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new 3bfcffa5 [CORE] Mark type-info lookup as pure (#699)
3bfcffa5 is described below
commit 3bfcffa58476935c9b08b7e6e74f8491b4ec54cf
Author: Tianqi Chen <[email protected]>
AuthorDate: Mon Aug 3 06:29:12 2026 +0800
[CORE] Mark type-info lookup as pure (#699)
## Rationale
`TVMFFIGetTypeInfo` returns the stable entry for a registered type index
without modifying observable state. Exposing this contract lets
supporting compilers coalesce repeated lookups.
## Change
- Add a portable `TVM_FFI_ATTRIBUTE_PURE` macro for GCC and Clang, with
a safe no-op fallback.
- State the registered-index precondition and annotate
`TVMFFIGetTypeInfo`.
## Validation
The C and C++ header checks, C++ test suite, formatting, and a focused
optimized compiler benchmark pass.
---
include/tvm/ffi/c_api.h | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/include/tvm/ffi/c_api.h b/include/tvm/ffi/c_api.h
index 5077e16f..21092cbe 100644
--- a/include/tvm/ffi/c_api.h
+++ b/include/tvm/ffi/c_api.h
@@ -56,6 +56,14 @@
#define TVM_FFI_DLL_EXPORT __attribute__((visibility("default")))
#endif
+// Marks a function that has no observable effects and whose return value
depends
+// only on its arguments and non-volatile memory.
+#if defined(__GNUC__) || defined(__clang__)
+#define TVM_FFI_ATTRIBUTE_PURE __attribute__((__pure__))
+#else
+#define TVM_FFI_ATTRIBUTE_PURE
+#endif
+
// NOLINTBEGIN(modernize-macro-to-enum)
/*! \brief TVM FFI major version. */
#define TVM_FFI_VERSION_MAJOR 0
@@ -1484,9 +1492,10 @@ TVM_FFI_DLL int32_t TVMFFITypeGetOrAllocIndex(const
TVMFFIByteArray* type_key,
/*!
* \brief Get dynamic type info by type index.
+ * \pre type_index identifies a registered type.
* \return The type info.
*/
-TVM_FFI_DLL const TVMFFITypeInfo* TVMFFIGetTypeInfo(int32_t type_index);
+TVM_FFI_DLL TVM_FFI_ATTRIBUTE_PURE const TVMFFITypeInfo*
TVMFFIGetTypeInfo(int32_t type_index);
// ----------------------------------------------------------------------------
// Static handle initialization and deinitialization API
