------------------------------------===//

clang/lib/CIR/Dialect/IR/CIRAttrs.cpp

@@ -472,6 +472,49 @@ LogicalResult cir::VTableAttr::verify(
   return success();
 }
 
+//===----------------------------------------------------------------------===//
+// DynamicCastInfoAtttr definitions
+//===----------------------------------------------------------------------===//
+
+std::string DynamicCastInfoAttr::getAlias() const {
+  // The alias looks like: `dyn_cast_info_<src>_<dest>`
+
+  std::string alias = "dyn_cast_info_";
+
+  alias.append(getSrcRtti().getSymbol().getValue());
+  alias.push_back('_');
+  alias.append(getDestRtti().getSymbol().getValue());
+
+  return alias;
+}
+
+LogicalResult DynamicCastInfoAttr::verify(
+    function_ref<InFlightDiagnostic()> emitError, cir::GlobalViewAttr srcRtti,
+    cir::GlobalViewAttr destRtti, mlir::FlatSymbolRefAttr runtimeFunc,
+    mlir::FlatSymbolRefAttr badCastFunc, cir::IntAttr offsetHint) {
+  auto isRttiPtr = [](mlir::Type ty) {
+    // RTTI pointers are !cir.ptr<!u8i>.
+
+    auto ptrTy = mlir::dyn_cast<cir::PointerType>(ty);
+    if (!ptrTy)
+      return false;
+
+    auto pointeeIntTy = mlir::dyn_cast<cir::IntType>(ptrTy.getPointee());
+    if (!pointeeIntTy)
+      return false;
+
+    return pointeeIntTy.isUnsigned() && pointeeIntTy.getWidth() == 8;
+  };
+
+  if (!isRttiPtr(srcRtti.getType()))
+    return emitError() << "srcRtti must be an RTTI pointer";
+
+  if (!isRttiPtr(destRtti.getType()))
+    return emitError() << "destRtti must be an RTTI pointer";
+
+  return success();
+}
+
 //===----------------------------------------------------------------------===//
 // CIR Dialect
 //===----------------------------------------------------------------------===//

clang/lib/CIR/Dialect/IR/CIRDialect.cpp

@@ -71,6 +71,10 @@ struct CIROpAsmDialectInterface : public OpAsmDialectInterface {
       os << "bfi_" << bitfield.getName().str();
       return AliasResult::FinalAlias;
     }
+    if (auto dynCastInfoAttr = mlir::dyn_cast<cir::DynamicCastInfoAttr>(attr)) {
+      os << dynCastInfoAttr.getAlias();
+      return AliasResult::FinalAlias;
+    }
     return AliasResult::NoAlias;
   }
 };

clang/test/CIR/IR/dynamic-cast.cir

@@ -0,0 +1,59 @@
+// RUN: cir-opt --verify-roundtrip %s | FileCheck %s
+
+!s64i = !cir.int<s, 64>
+!u8i = !cir.int<u, 8>
+!void = !cir.void
+
+!rec_Base = !cir.record<struct "Base" {!cir.vptr}>
+!rec_Derived = !cir.record<struct "Derived" {!rec_Base}>
+
+#dyn_cast_info__ZTI4Base__ZTI7Derived = #cir.dyn_cast_info<src_rtti = #cir.global_view<@_ZTI4Base> : !cir.ptr<!u8i>, dest_rtti = #cir.global_view<@_ZTI7Derived> : !cir.ptr<!u8i>, runtime_func = @__dynamic_cast, bad_cast_func = @__cxa_bad_cast, offset_hint = #cir.int<0> : !s64i>
+
+// CHECK: #dyn_cast_info__ZTI4Base__ZTI7Derived = #cir.dyn_cast_info<src_rtti = #cir.global_view<@_ZTI4Base> : !cir.ptr<!u8i>, dest_rtti = #cir.global_view<@_ZTI7Derived> : !cir.ptr<!u8i>, runtime_func = @__dynamic_cast, bad_cast_func = @__cxa_bad_cast, offset_hint = #cir.int<0> : !s64i>
+
+module {
+  cir.global "private" constant external @_ZTI4Base : !cir.ptr<!u8i>
+  cir.global "private" constant external @_ZTI7Derived : !cir.ptr<!u8i>
+  cir.func private @__dynamic_cast(!cir.ptr<!void>, !cir.ptr<!u8i>, !cir.ptr<!u8i>, !s64i) -> !cir.ptr<!void>
+  cir.func private @__cxa_bad_cast()
+
+  cir.func @test_ptr_cast(%arg0: !cir.ptr<!rec_Base>) -> !cir.ptr<!rec_Derived> {
+    %0 = cir.dyn_cast ptr %arg0 : !cir.ptr<!rec_Base> -> !cir.ptr<!rec_Derived> #dyn_cast_info__ZTI4Base__ZTI7Derived
+    cir.return %0 : !cir.ptr<!rec_Derived>
+  }
+
+  // CHECK:   cir.func @test_ptr_cast(%arg0: !cir.ptr<!rec_Base>) -> !cir.ptr<!rec_Derived> {
+  // CHECK:     %0 = cir.dyn_cast ptr %arg0 : !cir.ptr<!rec_Base> -> !cir.ptr<!rec_Derived> #dyn_cast_info__ZTI4Base__ZTI7Derived
+  // CHECK:     cir.return %0 : !cir.ptr<!rec_Derived>
+  // CHECK:   }
+
+  cir.func @test_ref_cast(%arg0: !cir.ptr<!rec_Base>) -> !cir.ptr<!rec_Derived> {
+    %0 = cir.dyn_cast ref %arg0 : !cir.ptr<!rec_Base> -> !cir.ptr<!rec_Derived> #dyn_cast_info__ZTI4Base__ZTI7Derived
+    cir.return %0 : !cir.ptr<!rec_Derived>
+  }
+
+  // CHECK:   cir.func @test_ref_cast(%arg0: !cir.ptr<!rec_Base>) -> !cir.ptr<!rec_Derived> {
+  // CHECK:     %0 = cir.dyn_cast ref %arg0 : !cir.ptr<!rec_Base> -> !cir.ptr<!rec_Derived> #dyn_cast_info__ZTI4Base__ZTI7Derived
+  // CHECK:     cir.return %0 : !cir.ptr<!rec_Derived>
+  // CHECK:   }
+
+  cir.func dso_local @test_cast_to_void(%arg0: !cir.ptr<!rec_Base>) -> !cir.ptr<!void> {
+   %0 = cir.dyn_cast ptr %arg0 : !cir.ptr<!rec_Base> -> !cir.ptr<!void>
+   cir.return %0 : !cir.ptr<!void>
+  }
+
+  // CHECK: cir.func dso_local @test_cast_to_void(%arg0: !cir.ptr<!rec_Base>) -> !cir.ptr<!void> {
+  // CHECK:     %0 = cir.dyn_cast ptr %arg0 : !cir.ptr<!rec_Base> -> !cir.ptr<!void>
+  // CHECK:     cir.return %0 : !cir.ptr<!void>
+  // CHECK:   }
+
+  cir.func dso_local @test_relative_layout_cast(%arg0: !cir.ptr<!rec_Base>) -> !cir.ptr<!void> {
+   %0 = cir.dyn_cast ptr relative_layout %arg0 : !cir.ptr<!rec_Base> -> !cir.ptr<!void>
+   cir.return %0 : !cir.ptr<!void>
+  }
+
+  // CHECK: cir.func dso_local @test_relative_layout_cast(%arg0: !cir.ptr<!rec_Base>) -> !cir.ptr<!void> {
+  // CHECK:     %0 = cir.dyn_cast ptr relative_layout %arg0 : !cir.ptr<!rec_Base> -> !cir.ptr<!void>
+  // CHECK:     cir.return %0 : !cir.ptr<!void>
+  // CHECK:   }
+}

clang/test/CIR/IR/invalid-dyn-cast.cir

@@ -0,0 +1,43 @@
+// RUN: cir-opt %s -verify-diagnostics -split-input-file
+
+!s64i = !cir.int<s, 64>
+!s8i = !cir.int<s, 8>
+!u32i = !cir.int<u, 32>
+!u8i = !cir.int<u, 8>
+!void = !cir.void
+
+!Base = !cir.record<struct "Base" {!cir.ptr<!cir.ptr<!cir.func<() -> !cir.int<u, 32>>>>}>
+!Derived = !cir.record<struct "Derived" {!cir.record<struct "Base" {!cir.ptr<!cir.ptr<!cir.func<() -> !cir.int<u, 32>>>>}>}>
+
+module {
+  cir.global "private" constant external @_ZTI4Base : !cir.ptr<!u32i>
+  cir.global "private" constant external @_ZTI7Derived : !cir.ptr<!u8i>
+  cir.func private @__dynamic_cast(!cir.ptr<!void>, !cir.ptr<!u8i>, !cir.ptr<!u8i>, !s64i) -> !cir.ptr<!void>
+  cir.func private @__cxa_bad_cast()
+  cir.func @test(%arg0 : !cir.ptr<!Base>) {
+    // expected-error@+1 {{srcRtti must be an RTTI pointer}}
+    %0 = cir.dyn_cast ptr %arg0 : !cir.ptr<!Base> -> !cir.ptr<!Derived> #cir.dyn_cast_info<src_rtti = #cir.global_view<@_ZTI4Base> : !cir.ptr<!u32i>, dest_rtti = #cir.global_view<@_ZTI7Derived> : !cir.ptr<!u8i>, runtime_func = @__dynamic_cast, bad_cast_func = @__cxa_bad_cast, offset_hint = #cir.int<0> : !s64i>
+  }
+}
+
+// -----
+
+!s64i = !cir.int<s, 64>
+!s8i = !cir.int<s, 8>
+!u32i = !cir.int<u, 32>
+!u8i = !cir.int<u, 8>
+!void = !cir.void
+
+!Base = !cir.record<struct "Base" {!cir.ptr<!cir.ptr<!cir.func<() -> !cir.int<u, 32>>>>}>
+!Derived = !cir.record<struct "Derived" {!cir.record<struct "Base" {!cir.ptr<!cir.ptr<!cir.func<() -> !cir.int<u, 32>>>>}>}>
+
+module {
+  cir.global "private" constant external @_ZTI4Base : !cir.ptr<!u8i>
+  cir.global "private" constant external @_ZTI7Derived : !cir.ptr<!u32i>
+  cir.func private @__dynamic_cast(!cir.ptr<!void>, !cir.ptr<!u8i>, !cir.ptr<!u8i>, !s64i) -> !cir.ptr<!void>
+  cir.func private @__cxa_bad_cast()
+  cir.func @test(%arg0 : !cir.ptr<!Base>) {
+    // expected-error@+1 {{destRtti must be an RTTI pointer}}
+    %0 = cir.dyn_cast ptr %arg0 : !cir.ptr<!Base> -> !cir.ptr<!Derived> #cir.dyn_cast_info<src_rtti = #cir.global_view<@_ZTI4Base> : !cir.ptr<!u8i>, dest_rtti = #cir.global_view<@_ZTI7Derived> : !cir.ptr<!u32i>, runtime_func = @__dynamic_cast, bad_cast_func = @__cxa_bad_cast, offset_hint = #cir.int<0> : !s64i>
+  }
+}