common: add STATIC_IF and STATIC_IF_NOT macros
A common pattern to use with IS_ENABLED is like this: /* * This var should only be used if CONFIG_FOO. The linker errors if * CONFIG_FOO is not defined is intentional. */ #ifdef CONFIG_FOO static #else extern #endif int some_var; The issue with this is that it leads to an over-verbose and potentially hard to read pattern, and does not have the check that CONFIG_FOO was only defined to blank. Suppose a macro like this existed: STATIC_IF(CONFIG_FOO) int some_var; ... which expands to "static" when CONFIG_FOO is defined to empty, "extern" when CONFIG_FOO is not defined, and errors when CONFIG_FOO is defined to non-empty. This CL implements that, as well as the inverse (STATIC_IF_NOT). BUG=chromium:989786 BRANCH=none TEST=provided unit tests, buildall Change-Id: Ib57aaba62bc184fda9aa782a780d5f13ba44ae88 Signed-off-by: Jack Rosenthal <jrosenth@chromium.org> Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/1731859 Reviewed-by: Daisuke Nojiri <dnojiri@chromium.org>
This commit is contained in:
Jack Rosenthal
Commit Bot
parent
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commit
4cd06cf22b
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@ -9,6 +9,7 @@
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#define __CROS_EC_COMMON_H
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#include <stdint.h>
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#include "compile_time_macros.h"
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/*
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* Macros to concatenate 2 - 4 tokens together to form a single token.
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@ -272,6 +273,41 @@ enum ec_error_list {
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/* find the most significant bit. Not defined in n == 0. */
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#define __fls(n) (31 - __builtin_clz(n))
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/*
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* __cfg_select(CONFIG_NAME, EMPTY, OTHERWISE) is a macro used for
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* defining other macros which conditionally select code based on a
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* config option. It will generate the argument passed as EMPTY
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* when CONFIG_NAME was defined to the empty string, and OTHERWISE
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* when the argument was not defined or defined to something
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* non-empty.
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*
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* Generally speaking, macros which use this should make some sort of
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* context-dependent assertion in OTHERWISE that CONFIG_NAME is
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* undefined, rather than defined to something else. This usually
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* involves tricks with __builtin_strcmp.
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*/
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#define __cfg_select(cfg, empty, otherwise) \
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__cfg_select_1(cfg, empty, otherwise)
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#define __cfg_select_placeholder_ _,
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#define __cfg_select_1(value, empty, otherwise) \
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__cfg_select_2(__cfg_select_placeholder_##value, empty, otherwise)
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#define __cfg_select_2(arg1_or_junk, empty, otherwise) \
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__cfg_select_3(arg1_or_junk _, empty, otherwise)
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#define __cfg_select_3(_ignore1, _ignore2, select, ...) select
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/*
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* This version concatenates a BUILD_ASSERT(...); before OTHERWISE,
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* handling the __builtin_strcmp trickery where a BUILD_ASSERT is
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* appropriate in the context.
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*/
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#define __cfg_select_build_assert(cfg, value, empty, undef) \
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__cfg_select( \
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value, \
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empty, \
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BUILD_ASSERT( \
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__builtin_strcmp(cfg, #value) == 0); \
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undef)
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/*
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* Attribute for generating an error if a function is used.
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*
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@ -286,26 +322,18 @@ enum ec_error_list {
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/*
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* Getting something that works in C and CPP for an arg that may or may
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* not be defined is tricky. Here, if we have "#define CONFIG_FOO"
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* we match on the placeholder define, insert the "_, 1," for arg1 and generate
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* the triplet (_, 1, _, (...)). Then the last step cherry picks the 2nd arg
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* (a one).
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* When CONFIG_FOO is not defined, we generate a (_, (...)) pair, and when
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* the last step cherry picks the 2nd arg, we get a code block that verifies
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* the value of the option. Since the preprocessor won't replace an unknown
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* token, we compare the option name with the value string. If they are
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* identical we assume that the value was undefined and return 0. If the value
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* happens to be anything else we call an undefined method that will raise
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* a compiler error. This technique requires that the optimizer be enabled so it
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* can remove the undefined function call.
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* not be defined is tricky.
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*
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* Compare the option name with the value string in the OTHERWISE to
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* __cfg_select. If they are identical we assume that the value was
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* undefined and return 0. If the value happens to be anything else we
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* call an undefined method that will raise a compiler error. This
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* technique requires that the optimizer be enabled so it can remove
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* the undefined function call.
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*/
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#define __ARG_PLACEHOLDER_ _, 1,
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#define _config_enabled(cfg, value) \
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__config_enabled(__ARG_PLACEHOLDER_##value, cfg, value)
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#define __config_enabled(arg1_or_junk, cfg, value) \
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___config_enabled( \
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arg1_or_junk _, ({ \
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#define __config_enabled(cfg, value) \
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__cfg_select( \
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value, 1, ({ \
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int __undefined = __builtin_strcmp(cfg, #value) == 0; \
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extern int IS_ENABLED_BAD_ARGS(void) __error( \
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cfg " must be <blank>, or not defined."); \
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@ -313,7 +341,6 @@ enum ec_error_list {
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IS_ENABLED_BAD_ARGS(); \
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0; \
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}))
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#define ___config_enabled(__ignored, val, ...) val
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/**
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* Checks if a config option is enabled or disabled
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@ -329,6 +356,28 @@ enum ec_error_list {
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* Note: This macro will only function inside a code block due to the way
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* it checks for unknown values.
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*/
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#define IS_ENABLED(option) _config_enabled(#option, option)
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#define IS_ENABLED(option) __config_enabled(#option, option)
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/**
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* Makes a global variable static when a config option is enabled,
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* extern otherwise (with the intention to cause linker errors if the
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* variable is used outside of a config context, for example thru
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* IS_ENABLED, that it should be).
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*
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* This follows the same constraints as IS_ENABLED, the config option
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* should be defined to nothing or undefined.
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*/
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#define STATIC_IF(option) \
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__cfg_select_build_assert(#option, option, static, extern)
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/**
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* STATIC_IF_NOT is just like STATIC_IF, but makes the variable static
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* only if the config option is *not* defined, extern if it is.
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*
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* This is to assert that a variable will go unused with a certain
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* config option.
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*/
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#define STATIC_IF_NOT(option) \
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__cfg_select_build_assert(#option, option, extern, static)
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#endif /* __CROS_EC_COMMON_H */
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@ -61,6 +61,8 @@ test-list-host += sbs_charging_v2
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test-list-host += sha256
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test-list-host += sha256_unrolled
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test-list-host += shmalloc
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test-list-host += static_if
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test-list-host += static_if_error
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test-list-host += system
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test-list-host += thermal
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test-list-host += timer_dos
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@ -132,6 +134,7 @@ sbs_charging_v2-y=sbs_charging_v2.o
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sha256-y=sha256.o
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sha256_unrolled-y=sha256.o
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shmalloc-y=shmalloc.o
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static_if-y=static_if.o
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stress-y=stress.o
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system-y=system.o
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thermal-y=thermal.o
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@ -163,3 +166,6 @@ $(out)/RO/test/nvmem_tpm2_mock.o: CFLAGS += -I$(TPM2_ROOT)
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host-is_enabled_error: TEST_SCRIPT=is_enabled_error.sh
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is_enabled_error-y=is_enabled_error.o.cmd
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host-static_if_error: TEST_SCRIPT=static_if_error.sh
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static_if_error-y=static_if_error.o.cmd
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@ -0,0 +1,50 @@
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/* Copyright 2019 The Chromium OS Authors. All rights reserved.
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*/
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/* Test the STATIC_IF and STATIC_IF_NOT macros. */
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#include "common.h"
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#include "test_util.h"
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#undef CONFIG_UNDEFINED
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#define CONFIG_BLANK
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STATIC_IF(CONFIG_UNDEFINED) int this_var_is_extern;
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STATIC_IF_NOT(CONFIG_BLANK) int this_var_is_extern_too;
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STATIC_IF(CONFIG_BLANK) int this_var_is_static;
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STATIC_IF_NOT(CONFIG_UNDEFINED) int this_var_is_static_too;
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static int test_static_if_blank(void)
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{
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TEST_ASSERT(this_var_is_static == 0);
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TEST_ASSERT(this_var_is_static_too == 0);
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return EC_SUCCESS;
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}
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static int test_static_if_unused_no_fail(void)
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{
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/*
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* This should not cause linker errors because the variables
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* go unused (usage is optimized away).
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*/
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if (IS_ENABLED(CONFIG_UNDEFINED))
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this_var_is_extern = 1;
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if (!IS_ENABLED(CONFIG_BLANK))
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this_var_is_extern_too = 1;
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return EC_SUCCESS;
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}
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void run_test(void)
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{
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test_reset();
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RUN_TEST(test_static_if_blank);
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RUN_TEST(test_static_if_unused_no_fail);
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test_print_result();
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}
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@ -0,0 +1,9 @@
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/* Copyright 2019 The Chromium OS Authors. All rights reserved.
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*/
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/**
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* See CONFIG_TASK_LIST in config.h for details.
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*/
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#define CONFIG_TEST_TASK_LIST /* No test task */
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@ -0,0 +1,34 @@
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/* Copyright 2019 The Chromium OS Authors. All rights reserved.
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*/
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/*
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* Test the STATIC_IF and STATIC_IF_NOT macros fail on unexpected
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* input.
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*/
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#include "common.h"
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#include "test_util.h"
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#define CONFIG_FOO TEST_VALUE
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/*
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* At compiler invocation, define TEST_MACRO to STATIC_IF or
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* STATIC_IF_NOT.
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*/
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#ifndef TEST_MACRO
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#error "This error should not be seen in the compiler output!"
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#endif
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/* This is intended to cause a compilation error. */
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TEST_MACRO(CONFIG_FOO) __maybe_unused int foo;
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void run_test(void)
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{
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test_reset();
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/* Nothing to do, observe compilation error */
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test_print_result();
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}
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@ -0,0 +1,42 @@
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#!/bin/bash -e
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# Copyright 2019 The Chromium OS Authors. All rights reserved.
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# Use of this source code is governed by a BSD-style license that can be
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# found in the LICENSE file.
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# This file is implemented similar to is_enabled_error.sh
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TEST_DIR="$(dirname "${BASH_SOURCE[0]}")"
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TEST_CMD="$(cat "${TEST_DIR}/RO/test/static_if_error.o.cmd")"
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TEST_ERROR_COUNT=0
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BAD_ERROR_MSG="This error should not be seen in the compiler output!"
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fail() {
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echo "Fail"
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echo "$1"
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echo "$BUILD_OUTPUT"
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TEST_ERROR_COUNT=$((TEST_ERROR_COUNT+1))
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}
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for test_macro in STATIC_IF STATIC_IF_NOT; do
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for test_value in 0 1 2 A "5 + 5"; do
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echo -n "Running TEST_MACRO=${test_macro} TEST_VALUE=${test_value}..."
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TEST_CMD_COMPLETE="
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${TEST_CMD} \"-DTEST_MACRO=${test_macro}\" \"-DTEST_VALUE=${test_value}\""
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echo "$TEST_CMD_COMPLETE"
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if BUILD_OUTPUT="$(sh -c "$TEST_CMD_COMPLETE" 2>&1)"; then
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fail "Compilation should not have succeeded."
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continue
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fi
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if grep -q "$BAD_ERROR_MSG" <<<"$BUILD_OUTPUT"; then
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fail "TEST_MACRO was not defined."
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continue
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fi
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done
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done
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if [[ $TEST_ERROR_COUNT -eq 0 ]]; then
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echo "Pass!"
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else
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echo "Fail! (${TEST_ERROR_COUNT} tests)"
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fi
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@ -0,0 +1,9 @@
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/* Copyright 2019 The Chromium OS Authors. All rights reserved.
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*/
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/**
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* See CONFIG_TASK_LIST in config.h for details.
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*/
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#define CONFIG_TEST_TASK_LIST /* No test task */
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