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# This file is licensed 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
"""LLVM libc starlark rules for building individual functions."""
load(":platforms.bzl", "PLATFORM_CPU_ARM64", "PLATFORM_CPU_X86_64")
load("@bazel_skylib//lib:selects.bzl", "selects")
LIBC_ROOT_TARGET = ":libc_root"
INTERNAL_SUFFIX = ".__internal__"
def libc_function(name, srcs, deps = None, copts = None, **kwargs):
"""Add target for a libc function.
The libc function is eventually available as a cc_library target by name
"name". LLVM libc implementations of libc functions are in C++. So, this
rule internally generates a C wrapper for the C++ implementation and adds
it to the source list of the cc_library. This way, the C++ implementation
and the C wrapper are both available in the cc_library.
Args:
name: Target name. It is normally the name of the function this target is
for.
srcs: The .cpp files which contain the function implementation.
deps: The list of target dependencies if any.
copts: The list of options to add to the C++ compilation command.
**kwargs: Other attributes relevant for a cc_library. For example, deps.
"""
deps = deps or []
deps.append(LIBC_ROOT_TARGET)
copts = copts or []
copts.append("-O3")
copts.append("-fno-builtin")
# We compile the code twice, the first target is suffixed with ".__internal__" and contains the
# C++ functions in the "__llvm_libc" namespace. This allows us to test the function in the
# presence of another libc.
native.cc_library(
name = name + INTERNAL_SUFFIX,
srcs = srcs,
deps = deps,
copts = copts,
linkstatic = 1,
**kwargs
)
# This second target is the llvm libc C function.
copts.append("-DLLVM_LIBC_PUBLIC_PACKAGING")
native.cc_library(
name = name,
srcs = srcs,
deps = deps,
copts = copts,
linkstatic = 1,
**kwargs
)
def libc_math_function(
name,
specializations = None,
additional_deps = None):
"""Add a target for a math function.
Args:
name: The name of the function.
specializations: List of machine specializations available for this
function. Possible specializations are "generic",
"aarch64" and "x86_64".
additional_deps: Other deps like helper cc_library targes used by the
math function.
"""
additional_deps = additional_deps or []
specializations = specializations or ["generic"]
select_map = {}
if "generic" in specializations:
select_map["//conditions:default"] = ["src/math/generic/" + name + ".cpp"]
if "aarch64" in specializations:
select_map[PLATFORM_CPU_ARM64] = ["src/math/aarch64/" + name + ".cpp"]
if "x86_64" in specializations:
select_map[PLATFORM_CPU_X86_64] = ["src/math/x86_64/" + name + ".cpp"]
libc_function(
name = name,
srcs = selects.with_or(select_map),
hdrs = ["src/math/" + name + ".h"],
deps = [":__support_common", ":__support_fputil"] + additional_deps,
)
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