双重编译

Question

我正在做某种解释器，由于本地标签地址，我正在计算一个静态const跳转表。
你知道该怎么做， [INFO] --- spring-boot-maven-plugin:2.3.0.RELEASE:build-image (default-cli) @ angular-spring-reactive-sample-server --- [INFO] Building image 'docker.io/hantsy/angular-spring-reactive-sample-server:lastest' [INFO] [INFO] > Pulling builder image 'gcr.io/paketo-buildpacks/builder:base-platform-api-0.3' 100% [INFO] ------------------------------------------------------------------------ [INFO] BUILD FAILURE [INFO] ------------------------------------------------------------------------ [INFO] Total time: 30.757 s [INFO] Finished at: 2020-05-17T16:38:02+08:00 [INFO] ------------------------------------------------------------------------ [ERROR] Failed to execute goal org.springframework.boot:spring-boot-maven-plugin:2.3.0.RELEASE:build-image (default-cli) on project angular-spring-reactive-sample-server: Execution default-cli of goal org.springframework.boot:spring-boot-maven-plugin:2.3.0.RELEASE:build-image failed: Docker API call to 'localhost/v1.24/images/create?fromImage=gcr.io%2Fpaketo-buildpacks%2Fbuilder%3Abase-platform-api-0.3' failed with status code 500 "Internal Server Error" -> [Help 1] org.apache.maven.lifecycle.LifecycleExecutionException: Failed to execute goal org.springframework.boot:spring-boot-maven-plugin:2.3.0.RELEASE:build-image (default-cli) on project angular-spring-reactive-sample-server: Execution default-cli of goal org.springframework.boot:spring-boot-maven-plugin:2.3.0.RELEASE:build-image failed: Docker API call to 'localhost/v1.24/images/create?fromImage=gcr.io%2Fpaketo-buildpacks%2Fbuilder%3Abase-platform-api-0.3' failed with status code 500 "Internal Server Error" at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:215) at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:156) at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:148) at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:117) at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:81) at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build (SingleThreadedBuilder.java:56) at org.apache.maven.lifecycle.internal.LifecycleStarter.execute (LifecycleStarter.java:128) at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:305) at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:192) at org.apache.maven.DefaultMaven.execute (DefaultMaven.java:105) at org.apache.maven.cli.MavenCli.execute (MavenCli.java:957) at org.apache.maven.cli.MavenCli.doMain (MavenCli.java:289) at org.apache.maven.cli.MavenCli.main (MavenCli.java:193) at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0 (Native Method) at jdk.internal.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:62) at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke (Method.java:566) at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced (Launcher.java:282) at org.codehaus.plexus.classworlds.launcher.Launcher.launch (Launcher.java:225) at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode (Launcher.java:406) at org.codehaus.plexus.classworlds.launcher.Launcher.main (Launcher.java:347) Caused by: org.apache.maven.plugin.PluginExecutionException: Execution default-cli of goal org.springframework.boot:spring-boot-maven-plugin:2.3.0.RELEASE:build-image failed: Docker API call to 'localhost/v1.24/images/create?fromImage=gcr.io%2Fpaketo-buildpacks%2Fbuilder%3Abase-platform-api-0.3' failed with status code 500 "Internal Server Error" at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo (DefaultBuildPluginManager.java:148) at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:210) at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:156) at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:148) at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:117) at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:81) at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build (SingleThreadedBuilder.java:56) at org.apache.maven.lifecycle.internal.LifecycleStarter.execute (LifecycleStarter.java:128) at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:305) at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:192) at org.apache.maven.DefaultMaven.execute (DefaultMaven.java:105) at org.apache.maven.cli.MavenCli.execute (MavenCli.java:957) at org.apache.maven.cli.MavenCli.doMain (MavenCli.java:289) at org.apache.maven.cli.MavenCli.main (MavenCli.java:193) at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0 (Native Method) at jdk.internal.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:62) at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke (Method.java:566) at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced (Launcher.java:282) at org.codehaus.plexus.classworlds.launcher.Launcher.launch (Launcher.java:225) at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode (Launcher.java:406) at org.codehaus.plexus.classworlds.launcher.Launcher.main (Launcher.java:347) Caused by: org.springframework.boot.buildpack.platform.docker.transport.DockerEngineException: Docker API call to 'localhost/v1.24/images/create?fromImage=gcr.io%2Fpaketo-buildpacks%2Fbuilder%3Abase-platform-api-0.3' failed with status code 500 "Internal Server Error" at org.springframework.boot.buildpack.platform.docker.transport.HttpClientTransport.execute (HttpClientTransport.java:135) at org.springframework.boot.buildpack.platform.docker.transport.HttpClientTransport.post (HttpClientTransport.java:82) at org.springframework.boot.buildpack.platform.docker.DockerApi$ImageApi.pull (DockerApi.java:155) at org.springframework.boot.buildpack.platform.build.Builder.pullBuilder (Builder.java:84) at org.springframework.boot.buildpack.platform.build.Builder.build (Builder.java:62) at org.springframework.boot.maven.BuildImageMojo.buildImage (BuildImageMojo.java:136) at org.springframework.boot.maven.BuildImageMojo.execute (BuildImageMojo.java:128) at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo (DefaultBuildPluginManager.java:137) at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:210) at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:156) at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:148) at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:117) at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:81) at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build (SingleThreadedBuilder.java:56) at org.apache.maven.lifecycle.internal.LifecycleStarter.execute (LifecycleStarter.java:128) at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:305) at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:192) at org.apache.maven.DefaultMaven.execute (DefaultMaven.java:105) at org.apache.maven.cli.MavenCli.execute (MavenCli.java:957) at org.apache.maven.cli.MavenCli.doMain (MavenCli.java:289) at org.apache.maven.cli.MavenCli.main (MavenCli.java:193) at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0 (Native Method) at jdk.internal.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:62) at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke (Method.java:566) at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced (Launcher.java:282) at org.codehaus.plexus.classworlds.launcher.Launcher.launch (Launcher.java:225) at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode (Launcher.java:406) at org.codehaus.plexus.classworlds.launcher.Launcher.main (Launcher.java:347) [ERROR] [ERROR] Re-run Maven using the -X switch to enable full debug logging. [ERROR] [ERROR] For more information about the errors and possible solutions, please read the following articles: [ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/PluginExecutionException等。
由于各种原因（主要是性能问题），我想在初始化期间在对象中复制/压缩此表。
我伤了头，因为我无法弄清楚如何逃避该函数的词法作用域！

如何以某种方式从另一个函数引用&& case0？

有人为此有一个好把戏吗？
预先感谢

Answer 1

我不知道在纯GNU C中实现此目标的方法，因此以下方法使用其他机制。

双重编译

您可以编译目标文件两次，在第一次运行时收集偏移，在第二次运行中使用偏移。例如

int foo(int x) {
#ifdef GENERATE_ADDRESSES
    static __attribute__((section(".foo_offsets"))) unsigned offsets[] = { &&case0 - &&case0, &&case1 - &&case0 };
#endif
    switch (x) {
case0:
        case 0:
            return 1;
case1:
        case 1:
            return 2;
    }
    return 0;
}

现在，您可以编译，从.foo_offsets节中提取字节，并在第二次运行时将其嵌入到您的应用中

$ gcc tmp.c -c -DGENERATE_ADDRESSES
$ objcopy -j .foo_offsets -O binary tmp.o
$ xxd -i tmp.o | tee offsets.inc
unsigned char tmp_o[] = {
  0x00, 0x00, 0x00, 0x00, 0x07, 0x00, 0x00, 0x00
};
unsigned int tmp_o_len = 8;

内联汇编

您可以使用内联汇编程序来全球化标签：

extern char foo_case0[];
extern char foo_case1[];
const void *foo_addresses[] = { &foo_case0[0], &foo_case1[0] };

int foo(int x) {
    switch (x) {
        case 0:
asm("foo_case0:");
            return 1;
        case 1:
asm("foo_case1:");
            return 2;
    }
    return 0;
}

不幸的是，在这种情况下，您只能收集地址（而不是偏移量），因此您需要在启动时手动计算偏移量。

从gcc / clang（C ++）的功能范围中获取标签地址

1 个答案:

双重编译

内联汇编