[libc][math][c23] Add cosf16 function #118785
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wldfngrs
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Dec 5, 2024
wldfngrs
commented
- Implementation of cos for 16-bit floating point inputs
- Exhaustive tests across the 16-bit input range
|
@llvm/pr-subscribers-libc Author: wldfngrs (wldfngrs) Changes
Full diff: https://github.com./llvm/llvm-project/pull/118785.diff 13 Files Affected:
diff --git a/libc/config/linux/x86_64/entrypoints.txt b/libc/config/linux/x86_64/entrypoints.txt
index 5e9cc71279ab16..34366433b87c51 100644
--- a/libc/config/linux/x86_64/entrypoints.txt
+++ b/libc/config/linux/x86_64/entrypoints.txt
@@ -627,6 +627,7 @@ if(LIBC_TYPES_HAS_FLOAT16)
libc.src.math.canonicalizef16
libc.src.math.ceilf16
libc.src.math.copysignf16
+ libc.src.math.cosf16
libc.src.math.coshf16
libc.src.math.cospif16
libc.src.math.exp10f16
diff --git a/libc/docs/math/index.rst b/libc/docs/math/index.rst
index 4934e93ccb1645..53c4e8ed2962ce 100644
--- a/libc/docs/math/index.rst
+++ b/libc/docs/math/index.rst
@@ -276,7 +276,7 @@ Higher Math Functions
+-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
| compoundn | | | | | | 7.12.7.2 | F.10.4.2 |
+-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
-| cos | |check| | |check| | | | | 7.12.4.5 | F.10.1.5 |
+| cos | |check| | |check| | | |check| | | 7.12.4.5 | F.10.1.5 |
+-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
| cosh | |check| | | | |check| | | 7.12.5.4 | F.10.2.4 |
+-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
diff --git a/libc/newhdrgen/yaml/math.yaml b/libc/newhdrgen/yaml/math.yaml
index 00efc34789667e..3b8caec66bbfd2 100644
--- a/libc/newhdrgen/yaml/math.yaml
+++ b/libc/newhdrgen/yaml/math.yaml
@@ -200,6 +200,13 @@ functions:
return_type: float
arguments:
- type: float
+ - name: cosf16
+ standards:
+ - stdc
+ return_type: _Float16
+ arguments:
+ - type: _Float16
+ guard: LIBC_TYPES_HAS_FLOAT16
- name: coshf
standards:
- stdc
diff --git a/libc/src/math/CMakeLists.txt b/libc/src/math/CMakeLists.txt
index 390a59d07a28bc..e4e2c49642f2d0 100644
--- a/libc/src/math/CMakeLists.txt
+++ b/libc/src/math/CMakeLists.txt
@@ -89,6 +89,7 @@ add_math_entrypoint_object(copysignf128)
add_math_entrypoint_object(cos)
add_math_entrypoint_object(cosf)
+add_math_entrypoint_object(cosf16)
add_math_entrypoint_object(cosh)
add_math_entrypoint_object(coshf)
diff --git a/libc/src/math/cosf16.h b/libc/src/math/cosf16.h
new file mode 100644
index 00000000000000..cc179a6e16c626
--- /dev/null
+++ b/libc/src/math/cosf16.h
@@ -0,0 +1,21 @@
+//===-- Implementation header for cosf16 ------------------------*- 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_MATH_COSF16_H
+#define LLVM_LIBC_SRC_MATH_COSF16_H
+
+#include "src/__support/macros/config.h"
+#include "src/__support/macros/properties/types.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+float16 cosf16(float16 x);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_MATH_COSF16_H
diff --git a/libc/src/math/generic/CMakeLists.txt b/libc/src/math/generic/CMakeLists.txt
index aeb758d4a092da..b3d46129151974 100644
--- a/libc/src/math/generic/CMakeLists.txt
+++ b/libc/src/math/generic/CMakeLists.txt
@@ -418,6 +418,25 @@ add_entrypoint_object(
${libc_opt_high_flag}
)
+add_entrypoint_object(
+ cosf16
+ SRCS
+ cosf16.cpp
+ HDRS
+ ../cosf16.h
+ DEPENDS
+ .sincosf16_utils
+ libc.hdr.errno_macros
+ libc.hdr.fenv_macros
+ libc.src.__support.FPUtil.cast
+ libc.src.__support.FPUtil.fenv_impl
+ libc.src.__support.FPUtil.fp_bits
+ libc.src.__support.FPUtil.except_value_utils
+ libc.src.__support.FPUtil.multiply_add
+ libc.src.__support.macros.optimization
+ libc.src.__support.macros.properties.types
+)
+
add_entrypoint_object(
cospif
SRCS
diff --git a/libc/src/math/generic/cosf16.cpp b/libc/src/math/generic/cosf16.cpp
new file mode 100644
index 00000000000000..2fad3b010172c4
--- /dev/null
+++ b/libc/src/math/generic/cosf16.cpp
@@ -0,0 +1,84 @@
+//===-- Half-precision cos(x) function ------------------------------------===//
+//
+// 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 "src/math/cosf16.h"
+#include "hdr/errno_macros.h"
+#include "hdr/fenv_macros.h"
+#include "sincosf16_utils.h"
+#include "src/__support/FPUtil/FEnvImpl.h"
+#include "src/__support/FPUtil/FPBits.h"
+#include "src/__support/FPUtil/cast.h"
+#include "src/__support/FPUtil/except_value_utils.h"
+#include "src/__support/FPUtil/multiply_add.h"
+#include "src/__support/macros/optimization.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+constexpr size_t N_EXCEPTS = 4;
+
+constexpr fputil::ExceptValues<float16, N_EXCEPTS> COSF16_EXCEPTS{{
+ // (input, RZ output, RU offset, RD offset, RN offset)
+ {0x2b7c, 0x3bfc, 1, 0, 1},
+ {0x4ac1, 0x38b5, 1, 0, 0},
+ {0x5c49, 0xb8c6, 0, 1, 0},
+ {0x7acc, 0xa474, 0, 1, 0},
+}};
+
+LLVM_LIBC_FUNCTION(float16, cosf16, (float16 x)) {
+ using FPBits = fputil::FPBits<float16>;
+ FPBits xbits(x);
+
+ uint16_t x_u = xbits.uintval();
+ uint16_t x_abs = x_u & 0x7fff;
+ float xf = x;
+
+ // Range reduction:
+ // For |x| > pi/32, we perform range reduction as follows:
+ // Find k and y such that:
+ // x = (k + y) * pi/32
+ // k is an integer, |y| < 0.5
+ //
+ // This is done by performing:
+ // k = round(x * 32/pi)
+ // y = x * 32/pi - k
+ //
+ // Once k and y are computed, we then deduce the answer by the cosine of sum
+ // formula:
+ // cos(x) = cos((k + y) * pi/32)
+ // = cos(k * pi/32) * cos(y * pi/32) -
+ // sin(k * pi/32) * sin(y * pi/32)
+
+ // Handle exceptional values
+
+ if (LIBC_UNLIKELY(x_abs == 0x2b7c || x_abs == 0x4ac1 || x_abs == 0x5c49 ||
+ x_abs == 0x7acc)) {
+ if (auto r = COSF16_EXCEPTS.lookup(x_abs); LIBC_UNLIKELY(r.has_value()))
+ return r.value();
+ }
+
+ if (LIBC_UNLIKELY(x_abs == 0U))
+ return fputil::cast<float16>(1.0f);
+
+ if (xbits.is_inf_or_nan()) {
+ if (xbits.is_inf()) {
+ fputil::set_errno_if_required(EDOM);
+ fputil::raise_except_if_required(FE_INVALID);
+ }
+
+ return x + FPBits::quiet_nan().get_val();
+ }
+
+ float sin_k, cos_k, sin_y, cosm1_y;
+ sincosf16_eval(xf, sin_k, cos_k, sin_y, cosm1_y);
+ // Since, cosm1_y = cos_y - 1, therefore:
+ // cos(x) = cos_k * cosm1_y - sin_k * sin_y
+ return fputil::cast<float16>(fputil::multiply_add(
+ cos_k, cosm1_y, fputil::multiply_add(-sin_k, sin_y, cos_k)));
+}
+
+} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/math/generic/cospif16.cpp b/libc/src/math/generic/cospif16.cpp
index 384b39ff8e2c44..ee74bdb4a36937 100644
--- a/libc/src/math/generic/cospif16.cpp
+++ b/libc/src/math/generic/cospif16.cpp
@@ -73,7 +73,7 @@ LLVM_LIBC_FUNCTION(float16, cospif16, (float16 x)) {
return fputil::cast<float16>(0.0f);
// Since, cosm1_y = cos_y - 1, therefore:
- // cos(x * pi) = cos_k(cosm1_y) + cos_k - sin_k * sin_y
+ // cos(x * pi) = cos_k(cosm1_y) + cos_k - sin_k * sin_y
return fputil::cast<float16>(fputil::multiply_add(
cos_k, cosm1_y, fputil::multiply_add(-sin_k, sin_y, cos_k)));
}
diff --git a/libc/src/math/generic/sinf16.cpp b/libc/src/math/generic/sinf16.cpp
index 86546348ba7392..d5a4aa56063ae4 100644
--- a/libc/src/math/generic/sinf16.cpp
+++ b/libc/src/math/generic/sinf16.cpp
@@ -99,8 +99,8 @@ LLVM_LIBC_FUNCTION(float16, sinf16, (float16 x)) {
if (LIBC_UNLIKELY(sin_y == 0 && sin_k == 0))
return FPBits::zero(xbits.sign()).get_val();
- // Since, cosm1_y = cos_y - 1, therfore:
- // sin(x) = cos_k * sin_y + sin_k + (cosm1_y * sin_k)
+ // Since, cosm1_y = cos_y - 1, therefore:
+ // sin(x) = cos_k * sin_y + sin_k + (cosm1_y * sin_k)
return fputil::cast<float16>(fputil::multiply_add(
sin_y, cos_k, fputil::multiply_add(cosm1_y, sin_k, sin_k)));
}
diff --git a/libc/test/src/math/CMakeLists.txt b/libc/test/src/math/CMakeLists.txt
index ea75720df4f430..44a29f0c48e400 100644
--- a/libc/test/src/math/CMakeLists.txt
+++ b/libc/test/src/math/CMakeLists.txt
@@ -28,6 +28,17 @@ add_fp_unittest(
libc.src.__support.FPUtil.fp_bits
)
+add_fp_unittest(
+ cosf16_test
+ NEED_MPFR
+ SUITE
+ libc-math-unittests
+ SRCS
+ cosf16_test.cpp
+ DEPENDS
+ libc.src.math.cosf16
+)
+
add_fp_unittest(
cospif_test
NEED_MPFR
diff --git a/libc/test/src/math/cosf16_test.cpp b/libc/test/src/math/cosf16_test.cpp
new file mode 100644
index 00000000000000..9e4687f0325c49
--- /dev/null
+++ b/libc/test/src/math/cosf16_test.cpp
@@ -0,0 +1,40 @@
+//===-- Exhaustive test for cosf16 ----------------------------------------===//
+//
+// 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 "src/math/cosf16.h"
+#include "test/UnitTest/FPMatcher.h"
+#include "test/UnitTest/Test.h"
+#include "utils/MPFRWrapper/MPFRUtils.h"
+
+using LlvmLibcCosf16Test = LIBC_NAMESPACE::testing::FPTest<float16>;
+
+namespace mpfr = LIBC_NAMESPACE::testing::mpfr;
+
+// Range: [0, Inf]
+static constexpr uint16_t POS_START = 0x0000U;
+static constexpr uint16_t POS_STOP = 0x7c00u;
+
+// Range: [-Inf, 0]
+static constexpr uint16_t NEG_START = 0x8000U;
+static constexpr uint16_t NEG_STOP = 0xfc00U;
+
+TEST_F(LlvmLibcCosf16Test, PositiveRange) {
+ for (uint16_t v = POS_START; v <= POS_STOP; ++v) {
+ float16 x = FPBits(v).get_val();
+ EXPECT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Cos, x,
+ LIBC_NAMESPACE::cosf16(x), 0.5);
+ }
+}
+
+TEST_F(LlvmLibcCosf16Test, NegativeRange) {
+ for (uint16_t v = NEG_START; v <= NEG_STOP; ++v) {
+ float16 x = FPBits(v).get_val();
+ EXPECT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Cos, x,
+ LIBC_NAMESPACE::cosf16(x), 0.5);
+ }
+}
diff --git a/libc/test/src/math/smoke/CMakeLists.txt b/libc/test/src/math/smoke/CMakeLists.txt
index 2c1c4dba738465..31f85a3ecfd27b 100644
--- a/libc/test/src/math/smoke/CMakeLists.txt
+++ b/libc/test/src/math/smoke/CMakeLists.txt
@@ -12,6 +12,17 @@ add_fp_unittest(
libc.src.math.cosf
)
+add_fp_unittest(
+ cosf16_test
+ SUITE
+ libc-math-smoke-tests
+ SRCS
+ cosf16_test.cpp
+ DEPENDS
+ libc.src.errno.errno
+ libc.src.math.cosf16
+)
+
add_fp_unittest(
cospif_test
SUITE
diff --git a/libc/test/src/math/smoke/cosf16_test.cpp b/libc/test/src/math/smoke/cosf16_test.cpp
new file mode 100644
index 00000000000000..9a51d1015da340
--- /dev/null
+++ b/libc/test/src/math/smoke/cosf16_test.cpp
@@ -0,0 +1,33 @@
+//===-- Unittests for cosf16 ----------------------------------------------===//
+//
+// 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 "src/errno/libc_errno.h"
+#include "src/math/cosf16.h"
+#include "test/UnitTest/FPMatcher.h"
+#include "test/UnitTest/Test.h"
+
+using LlvmLibcCosf16Test = LIBC_NAMESPACE::testing::FPTest<float16>;
+
+TEST_F(LlvmLibcCosf16Test, SpecialNumbers) {
+ LIBC_NAMESPACE::libc_errno = 0;
+
+ EXPECT_FP_EQ(aNaN, LIBC_NAMESPACE::cosf16(aNaN));
+ EXPECT_MATH_ERRNO(0);
+
+ EXPECT_FP_EQ(1.0f, LIBC_NAMESPACE::cosf16(zero));
+ EXPECT_MATH_ERRNO(0);
+
+ EXPECT_FP_EQ(1.0f, LIBC_NAMESPACE::cosf16(neg_zero));
+ EXPECT_MATH_ERRNO(0);
+
+ EXPECT_FP_EQ(aNaN, LIBC_NAMESPACE::cosf16(inf));
+ EXPECT_MATH_ERRNO(EDOM);
+
+ EXPECT_FP_EQ(aNaN, LIBC_NAMESPACE::cosf16(neg_inf));
+ EXPECT_MATH_ERRNO(EDOM);
+}
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Yeah, that's fine. |
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