gecko-dev/mozglue/build/arm.cpp
serge-sans-paille 8a0a0f7524 Bug 1920718 - Annotate all global variable with runtime initialization attributes r=glandium,application-update-reviewers,media-playback-reviewers,anti-tracking-reviewers,places-reviewers,profiler-reviewers,gfx-reviewers,aosmond,lina,nalexander,aabh,geckoview-reviewers,win-reviewers,gstoll,m_kato
MOZ_RUNINIT => initialized at runtime
MOZ_CONSTINIT => initialized at compile time
MOZ_GLOBINIT => initialized either at runtime or compile time, depending on template parameter, macro parameter etc
This annotation is only understood by our clang-tidy plugin. It has no
effect on regular compilation.

Differential Revision: https://phabricator.services.mozilla.com/D223341
2024-10-30 11:05:24 +00:00

147 lines
4.6 KiB
C++

/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
/* compile-time and runtime tests for whether to use various ARM extensions */
#include "arm.h"
#include "mozilla/Attributes.h"
#if defined(MOZILLA_ARM_HAVE_CPUID_DETECTION)
// arm.h has parallel #ifs which declare MOZILLA_ARM_HAVE_CPUID_DETECTION.
// We don't check it here so that we get compile errors if it's defined, but
// we don't compile one of these detection methods. The detection code here is
// based on the CPU detection in libtheora.
# if defined(__linux__) || defined(ANDROID)
# include <stdio.h>
# include <stdlib.h>
# include <string.h>
enum {
MOZILLA_HAS_EDSP_FLAG = 1,
MOZILLA_HAS_ARMV6_FLAG = 2,
MOZILLA_HAS_ARMV7_FLAG = 4,
MOZILLA_HAS_NEON_FLAG = 8,
MOZILLA_HAS_AES_FLAG = 16
};
static unsigned get_arm_cpu_flags(void) {
unsigned flags;
FILE* fin;
bool armv6_processor = false;
flags = 0;
/*Reading /proc/self/auxv would be easier, but that doesn't work reliably on
Android. This also means that detection will fail in Scratchbox, which is
desirable, as NEON does not work in the qemu shipped with the Maemo 5 SDK.
I don't know if /proc/self/auxv would do any better in that case, anyway,
or if it would return random flags from the host CPU.*/
fin = fopen("/proc/cpuinfo", "r");
if (fin != nullptr) {
/*512 should be enough for anybody (it's even enough for all the flags that
x86 has accumulated... so far).*/
char buf[512];
while (fgets(buf, 511, fin) != nullptr) {
if (memcmp(buf, "Features", 8) == 0) {
char* p;
p = strstr(buf, " edsp");
if (p != nullptr && (p[5] == ' ' || p[5] == '\n'))
flags |= MOZILLA_HAS_EDSP_FLAG;
p = strstr(buf, " neon");
if (p != nullptr && (p[5] == ' ' || p[5] == '\n'))
flags |= MOZILLA_HAS_NEON_FLAG;
p = strstr(buf, " aes");
if (p != nullptr && (p[4] == ' ' || p[4] == '\n')) {
flags |= MOZILLA_HAS_AES_FLAG;
}
}
if (memcmp(buf, "CPU architecture:", 17) == 0) {
int version;
version = atoi(buf + 17);
if (version >= 6) flags |= MOZILLA_HAS_ARMV6_FLAG;
if (version >= 7) flags |= MOZILLA_HAS_ARMV7_FLAG;
}
/* media/webrtc/trunk/src/system_wrappers/source/cpu_features_arm.c
* Unfortunately, it seems that certain ARMv6-based CPUs
* report an incorrect architecture number of 7!
*
* We try to correct this by looking at the 'elf_format'
* field reported by the 'Processor' field, which is of the
* form of "(v7l)" for an ARMv7-based CPU, and "(v6l)" for
* an ARMv6-one.
*/
if (memcmp(buf, "Processor\t:", 11) == 0) {
if (strstr(buf, "(v6l)") != 0) {
armv6_processor = true;
}
}
}
fclose(fin);
}
if (armv6_processor) {
// ARMv6 pretending to be ARMv7? clear flag
if (flags & MOZILLA_HAS_ARMV7_FLAG) {
flags &= ~MOZILLA_HAS_ARMV7_FLAG;
}
}
return flags;
}
// Cache a local copy so we only have to read /proc/cpuinfo once.
MOZ_RUNINIT static unsigned arm_cpu_flags = get_arm_cpu_flags();
# if !defined(MOZILLA_PRESUME_EDSP)
static bool check_edsp(void) {
return (arm_cpu_flags & MOZILLA_HAS_EDSP_FLAG) != 0;
}
# endif
# if !defined(MOZILLA_PRESUME_ARMV6)
static bool check_armv6(void) {
return (arm_cpu_flags & MOZILLA_HAS_ARMV6_FLAG) != 0;
}
# endif
# if !defined(MOZILLA_PRESUME_ARMV7)
static bool check_armv7(void) {
return (arm_cpu_flags & MOZILLA_HAS_ARMV7_FLAG) != 0;
}
# endif
# if !defined(MOZILLA_PRESUME_NEON)
static bool check_neon(void) {
return (arm_cpu_flags & MOZILLA_HAS_NEON_FLAG) != 0;
}
# endif
# if !defined(MOZILLA_PRESUME_ARM_AES)
static bool check_aes(void) {
return (arm_cpu_flags & MOZILLA_HAS_AES_FLAG) != 0;
}
# endif
# endif // defined(__linux__) || defined(ANDROID)
namespace mozilla {
namespace arm_private {
# if !defined(MOZILLA_PRESUME_EDSP)
MOZ_RUNINIT bool edsp_enabled = check_edsp();
# endif
# if !defined(MOZILLA_PRESUME_ARMV6)
MOZ_RUNINIT bool armv6_enabled = check_armv6();
# endif
# if !defined(MOZILLA_PRESUME_ARMV7)
MOZ_RUNINIT bool armv7_enabled = check_armv7();
# endif
# if !defined(MOZILLA_PRESUME_NEON)
MOZ_RUNINIT bool neon_enabled = check_neon();
# endif
# if !defined(MOZILLA_PRESUME_ARM_AES)
MOZ_RUNINIT bool aes_enabled = check_aes();
# endif
} // namespace arm_private
} // namespace mozilla
#endif // MOZILLA_ARM_HAVE_CPUID_DETECTION