Changes the flag for using far branches from static to volatile.

runtime/vm/compiler.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/compiler.h"
 
 #include "vm/assembler.h"
 
 #include "vm/ast_printer.h"
 #include "vm/code_generator.h"
@@ skipping 242 matching lines @@
   Isolate* isolate = Isolate::Current();
   HANDLESCOPE(isolate);
 
   // We may reattempt compilation if the function needs to be assembled using
   // far branches on ARM and MIPS. In the else branch of the setjmp call,
   // done is set to false, and use_far_branches is set to true if there is a
   // longjmp from the ARM or MIPS assemblers. In all other paths through this
   // while loop, done is set to true. use_far_branches is always false on ia32
   // and x64.
   bool done = false;
-  // static to evade gcc's longjmp variable smashing checks.
-  static bool use_far_branches = false;
+  // volatile because the variable may be clobbered by a longjmp.
+  volatile bool use_far_branches = false;
   while (!done) {
     const intptr_t prev_deopt_id = isolate->deopt_id();
     isolate->set_deopt_id(0);
     LongJump* old_base = isolate->long_jump_base();
     LongJump bailout_jump;
     isolate->set_long_jump_base(&bailout_jump);
     if (setjmp(*bailout_jump.Set()) == 0) {
       FlowGraph* flow_graph = NULL;
       // TimerScope needs an isolate to be properly terminated in case of a
       // LongJump.
@@ skipping 269 matching lines @@
           ASSERT(CodePatcher::CodeIsPatchable(code));
         }
       }
       is_compiled = true;
       done = true;
     } else {
       // We bailed out.
       const Error& bailout_error = Error::Handle(
           isolate->object_store()->sticky_error());
 
       ASSERT(bailout_error.IsLanguageError());

[Ivan Posva, 2013/08/09 17:07:25]

We should be prepared to handle different errors here without asserting. Maybe
in a different CL.

[zra, 2013/08/09 17:12:20]

Yes. I'll make the change in a new CL.

       const LanguageError& le = LanguageError::CheckedHandle(
           isolate->object_store()->sticky_error());
       const String& msg = String::Handle(le.message());
       if (msg.Equals("Branch offset overflow")) {
         done = false;
         ASSERT(!use_far_branches);
         use_far_branches = true;
       } else {
         // If not for a branch offset overflow, we only bail out from
         // generating ssa code.
         if (FLAG_trace_bailout) {
           OS::Print("%s\n", bailout_error.ToErrorCString());
         }
         done = true;
         ASSERT(optimized);
       }
 
       isolate->object_store()->clear_sticky_error();
       is_compiled = false;
     }
     // Reset global isolate state.
     isolate->set_long_jump_base(old_base);
     isolate->set_deopt_id(prev_deopt_id);
   }
-  use_far_branches = false;
   return is_compiled;
 }
 
 
 static void DisassembleCode(const Function& function, bool optimized) {
   const char* function_fullname = function.ToFullyQualifiedCString();
   OS::Print("Code for %sfunction '%s' {\n",
             optimized ? "optimized " : "",
             function_fullname);
   const Code& code = Code::Handle(function.CurrentCode());
@@ skipping 319 matching lines @@
       Object::Handle(isolate->object_store()->sticky_error());
     isolate->object_store()->clear_sticky_error();
     isolate->set_long_jump_base(base);
     return result.raw();
   }
   UNREACHABLE();
   return Object::null();
 }
 
 }  // namespace dart