Current File : /home/vacivi36/vittasync.vacivitta.com.br/vittasync/node/deps/v8/src/flags/flags.cc
// Copyright 2006-2008 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "src/flags/flags.h"
#include <cctype>
#include <cerrno>
#include <cinttypes>
#include <cstdlib>
#include <cstring>
#include <iomanip>
#include <set>
#include <sstream>
#include "src/base/functional.h"
#include "src/base/logging.h"
#include "src/base/platform/platform.h"
#include "src/codegen/cpu-features.h"
#include "src/logging/counters.h"
#include "src/logging/tracing-flags.h"
#include "src/tracing/tracing-category-observer.h"
#include "src/utils/allocation.h"
#include "src/utils/memcopy.h"
#include "src/utils/ostreams.h"
#include "src/utils/utils.h"
#if V8_ENABLE_WEBASSEMBLY
#include "src/wasm/wasm-limits.h"
#endif // V8_ENABLE_WEBASSEMBLY
namespace v8::internal {
// Define {v8_flags}, declared in flags.h.
FlagValues v8_flags;
// {v8_flags} needs to be aligned to a memory page, and the size needs to be a
// multiple of a page size. This is required for memory-protection of the memory
// holding the {v8_flags} struct.
// Both is guaranteed by the {alignas(kMinimumOSPageSize)} annotation on
// {FlagValues}.
static_assert(alignof(FlagValues) == kMinimumOSPageSize);
static_assert(sizeof(FlagValues) % kMinimumOSPageSize == 0);
// Define all of our flags default values.
#define FLAG_MODE_DEFINE_DEFAULTS
#include "src/flags/flag-definitions.h" // NOLINT(build/include)
#undef FLAG_MODE_DEFINE_DEFAULTS
namespace {
char NormalizeChar(char ch) { return ch == '_' ? '-' : ch; }
struct Flag;
Flag* FindFlagByPointer(const void* ptr);
Flag* FindFlagByName(const char* name);
// Helper struct for printing normalized flag names.
struct FlagName {
const char* name;
bool negated;
constexpr FlagName(const char* name, bool negated)
: name(name), negated(negated) {
DCHECK_NE('\0', name[0]);
DCHECK_NE('!', name[0]);
}
constexpr explicit FlagName(const char* name)
: FlagName(name[0] == '!' ? name + 1 : name, name[0] == '!') {}
};
std::ostream& operator<<(std::ostream& os, FlagName flag_name) {
os << (flag_name.negated ? "--no-" : "--");
for (const char* p = flag_name.name; *p; ++p) os << NormalizeChar(*p);
return os;
}
// This structure represents a single entry in the flag system, with a pointer
// to the actual flag, default value, comment, etc. This is designed to be POD
// initialized as to avoid requiring static constructors.
struct Flag {
enum FlagType {
TYPE_BOOL,
TYPE_MAYBE_BOOL,
TYPE_INT,
TYPE_UINT,
TYPE_UINT64,
TYPE_FLOAT,
TYPE_SIZE_T,
TYPE_STRING,
};
enum class SetBy { kDefault, kWeakImplication, kImplication, kCommandLine };
constexpr bool IsAnyImplication(Flag::SetBy set_by) {
return set_by == SetBy::kWeakImplication || set_by == SetBy::kImplication;
}
FlagType type_; // What type of flag, bool, int, or string.
const char* name_; // Name of the flag, ex "my_flag".
void* valptr_; // Pointer to the global flag variable.
const void* defptr_; // Pointer to the default value.
const char* cmt_; // A comment about the flags purpose.
bool owns_ptr_; // Does the flag own its string value?
SetBy set_by_ = SetBy::kDefault;
// Name of the flag implying this flag, if any.
const char* implied_by_ = nullptr;
#ifdef DEBUG
// Pointer to the flag implying this flag, if any.
const Flag* implied_by_ptr_ = nullptr;
#endif
FlagType type() const { return type_; }
const char* name() const { return name_; }
const char* comment() const { return cmt_; }
bool PointsTo(const void* ptr) const { return valptr_ == ptr; }
#ifdef DEBUG
bool ImpliedBy(const void* ptr) const {
const Flag* current = this->implied_by_ptr_;
while (current != nullptr) {
if (current->PointsTo(ptr)) return true;
current = current->implied_by_ptr_;
}
return false;
}
#endif
bool bool_variable() const { return GetValue<TYPE_BOOL, bool>(); }
void set_bool_variable(bool value, SetBy set_by) {
SetValue<TYPE_BOOL, bool>(value, set_by);
}
base::Optional<bool> maybe_bool_variable() const {
return GetValue<TYPE_MAYBE_BOOL, base::Optional<bool>>();
}
void set_maybe_bool_variable(base::Optional<bool> value, SetBy set_by) {
SetValue<TYPE_MAYBE_BOOL, base::Optional<bool>>(value, set_by);
}
int int_variable() const { return GetValue<TYPE_INT, int>(); }
void set_int_variable(int value, SetBy set_by) {
SetValue<TYPE_INT, int>(value, set_by);
}
unsigned int uint_variable() const {
return GetValue<TYPE_UINT, unsigned int>();
}
void set_uint_variable(unsigned int value, SetBy set_by) {
SetValue<TYPE_UINT, unsigned int>(value, set_by);
}
uint64_t uint64_variable() const { return GetValue<TYPE_UINT64, uint64_t>(); }
void set_uint64_variable(uint64_t value, SetBy set_by) {
SetValue<TYPE_UINT64, uint64_t>(value, set_by);
}
double float_variable() const { return GetValue<TYPE_FLOAT, double>(); }
void set_float_variable(double value, SetBy set_by) {
SetValue<TYPE_FLOAT, double>(value, set_by);
}
size_t size_t_variable() const { return GetValue<TYPE_SIZE_T, size_t>(); }
void set_size_t_variable(size_t value, SetBy set_by) {
SetValue<TYPE_SIZE_T, size_t>(value, set_by);
}
const char* string_value() const {
return GetValue<TYPE_STRING, const char*>();
}
void set_string_value(const char* new_value, bool owns_new_value,
SetBy set_by) {
DCHECK_EQ(TYPE_STRING, type_);
DCHECK_IMPLIES(owns_new_value, new_value != nullptr);
auto* flag_value = reinterpret_cast<FlagValue<const char*>*>(valptr_);
const char* old_value = *flag_value;
DCHECK_IMPLIES(owns_ptr_, old_value != nullptr);
bool change_flag =
old_value ? !new_value || std::strcmp(old_value, new_value) != 0
: !!new_value;
change_flag = CheckFlagChange(set_by, change_flag);
if (change_flag) {
if (owns_ptr_) DeleteArray(old_value);
*flag_value = new_value;
owns_ptr_ = owns_new_value;
} else {
if (owns_new_value) DeleteArray(new_value);
}
}
template <typename T>
T GetDefaultValue() const {
return *reinterpret_cast<const T*>(defptr_);
}
bool bool_default() const {
DCHECK_EQ(TYPE_BOOL, type_);
return GetDefaultValue<bool>();
}
int int_default() const {
DCHECK_EQ(TYPE_INT, type_);
return GetDefaultValue<int>();
}
unsigned int uint_default() const {
DCHECK_EQ(TYPE_UINT, type_);
return GetDefaultValue<unsigned int>();
}
uint64_t uint64_default() const {
DCHECK_EQ(TYPE_UINT64, type_);
return GetDefaultValue<uint64_t>();
}
double float_default() const {
DCHECK_EQ(TYPE_FLOAT, type_);
return GetDefaultValue<double>();
}
size_t size_t_default() const {
DCHECK_EQ(TYPE_SIZE_T, type_);
return GetDefaultValue<size_t>();
}
const char* string_default() const {
DCHECK_EQ(TYPE_STRING, type_);
return GetDefaultValue<const char*>();
}
static bool ShouldCheckFlagContradictions() {
if (v8_flags.allow_overwriting_for_next_flag) {
// Setting the flag manually to false before calling Reset() avoids this
// becoming re-entrant.
v8_flags.allow_overwriting_for_next_flag = false;
FindFlagByPointer(&v8_flags.allow_overwriting_for_next_flag)->Reset();
return false;
}
return v8_flags.abort_on_contradictory_flags && !v8_flags.fuzzing;
}
// {change_flag} indicates if we're going to change the flag value.
// Returns an updated value for {change_flag}, which is changed to false if a
// weak implication is being ignored beause a flag is already set by a normal
// implication or from the command-line.
bool CheckFlagChange(SetBy new_set_by, bool change_flag,
const char* implied_by = nullptr) {
if (new_set_by == SetBy::kWeakImplication &&
(set_by_ == SetBy::kImplication || set_by_ == SetBy::kCommandLine)) {
return false;
}
if (ShouldCheckFlagContradictions()) {
static constexpr const char kHint[] =
"If a test variant caused this, it might be necessary to specify "
"additional contradictory flags in "
"tools/testrunner/local/variants.py.";
struct FatalError : public std::ostringstream {
// MSVC complains about non-returning destructor; disable that.
MSVC_SUPPRESS_WARNING(4722)
~FatalError() { FATAL("%s.\n%s", str().c_str(), kHint); }
};
// Readonly flags cannot change value.
if (change_flag && IsReadOnly()) {
// Exit instead of abort for certain testing situations.
if (v8_flags.exit_on_contradictory_flags) base::OS::ExitProcess(0);
if (implied_by == nullptr) {
FatalError{} << "Contradictory value for readonly flag "
<< FlagName{name()};
} else {
DCHECK(IsAnyImplication(new_set_by));
FatalError{} << "Contradictory value for readonly flag "
<< FlagName{name()} << " implied by " << implied_by;
}
}
// For bool flags, we only check for a conflict if the value actually
// changes. So specifying the same flag with the same value multiple times
// is allowed.
// For other flags, we disallow specifying them explicitly or in the
// presence of an implication even if the value is the same.
// This is to simplify the rules describing conflicts in variants.py: A
// repeated non-boolean flag is considered an error independently of its
// value.
bool is_bool_flag = type_ == TYPE_MAYBE_BOOL || type_ == TYPE_BOOL;
bool check_implications = change_flag;
bool check_command_line_flags = change_flag || !is_bool_flag;
switch (set_by_) {
case SetBy::kDefault:
break;
case SetBy::kWeakImplication:
if (new_set_by == SetBy::kWeakImplication && check_implications) {
FatalError{} << "Contradictory weak flag implications from "
<< FlagName{implied_by_} << " and "
<< FlagName{implied_by} << " for flag "
<< FlagName{name()};
}
break;
case SetBy::kImplication:
if (new_set_by == SetBy::kImplication && check_implications) {
FatalError{} << "Contradictory flag implications from "
<< FlagName{implied_by_} << " and "
<< FlagName{implied_by} << " for flag "
<< FlagName{name()};
}
break;
case SetBy::kCommandLine:
if (new_set_by == SetBy::kImplication && check_command_line_flags) {
// Exit instead of abort for certain testing situations.
if (v8_flags.exit_on_contradictory_flags) base::OS::ExitProcess(0);
if (is_bool_flag) {
FatalError{} << "Flag " << FlagName{name()}
<< ": value implied by " << FlagName{implied_by}
<< " conflicts with explicit specification";
} else {
FatalError{} << "Flag " << FlagName{name()} << " is implied by "
<< FlagName{implied_by}
<< " but also specified explicitly";
}
} else if (new_set_by == SetBy::kCommandLine &&
check_command_line_flags) {
// Exit instead of abort for certain testing situations.
if (v8_flags.exit_on_contradictory_flags) base::OS::ExitProcess(0);
if (is_bool_flag) {
FatalError{} << "Command-line provided flag " << FlagName{name()}
<< " specified as both true and false";
} else {
FatalError{} << "Command-line provided flag " << FlagName{name()}
<< " specified multiple times";
}
}
break;
}
}
if (change_flag && IsReadOnly()) {
// Readonly flags must never change value.
return false;
}
set_by_ = new_set_by;
if (IsAnyImplication(new_set_by)) {
DCHECK_NOT_NULL(implied_by);
implied_by_ = implied_by;
#ifdef DEBUG
// This only works when implied_by is a flag_name or !flag_name, but it
// can also be a condition e.g. flag_name > 3. Since this is only used for
// checks in DEBUG mode, we will just ignore the more complex conditions
// for now - that will just lead to a nullptr which won't be followed.
implied_by_ptr_ = static_cast<Flag*>(
FindFlagByName(implied_by[0] == '!' ? implied_by + 1 : implied_by));
DCHECK_NE(implied_by_ptr_, this);
#endif
}
return change_flag;
}
bool IsReadOnly() const {
// See the FLAG_READONLY definition for FLAG_MODE_META.
return valptr_ == nullptr;
}
template <FlagType flag_type, typename T>
T GetValue() const {
DCHECK_EQ(flag_type, type_);
if (IsReadOnly()) return GetDefaultValue<T>();
return *reinterpret_cast<const FlagValue<T>*>(valptr_);
}
template <FlagType flag_type, typename T>
void SetValue(T new_value, SetBy set_by) {
DCHECK_EQ(flag_type, type_);
bool change_flag = GetValue<flag_type, T>() != new_value;
change_flag = CheckFlagChange(set_by, change_flag);
if (change_flag) {
DCHECK(!IsReadOnly());
*reinterpret_cast<FlagValue<T>*>(valptr_) = new_value;
}
}
// Compare this flag's current value against the default.
bool IsDefault() const {
switch (type_) {
case TYPE_BOOL:
return bool_variable() == bool_default();
case TYPE_MAYBE_BOOL:
return maybe_bool_variable().has_value() == false;
case TYPE_INT:
return int_variable() == int_default();
case TYPE_UINT:
return uint_variable() == uint_default();
case TYPE_UINT64:
return uint64_variable() == uint64_default();
case TYPE_FLOAT:
return float_variable() == float_default();
case TYPE_SIZE_T:
return size_t_variable() == size_t_default();
case TYPE_STRING: {
const char* str1 = string_value();
const char* str2 = string_default();
if (str2 == nullptr) return str1 == nullptr;
if (str1 == nullptr) return str2 == nullptr;
return strcmp(str1, str2) == 0;
}
}
UNREACHABLE();
}
void ReleaseDynamicAllocations() {
if (type_ != TYPE_STRING) return;
if (owns_ptr_) DeleteArray(string_value());
}
// Set a flag back to it's default value.
void Reset() {
switch (type_) {
case TYPE_BOOL:
set_bool_variable(bool_default(), SetBy::kDefault);
break;
case TYPE_MAYBE_BOOL:
set_maybe_bool_variable(base::nullopt, SetBy::kDefault);
break;
case TYPE_INT:
set_int_variable(int_default(), SetBy::kDefault);
break;
case TYPE_UINT:
set_uint_variable(uint_default(), SetBy::kDefault);
break;
case TYPE_UINT64:
set_uint64_variable(uint64_default(), SetBy::kDefault);
break;
case TYPE_FLOAT:
set_float_variable(float_default(), SetBy::kDefault);
break;
case TYPE_SIZE_T:
set_size_t_variable(size_t_default(), SetBy::kDefault);
break;
case TYPE_STRING:
set_string_value(string_default(), false, SetBy::kDefault);
break;
}
}
void AllowOverwriting() { set_by_ = SetBy::kDefault; }
};
Flag flags[] = {
#define FLAG_MODE_META
#include "src/flags/flag-definitions.h" // NOLINT(build/include)
#undef FLAG_MODE_META
};
constexpr size_t kNumFlags = arraysize(flags);
bool EqualNames(const char* a, const char* b) {
for (int i = 0; NormalizeChar(a[i]) == NormalizeChar(b[i]); i++) {
if (a[i] == '\0') {
return true;
}
}
return false;
}
Flag* FindFlagByName(const char* name) {
for (size_t i = 0; i < kNumFlags; ++i) {
if (EqualNames(name, flags[i].name())) return &flags[i];
}
return nullptr;
}
Flag* FindFlagByPointer(const void* ptr) {
for (size_t i = 0; i < kNumFlags; ++i) {
if (flags[i].PointsTo(ptr)) return &flags[i];
}
return nullptr;
}
static const char* Type2String(Flag::FlagType type) {
switch (type) {
case Flag::TYPE_BOOL:
return "bool";
case Flag::TYPE_MAYBE_BOOL:
return "maybe_bool";
case Flag::TYPE_INT:
return "int";
case Flag::TYPE_UINT:
return "uint";
case Flag::TYPE_UINT64:
return "uint64";
case Flag::TYPE_FLOAT:
return "float";
case Flag::TYPE_SIZE_T:
return "size_t";
case Flag::TYPE_STRING:
return "string";
}
}
// Helper for printing flag values.
struct PrintFlagValue {
const Flag& flag;
};
std::ostream& operator<<(std::ostream& os, PrintFlagValue flag_value) {
const Flag& flag = flag_value.flag;
switch (flag.type()) {
case Flag::TYPE_BOOL:
os << (flag.bool_variable() ? "true" : "false");
break;
case Flag::TYPE_MAYBE_BOOL:
os << (flag.maybe_bool_variable().has_value()
? (flag.maybe_bool_variable().value() ? "true" : "false")
: "unset");
break;
case Flag::TYPE_INT:
os << flag.int_variable();
break;
case Flag::TYPE_UINT:
os << flag.uint_variable();
break;
case Flag::TYPE_UINT64:
os << flag.uint64_variable();
break;
case Flag::TYPE_FLOAT:
os << flag.float_variable();
break;
case Flag::TYPE_SIZE_T:
os << flag.size_t_variable();
break;
case Flag::TYPE_STRING: {
const char* str = flag.string_value();
os << std::quoted(str ? str : "");
break;
}
}
return os;
}
std::ostream& operator<<(std::ostream& os, const Flag& flag) {
if (flag.type() == Flag::TYPE_BOOL) {
os << FlagName{flag.name(), !flag.bool_variable()};
} else {
os << FlagName{flag.name()} << "=" << PrintFlagValue{flag};
}
return os;
}
static std::atomic<uint32_t> flag_hash{0};
static std::atomic<bool> flags_frozen{false};
uint32_t ComputeFlagListHash() {
std::ostringstream modified_args_as_string;
if (COMPRESS_POINTERS_BOOL) modified_args_as_string << "ptr-compr";
if (DEBUG_BOOL) modified_args_as_string << "debug";
#ifdef DEBUG
// These two sets are used to check that we don't leave out any flags
// implied by --predictable in the list below.
std::set<const char*> flags_implied_by_predictable;
std::set<const char*> flags_ignored_because_of_predictable;
#endif
for (const Flag& flag : flags) {
if (flag.IsDefault()) continue;
#ifdef DEBUG
if (flag.ImpliedBy(&v8_flags.predictable)) {
flags_implied_by_predictable.insert(flag.name());
}
#endif
// We want to be able to flip --profile-deserialization without
// causing the code cache to get invalidated by this hash.
if (flag.PointsTo(&v8_flags.profile_deserialization)) continue;
// Skip v8_flags.random_seed and v8_flags.predictable to allow predictable
// code caching.
if (flag.PointsTo(&v8_flags.random_seed)) continue;
if (flag.PointsTo(&v8_flags.predictable)) continue;
// The following flags are implied by --predictable (some negated).
if (flag.PointsTo(&v8_flags.concurrent_sparkplug) ||
flag.PointsTo(&v8_flags.concurrent_recompilation) ||
#ifdef V8_ENABLE_MAGLEV
flag.PointsTo(&v8_flags.maglev_deopt_data_on_background) ||
flag.PointsTo(&v8_flags.maglev_build_code_on_background) ||
#endif
flag.PointsTo(&v8_flags.parallel_scavenge) ||
flag.PointsTo(&v8_flags.concurrent_marking) ||
flag.PointsTo(&v8_flags.concurrent_minor_ms_marking) ||
flag.PointsTo(&v8_flags.concurrent_array_buffer_sweeping) ||
flag.PointsTo(&v8_flags.parallel_marking) ||
flag.PointsTo(&v8_flags.concurrent_sweeping) ||
flag.PointsTo(&v8_flags.parallel_compaction) ||
flag.PointsTo(&v8_flags.parallel_pointer_update) ||
flag.PointsTo(&v8_flags.parallel_weak_ref_clearing) ||
flag.PointsTo(&v8_flags.memory_reducer) ||
flag.PointsTo(&v8_flags.cppheap_concurrent_marking) ||
flag.PointsTo(&v8_flags.cppheap_incremental_marking) ||
flag.PointsTo(&v8_flags.single_threaded_gc)) {
#ifdef DEBUG
if (flag.ImpliedBy(&v8_flags.predictable)) {
flags_ignored_because_of_predictable.insert(flag.name());
}
#endif
continue;
}
modified_args_as_string << flag;
}
#ifdef DEBUG
for (const char* name : flags_implied_by_predictable) {
if (flags_ignored_because_of_predictable.find(name) ==
flags_ignored_because_of_predictable.end()) {
PrintF(
"%s should be added to the list of "
"flags_ignored_because_of_predictable\n",
name);
UNREACHABLE();
}
}
#endif
std::string args(modified_args_as_string.str());
// Generate a hash that is not 0.
uint32_t hash = static_cast<uint32_t>(base::hash_range(
args.c_str(), args.c_str() + args.length())) |
1;
DCHECK_NE(hash, 0);
return hash;
}
} // namespace
// Helper function to parse flags: Takes an argument arg and splits it into
// a flag name and flag value (or nullptr if they are missing). negated is set
// if the arg started with "-no" or "--no". The buffer may be used to NUL-
// terminate the name, it must be large enough to hold any possible name.
static void SplitArgument(const char* arg, char* buffer, int buffer_size,
const char** name, const char** value,
bool* negated) {
*name = nullptr;
*value = nullptr;
*negated = false;
if (arg != nullptr && *arg == '-') {
// find the begin of the flag name
arg++; // remove 1st '-'
if (*arg == '-') {
arg++; // remove 2nd '-'
DCHECK_NE('\0', arg[0]); // '--' arguments are handled in the caller.
}
if (arg[0] == 'n' && arg[1] == 'o') {
arg += 2; // remove "no"
if (NormalizeChar(arg[0]) == '-') arg++; // remove dash after "no".
*negated = true;
}
*name = arg;
// find the end of the flag name
while (*arg != '\0' && *arg != '=') arg++;
// get the value if any
if (*arg == '=') {
// make a copy so we can NUL-terminate flag name
size_t n = arg - *name;
CHECK(n < static_cast<size_t>(buffer_size)); // buffer is too small
MemCopy(buffer, *name, n);
buffer[n] = '\0';
*name = buffer;
// get the value
*value = arg + 1;
}
}
}
template <typename T>
bool TryParseUnsigned(Flag* flag, const char* arg, const char* value,
char** endp, T* out_val) {
// We do not use strtoul because it accepts negative numbers.
// Rejects values >= 2**63 when T is 64 bits wide but that
// seems like an acceptable trade-off.
uint64_t max = static_cast<uint64_t>(std::numeric_limits<T>::max());
errno = 0;
int64_t val = static_cast<int64_t>(strtoll(value, endp, 10));
if (val < 0 || static_cast<uint64_t>(val) > max || errno != 0) {
PrintF(stderr,
"Error: Value for flag %s of type %s is out of bounds "
"[0-%" PRIu64 "]\n",
arg, Type2String(flag->type()), max);
return false;
}
*out_val = static_cast<T>(val);
return true;
}
// static
int FlagList::SetFlagsFromCommandLine(int* argc, char** argv, bool remove_flags,
HelpOptions help_options) {
int return_code = 0;
// parse arguments
for (int i = 1; i < *argc;) {
int j = i; // j > 0
const char* arg = argv[i++];
// split arg into flag components
char buffer[1 * KB];
const char* name;
const char* value;
bool negated;
SplitArgument(arg, buffer, sizeof buffer, &name, &value, &negated);
if (name != nullptr) {
// lookup the flag
Flag* flag = FindFlagByName(name);
if (flag == nullptr) {
if (remove_flags) {
// We don't recognize this flag but since we're removing
// the flags we recognize we assume that the remaining flags
// will be processed somewhere else so this flag might make
// sense there.
continue;
} else {
PrintF(stderr, "Error: unrecognized flag %s\n", arg);
return_code = j;
break;
}
}
// if we still need a flag value, use the next argument if available
if (flag->type() != Flag::TYPE_BOOL &&
flag->type() != Flag::TYPE_MAYBE_BOOL && value == nullptr) {
if (i < *argc) {
value = argv[i++];
}
if (!value) {
PrintF(stderr, "Error: missing value for flag %s of type %s\n", arg,
Type2String(flag->type()));
return_code = j;
break;
}
}
// set the flag
char* endp = const_cast<char*>(""); // *endp is only read
switch (flag->type()) {
case Flag::TYPE_BOOL:
flag->set_bool_variable(!negated, Flag::SetBy::kCommandLine);
break;
case Flag::TYPE_MAYBE_BOOL:
flag->set_maybe_bool_variable(!negated, Flag::SetBy::kCommandLine);
break;
case Flag::TYPE_INT:
flag->set_int_variable(static_cast<int>(strtol(value, &endp, 10)),
Flag::SetBy::kCommandLine);
break;
case Flag::TYPE_UINT: {
unsigned int parsed_value;
if (TryParseUnsigned(flag, arg, value, &endp, &parsed_value)) {
flag->set_uint_variable(parsed_value, Flag::SetBy::kCommandLine);
} else {
return_code = j;
}
break;
}
case Flag::TYPE_UINT64: {
uint64_t parsed_value;
if (TryParseUnsigned(flag, arg, value, &endp, &parsed_value)) {
flag->set_uint64_variable(parsed_value, Flag::SetBy::kCommandLine);
} else {
return_code = j;
}
break;
}
case Flag::TYPE_FLOAT:
flag->set_float_variable(strtod(value, &endp),
Flag::SetBy::kCommandLine);
break;
case Flag::TYPE_SIZE_T: {
size_t parsed_value;
if (TryParseUnsigned(flag, arg, value, &endp, &parsed_value)) {
flag->set_size_t_variable(parsed_value, Flag::SetBy::kCommandLine);
} else {
return_code = j;
}
break;
}
case Flag::TYPE_STRING:
flag->set_string_value(value ? StrDup(value) : nullptr, true,
Flag::SetBy::kCommandLine);
break;
}
// handle errors
bool is_bool_type = flag->type() == Flag::TYPE_BOOL ||
flag->type() == Flag::TYPE_MAYBE_BOOL;
if ((is_bool_type && value != nullptr) || (!is_bool_type && negated) ||
*endp != '\0') {
// TODO(neis): TryParseUnsigned may return with {*endp == '\0'} even in
// an error case.
PrintF(stderr, "Error: illegal value for flag %s of type %s\n", arg,
Type2String(flag->type()));
if (is_bool_type) {
PrintF(stderr,
"To set or unset a boolean flag, use --flag or --no-flag.\n");
}
return_code = j;
break;
}
// remove the flag & value from the command
if (remove_flags) {
while (j < i) {
argv[j++] = nullptr;
}
}
}
}
if (v8_flags.help) {
if (help_options.HasUsage()) {
PrintF(stdout, "%s", help_options.usage());
}
PrintHelp();
if (help_options.ShouldExit()) {
exit(0);
}
}
if (remove_flags) {
// shrink the argument list
int j = 1;
for (int i = 1; i < *argc; i++) {
if (argv[i] != nullptr) argv[j++] = argv[i];
}
*argc = j;
} else if (return_code != 0) {
if (return_code + 1 < *argc) {
PrintF(stderr, "The remaining arguments were ignored:");
for (int i = return_code + 1; i < *argc; ++i) {
PrintF(stderr, " %s", argv[i]);
}
PrintF(stderr, "\n");
}
}
if (return_code != 0) PrintF(stderr, "Try --help for options\n");
return return_code;
}
static char* SkipWhiteSpace(char* p) {
while (*p != '\0' && isspace(*p) != 0) p++;
return p;
}
static char* SkipBlackSpace(char* p) {
while (*p != '\0' && isspace(*p) == 0) p++;
return p;
}
// static
int FlagList::SetFlagsFromString(const char* str, size_t len) {
// make a 0-terminated copy of str
std::unique_ptr<char[]> copy0{NewArray<char>(len + 1)};
MemCopy(copy0.get(), str, len);
copy0[len] = '\0';
// strip leading white space
char* copy = SkipWhiteSpace(copy0.get());
// count the number of 'arguments'
int argc = 1; // be compatible with SetFlagsFromCommandLine()
for (char* p = copy; *p != '\0'; argc++) {
p = SkipBlackSpace(p);
p = SkipWhiteSpace(p);
}
// allocate argument array
base::ScopedVector<char*> argv(argc);
// split the flags string into arguments
argc = 1; // be compatible with SetFlagsFromCommandLine()
for (char* p = copy; *p != '\0'; argc++) {
argv[argc] = p;
p = SkipBlackSpace(p);
if (*p != '\0') *p++ = '\0'; // 0-terminate argument
p = SkipWhiteSpace(p);
}
return SetFlagsFromCommandLine(&argc, argv.begin(), false);
}
// static
void FlagList::FreezeFlags() {
// Disallow changes via the API by setting {flags_frozen}.
flags_frozen.store(true, std::memory_order_relaxed);
// Also memory-protect the memory that holds the flag values. This makes it
// impossible for attackers to overwrite values, except if they find a way to
// first unprotect the memory again.
// Note that for string flags we only protect the pointer itself, but not the
// string storage. TODO(12887): Fix this.
base::OS::SetDataReadOnly(&v8_flags, sizeof(v8_flags));
}
// static
bool FlagList::IsFrozen() {
return flags_frozen.load(std::memory_order_relaxed);
}
// static
void FlagList::ReleaseDynamicAllocations() {
flag_hash = 0;
for (size_t i = 0; i < kNumFlags; ++i) {
flags[i].ReleaseDynamicAllocations();
}
}
// static
void FlagList::PrintHelp() {
CpuFeatures::Probe(false);
CpuFeatures::PrintTarget();
CpuFeatures::PrintFeatures();
StdoutStream os;
os << "The following syntax for options is accepted (both '-' and '--' are "
"ok):\n"
" --flag (bool flags only)\n"
" --no-flag (bool flags only)\n"
" --flag=value (non-bool flags only, no spaces around '=')\n"
" --flag value (non-bool flags only)\n"
" -- (captures all remaining args in JavaScript)\n\n";
os << "Options:\n";
for (const Flag& f : flags) {
os << " " << FlagName{f.name()} << " (" << f.comment() << ")\n"
<< " type: " << Type2String(f.type()) << " default: " << f
<< "\n";
}
}
// static
void FlagList::PrintValues() {
StdoutStream os;
for (const Flag& f : flags) {
os << f << "\n";
}
}
namespace {
class ImplicationProcessor {
public:
// Returns {true} if any flag value was changed.
bool EnforceImplications() {
bool changed = false;
#define FLAG_MODE_DEFINE_IMPLICATIONS
#include "src/flags/flag-definitions.h" // NOLINT(build/include)
#undef FLAG_MODE_DEFINE_IMPLICATIONS
CheckForCycle();
return changed;
}
private:
// Called from {DEFINE_*_IMPLICATION} in flag-definitions.h.
template <class T>
bool TriggerImplication(bool premise, const char* premise_name,
FlagValue<T>* conclusion_value,
const char* conclusion_name, T value,
bool weak_implication) {
if (!premise) return false;
Flag* conclusion_flag = FindFlagByName(conclusion_name);
if (!conclusion_flag->CheckFlagChange(
weak_implication ? Flag::SetBy::kWeakImplication
: Flag::SetBy::kImplication,
conclusion_value->value() != value, premise_name)) {
return false;
}
if (V8_UNLIKELY(num_iterations_ >= kMaxNumIterations)) {
cycle_ << "\n" << FlagName{premise_name} << " -> ";
if constexpr (std::is_same_v<T, bool>) {
cycle_ << FlagName{conclusion_flag->name(), !value};
} else {
cycle_ << FlagName{conclusion_flag->name()} << " = " << value;
}
}
*conclusion_value = value;
return true;
}
// Called from {DEFINE_*_IMPLICATION} in flag-definitions.h, when the
// conclusion flag is read-only (note this is the const overload of the
// function just above).
template <class T>
bool TriggerImplication(bool premise, const char* premise_name,
const FlagValue<T>* conclusion_value,
const char* conclusion_name, T value,
bool weak_implication) {
if (!premise) return false;
Flag* conclusion_flag = FindFlagByName(conclusion_name);
// Because this is the `const FlagValue*` overload:
DCHECK(conclusion_flag->IsReadOnly());
if (!conclusion_flag->CheckFlagChange(
weak_implication ? Flag::SetBy::kWeakImplication
: Flag::SetBy::kImplication,
conclusion_value->value() != value, premise_name)) {
return false;
}
// Must equal the default value, otherwise CheckFlagChange should've
// returned false.
DCHECK_EQ(value, conclusion_flag->GetDefaultValue<T>());
return true;
}
void CheckForCycle() {
// Make sure flag implications reach a fixed point within
// {kMaxNumIterations} iterations.
if (++num_iterations_ < kMaxNumIterations) return;
if (num_iterations_ == kMaxNumIterations) {
// Start cycle detection.
DCHECK(cycle_.str().empty());
cycle_start_hash_ = ComputeFlagListHash();
return;
}
DCHECK_NE(0, cycle_start_hash_);
// We accept spurious but highly unlikely hash collisions here. This is
// only a debug output anyway.
if (ComputeFlagListHash() == cycle_start_hash_) {
DCHECK(!cycle_.str().empty());
// {cycle_} starts with a newline.
FATAL("Cycle in flag implications:%s", cycle_.str().c_str());
}
// We must have found a cycle within another {kMaxNumIterations}.
DCHECK_GE(2 * kMaxNumIterations, num_iterations_);
}
static constexpr size_t kMaxNumIterations = kNumFlags;
size_t num_iterations_ = 0;
// After {kMaxNumIterations} we use the following two fields for finding
// cycles in flags.
uint32_t cycle_start_hash_;
std::ostringstream cycle_;
};
} // namespace
// static
void FlagList::EnforceFlagImplications() {
for (ImplicationProcessor proc; proc.EnforceImplications();) {
// Continue processing (recursive) implications. The processor has an
// internal limit to avoid endless recursion.
}
}
// static
uint32_t FlagList::Hash() {
if (uint32_t hash = flag_hash.load(std::memory_order_relaxed)) return hash;
uint32_t hash = ComputeFlagListHash();
flag_hash.store(hash, std::memory_order_relaxed);
return hash;
}
// static
void FlagList::ResetFlagHash() {
// If flags are frozen, we should not need to reset the hash since we cannot
// change flag values anyway.
CHECK(!IsFrozen());
flag_hash = 0;
}
} // namespace v8::internal
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