[libc] introduce shared compiler-rt builtins

[hulxv]

Introduce shared compiler-rt builtins to libc and addtf3 builtin

Split from #197950

Part of #197824

[llvmorg-github-actions]

@llvm/pr-subscribers-libc

Author: hulxv (hulxv)

Changes

Introduce shared compiler-rt builtins to libc and addtf3 builtin

Split from #197950

Part of #197824

---

Full diff: https://github.com/llvm/llvm-project/pull/200094.diff

8 Files Affected:

• (added) libc/shared/builtins.h (+16)
• (added) libc/shared/builtins/addtf3.h (+35)
• (modified) libc/src/__support/CMakeLists.txt (+1)
• (modified) libc/src/__support/FPUtil/dyadic_float.h (+3)
• (added) libc/src/__support/builtins/CMakeLists.txt (+9)
• (added) libc/src/__support/builtins/addtf3.h (+32)
• (modified) libc/test/shared/CMakeLists.txt (+10)
• (added) libc/test/shared/shared_builtins_test.cpp (+21)

diff --git a/libc/shared/builtins.h b/libc/shared/builtins.h
new file mode 100644
index 0000000000000..157b6622cbcff
--- /dev/null
+++ b/libc/shared/builtins.h
@@ -0,0 +1,16 @@
+//===-- Compiler-runtime builtin primitives ---------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SHARED_BUILTINS_H
+#define LLVM_LIBC_SHARED_BUILTINS_H
+
+#include "libc_common.h"
+
+#include "builtins/addtf3.h"
+
+#endif // LLVM_LIBC_SHARED_BUILTINS_H
diff --git a/libc/shared/builtins/addtf3.h b/libc/shared/builtins/addtf3.h
new file mode 100644
index 0000000000000..9c39e6e9a8406
--- /dev/null
+++ b/libc/shared/builtins/addtf3.h
@@ -0,0 +1,35 @@
+//===-- Shared __addtf3 function -------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This header exposes LLVM-libc's __addtf3 implementation as shared::addtf3
+// so that it can be reused by other LLVM projects, such as compiler-rt's
+// builtins library.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SHARED_BUILTINS_ADDTF3_H
+#define LLVM_LIBC_SHARED_BUILTINS_ADDTF3_H
+
+#include "include/llvm-libc-types/float128.h"
+
+#ifdef LIBC_TYPES_HAS_FLOAT128
+
+#include "shared/libc_common.h"
+#include "src/__support/builtins/addtf3.h"
+
+namespace LIBC_NAMESPACE_DECL {
+namespace shared {
+
+using builtins::addtf3;
+
+} // namespace shared
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LIBC_TYPES_HAS_FLOAT128
+
+#endif // LLVM_LIBC_SHARED_BUILTINS_ADDTF3_H
diff --git a/libc/src/__support/CMakeLists.txt b/libc/src/__support/CMakeLists.txt
index ada489046ef9e..0246bcd8f01b6 100644
--- a/libc/src/__support/CMakeLists.txt
+++ b/libc/src/__support/CMakeLists.txt
@@ -470,6 +470,7 @@ add_subdirectory(wchar)
 add_subdirectory(wctype)
 
 add_subdirectory(math)
+add_subdirectory(builtins)
 if(LIBC_COMPILER_HAS_EXT_VECTOR_TYPE)
   add_subdirectory(mathvec)
 endif()
diff --git a/libc/src/__support/FPUtil/dyadic_float.h b/libc/src/__support/FPUtil/dyadic_float.h
index 8ce041247716b..04e7c0c34859b 100644
--- a/libc/src/__support/FPUtil/dyadic_float.h
+++ b/libc/src/__support/FPUtil/dyadic_float.h
@@ -415,6 +415,9 @@ template <size_t Bits> struct DyadicFloat {
     if constexpr (cpp::is_same_v<T, bfloat16>
 #if defined(LIBC_TYPES_HAS_FLOAT16) && !defined(__LIBC_USE_FLOAT16_CONVERSION)
                   || cpp::is_same_v<T, float16>
+#endif
+#if defined(LIBC_TYPES_HAS_FLOAT128)
+                  || cpp::is_same_v<T, float128>
 #endif
     )
       return generic_as<T, ShouldSignalExceptions>();
diff --git a/libc/src/__support/builtins/CMakeLists.txt b/libc/src/__support/builtins/CMakeLists.txt
new file mode 100644
index 0000000000000..c4982887d0a7c
--- /dev/null
+++ b/libc/src/__support/builtins/CMakeLists.txt
@@ -0,0 +1,9 @@
+add_header_library(
+  addtf3
+  HDRS
+    addtf3.h
+  DEPENDS
+    libc.include.llvm-libc-types.float128
+    libc.src.__support.FPUtil.generic.add_sub
+    libc.src.__support.macros.config
+)
diff --git a/libc/src/__support/builtins/addtf3.h b/libc/src/__support/builtins/addtf3.h
new file mode 100644
index 0000000000000..129ad2a81e827
--- /dev/null
+++ b/libc/src/__support/builtins/addtf3.h
@@ -0,0 +1,32 @@
+//===-- Implementation header for __addtf3 ----------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC___SUPPORT_BUILTINS_ADDTF3_H
+#define LLVM_LIBC_SRC___SUPPORT_BUILTINS_ADDTF3_H
+
+#include "include/llvm-libc-types/float128.h"
+
+#ifdef LIBC_TYPES_HAS_FLOAT128
+
+#include "src/__support/FPUtil/generic/add_sub.h"
+#include "src/__support/macros/config.h"
+
+namespace LIBC_NAMESPACE_DECL {
+namespace builtins {
+
+// Mirrors the compiler-rt __addtf3 ABI: a + b at float128 precision.
+LIBC_INLINE float128 addtf3(float128 x, float128 y) {
+  return fputil::generic::add<float128>(x, y);
+}
+
+} // namespace builtins
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LIBC_TYPES_HAS_FLOAT128
+
+#endif // LLVM_LIBC_SRC___SUPPORT_BUILTINS_ADDTF3_H
diff --git a/libc/test/shared/CMakeLists.txt b/libc/test/shared/CMakeLists.txt
index 84a8d4bf79b3d..0a4d7e2e30723 100644
--- a/libc/test/shared/CMakeLists.txt
+++ b/libc/test/shared/CMakeLists.txt
@@ -801,6 +801,16 @@ add_fp_unittest(
     libc.src.__support.math.totalordermagl
 )
 
+add_fp_unittest(
+  shared_builtins_test
+  SUITE
+    libc-shared-tests
+  SRCS
+    shared_builtins_test.cpp
+  DEPENDS
+    libc.src.__support.builtins.addtf3
+)
+
 add_fp_unittest(
   shared_str_to_num_test
   SUITE
diff --git a/libc/test/shared/shared_builtins_test.cpp b/libc/test/shared/shared_builtins_test.cpp
new file mode 100644
index 0000000000000..1cc0025487680
--- /dev/null
+++ b/libc/test/shared/shared_builtins_test.cpp
@@ -0,0 +1,21 @@
+//===-- Unittests for shared builtins -------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "shared/builtins.h"
+#include "test/UnitTest/FPMatcher.h"
+#include "test/UnitTest/Test.h"
+
+#ifdef LIBC_TYPES_HAS_FLOAT128
+
+TEST(LlvmLibcSharedBuiltinsTest, AllFloat128) {
+  namespace shared = LIBC_NAMESPACE::shared;
+
+  EXPECT_FP_EQ(float128(3.0), shared::addtf3(float128(1.0), float128(2.0)));
+}
+
+#endif // LIBC_TYPES_HAS_FLOAT128

[github-actions]

🪟 Windows x64 Test Results

• 124803 tests passed
• 2944 tests skipped

✅ The build succeeded and all tests passed.

[kaladron]

I'm having trouble telling what I'm looking at. Could you please flesh out the commit message a bit? This says it's introducing compiler-rt builtins - but it doesn't link in compiler-rt?

libc/src/__support/builtins/addtf3.h returns something from fputil into a bulitins namespace, but this doesn't appear builtin?

I need more of a roadmap than I've got here, sorry!

[hulxv]

I'm having trouble telling what I'm looking at. Could you please flesh out the commit message a bit? This says it's introducing compiler-rt builtins - but it doesn't link in compiler-rt?

libc/src/__support/builtins/addtf3.h returns something from fputil into a bulitins namespace, but this doesn't appear builtin?

I need more of a roadmap than I've got here, sorry!

It's split from the main pr about the integration with compiler-rt. Take a look here #197950. We decided to split the main Pr into 3 different PRs to make it cleaner

[kaladron]

Minor changes left, thanks!

[hulxv]

Minor changes left, thanks!

done. thanks!

[kaladron]

Thanks for the fixes and this commit!