iOS 二进制重排Clang插桩使用

iOS 启动优化 二进制重排  

1. 在Build Settings中添加编译选项Other C Flags增加`-fsanitize-coverage=func,trace-pc-guard

 如果是OC Swift混编，

则在Other Swift Flags增加`-sanitize-coverage=func`,`-sanitize=undefined

 2.统计程序启动的函数执行情况在首页的viewDidAppear函数中加上生成orderFile的函数，然后运行app 

-(void)viewDidAppear:(BOOL)animated { [super viewDidAppear:animated];

 [HTClangTrace generateOrderFile]; 

} 

 会在app的沙盒的tmp目录下生成，

htclangtrace.order的文件 ,获取tmp 下的htclangtrace.order 导入工程

 3. 在Build Settings中搜索Order File 设置为htclangtrace.order的路径

 HTClangTrace.h 文件如下 

#import <Foundation/Foundation.h>

NS_ASSUME_NONNULL_BEGIN

@interface HTClangTrace : NSObject

/// 生成trace.order文件；一般我们要检测启动前执行的函数，所以放到首页的viewDidAppear中调用该函数+ (void)generateOrderFile;

@endNS_ASSUME_NONNULL_END

 HTClangTrace.m 文件代码如下 

// //  HTClangTrace.m //  HTScore_iOS // //  Created by muxinjian on 2020/6/3. //  Copyright © 2020 huatu. All rights reserved. // #import "HTClangTrace.h" #import <dlfcn.h> #import <libkern/OSAtomic.h> @implementation HTClangTrace void __sanitizer_cov_trace_pc_guard_init(uint32_t *start,                                          uint32_t *stop) {     static uint64_t N;  // Counter for the guards.     if (start == stop || *start) return;  // Initialize only once.     for (uint32_t *x = start; x < stop; x++)         *x = ++N;  // Guards should start from 1. } //原子队列 static  OSQueueHead symbolList = OS_ATOMIC_QUEUE_INIT; //定义符号结构体 typedef struct {     void *pc;     void *next; } SymbolNode; void __sanitizer_cov_trace_pc_guard(uint32_t *guard) {     if (!*guard) return;     void *PC = __builtin_return_address(0);     SymbolNode *node = malloc(sizeof(SymbolNode));     *node = (SymbolNode){PC, NULL};     OSAtomicEnqueue(&symbolList, node, offsetof(SymbolNode, next)); } + (void)generateOrderFile {     NSMutableArray <NSString *> *symbolNames = [NSMutableArray array];     while (YES) {         SymbolNode * node = OSAtomicDequeue(&symbolList, offsetof(SymbolNode, next));         if (node == NULL) {             break;         }         Dl_info info;         dladdr(node->pc, &info);         NSString *name = @(info.dli_sname);         // 判断是不是oc方法，是的话直接加入符号数组         BOOL isInstanceMethod = [name hasPrefix:@"-["];         BOOL isClassMethod = [name hasPrefix:@"+["];         BOOL isObjc = isInstanceMethod || isClassMethod;         NSString * symbolName = isObjc ? name: [@"_" stringByAppendingString:name];         [symbolNames addObject:symbolName];     }     // 取反:将先调用的函数放到前面     NSEnumerator * emt = [symbolNames reverseObjectEnumerator];     // 去重：由于一个函数可能执行多次，__sanitizer_cov_trace_pc_guard会执行多次，就加了重复的了，所以去重一下     NSMutableArray<NSString *> *funcs = [NSMutableArray arrayWithCapacity:symbolNames.count];     NSString *name;     while (name = [emt nextObject]) {         if (![funcs containsObject:name]) {             [funcs addObject:name];         }     }     // 由于trace了所有执行的函数，这里我们就把本函数移除掉     [funcs removeObject:[NSString stringWithFormat:@"%s",__FUNCTION__]];     // 写order文件     NSString *funcStr = [funcs componentsJoinedByString:@"\n"];     NSString *filePath = [NSTemporaryDirectory() stringByAppendingPathComponent:@"htclangtrace.order"];     NSData *fileContents = [funcStr dataUsingEncoding:NSUTF8StringEncoding];     [[NSFileManager defaultManager] createFileAtPath:filePath contents:fileContents attributes:nil];     if ([[NSFileManager defaultManager] fileExistsAtPath:filePath]){          NSLog(@"orderPath:%@",filePath);     }else{          NSLog(@"生成orderPath失败");     } } #pragma mark - Util + (BOOL)isObjcMethodBySymbolName:(NSString *)symbolName {          BOOL isInstanceMethod = [symbolName hasPrefix:@"-["];     BOOL isClassMethod = [symbolName hasPrefix:@"+["];     return isInstanceMethod || isClassMethod; } @end

 参考链接:抖音研发实践：基于二进制文件重排的解决方案 APP启动速度提升超15%