Working on reconciling out-of-tree patches to compiler-rt for building for iOS.

[beanz]

Summary

This is one of many changes needed for compiler-rt to get it building on iOS.

This change does the following:

• Don't include crt_externs on iOS (it isn't available)
• Support ARM thread state objects

Note: this change does not enable building for iOS, as there are more changes to come.

[beanz]

Looping in Alexander Potapenko because git blame :-).

[beanz]

Adding Kuba and Justin for review.

[samsonov]

lib/sanitizer_common/sanitizer_mac.cc

33 ↗

(On Diff #27847)

Please use SANITIZER_IOS instead. It is already defined in sanitizer_platform.h (here and below)

371 ↗

(On Diff #27847)

Please use indentation in nested #ifs

# if foo
  a = x;
#  if bar
  b = y;
#  else
  b = yy;
#  endif
  c = z;
# endif

[beanz]

Updating based on feedback from samsonov.

[samsonov]

LGTM, though I really think we should move _NSGetEnviron logic to a function.

lib/sanitizer_common/sanitizer_mac.cc

200 ↗

(On Diff #28266)

We have similar code in asan_mac.cc. Please consider factoring it to a function, which we could call from there instead.

[beanz]

Refactoring reading environ out into a funciton.

[samsonov]

LGTM. Let me know if there are more patches you're blocked on.

compiler-rt/trunk/lib/asan/asan_mac.cc

 static const char kDyldInsertLibraries[] = "DYLD_INSERT_LIBRARIES";
 LowLevelAllocator allocator_for_env;
 
 // Change the value of the env var |name|, leaking the original value.
 // If |name_value| is NULL, the variable is deleted from the environment,
 // otherwise the corresponding "NAME=value" string is replaced with
 // |name_value|.
 void LeakyResetEnv(const char *name, const char *name_value) {
-  char ***env_ptr = _NSGetEnviron();
-  CHECK(env_ptr);
-  char **environ = *env_ptr;
-  CHECK(environ);
+  char **env = GetEnviron();
   uptr name_len = internal_strlen(name);
-  while (*environ != 0) {
-    uptr len = internal_strlen(*environ);
+  while (*env != 0) {
+    uptr len = internal_strlen(*env);
     if (len > name_len) {
-      const char *p = *environ;
+      const char *p = *env;
       if (!internal_memcmp(p, name, name_len) && p[name_len] == '=') {
         // Match.
         if (name_value) {
           // Replace the old value with the new one.
-          *environ = const_cast<char*>(name_value);
+          *env = const_cast<char*>(name_value);
         } else {
           // Shift the subsequent pointers back.
-          char **del = environ;
+          char **del = env;
           do {
             del[0] = del[1];
           } while (*del++);
         }
       }
     }
-    environ++;
+    env++;
   }
 }
 
 static bool reexec_disabled = false;
 
 void DisableReexec() {
   reexec_disabled = true;
 }

compiler-rt/trunk/lib/sanitizer_common/sanitizer_mac.h

enum MacosVersion {
   MACOS_VERSION_MOUNTAIN_LION,
   MACOS_VERSION_MAVERICKS,
   MACOS_VERSION_YOSEMITE,
   MACOS_VERSION_UNKNOWN_NEWER
 };
 
 MacosVersion GetMacosVersion();
 
+char **GetEnviron();
+
 }  // namespace __sanitizer
 
 #endif  // SANITIZER_MAC
 #endif  // SANITIZER_MAC_H

compiler-rt/trunk/lib/sanitizer_common/sanitizer_mac.cc

 #include "sanitizer_flags.h"
 #include "sanitizer_internal_defs.h"
 #include "sanitizer_libc.h"
 #include "sanitizer_mac.h"
 #include "sanitizer_placement_new.h"
 #include "sanitizer_platform_limits_posix.h"
 #include "sanitizer_procmaps.h"
 
+#if !SANITIZER_IOS
 #include <crt_externs.h>  // for _NSGetEnviron
+#else
+extern char **environ;
+#endif
+
 #include <errno.h>
 #include <fcntl.h>
 #include <libkern/OSAtomic.h>
 #include <mach-o/dyld.h>
 #include <mach/mach.h>
 #include <pthread.h>
 #include <sched.h>
 #include <signal.h>
if (rl.rlim_cur < kMaxThreadStackSize) {
       stacksize = kMaxThreadStackSize;
     }
   }
   void *stackaddr = pthread_get_stackaddr_np(pthread_self());
   *stack_top = (uptr)stackaddr;
   *stack_bottom = *stack_top - stacksize;
 }
 
-const char *GetEnv(const char *name) {
+char **GetEnviron() {
+#if !SANITIZER_IOS
   char ***env_ptr = _NSGetEnviron();
   if (!env_ptr) {
     Report("_NSGetEnviron() returned NULL. Please make sure __asan_init() is "
            "called after libSystem_initializer().\n");
     CHECK(env_ptr);
   }
   char **environ = *env_ptr;
+#endif
   CHECK(environ);
+  return environ;
+}
+
+const char *GetEnv(const char *name) {
+  char **env = GetEnviron();
   uptr name_len = internal_strlen(name);
-  while (*environ != 0) {
-    uptr len = internal_strlen(*environ);
+  while (*env != 0) {
+    uptr len = internal_strlen(*env);
     if (len > name_len) {
-      const char *p = *environ;
+      const char *p = *env;
       if (!internal_memcmp(p, name, name_len) &&
           p[name_len] == '=') {  // Match.
-        return *environ + name_len + 1;  // String starting after =.
+        return *env + name_len + 1;  // String starting after =.
       }
     }
-    environ++;
+    env++;
   }
   return 0;
 }
 
 uptr ReadBinaryName(/*out*/char *buf, uptr buf_len) {
   CHECK_LE(kMaxPathLength, buf_len);
 
   // On OS X the executable path is saved to the stack by dyld. Reading it
uptr GetRSS() {
   return info.resident_size;
 }
 
 void *internal_start_thread(void (*func)(void *arg), void *arg) { return 0; }
 void internal_join_thread(void *th) { }
 
 void GetPcSpBp(void *context, uptr *pc, uptr *sp, uptr *bp) {
   ucontext_t *ucontext = (ucontext_t*)context;
-# if SANITIZER_WORDSIZE == 64
+# if defined(__aarch64__)
+  *pc = ucontext->uc_mcontext->__ss.__pc;
+#   if defined(__IPHONE_8_0) && __IPHONE_OS_VERSION_MAX_ALLOWED >= __IPHONE_8_0
+  *bp = ucontext->uc_mcontext->__ss.__fp;
+#   else
+  *bp = ucontext->uc_mcontext->__ss.__lr;
+#   endif
+  *sp = ucontext->uc_mcontext->__ss.__sp;
+# elif defined(__x86_64__)
   *pc = ucontext->uc_mcontext->__ss.__rip;
   *bp = ucontext->uc_mcontext->__ss.__rbp;
   *sp = ucontext->uc_mcontext->__ss.__rsp;
-# else
+# elif defined(__arm__)
+  *pc = ucontext->uc_mcontext->__ss.__pc;
+  *bp = ucontext->uc_mcontext->__ss.__r[7];
+  *sp = ucontext->uc_mcontext->__ss.__sp;
+# elif defined(__i386__)
   *pc = ucontext->uc_mcontext->__ss.__eip;
   *bp = ucontext->uc_mcontext->__ss.__ebp;
   *sp = ucontext->uc_mcontext->__ss.__esp;
-# endif  // SANITIZER_WORDSIZE
+# else
+# error "Unknown architecture"
+# endif
 }
 
 }  // namespace __sanitizer
 
 #endif  // SANITIZER_MAC