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new 84fbd77468 [REFACTOR][RUNTIME] Phase out
include/tvm/runtime/builtin_fp16.h (#19472)
84fbd77468 is described below
commit 84fbd77468f0cb69cd6e5a2f2c1161e37b9d1fe5
Author: Tianqi Chen <[email protected]>
AuthorDate: Wed Apr 29 13:22:36 2026 -0400
[REFACTOR][RUNTIME] Phase out include/tvm/runtime/builtin_fp16.h (#19472)
## Summary
`include/tvm/runtime/builtin_fp16.h` has been in the public include tree
without serving a public-API purpose. The header declared fp16 ABI
symbols (`__gnu_f2h_ieee`, `__gnu_h2f_ieee`, etc.) for compiler-side
callers; `support/scalars.cc` was already phased out upstream, and this
PR migrates the lone remaining caller
(`src/relax/backend/contrib/cublas/codegen.cc`) to the 3rdparty inline
header (`3rdparty/compiler-rt/builtin_fp16.h`, already on the CMake
SYSTEM include path), then deletes the public header outright.
---
include/tvm/runtime/builtin_fp16.h | 39 --------------------------
src/relax/backend/contrib/cublas/codegen.cc | 5 ++--
src/runtime/builtin_fp16.cc | 18 ++++++++++++
src/runtime/contrib/random/mt_random_engine.cc | 3 +-
4 files changed, 22 insertions(+), 43 deletions(-)
diff --git a/include/tvm/runtime/builtin_fp16.h
b/include/tvm/runtime/builtin_fp16.h
deleted file mode 100644
index 30383df97a..0000000000
--- a/include/tvm/runtime/builtin_fp16.h
+++ /dev/null
@@ -1,39 +0,0 @@
-/*
- * Licensed to the Apache Software Foundation (ASF) under one
- * or more contributor license agreements. See the NOTICE file
- * distributed with this work for additional information
- * regarding copyright ownership. The ASF licenses this file
- * to you under the Apache License, Version 2.0 (the
- * "License"); you may not use this file except in compliance
- * with the License. You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing,
- * software distributed under the License is distributed on an
- * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
- * KIND, either express or implied. See the License for the
- * specific language governing permissions and limitations
- * under the License.
- */
-
-/*!
- * \file builtin_fp16.h
- * \brief Functions for conversion between fp32 and fp16
- */
-#ifndef TVM_RUNTIME_BUILTIN_FP16_H_
-#define TVM_RUNTIME_BUILTIN_FP16_H_
-
-#include <tvm/runtime/base.h>
-
-#include <cstdint>
-
-extern "C" {
-TVM_RUNTIME_DLL uint16_t __gnu_f2h_ieee(float);
-TVM_RUNTIME_DLL float __gnu_h2f_ieee(uint16_t);
-TVM_RUNTIME_DLL uint16_t __truncsfhf2(float v);
-TVM_RUNTIME_DLL uint16_t __truncdfhf2(double v);
-TVM_RUNTIME_DLL float __extendhfsf2(uint16_t v);
-}
-
-#endif // TVM_RUNTIME_BUILTIN_FP16_H_
diff --git a/src/relax/backend/contrib/cublas/codegen.cc
b/src/relax/backend/contrib/cublas/codegen.cc
index 7e750e2ec8..2dc1518b56 100644
--- a/src/relax/backend/contrib/cublas/codegen.cc
+++ b/src/relax/backend/contrib/cublas/codegen.cc
@@ -21,9 +21,9 @@
* \file src/relax/backend/contrib/cublas/codegen.cc
* \brief Implementation of the CUBLAS JSON serializer.
*/
+#include <builtin_fp16.h>
#include <tvm/ffi/reflection/registry.h>
#include <tvm/ir/module.h>
-#include <tvm/runtime/builtin_fp16.h>
#include <string>
@@ -86,7 +86,8 @@ class CublasJSONSerializer : public JSONSerializer {
auto sinfo = Downcast<TensorStructInfo>(const_expr->struct_info_);
float alpha = 1.0;
if (sinfo->dtype == DataType::Float(16)) {
- alpha =
__gnu_h2f_ieee(static_cast<uint16_t*>(const_expr->data->data)[0]);
+ alpha = __extendXfYf2__<uint16_t, uint16_t, 10, float, uint32_t, 23>(
+ static_cast<uint16_t*>(const_expr->data->data)[0]);
} else {
TVM_FFI_ICHECK(sinfo->dtype == DataType::Float(32));
alpha = static_cast<float*>(const_expr->data->data)[0];
diff --git a/src/runtime/builtin_fp16.cc b/src/runtime/builtin_fp16.cc
index 99797159bf..096bdadb26 100644
--- a/src/runtime/builtin_fp16.cc
+++ b/src/runtime/builtin_fp16.cc
@@ -20,6 +20,24 @@
/*!
* \file builtin_fp16.cc
* \brief Functions for conversion between fp32 and fp16
+ *
+ * JIT-fallback rationale
+ * ----------------------
+ * This file exports TVM_RUNTIME_DLL symbols (__gnu_f2h_ieee, __gnu_h2f_ieee,
+ * __truncdfhf2) so that loaded/JIT-compiled modules can resolve fp16 ABI calls
+ * at load time. In JIT and AOT-module-load scenarios the host process may not
+ * have libgcc or compiler-rt fp16 builtins linked in; TVM codegen emits calls
+ * to these symbols for fp16 ops, and without this fallback those calls would
+ * fail symbol resolution at load time on such platforms.
+ *
+ * The TVM_FFI_WEAK attribute means the OS dynamic linker prefers the
platform's
+ * own compiler-rt symbols when they are present; TVM's copy only "wins" when
no
+ * other implementation is linked into the process.
+ *
+ * The inline implementations are provided by
+ * 3rdparty/compiler-rt/builtin_fp16.h (included below as <builtin_fp16.h>,
+ * which is on the CMake SYSTEM include path). This file is NOT a duplicate of
+ * that header -- it provides runtime symbol export, not inline-only usage.
*/
#include <builtin_fp16.h>
#include <tvm/runtime/base.h>
diff --git a/src/runtime/contrib/random/mt_random_engine.cc
b/src/runtime/contrib/random/mt_random_engine.cc
index 506963df50..64c3ff66a7 100644
--- a/src/runtime/contrib/random/mt_random_engine.cc
+++ b/src/runtime/contrib/random/mt_random_engine.cc
@@ -21,6 +21,7 @@
* \file random/mt_random_engine.cc
* \brief mt19937 random engine
*/
+#include <builtin_fp16.h>
#include <tvm/runtime/c_backend_api.h>
#include <tvm/runtime/device_api.h>
#include <tvm/runtime/logging.h>
@@ -31,8 +32,6 @@
#include <random>
#include <thread>
-#include "../3rdparty/compiler-rt/builtin_fp16.h"
-
namespace tvm {
namespace contrib {
