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aaronmondalaaronmondal
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[Bazel] Make LLVM and Clang config headers configurable
This change implements the following flags and provides the infrastructure for future additions: bazel query 'kind(".*_flag", @llvm-project//config:all)' @llvm-project//config:LLVM_ENABLE_BACKTRACES @llvm-project//config:LLVM_ENABLE_CRASH_DUMPS @llvm-project//config:LLVM_ENABLE_CRASH_OVERRIDES @llvm-project//config:LLVM_ENABLE_DEBUGLOC_COVERAGE_TRACKING @llvm-project//config:LLVM_ENABLE_PLUGINS @llvm-project//config:LLVM_ENABLE_ZLIB @llvm-project//config:LLVM_ENABLE_ZSTD @llvm-project//config:LLVM_HAS_LOGF128 @llvm-project//config:LLVM_WINDOWS_PREFER_FORWARD_SLASH For instance: bazel build ... \ --@llvm-project//config:LLVM_ENABLE_BACKTRACES=false The following flags have been moved to mirror CMake and simplify migration to bzlmod: @llvm_zlib//:llvm_enable_zlib -> @llvm-project//config:LLVM_ENABLE_ZLIB @llvm_zstd//:llvm_enable_zstd -> @llvm-project//config:LLVM_ENABLE_ZSTD The overlay now has platform definitions at `@llvm-project//platform`. You can use these to cross compile the config headers to see how they'd look like on other systems. For instance: bazel build @llvm-project//llvm:config_h \ --platforms=@llvm-project//platform:aarch64-unknown-linux-gnu bazel build @llvm-project//llvm:llvm-config_h \ --platforms=@llvm-project//platform:x86_64-pc-win32 The new implementation uses the original CMake templates as source of truth. This makes it easier to detect and prevent drift as unhandled substitutions tend to turn into compiler errors. Saves 16 defines on windows and ~35 defines on other platforms which previously leaked into the command lines of all targets that depended transitively on the llvm configuration. For a full build of the overlay this amounts to ~380k fewer defines.
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19 files changed

+943
-1408
lines changed

19 files changed

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-1408
lines changed

‎utils/bazel/.bazelrc‎

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@@ -58,14 +58,6 @@ build --experimental_cc_shared_library
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# https://github.com/bazelbuild/bazel/commit/03246077f948f2790a83520e7dccc2625650e6df
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build --build_runfile_links=false
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###############################################################################
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# Options to select different strategies for linking potential dependent
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# libraries. The default leaves it disabled.
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###############################################################################
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build:zlib_external --repo_env=BAZEL_LLVM_ZLIB_STRATEGY=external
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build:zlib_system --repo_env=BAZEL_LLVM_ZLIB_STRATEGY=system
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###############################################################################
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# Options for "generic_clang" builds: these options should generally apply to
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# builds using a Clang-based compiler, and default to the `clang` executable on

‎utils/bazel/llvm-project-overlay/clang/BUILD.bazel‎

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# See https://llvm.org/LICENSE.txt for license information.
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# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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load("@bazel_skylib//rules:common_settings.bzl", "bool_flag")
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load("@bazel_skylib//rules:expand_template.bzl", "expand_template")
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load("@rules_python//python:defs.bzl", "py_binary")
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load(
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"//:vars.bzl",
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load("//:workspace_root.bzl", "workspace_root")
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load("//llvm:binary_alias.bzl", "binary_alias")
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load("//llvm:cc_plugin_library.bzl", "cc_plugin_library")
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load(
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"//config:cmakehelpers.bzl",
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"cmakedefine",
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"cmakedefine01_off",
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"cmakedefine01_on",
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"cmakedefine_sunset",
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"cmakedefine_unset",
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"cmakedefine_vset",
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"cmakedefine_vunset",
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)
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load("//llvm:driver.bzl", "llvm_driver_cc_binary")
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load("//mlir:tblgen.bzl", "gentbl_cc_library", "td_library")
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@@ -614,6 +626,49 @@ genrule(
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),
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)
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expand_template(
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name = "config_h",
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out = "include/clang/Config/config.h",
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substitutions = (
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{"${BUG_REPORT_URL}": "https://github.com/llvm/llvm-project/issues/"} |
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cmakedefine01_on("CLANG_DEFAULT_PIE_ON_LINUX") |
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{
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"${CLANG_DEFAULT_LINKER}": "",
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"${CLANG_DEFAULT_CXX_STDLIB}": "",
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"${CLANG_DEFAULT_RTLIB}": "",
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"${CLANG_DEFAULT_UNWINDLIB}": "",
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"${CLANG_DEFAULT_OBJCOPY}": "objcopy",
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"${CLANG_DEFAULT_OPENMP_RUNTIME}": "libomp",
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"${CLANG_SYSTEMZ_DEFAULT_ARCH}": "z10",
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"${CLANG_INSTALL_LIBDIR_BASENAME}": "lib",
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"${CLANG_RESOURCE_DIR}": "",
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"${C_INCLUDE_DIRS}": "",
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} |
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cmakedefine_sunset("CLANG_CONFIG_FILE_SYSTEM_DIR") |
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cmakedefine_sunset("CLANG_CONFIG_FILE_USER_DIR") |
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{
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"${DEFAULT_SYSROOT}": "",
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"${GCC_INSTALL_PREFIX}": "",
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} |
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cmakedefine_vunset("CLANG_HAVE_LIBXML") |
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cmakedefine(
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"CLANG_HAVE_RLIMITS",
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disable = "@platforms//os:windows",
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) |
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cmakedefine_vset("CLANG_HAVE_DLFCN_H") |
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cmakedefine_vset("CLANG_HAVE_DLADDR") |
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cmakedefine_sunset("HOST_LINK_VERSION") |
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cmakedefine_unset("ENABLE_LINKER_BUILD_ID") |
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cmakedefine01_on("ENABLE_X86_RELAX_RELOCATIONS") |
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cmakedefine01_off("PPC_LINUX_DEFAULT_IEEELONGDOUBLE") |
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cmakedefine01_off("CLANG_ENABLE_OBJC_REWRITER") |
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cmakedefine01_on("CLANG_ENABLE_STATIC_ANALYZER") |
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cmakedefine01_off("CLANG_SPAWN_CC1") |
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cmakedefine01_off("CLANG_ENABLE_CIR")
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),
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template = "include/clang/Config/config.h.cmake",
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)
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cc_library(
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name = "config",
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hdrs = [

‎utils/bazel/llvm-project-overlay/clang/include/clang/Config/config.h‎

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This file was deleted.

‎utils/bazel/llvm-project-overlay/config/BUILD.bazel‎

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# This file is licensed under the Apache License v2.0 with LLVM Exceptions.
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# See https://llvm.org/LICENSE.txt for license information.
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# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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"""Configurable build attributes for the overlay.
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To view the configurable build attributes in this file:
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bazel query 'kind(".*_flag", @llvm-project//config:all)'
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"""
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load("@bazel_skylib//lib:selects.bzl", "selects")
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load("@bazel_skylib//rules:common_settings.bzl", "bool_flag", "string_flag")
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# Common config settings mapping to platform triples.
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#
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# See also: //platform:BUILD.bazel.
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#
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# TODO(aaronmondal): Add triples for more useful configurations as per
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# `llvm/include/llvm/TargetParser/Triple.h`.
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selects.config_setting_group(
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name = "aarch64-unknown-linux-gnu",
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match_all = [
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"@platforms//cpu:aarch64",
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"@platforms//os:linux",
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],
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)
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selects.config_setting_group(
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name = "arm64-apple-darwin",
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match_all = [
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"@platforms//cpu:arm64",
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"@platforms//os:macos",
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],
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)
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selects.config_setting_group(
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name = "powerpc64le-unknown-linux-gnu",
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match_all = [
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"@platforms//cpu:ppc64le",
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"@platforms//os:linux",
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],
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)
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selects.config_setting_group(
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name = "systemz-unknown-linux_gnu",
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match_all = [
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"@platforms//cpu:s390x",
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"@platforms//os:linux",
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],
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)
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selects.config_setting_group(
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name = "x86_64-pc-win32",
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match_all = [
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"@platforms//cpu:x86_64",
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"@platforms//os:windows",
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],
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)
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selects.config_setting_group(
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name = "x86_64-unknown-darwin",
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match_all = [
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"@platforms//cpu:x86_64",
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"@platforms//os:macos",
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],
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)
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selects.config_setting_group(
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name = "x86_64-unknown-linux-gnu",
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match_all = [
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"@platforms//cpu:x86_64",
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"@platforms//os:linux",
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],
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)
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# Useful helpers.
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selects.config_setting_group(
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name = "posix",
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match_any = [
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"@platforms//os:linux",
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"@platforms//os:macos",
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"@platforms//os:freebsd",
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],
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)
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# Configurable build attributes for llvm.
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# These map to CMake `option` fields on a best-effort basis. The default maps to
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# CMake's `ON` or `OFF` value.
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[
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(
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bool_flag(
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name = option,
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build_setting_default = default,
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),
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# Only define the opposite of the default value to reduce target count
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# and prevent accidental default redeclarations.
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#
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# This also acts as a failsafe to prevent drift if a default is flipped
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# as a changed default triggers straightfoward errors in all places
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# where no longer existing config_settings need to be adjusted.
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(
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config_setting(
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name = "{}_enabled".format(option),
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flag_values = {":{}".format(option): "true"},
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) if not default else config_setting(
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name = "{}_disabled".format(option),
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flag_values = {":{}".format(option): "false"},
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)
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),
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)
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for option, default in [
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("LLVM_ENABLE_BACKTRACES", True),
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("LLVM_ENABLE_CRASH_OVERRIDES", True),
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("LLVM_ENABLE_CRASH_DUMPS", False),
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# These deviate slightly from CMake in that we use a boolean rather than
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# ON/OFF/FORCE_ON since in Bazel ON collapses into FORCE_ON anyways.
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("LLVM_ENABLE_ZLIB", True),
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("LLVM_ENABLE_ZSTD", True),
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("LLVM_HAS_LOGF128", False),
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]
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]
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# This doesn't have a common default as most builds expect this to be disabled
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# by default but MinGW builds expect it enabled by default.
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bool_flag(
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name = "LLVM_WINDOWS_PREFER_FORWARD_SLASH",
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build_setting_default = False,
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)
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config_setting(
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name = "LLVM_WINDOWS_PREFER_FORWARD_SLASH_enabled",
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flag_values = {":LLVM_WINDOWS_PREFER_FORWARD_SLASH": "true"},
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)
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config_setting(
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name = "LLVM_WINDOWS_PREFER_FORWARD_SLASH_disabled",
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flag_values = {":LLVM_WINDOWS_PREFER_FORWARD_SLASH": "false"},
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)
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string_flag(
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name = "LLVM_ENABLE_DEBUGLOC_COVERAGE_TRACKING",
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build_setting_default = "DISABLED",
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values = [
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"COVERAGE",
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"DISABLED",
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],
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)
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config_setting(
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name = "LLVM_ENABLE_DEBUGLOC_COVERAGE_TRACKING_coverage",
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flag_values = {":LLVM_ENABLE_DEBUGLOC_COVERAGE_TRACKING": "COVERAGE"},
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)
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bool_flag(
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name = "LLVM_ENABLE_PLUGINS",
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# TODO(aaronmondal): This should be enabled by default, but that currently
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# breaks @llvm-project//llvm/unittests:analysis_tests.
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build_setting_default = False,
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)
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config_setting(
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name = "LLVM_ENABLE_PLUGINS_enabled",
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flag_values = {":LLVM_ENABLE_PLUGINS": "true"},
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)
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config_setting(
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name = "LLVM_ENABLE_PLUGINS_disabled",
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flag_values = {":LLVM_ENABLE_PLUGINS": "false"},
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)

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