code review 7229044: runtime: implement range access functions in race detector.

src/pkg/runtime/race.h

 // Copyright 2012 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
 // Definitions related to data race detection.
 
 #ifdef RACE
 enum { raceenabled = 1 };
 #else
 enum { raceenabled = 0 };
 #endif
 
 // Initialize race detection subsystem.
 void    runtime·raceinit(void);
 // Finalize race detection subsystem, does not return.
 void    runtime·racefini(void);
 
 void    runtime·racemapshadow(void *addr, uintptr size);
 void    runtime·racemalloc(void *p, uintptr sz, void *pc);
 void    runtime·racefree(void *p);
 void    runtime·racegostart(int32 goid, void *pc);
 void    runtime·racegoend(int32 goid);
 void    runtime·racewritepc(void *addr, void *callpc, void *pc);
 void    runtime·racereadpc(void *addr, void *callpc, void *pc);
+void    runtime·racewriterangepc(void *addr, uintptr sz, uintptr step, void *callpc, void *pc);
+void    runtime·racereadrangepc(void *addr, uintptr sz, uintptr step, void *callpc, void *pc);
 void    runtime·racefingo(void);
 void    runtime·raceacquire(void *addr);
 void    runtime·raceacquireg(G *gp, void *addr);
 void    runtime·racerelease(void *addr);
 void    runtime·racereleaseg(G *gp, void *addr);
 void    runtime·racereleasemerge(void *addr);
 void    runtime·racereleasemergeg(G *gp, void *addr);