anv: ANV_DEBUG_WAIT_FOR_ATTACH

Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/35324>

docs/envvars.rst

@@ -904,6 +904,12 @@ Anvil(ANV) driver environment variables
    modifying command buffers to implement ``vkCmdExecuteCommands``. As
    a result of this, it will also disable :ext:`VK_KHR_performance_query`.
 
+.. envvar:: ANV_DEBUG_WAIT_FOR_ATTACH
+
+   If defined, the value is parsed as a regular expression. If the current
+   process name matches the regex, ANV will wait 30 seconds for a debugger
+   to attach before starting device creation.
+
 .. envvar:: ANV_PRIMITIVE_REPLICATION_MAX_VIEWS
 
    Specifies up to how many view shaders can be lowered to handle

src/intel/vulkan/anv_device.c

@@ -312,6 +312,7 @@ VkResult anv_CreateDevice(
     const VkAllocationCallbacks*                pAllocator,
     VkDevice*                                   pDevice)
 {
+   anv_wait_for_attach();
    ANV_FROM_HANDLE(anv_physical_device, physical_device, physicalDevice);
    VkResult result;
    struct anv_device *device;

src/intel/vulkan/anv_private.h

@@ -2390,6 +2390,8 @@ void anv_device_print_fini(struct anv_device *device);
 
 void anv_dump_bvh_to_files(struct anv_device *device);
 
+void anv_wait_for_attach(void);
+
 VkResult anv_queue_init(struct anv_device *device, struct anv_queue *queue,
                         const VkDeviceQueueCreateInfo *pCreateInfo,
                         uint32_t index_in_family);

src/intel/vulkan/anv_util.c

@@ -33,6 +33,19 @@
 #include "anv_private.h"
 #include "vk_enum_to_str.h"
 
+#ifdef NO_REGEX
+typedef int regex_t;
+#define REG_EXTENDED 0
+#define REG_NOSUB 0
+#define REG_NOMATCH 1
+static inline int regcomp(regex_t *r, const char *s, int f) { return 0; }
+static inline int regexec(regex_t *r, const char *s, int n, void *p, int f) { return REG_NOMATCH; }
+static inline void regfree(regex_t* r) {}
+#else
+#include <regex.h>
+#endif
+#include "util/u_process.h"
+
 void
 __anv_perf_warn(struct anv_device *device,
                 const struct vk_object_base *object,
@@ -289,3 +302,31 @@ void anv_dump_bvh_to_files(struct anv_device *device)
       free(bvh_dump);
    }
 }
+
+DEBUG_GET_ONCE_OPTION(anv_debug_wait_for_attach, "ANV_DEBUG_WAIT_FOR_ATTACH", NULL);
+
+void anv_wait_for_attach() {
+   const char *attach_regex =
+      debug_get_option_anv_debug_wait_for_attach();
+   if (unlikely(attach_regex != NULL)) {
+      bool wait_for_attach = false;
+      const char *exec_name = util_get_process_name();
+      regex_t re;
+      int compile_res = regcomp(&re, attach_regex, REG_EXTENDED|REG_NOSUB);
+      if (compile_res != 0) {
+         char compile_err[256];
+         regerror(compile_res, &re, compile_err, 256);
+         fprintf(stderr, "ANV_DEBUG_WAIT_FOR_ATTACH regex compile fail: %s\n",
+                 compile_err);
+      } else {
+         wait_for_attach = (regexec(&re, exec_name, 0, NULL, 0) == 0);
+         regfree(&re);
+      }
+
+      if (wait_for_attach) {
+         fprintf(stderr, "Sleeping 30 seconds for debugger attach...\n");
+         fprintf(stderr, "PID for debugger: %d\n", getpid());
+         sleep(30);
+      }
+   }
+}