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# ignore-this-changeset Depends on D28954 Differential Revision: https://phabricator.services.mozilla.com/D28956 --HG-- extra : moz-landing-system : lando
132 lines
4.1 KiB
C++
132 lines
4.1 KiB
C++
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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/* compile-time and runtime tests for whether to use various ARM extensions */
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#include "arm.h"
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#if defined(MOZILLA_ARM_HAVE_CPUID_DETECTION)
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// arm.h has parallel #ifs which declare MOZILLA_ARM_HAVE_CPUID_DETECTION.
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// We don't check it here so that we get compile errors if it's defined, but
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// we don't compile one of these detection methods. The detection code here is
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// based on the CPU detection in libtheora.
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# if defined(__linux__) || defined(ANDROID)
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# include <stdio.h>
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# include <stdlib.h>
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# include <string.h>
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enum {
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MOZILLA_HAS_EDSP_FLAG = 1,
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MOZILLA_HAS_ARMV6_FLAG = 2,
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MOZILLA_HAS_ARMV7_FLAG = 4,
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MOZILLA_HAS_NEON_FLAG = 8
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};
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static unsigned get_arm_cpu_flags(void) {
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unsigned flags;
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FILE* fin;
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bool armv6_processor = false;
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flags = 0;
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/*Reading /proc/self/auxv would be easier, but that doesn't work reliably on
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Android. This also means that detection will fail in Scratchbox, which is
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desirable, as NEON does not work in the qemu shipped with the Maemo 5 SDK.
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I don't know if /proc/self/auxv would do any better in that case, anyway,
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or if it would return random flags from the host CPU.*/
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fin = fopen("/proc/cpuinfo", "r");
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if (fin != nullptr) {
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/*512 should be enough for anybody (it's even enough for all the flags that
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x86 has accumulated... so far).*/
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char buf[512];
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while (fgets(buf, 511, fin) != nullptr) {
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if (memcmp(buf, "Features", 8) == 0) {
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char* p;
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p = strstr(buf, " edsp");
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if (p != nullptr && (p[5] == ' ' || p[5] == '\n'))
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flags |= MOZILLA_HAS_EDSP_FLAG;
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p = strstr(buf, " neon");
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if (p != nullptr && (p[5] == ' ' || p[5] == '\n'))
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flags |= MOZILLA_HAS_NEON_FLAG;
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}
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if (memcmp(buf, "CPU architecture:", 17) == 0) {
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int version;
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version = atoi(buf + 17);
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if (version >= 6) flags |= MOZILLA_HAS_ARMV6_FLAG;
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if (version >= 7) flags |= MOZILLA_HAS_ARMV7_FLAG;
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}
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/* media/webrtc/trunk/src/system_wrappers/source/cpu_features_arm.c
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* Unfortunately, it seems that certain ARMv6-based CPUs
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* report an incorrect architecture number of 7!
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*
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* We try to correct this by looking at the 'elf_format'
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* field reported by the 'Processor' field, which is of the
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* form of "(v7l)" for an ARMv7-based CPU, and "(v6l)" for
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* an ARMv6-one.
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*/
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if (memcmp(buf, "Processor\t:", 11) == 0) {
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if (strstr(buf, "(v6l)") != 0) {
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armv6_processor = true;
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}
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}
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}
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fclose(fin);
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}
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if (armv6_processor) {
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// ARMv6 pretending to be ARMv7? clear flag
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if (flags & MOZILLA_HAS_ARMV7_FLAG) {
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flags &= ~MOZILLA_HAS_ARMV7_FLAG;
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}
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}
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return flags;
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}
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// Cache a local copy so we only have to read /proc/cpuinfo once.
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static unsigned arm_cpu_flags = get_arm_cpu_flags();
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# if !defined(MOZILLA_PRESUME_EDSP)
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static bool check_edsp(void) {
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return (arm_cpu_flags & MOZILLA_HAS_EDSP_FLAG) != 0;
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}
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# endif
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# if !defined(MOZILLA_PRESUME_ARMV6)
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static bool check_armv6(void) {
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return (arm_cpu_flags & MOZILLA_HAS_ARMV6_FLAG) != 0;
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}
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# endif
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# if !defined(MOZILLA_PRESUME_ARMV7)
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static bool check_armv7(void) {
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return (arm_cpu_flags & MOZILLA_HAS_ARMV7_FLAG) != 0;
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}
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# endif
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# if !defined(MOZILLA_PRESUME_NEON)
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static bool check_neon(void) {
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return (arm_cpu_flags & MOZILLA_HAS_NEON_FLAG) != 0;
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}
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# endif
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# endif // defined(__linux__) || defined(ANDROID)
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namespace mozilla {
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namespace arm_private {
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# if !defined(MOZILLA_PRESUME_EDSP)
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bool edsp_enabled = check_edsp();
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# endif
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# if !defined(MOZILLA_PRESUME_ARMV6)
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bool armv6_enabled = check_armv6();
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# endif
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# if !defined(MOZILLA_PRESUME_ARMV7)
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bool armv7_enabled = check_armv7();
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# endif
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# if !defined(MOZILLA_PRESUME_NEON)
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bool neon_enabled = check_neon();
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# endif
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} // namespace arm_private
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} // namespace mozilla
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#endif // MOZILLA_ARM_HAVE_CPUID_DETECTION
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