[libc][bazel] Allow configure options to alter all targets (#89251)

The previous state was leading to inconsistencies. Some targets would
get the options and some wouldn't. As an example, the `MEMORY_COPTS`
definitions would only apply to the `:string_memory_utils` target but
not to the `:memcpy` target. This patch makes sure definitions are
applied throughout the LLVM libc targets as `local_defines`. This
ensures that the preprocessor definitions don't propagate to depending
targets outside of LLVM libc, and that all libc targets have consistent
preprocessor definitions.

Author: gchatelet

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

@@ -23,17 +23,6 @@ package(
 
 licenses(["notice"])
 
-PRINTF_COPTS = [
-    "LIBC_COPT_STDIO_USE_SYSTEM_FILE",
-    "LIBC_COPT_PRINTF_DISABLE_WRITE_INT",
-]
-
-MEMORY_COPTS = [
-    # "LIBC_COPT_MEMCPY_X86_USE_REPMOVSB_FROM_SIZE=0",
-    # "LIBC_COPT_MEMCPY_X86_USE_SOFTWARE_PREFETCHING",
-    # "LIBC_COPT_MEMSET_X86_USE_SOFTWARE_PREFETCHING",
-]
-
 # A flag to pick which `mpfr` to use for math tests.
 # Usage: `--@llvm-project//libc:mpfr=<disable|external|system>`.
 # Flag documentation: https://bazel.build/extending/config
@@ -2421,7 +2410,6 @@ libc_support_library(
         "src/string/memory_utils/op_x86.h",
         "src/string/memory_utils/utils.h",
     ],
-    defines = MEMORY_COPTS,
     textual_hdrs = [
         "src/string/memory_utils/aarch64/inline_bcmp.h",
         "src/string/memory_utils/aarch64/inline_memcmp.h",
@@ -3191,15 +3179,13 @@ libc_function(
 libc_support_library(
     name = "printf_config",
     hdrs = ["src/stdio/printf_core/printf_config.h"],
-    defines = PRINTF_COPTS,
     deps = [
     ],
 )
 
 libc_support_library(
     name = "printf_core_structs",
     hdrs = ["src/stdio/printf_core/core_structs.h"],
-    defines = PRINTF_COPTS,
     deps = [
         ":__support_cpp_string_view",
         ":__support_fputil_fp_bits",
@@ -3210,7 +3196,6 @@ libc_support_library(
 libc_support_library(
     name = "printf_parser",
     hdrs = ["src/stdio/printf_core/parser.h"],
-    defines = PRINTF_COPTS,
     deps = [
         ":__support_arg_list",
         ":__support_common",
@@ -3231,7 +3216,7 @@ libc_support_library(
 libc_support_library(
     name = "printf_mock_parser",
     hdrs = ["src/stdio/printf_core/parser.h"],
-    defines = PRINTF_COPTS + ["LIBC_COPT_MOCK_ARG_LIST"],
+    local_defines = ["LIBC_COPT_MOCK_ARG_LIST"],
     deps = [
         ":__support_arg_list",
         ":__support_common",
@@ -3251,7 +3236,6 @@ libc_support_library(
     name = "printf_writer",
     srcs = ["src/stdio/printf_core/writer.cpp"],
     hdrs = ["src/stdio/printf_core/writer.h"],
-    defines = PRINTF_COPTS,
     deps = [
         ":__support_cpp_string_view",
         ":__support_macros_optimization",
@@ -3276,7 +3260,6 @@ libc_support_library(
         "src/stdio/printf_core/string_converter.h",
         "src/stdio/printf_core/write_int_converter.h",
     ],
-    defines = PRINTF_COPTS,
     deps = [
         ":__support_big_int",
         ":__support_common",
@@ -3300,7 +3283,6 @@ libc_support_library(
     name = "printf_main",
     srcs = ["src/stdio/printf_core/printf_main.cpp"],
     hdrs = ["src/stdio/printf_core/printf_main.h"],
-    defines = PRINTF_COPTS,
     deps = [
         ":__support_arg_list",
         ":printf_converter",
@@ -3313,7 +3295,6 @@ libc_support_library(
 libc_support_library(
     name = "vfprintf_internal",
     hdrs = ["src/stdio/printf_core/vfprintf_internal.h"],
-    defines = PRINTF_COPTS,
     deps = [
         ":__support_arg_list",
         ":__support_file_file",
@@ -3327,7 +3308,6 @@ libc_function(
     name = "sprintf",
     srcs = ["src/stdio/sprintf.cpp"],
     hdrs = ["src/stdio/sprintf.h"],
-    defines = PRINTF_COPTS,
     deps = [
         ":__support_arg_list",
         ":__support_cpp_limits",
@@ -3341,7 +3321,6 @@ libc_function(
     name = "snprintf",
     srcs = ["src/stdio/snprintf.cpp"],
     hdrs = ["src/stdio/snprintf.h"],
-    defines = PRINTF_COPTS,
     deps = [
         ":__support_arg_list",
         ":errno",
@@ -3354,7 +3333,6 @@ libc_function(
     name = "printf",
     srcs = ["src/stdio/printf.cpp"],
     hdrs = ["src/stdio/printf.h"],
-    defines = PRINTF_COPTS,
     deps = [
         ":__support_arg_list",
         ":__support_file_file",
@@ -3367,7 +3345,6 @@ libc_function(
     name = "fprintf",
     srcs = ["src/stdio/fprintf.cpp"],
     hdrs = ["src/stdio/fprintf.h"],
-    defines = PRINTF_COPTS,
     deps = [
         ":__support_arg_list",
         ":__support_file_file",
@@ -3380,7 +3357,6 @@ libc_function(
     name = "vsprintf",
     srcs = ["src/stdio/vsprintf.cpp"],
     hdrs = ["src/stdio/vsprintf.h"],
-    defines = PRINTF_COPTS,
     deps = [
         ":__support_arg_list",
         ":__support_cpp_limits",
@@ -3394,7 +3370,6 @@ libc_function(
     name = "vsnprintf",
     srcs = ["src/stdio/vsnprintf.cpp"],
     hdrs = ["src/stdio/vsnprintf.h"],
-    defines = PRINTF_COPTS,
     deps = [
         ":__support_arg_list",
         ":errno",
@@ -3407,7 +3382,6 @@ libc_function(
     name = "vprintf",
     srcs = ["src/stdio/vprintf.cpp"],
     hdrs = ["src/stdio/vprintf.h"],
-    defines = PRINTF_COPTS,
     deps = [
         ":__support_arg_list",
         ":__support_file_file",
@@ -3420,7 +3394,6 @@ libc_function(
     name = "vfprintf",
     srcs = ["src/stdio/vfprintf.cpp"],
     hdrs = ["src/stdio/vfprintf.h"],
-    defines = PRINTF_COPTS,
     deps = [
         ":__support_arg_list",
         ":__support_file_file",

utils/bazel/llvm-project-overlay/libc/libc_build_rules.bzl

@@ -6,6 +6,7 @@
 
 load("@bazel_skylib//lib:paths.bzl", "paths")
 load("@bazel_skylib//lib:selects.bzl", "selects")
+load(":libc_configure_options.bzl", "LIBC_CONFIGURE_OPTIONS")
 load(":libc_namespace.bzl", "LIBC_NAMESPACE")
 load(":platforms.bzl", "PLATFORM_CPU_ARM64", "PLATFORM_CPU_X86_64")
 
@@ -21,13 +22,14 @@ def libc_common_copts():
         "-DLIBC_NAMESPACE=" + LIBC_NAMESPACE,
     ]
 
-def _libc_library(name, hidden, copts = [], deps = [], **kwargs):
+def _libc_library(name, hidden, copts = [], deps = [], local_defines = [], **kwargs):
     """Internal macro to serve as a base for all other libc library rules.
 
     Args:
       name: Target name.
       copts: The special compiler options for the target.
       deps: The list of target dependencies if any.
+      local_defines: The list of target local_defines if any.
       hidden: Whether the symbols should be explicitly hidden or not.
       **kwargs: All other attributes relevant for the cc_library rule.
     """
@@ -40,6 +42,7 @@ def _libc_library(name, hidden, copts = [], deps = [], **kwargs):
     native.cc_library(
         name = name,
         copts = copts + libc_common_copts(),
+        local_defines = local_defines + LIBC_CONFIGURE_OPTIONS,
         deps = deps,
         linkstatic = 1,
         **kwargs

utils/bazel/llvm-project-overlay/libc/libc_configure_options.bzl

@@ -0,0 +1,49 @@
+# 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 configuration options.
+The canonical list of user options is in 'libc/config/config.json'.
+These options are then processed by CMake and turned into preprocessor
+definitions. We don't have this logic in Bazel yet but the list of definitions
+is discoverable with the following command:
+
+> git grep -hoE '\bLIBC_COPT_\\w*'  -- '*.h' '*.cpp' | sort -u
+"""
+
+# This list of definitions is used to customize LLVM libc.
+LIBC_CONFIGURE_OPTIONS = [
+    # Documentation in libc/docs/dev/printf_behavior.rst
+    # "LIBC_COPT_FLOAT_TO_STR_NO_SPECIALIZE_LD",
+    # "LIBC_COPT_FLOAT_TO_STR_NO_TABLE",
+    # "LIBC_COPT_FLOAT_TO_STR_USE_DYADIC_FLOAT",
+    # "LIBC_COPT_FLOAT_TO_STR_USE_DYADIC_FLOAT_LD",
+    # "LIBC_COPT_FLOAT_TO_STR_USE_INT_CALC",
+    # "LIBC_COPT_FLOAT_TO_STR_USE_MEGA_LONG_DOUBLE_TABLE",
+
+    # Documentation in libc/src/string/memory_utils/...
+    # "LIBC_COPT_MEMCPY_USE_EMBEDDED_TINY",
+    # "LIBC_COPT_MEMCPY_X86_USE_REPMOVSB_FROM_SIZE",
+    # "LIBC_COPT_MEMCPY_X86_USE_SOFTWARE_PREFETCHING",
+    # "LIBC_COPT_MEMSET_X86_USE_SOFTWARE_PREFETCHING",
+
+    # Documentation in libc/docs/dev/printf_behavior.rst
+    # "LIBC_COPT_PRINTF_CONV_ATLAS",
+    # "LIBC_COPT_PRINTF_DISABLE_FIXED_POINT",
+    # "LIBC_COPT_PRINTF_DISABLE_FLOAT",
+    # "LIBC_COPT_PRINTF_DISABLE_INDEX_MODE",
+    "LIBC_COPT_PRINTF_DISABLE_WRITE_INT",
+    # "LIBC_COPT_PRINTF_HEX_LONG_DOUBLE",
+    # "LIBC_COPT_PRINTF_INDEX_ARR_LEN",
+    # "LIBC_COPT_PRINTF_NO_NULLPTR_CHECKS",
+    # "LIBC_COPT_SCANF_DISABLE_FLOAT",
+    # "LIBC_COPT_SCANF_DISABLE_INDEX_MODE",
+    "LIBC_COPT_STDIO_USE_SYSTEM_FILE",
+    # "LIBC_COPT_STRING_UNSAFE_WIDE_READ",
+    # "LIBC_COPT_STRTOFLOAT_DISABLE_CLINGER_FAST_PATH",
+    # "LIBC_COPT_STRTOFLOAT_DISABLE_EISEL_LEMIRE",
+    # "LIBC_COPT_STRTOFLOAT_DISABLE_SIMPLE_DECIMAL_CONVERSION",
+
+    # Documentation in libc/src/__support/libc_assert.h
+    # "LIBC_COPT_USE_C_ASSERT",
+]

utils/bazel/llvm-project-overlay/libc/test/libc_test_rules.bzl

@@ -13,8 +13,9 @@ When performing tests we make sure to always use the internal version.
 """
 
 load("//libc:libc_build_rules.bzl", "libc_common_copts", "libc_internal_target")
+load("//libc:libc_configure_options.bzl", "LIBC_CONFIGURE_OPTIONS")
 
-def libc_test(name, srcs, libc_function_deps = [], copts = [], deps = [], **kwargs):
+def libc_test(name, srcs, libc_function_deps = [], copts = [], deps = [], local_defines = [], **kwargs):
     """Add target for a libc test.
 
     Args:
@@ -23,12 +24,14 @@ def libc_test(name, srcs, libc_function_deps = [], copts = [], deps = [], **kwar
       libc_function_deps: List of libc_function targets used by this test.
       copts: The list of options to add to the C++ compilation command.
       deps: The list of other libraries to be linked in to the test target.
+      local_defines: The list of target local_defines if any.
       **kwargs: Attributes relevant for a libc_test. For example, name, srcs.
     """
     all_function_deps = libc_function_deps + ["//libc:errno"]
     native.cc_test(
         name = name,
         srcs = srcs,
+        local_defines = local_defines + LIBC_CONFIGURE_OPTIONS,
         deps = [libc_internal_target(d) for d in all_function_deps] + [
             "//libc/test/UnitTest:LibcUnitTest",
         ] + deps,