[libc-commits] [libc] [libc] Modify `truncf128` to use emulated Float128 type (PR #216560)
via libc-commits
libc-commits at lists.llvm.org
Tue Aug 18 05:07:22 PDT 2026
https://github.com/Sukumarsawant updated https://github.com/llvm/llvm-project/pull/216560
>From 0060599b4a38d122061dfc7c976b7661714dcd10 Mon Sep 17 00:00:00 2001
From: Sukumarsawant <sawantsukumar at gmail.com>
Date: Sun, 16 Aug 2026 16:28:54 +0530
Subject: [PATCH 1/2] intial commit
---
libc/config/baremetal/aarch64/entrypoints.txt | 2 +-
libc/config/baremetal/arm/entrypoints.txt | 2 +-
libc/config/baremetal/riscv/entrypoints.txt | 2 +-
libc/config/darwin/aarch64/entrypoints.txt | 2 +-
libc/config/darwin/x86_64/entrypoints.txt | 1 +
libc/config/freebsd/x86_64/entrypoints.txt | 2 +-
libc/config/gpu/amdgpu/entrypoints.txt | 1 +
libc/config/gpu/nvptx/entrypoints.txt | 1 +
libc/config/linux/aarch64/entrypoints.txt | 2 +-
libc/config/linux/arm/entrypoints.txt | 1 +
libc/config/linux/riscv/entrypoints.txt | 2 +-
libc/config/linux/x86_64/entrypoints.txt | 2 +-
libc/config/windows/entrypoints.txt | 1 +
libc/shared/math/truncf128.h | 6 ------
libc/src/__support/math/CMakeLists.txt | 2 +-
libc/src/__support/math/truncf128.h | 11 ++++-------
libc/src/math/generic/CMakeLists.txt | 1 +
libc/src/math/generic/truncf128.cpp | 5 ++++-
libc/src/math/truncf128.h | 5 +++++
libc/test/shared/shared_math_constexpr_test.cpp | 4 ++--
libc/test/shared/shared_math_test.cpp | 2 +-
libc/test/src/math/smoke/CMakeLists.txt | 1 +
libc/test/src/math/smoke/truncf128_test.cpp | 6 +++++-
23 files changed, 37 insertions(+), 27 deletions(-)
diff --git a/libc/config/baremetal/aarch64/entrypoints.txt b/libc/config/baremetal/aarch64/entrypoints.txt
index 09b81be24c8d8..bb1ee32d5eb7d 100644
--- a/libc/config/baremetal/aarch64/entrypoints.txt
+++ b/libc/config/baremetal/aarch64/entrypoints.txt
@@ -581,6 +581,7 @@ set(TARGET_LIBM_ENTRYPOINTS
libc.src.math.totalordermagl
libc.src.math.trunc
libc.src.math.truncf
+ libc.src.math.truncf128
libc.src.math.truncl
libc.src.math.ufromfp
libc.src.math.ufromfpf
@@ -793,7 +794,6 @@ if(LIBC_TYPES_HAS_NATIVE_FLOAT128)
libc.src.math.sqrtf128
libc.src.math.totalorderf128
libc.src.math.totalordermagf128
- libc.src.math.truncf128
libc.src.math.ufromfpf128
libc.src.math.ufromfpxf128
)
diff --git a/libc/config/baremetal/arm/entrypoints.txt b/libc/config/baremetal/arm/entrypoints.txt
index d6cb433ba01a5..77e4dc2bf08c8 100644
--- a/libc/config/baremetal/arm/entrypoints.txt
+++ b/libc/config/baremetal/arm/entrypoints.txt
@@ -593,6 +593,7 @@ set(TARGET_LIBM_ENTRYPOINTS
libc.src.math.totalordermagl
libc.src.math.trunc
libc.src.math.truncf
+ libc.src.math.truncf128
libc.src.math.truncl
libc.src.math.ufromfp
libc.src.math.ufromfpf
@@ -804,7 +805,6 @@ if(LIBC_TYPES_HAS_NATIVE_FLOAT128)
libc.src.math.sqrtf128
libc.src.math.totalorderf128
libc.src.math.totalordermagf128
- libc.src.math.truncf128
libc.src.math.ufromfpf128
libc.src.math.ufromfpxf128
)
diff --git a/libc/config/baremetal/riscv/entrypoints.txt b/libc/config/baremetal/riscv/entrypoints.txt
index b7a7b9aa7142b..1d11afd5035cc 100644
--- a/libc/config/baremetal/riscv/entrypoints.txt
+++ b/libc/config/baremetal/riscv/entrypoints.txt
@@ -589,6 +589,7 @@ set(TARGET_LIBM_ENTRYPOINTS
libc.src.math.totalordermagl
libc.src.math.trunc
libc.src.math.truncf
+ libc.src.math.truncf128
libc.src.math.truncl
libc.src.math.ufromfp
libc.src.math.ufromfpf
@@ -801,7 +802,6 @@ if(LIBC_TYPES_HAS_NATIVE_FLOAT128)
libc.src.math.sqrtf128
libc.src.math.totalorderf128
libc.src.math.totalordermagf128
- libc.src.math.truncf128
libc.src.math.ufromfpf128
libc.src.math.ufromfpxf128
)
diff --git a/libc/config/darwin/aarch64/entrypoints.txt b/libc/config/darwin/aarch64/entrypoints.txt
index 9642dacf6426d..c114715550405 100644
--- a/libc/config/darwin/aarch64/entrypoints.txt
+++ b/libc/config/darwin/aarch64/entrypoints.txt
@@ -401,6 +401,7 @@ set(TARGET_LIBM_ENTRYPOINTS
libc.src.math.totalordermagl
libc.src.math.trunc
libc.src.math.truncf
+ libc.src.math.truncf128
libc.src.math.truncl
libc.src.math.ufromfp
libc.src.math.ufromfpf
@@ -613,7 +614,6 @@ if(LIBC_TYPES_HAS_NATIVE_FLOAT128)
libc.src.math.sqrtf128
libc.src.math.totalorderf128
libc.src.math.totalordermagf128
- libc.src.math.truncf128
libc.src.math.ufromfpf128
libc.src.math.ufromfpxf128
)
diff --git a/libc/config/darwin/x86_64/entrypoints.txt b/libc/config/darwin/x86_64/entrypoints.txt
index 9ece581ce10eb..c0ed97c788f82 100644
--- a/libc/config/darwin/x86_64/entrypoints.txt
+++ b/libc/config/darwin/x86_64/entrypoints.txt
@@ -232,6 +232,7 @@ set(TARGET_LIBM_ENTRYPOINTS
#libc.src.math.totalordermagl
#libc.src.math.trunc
#libc.src.math.truncf
+ #libc.src.math.truncf128
#libc.src.math.truncl
)
diff --git a/libc/config/freebsd/x86_64/entrypoints.txt b/libc/config/freebsd/x86_64/entrypoints.txt
index bb468f0467d23..82ca6e62f9393 100644
--- a/libc/config/freebsd/x86_64/entrypoints.txt
+++ b/libc/config/freebsd/x86_64/entrypoints.txt
@@ -288,6 +288,7 @@ set(TARGET_LIBM_ENTRYPOINTS
libc.src.math.tanhf
libc.src.math.trunc
libc.src.math.truncf
+ libc.src.math.truncf128
libc.src.math.truncl
)
@@ -551,7 +552,6 @@ if(LIBC_TYPES_HAS_NATIVE_FLOAT128)
libc.src.math.sqrtf128
libc.src.math.totalorderf128
libc.src.math.totalordermagf128
- libc.src.math.truncf128
libc.src.math.ufromfpf128
libc.src.math.ufromfpxf128
)
diff --git a/libc/config/gpu/amdgpu/entrypoints.txt b/libc/config/gpu/amdgpu/entrypoints.txt
index e44147e9699f4..a2b9c1bbf6909 100644
--- a/libc/config/gpu/amdgpu/entrypoints.txt
+++ b/libc/config/gpu/amdgpu/entrypoints.txt
@@ -527,6 +527,7 @@ set(TARGET_LIBM_ENTRYPOINTS
libc.src.math.totalordermagl
libc.src.math.trunc
libc.src.math.truncf
+ libc.src.math.truncf128
libc.src.math.truncl
libc.src.math.ufromfp
libc.src.math.ufromfpf
diff --git a/libc/config/gpu/nvptx/entrypoints.txt b/libc/config/gpu/nvptx/entrypoints.txt
index efd4fb8fc5682..6827b7f936003 100644
--- a/libc/config/gpu/nvptx/entrypoints.txt
+++ b/libc/config/gpu/nvptx/entrypoints.txt
@@ -524,6 +524,7 @@ set(TARGET_LIBM_ENTRYPOINTS
libc.src.math.totalordermagl
libc.src.math.trunc
libc.src.math.truncf
+ libc.src.math.truncf128
libc.src.math.truncl
# FIXME: Broken.
# libc.src.math.ufromfp
diff --git a/libc/config/linux/aarch64/entrypoints.txt b/libc/config/linux/aarch64/entrypoints.txt
index 04dbcb4e4cf9e..81b290df84e3a 100644
--- a/libc/config/linux/aarch64/entrypoints.txt
+++ b/libc/config/linux/aarch64/entrypoints.txt
@@ -736,6 +736,7 @@ set(TARGET_LIBM_ENTRYPOINTS
libc.src.math.totalordermagl
libc.src.math.trunc
libc.src.math.truncf
+ libc.src.math.truncf128
libc.src.math.truncl
libc.src.math.ufromfp
libc.src.math.ufromfpf
@@ -941,7 +942,6 @@ if(LIBC_TYPES_HAS_NATIVE_FLOAT128)
libc.src.math.sqrtf128
libc.src.math.totalorderf128
libc.src.math.totalordermagf128
- libc.src.math.truncf128
libc.src.math.ufromfpf128
libc.src.math.ufromfpxf128
)
diff --git a/libc/config/linux/arm/entrypoints.txt b/libc/config/linux/arm/entrypoints.txt
index 83c3b65498f0c..5171327be03cd 100644
--- a/libc/config/linux/arm/entrypoints.txt
+++ b/libc/config/linux/arm/entrypoints.txt
@@ -552,6 +552,7 @@ set(TARGET_LIBM_ENTRYPOINTS
libc.src.math.totalordermagl
libc.src.math.trunc
libc.src.math.truncf
+ libc.src.math.truncf128
libc.src.math.truncl
libc.src.math.ufromfp
libc.src.math.ufromfpf
diff --git a/libc/config/linux/riscv/entrypoints.txt b/libc/config/linux/riscv/entrypoints.txt
index 81ef813a1fa64..eca755174140c 100644
--- a/libc/config/linux/riscv/entrypoints.txt
+++ b/libc/config/linux/riscv/entrypoints.txt
@@ -809,6 +809,7 @@ set(TARGET_LIBM_ENTRYPOINTS
libc.src.math.totalordermagl
libc.src.math.trunc
libc.src.math.truncf
+ libc.src.math.truncf128
libc.src.math.truncl
libc.src.math.ufromfp
libc.src.math.ufromfpf
@@ -1031,7 +1032,6 @@ if(LIBC_TYPES_HAS_NATIVE_FLOAT128)
libc.src.math.sqrtf128
libc.src.math.totalorderf128
libc.src.math.totalordermagf128
- libc.src.math.truncf128
libc.src.math.ufromfpf128
libc.src.math.ufromfpxf128
)
diff --git a/libc/config/linux/x86_64/entrypoints.txt b/libc/config/linux/x86_64/entrypoints.txt
index 37576491a73bb..10f619d0b1ebc 100644
--- a/libc/config/linux/x86_64/entrypoints.txt
+++ b/libc/config/linux/x86_64/entrypoints.txt
@@ -814,6 +814,7 @@ set(TARGET_LIBM_ENTRYPOINTS
libc.src.math.totalordermagl
libc.src.math.trunc
libc.src.math.truncf
+ libc.src.math.truncf128
libc.src.math.truncl
libc.src.math.ufromfp
libc.src.math.ufromfpf
@@ -1036,7 +1037,6 @@ if(LIBC_TYPES_HAS_NATIVE_FLOAT128)
libc.src.math.sqrtf128
libc.src.math.totalorderf128
libc.src.math.totalordermagf128
- libc.src.math.truncf128
libc.src.math.ufromfpf128
libc.src.math.ufromfpxf128
)
diff --git a/libc/config/windows/entrypoints.txt b/libc/config/windows/entrypoints.txt
index bdc209bd330b5..982ba21cf1e2f 100644
--- a/libc/config/windows/entrypoints.txt
+++ b/libc/config/windows/entrypoints.txt
@@ -322,6 +322,7 @@ set(TARGET_LIBM_ENTRYPOINTS
libc.src.math.tanpif
libc.src.math.trunc
libc.src.math.truncf
+ libc.src.math.truncf128
libc.src.math.truncl
)
diff --git a/libc/shared/math/truncf128.h b/libc/shared/math/truncf128.h
index 0233775d6c6b8..e9de5418e0b30 100644
--- a/libc/shared/math/truncf128.h
+++ b/libc/shared/math/truncf128.h
@@ -9,10 +9,6 @@
#ifndef LLVM_LIBC_SHARED_MATH_TRUNCF128_H
#define LLVM_LIBC_SHARED_MATH_TRUNCF128_H
-#include "include/llvm-libc-types/float128.h"
-
-#ifdef LIBC_TYPES_HAS_NATIVE_FLOAT128
-
#include "shared/libc_common.h"
#include "src/__support/math/truncf128.h"
@@ -24,6 +20,4 @@ using math::truncf128;
} // namespace shared
} // namespace LIBC_NAMESPACE_DECL
-#endif // LIBC_TYPES_HAS_NATIVE_FLOAT128
-
#endif // LLVM_LIBC_SHARED_MATH_TRUNCF128_H
diff --git a/libc/src/__support/math/CMakeLists.txt b/libc/src/__support/math/CMakeLists.txt
index 613e0adf385c7..60442f2edab94 100644
--- a/libc/src/__support/math/CMakeLists.txt
+++ b/libc/src/__support/math/CMakeLists.txt
@@ -5703,7 +5703,7 @@ add_header_library(
HDRS
truncf128.h
DEPENDS
- libc.include.llvm-libc-types.float128
+ libc.src.__support.FPUtil.float128
libc.src.__support.FPUtil.nearest_integer_operations
libc.src.__support.macros.config
)
diff --git a/libc/src/__support/math/truncf128.h b/libc/src/__support/math/truncf128.h
index 454b8c1dc2ad5..72e3a100a0935 100644
--- a/libc/src/__support/math/truncf128.h
+++ b/libc/src/__support/math/truncf128.h
@@ -9,23 +9,20 @@
#ifndef LLVM_LIBC_SRC___SUPPORT_MATH_TRUNCF128_H
#define LLVM_LIBC_SRC___SUPPORT_MATH_TRUNCF128_H
-#include "include/llvm-libc-types/float128.h"
-
-#ifdef LIBC_TYPES_HAS_NATIVE_FLOAT128
-
#include "src/__support/FPUtil/NearestIntegerOperations.h"
+#include "src/__support/FPUtil/float128.h"
#include "src/__support/macros/config.h"
namespace LIBC_NAMESPACE_DECL {
namespace math {
-LIBC_INLINE constexpr float128 truncf128(float128 x) {
+using LIBC_NAMESPACE::fputil::Float128;
+
+LIBC_INLINE constexpr Float128 truncf128(Float128 x) {
return fputil::trunc(x);
}
} // namespace math
} // namespace LIBC_NAMESPACE_DECL
-#endif // LIBC_TYPES_HAS_NATIVE_FLOAT128
-
#endif // LLVM_LIBC_SRC___SUPPORT_MATH_TRUNCF128_H
diff --git a/libc/src/math/generic/CMakeLists.txt b/libc/src/math/generic/CMakeLists.txt
index 13c4ff8126c9f..81f839bde467c 100644
--- a/libc/src/math/generic/CMakeLists.txt
+++ b/libc/src/math/generic/CMakeLists.txt
@@ -604,6 +604,7 @@ add_entrypoint_object(
HDRS
../truncf128.h
DEPENDS
+ libc.src.__support.CPP.bit
libc.src.__support.math.truncf128
)
diff --git a/libc/src/math/generic/truncf128.cpp b/libc/src/math/generic/truncf128.cpp
index bef079cbbd6a5..083629a6f7a76 100644
--- a/libc/src/math/generic/truncf128.cpp
+++ b/libc/src/math/generic/truncf128.cpp
@@ -7,12 +7,15 @@
//===----------------------------------------------------------------------===//
#include "src/math/truncf128.h"
+#include "src/__support/CPP/bit.h"
#include "src/__support/math/truncf128.h"
namespace LIBC_NAMESPACE_DECL {
+using LIBC_NAMESPACE::fputil::Float128;
+
LLVM_LIBC_FUNCTION(float128, truncf128, (float128 x)) {
- return math::truncf128(x);
+ return cpp::bit_cast<float128>(math::truncf128(cpp::bit_cast<Float128>(x)));
}
} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/math/truncf128.h b/libc/src/math/truncf128.h
index df3899c35e668..265d8cadcdea6 100644
--- a/libc/src/math/truncf128.h
+++ b/libc/src/math/truncf128.h
@@ -9,11 +9,16 @@
#ifndef LLVM_LIBC_SRC_MATH_TRUNCF128_H
#define LLVM_LIBC_SRC_MATH_TRUNCF128_H
+#include "src/__support/FPUtil/float128.h"
#include "src/__support/macros/config.h"
#include "src/__support/macros/properties/types.h"
namespace LIBC_NAMESPACE_DECL {
+#ifndef LIBC_TYPES_HAS_NATIVE_FLOAT128
+using float128 = LIBC_NAMESPACE::fputil::Float128;
+#endif // LIBC_TYPES_HAS_NATIVE_FLOAT128
+
float128 truncf128(float128 x);
} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/test/shared/shared_math_constexpr_test.cpp b/libc/test/shared/shared_math_constexpr_test.cpp
index df5496c7af6bf..5217c9a769e80 100644
--- a/libc/test/shared/shared_math_constexpr_test.cpp
+++ b/libc/test/shared/shared_math_constexpr_test.cpp
@@ -383,6 +383,8 @@ static_assert(0 == LIBC_NAMESPACE::shared::isnanl(0.0L));
static_assert(Float128(0.0) == LIBC_NAMESPACE::shared::ceilf128(Float128(0.0)));
static_assert(Float128(0.0) ==
LIBC_NAMESPACE::shared::floorf128(Float128(0.0)));
+static_assert(Float128(0.0) ==
+ LIBC_NAMESPACE::shared::truncf128(Float128(0.0)));
//===----------------------------------------------------------------------===//
// Native Float128 Tests
@@ -511,8 +513,6 @@ static_assert(float128(0.0) ==
LIBC_NAMESPACE::shared::roundf128(float128(0.0)));
static_assert(float128(0.0) ==
LIBC_NAMESPACE::shared::roundevenf128(float128(0.0)));
-static_assert(float128(0.0) ==
- LIBC_NAMESPACE::shared::truncf128(float128(0.0)));
#endif // LIBC_TYPES_HAS_NATIVE_FLOAT128
diff --git a/libc/test/shared/shared_math_test.cpp b/libc/test/shared/shared_math_test.cpp
index c507c51d8b48a..d7ef436d1f30e 100644
--- a/libc/test/shared/shared_math_test.cpp
+++ b/libc/test/shared/shared_math_test.cpp
@@ -583,6 +583,7 @@ TEST(LlvmLibcSharedMathTest, AllLongDouble) {
TEST(LlvmLibcSharedMathTest, AllEmuFloat128) {
EXPECT_FP_EQ(Float128(0.0), LIBC_NAMESPACE::shared::ceilf128(Float128(0.0)));
EXPECT_FP_EQ(Float128(0.0), LIBC_NAMESPACE::shared::floorf128(Float128(0.0)));
+ EXPECT_FP_EQ(Float128(0.0), LIBC_NAMESPACE::shared::truncf128(Float128(0.0)));
}
#ifdef LIBC_TYPES_HAS_NATIVE_FLOAT128
@@ -755,7 +756,6 @@ TEST(LlvmLibcSharedMathTest, AllFloat128) {
EXPECT_FP_EQ(float128(0.0), LIBC_NAMESPACE::shared::roundf128(float128(0.0)));
EXPECT_FP_EQ(float128(0.0),
LIBC_NAMESPACE::shared::roundevenf128(float128(0.0)));
- EXPECT_FP_EQ(float128(0.0), LIBC_NAMESPACE::shared::truncf128(float128(0.0)));
}
#endif // LIBC_TYPES_HAS_NATIVE_FLOAT128
diff --git a/libc/test/src/math/smoke/CMakeLists.txt b/libc/test/src/math/smoke/CMakeLists.txt
index ba6d8764f1292..58a329751dfc2 100644
--- a/libc/test/src/math/smoke/CMakeLists.txt
+++ b/libc/test/src/math/smoke/CMakeLists.txt
@@ -363,6 +363,7 @@ add_fp_unittest(
TruncTest.h
DEPENDS
libc.src.math.truncf128
+ libc.src.__support.FPUtil.float128
libc.src.__support.FPUtil.fp_bits
)
diff --git a/libc/test/src/math/smoke/truncf128_test.cpp b/libc/test/src/math/smoke/truncf128_test.cpp
index 7d6487b7d8567..f486213110b6b 100644
--- a/libc/test/src/math/smoke/truncf128_test.cpp
+++ b/libc/test/src/math/smoke/truncf128_test.cpp
@@ -7,7 +7,11 @@
//===----------------------------------------------------------------------===//
#include "TruncTest.h"
-
+#include "src/__support/FPUtil/float128.h"
#include "src/math/truncf128.h"
+#ifndef LIBC_TYPES_HAS_NATIVE_FLOAT128
+using float128 = LIBC_NAMESPACE::fputil::Float128;
+#endif // LIBC_TYPES_HAS_NATIVE_FLOAT128
+
LIST_TRUNC_TESTS(float128, LIBC_NAMESPACE::truncf128)
>From e85c4bae418512f78e5217bd16c96a3a5eba8b02 Mon Sep 17 00:00:00 2001
From: Sukumarsawant <sawantsukumar at gmail.com>
Date: Tue, 18 Aug 2026 17:29:30 +0530
Subject: [PATCH 2/2] mpfr tests
---
libc/test/src/math/CMakeLists.txt | 16 ++++++++++++++++
libc/test/src/math/truncf128_test.cpp | 18 ++++++++++++++++++
2 files changed, 34 insertions(+)
create mode 100644 libc/test/src/math/truncf128_test.cpp
diff --git a/libc/test/src/math/CMakeLists.txt b/libc/test/src/math/CMakeLists.txt
index 17029bdcefd46..60da1e7025d4d 100644
--- a/libc/test/src/math/CMakeLists.txt
+++ b/libc/test/src/math/CMakeLists.txt
@@ -392,6 +392,22 @@ add_fp_unittest(
libc.src.__support.FPUtil.fp_bits
)
+add_fp_unittest(
+ truncf128_test
+ NEED_MPFR_F128
+ SUITE
+ libc-math-unittests
+ SRCS
+ truncf128_test.cpp
+ HDRS
+ TruncTest.h
+ DEPENDS
+ libc.src.math.truncf128
+ libc.src.__support.CPP.algorithm
+ libc.src.__support.FPUtil.float128
+ libc.src.__support.FPUtil.fp_bits
+)
+
add_fp_unittest(
truncf16_test
NEED_MPFR
diff --git a/libc/test/src/math/truncf128_test.cpp b/libc/test/src/math/truncf128_test.cpp
new file mode 100644
index 0000000000000..05af1a73b117b
--- /dev/null
+++ b/libc/test/src/math/truncf128_test.cpp
@@ -0,0 +1,18 @@
+//===-- Unittests for truncf128 -------------------------------------------===//
+//
+// 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 "TruncTest.h"
+
+#include "src/math/floorf128.h"
+#include "src/math/truncf128.h"
+
+#ifndef LIBC_TYPES_HAS_NATIVE_FLOAT128
+using float128 = LIBC_NAMESPACE::fputil::Float128;
+#endif // LIBC_TYPES_HAS_NATIVE_FLOAT128
+
+LIST_TRUNC_TESTS(float128, LIBC_NAMESPACE::truncf128)
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