[Cpp API Compatibility] add TypeMeta to replace ScalarType by youge325 · Pull Request #78257 · PaddlePaddle/Paddle

youge325 · 2026-03-10T15:16:11Z

PR Category

Execute Infrastructure

PR Types

New features

Description

新增 TypeMeta 类及其相关接口

是否引起精度变化

否

paddle-bot · 2026-03-10T15:16:20Z

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Pull request overview

This PR introduces a compat-layer caffe2::TypeMeta (mirroring PyTorch/Caffe2) and updates key C10/ATen compat APIs to treat TypeMeta as the canonical dtype representation while keeping legacy ScalarType overloads working.

Changes:

Add compat/c10/util/typeid.h implementing caffe2::TypeMeta / TypeIdentifier and CAFFE_KNOWN_TYPE macros.
Update c10::TensorOptions to store/return dtype as caffe2::TypeMeta, plus add ScalarType↔TypeMeta conversion helpers.
Adjust ATen op wrappers to use the get_default_dtype_as_scalartype() legacy accessor where ScalarType is still expected.

Reviewed changes

Copilot reviewed 16 out of 16 changed files in this pull request and generated 7 comments.

Show a summary per file

File	Description
paddle/phi/api/include/compat/utils/scalar_type_conversion.h	Adds `TypeMeta` overload for dtype conversion into `phi::DataType`.
paddle/phi/api/include/compat/c10/util/typeid.h	Adds `TypeIdentifier`/`TypeMeta` implementation and registration machinery.
paddle/phi/api/include/compat/c10/core/TensorOptions.h	Switches dtype storage/accessors to `TypeMeta` and adds legacy overloads.
paddle/phi/api/include/compat/c10/core/ScalarTypeToTypeMeta.h	Adds `ScalarType`↔`TypeMeta` conversion utilities and equality ops.
paddle/phi/api/include/compat/c10/core/DefaultDtype.h	Makes `get_default_dtype()` return `TypeMeta` and adds ScalarType legacy getter.
paddle/phi/api/include/compat/ATen/ops/zeros.h	Uses ScalarType legacy default dtype getter for value_or().
paddle/phi/api/include/compat/ATen/ops/ones.h	Uses ScalarType legacy default dtype getter for value_or().
paddle/phi/api/include/compat/ATen/ops/new_zeros.h	Uses `TypeMeta` dtype derivation from `TensorOptions`.
paddle/phi/api/include/compat/ATen/ops/new_ones.h	Uses `TypeMeta` dtype derivation from `TensorOptions`.
paddle/phi/api/include/compat/ATen/ops/new_full.h	Uses `TypeMeta` dtype derivation from `TensorOptions`.
paddle/phi/api/include/compat/ATen/ops/new_empty.h	Uses `TypeMeta` dtype derivation from `TensorOptions`.
paddle/phi/api/include/compat/ATen/ops/full.h	Uses ScalarType legacy default dtype getter for value_or().
paddle/phi/api/include/compat/ATen/ops/eye.h	Uses ScalarType legacy default dtype getter for value_or().
paddle/phi/api/include/compat/ATen/ops/empty_like.h	Uses `TypeMeta` dtype derivation from `TensorOptions`.
paddle/phi/api/include/compat/ATen/ops/empty.h	Uses ScalarType legacy default dtype getter for value_or().
paddle/phi/api/include/compat/ATen/ops/arange.h	Uses ScalarType legacy default dtype getter for value_or().

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Copilot · 2026-03-10T15:24:55Z

paddle/phi/api/include/compat/c10/util/typeid.h

+#ifndef C10_LIKELY
+#define C10_LIKELY(val) (__builtin_expect(static_cast<bool>(val), 1))
+#endif
+#ifndef C10_UNLIKELY
+#define C10_UNLIKELY(val) (__builtin_expect(static_cast<bool>(val), 0))
+#endif


C10_LIKELY/C10_UNLIKELY are defined via __builtin_expect, which is not supported by MSVC. Please add compiler guards (e.g., define them as (val) on MSVC) to avoid Windows build failures.

Suggested change

#ifndef C10_LIKELY

#define C10_LIKELY(val) (__builtin_expect(static_cast<bool>(val), 1))

#endif

#ifndef C10_UNLIKELY

#define C10_UNLIKELY(val) (__builtin_expect(static_cast<bool>(val), 0))

#endif

#ifndef C10_LIKELY

#ifdef _MSC_VER

#define C10_LIKELY(val) (val)

#else

#define C10_LIKELY(val) (__builtin_expect(static_cast<bool>(val), 1))

#endif

#endif

#ifndef C10_UNLIKELY

#ifdef _MSC_VER

#define C10_UNLIKELY(val) (val)

#else

#define C10_UNLIKELY(val) (__builtin_expect(static_cast<bool>(val), 0))

#endif

#endif

Copilot · 2026-03-10T15:24:56Z

paddle/phi/api/include/compat/c10/util/typeid.h

+#define C10_API PADDLE_API
+#endif
+#ifndef C10_EXPORT
+#define C10_EXPORT __attribute__((visibility("default")))


C10_EXPORT is defined with GCC/Clang-only attribute((visibility("default"))), which will not compile on MSVC. Please provide a compiler-conditional definition (e.g., map to PADDLE_API or __declspec(dllexport/dllimport) on Windows).

Suggested change

#define C10_EXPORT __attribute__((visibility("default")))

#define C10_EXPORT C10_API

Copilot · 2026-03-10T15:24:56Z

paddle/phi/api/include/compat/c10/util/typeid.h

+ * A unique run-time type identifier.  Unlike std::type_index it is stable
+ * across shared libraries (uses the address of a per-type static object).


The comment claims TypeIdentifier is stable across shared libraries, but deriving the ID from a function-local static inside a header-defined template is not stable across DSOs unless types are explicitly instantiated in a single shared library (e.g., via CAFFE_DECLARE/DEFINE_KNOWN_TYPE). Please clarify the comment or adjust the mechanism so the documented guarantee holds.

Suggested change

* A unique run-time type identifier. Unlike std::type_index it is stable

* across shared libraries (uses the address of a per-type static object).

* A unique run-time type identifier. It is derived from the address of a

* per-type static object and is intended to be unique within a process.

* Cross-shared-library (DSO) stability is not guaranteed by this mechanism.

Copilot · 2026-03-10T15:24:56Z

paddle/phi/api/include/compat/utils/scalar_type_conversion.h

 }

+// Overload that accepts caffe2::TypeMeta directly.
+inline phi::DataType _PD_AtenScalarTypeToPhiDataType(caffe2::TypeMeta dtype) {


This overload calls dtype.toScalarType(), which throws for non-scalar TypeMeta values. Since this helper is used to map to phi::DataType (which only represents scalar dtypes), it should explicitly check dtype.isScalarType() and raise a targeted Unsupported/InvalidArgument error that explains only scalar TypeMeta is accepted.

Suggested change

inline phi::DataType _PD_AtenScalarTypeToPhiDataType(caffe2::TypeMeta dtype) {

inline phi::DataType _PD_AtenScalarTypeToPhiDataType(caffe2::TypeMeta dtype) {

if (!dtype.isScalarType()) {

UNSUPPORTED_FEATURE_IN_PADDLE(

"Only scalar caffe2::TypeMeta values are supported when converting "

"to phi::DataType.");

return phi::DataType::UNDEFINED; // to avoid compile warning

}

Copilot · 2026-03-10T15:24:57Z

paddle/phi/api/include/compat/c10/core/TensorOptions.h

+  caffe2::TypeMeta dtype() const noexcept {
+    return dtype_or_default(dtype_opt());
+  }


TensorOptions::dtype() now returns caffe2::TypeMeta instead of ScalarType. There are existing compat unit tests (e.g., test/cpp/compat/c10_TensorOptions_test.cc and many ATen tests) that assert ScalarType returns/comparisons and will fail or no longer exercise the new behavior. Please update/add tests to cover the new TypeMeta-based API as well as the legacy ScalarType overloads.

Copilot · 2026-03-10T15:24:57Z

paddle/phi/api/include/compat/c10/util/typeid.h

+    for (uint16_t i = start; i < nxt; ++i) {
+      if (metas[i].id_ == identifier) return i;
+    }
+    return kMaxTypeIndex;
+  }


existingMetaDataIndexForType returns kMaxTypeIndex as the "not found" sentinel, but kMaxTypeIndex is also a valid slot in the table. This makes index 255 ambiguous and can break registration when the table reaches the last slot. Use a distinct invalid sentinel (e.g., std::numeric_limits<uint16_t>::max()) or reserve 255 and enforce nxt < kMaxTypeIndex.

Copilot · 2026-03-10T15:24:57Z

paddle/phi/api/include/compat/c10/util/typeid.h

+#define C10_EXPORT __attribute__((visibility("default")))
+#endif
+#ifndef C10_ALWAYS_INLINE
+#define C10_ALWAYS_INLINE __attribute__((always_inline)) inline


C10_ALWAYS_INLINE is defined with GCC/Clang-only attribute((always_inline)). This will not compile on MSVC; please use compiler-conditional definitions (e.g., __forceinline on MSVC) or reuse an existing Paddle inline macro.

Suggested change

#define C10_ALWAYS_INLINE __attribute__((always_inline)) inline

# ifdef _MSC_VER

# define C10_ALWAYS_INLINE __forceinline

# else

# define C10_ALWAYS_INLINE __attribute__((always_inline)) inline

# endif

[Cpp API Compatibility] add TypeMeta to replace ScalarType

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Copilot AI review requested due to automatic review settings March 10, 2026 15:16

paddle-bot bot added the contributor External developers label Mar 10, 2026

Copilot started reviewing on behalf of youge325 March 10, 2026 15:16 View session

Copilot AI reviewed Mar 10, 2026

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[Cpp API Compatibility] add TypeMeta to replace ScalarType#78257

[Cpp API Compatibility] add TypeMeta to replace ScalarType#78257
youge325 wants to merge 1 commit intoPaddlePaddle:developfrom
youge325:cTypeMeta

youge325 commented Mar 10, 2026 •

edited

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	#define C10_EXPORT __attribute__((visibility("default")))
	#define C10_EXPORT C10_API

		* A unique run-time type identifier. Unlike std::type_index it is stable
		* across shared libraries (uses the address of a per-type static object).

- * A unique run-time type identifier.  Unlike std::type_index it is stable
- * across shared libraries (uses the address of a per-type static object).
+ * A unique run-time type identifier. It is derived from the address of a
+ * per-type static object and is intended to be unique within a process.
+ * Cross-shared-library (DSO) stability is not guaranteed by this mechanism.

-inline phi::DataType _PD_AtenScalarTypeToPhiDataType(caffe2::TypeMeta dtype) {
+inline phi::DataType _PD_AtenScalarTypeToPhiDataType(caffe2::TypeMeta dtype) {
+  if (!dtype.isScalarType()) {
+    UNSUPPORTED_FEATURE_IN_PADDLE(
+        "Only scalar caffe2::TypeMeta values are supported when converting "
+        "to phi::DataType.");
+    return phi::DataType::UNDEFINED;  // to avoid compile warning
+  }

-#define C10_ALWAYS_INLINE __attribute__((always_inline)) inline
+#  ifdef _MSC_VER
+#    define C10_ALWAYS_INLINE __forceinline
+#  else
+#    define C10_ALWAYS_INLINE __attribute__((always_inline)) inline
+#  endif

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是否引起精度变化

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youge325 commented Mar 10, 2026 •

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