Subzero: Elide redundant access checks within basic blocks

runtime/szrt_asan.c

 //===- subzero/runtime/szrt_asan.c - AddressSanitizer Runtime -----*- C -*-===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
@@ skipping 32 matching lines @@
   while (__sync_swap((mutex), 1) != 0) {                                       \
     sched_yield();                                                             \
   }
 #define MUTEX_UNLOCK(mutex) (__sync_swap((mutex), 0))
 
 #endif // _POSIX_THREADS
 
 #define RZ_SIZE (32)
 #define SHADOW_SCALE_LOG2 (3)
 #define SHADOW_SCALE ((size_t)1 << SHADOW_SCALE_LOG2)
-#define DEBUG (1)
+#define DEBUG (0)
 
 // Assuming 48 bit address space on 64 bit systems
 #define SHADOW_LENGTH_64 (1u << (48 - SHADOW_SCALE_LOG2))
 #define SHADOW_LENGTH_32 (1u << (32 - SHADOW_SCALE_LOG2))
 #define WORD_SIZE (sizeof(uint32_t))
 #define IS_32_BIT (sizeof(void *) == WORD_SIZE)
 
 #define SHADOW_OFFSET(p) ((uintptr_t)(p) % SHADOW_SCALE)
 #define IS_SHADOW_ALIGNED(p) (SHADOW_OFFSET(p) == 0)
 
@@ skipping 241 matching lines @@
 void __asan_unpoison(char *ptr, int size) {
   char *end = ptr + size;
   assert(IS_SHADOW_ALIGNED(end));
   DUMP("unpoison %d bytes at %p: %p - %p\n", size, ptr, MEM2SHADOW(ptr),
        MEM2SHADOW(end));
   *(char *)MEM2SHADOW(ptr) = 0;
   ptr += SHADOW_OFFSET(size);
   assert(IS_SHADOW_ALIGNED(ptr));
   memset(MEM2SHADOW(ptr), 0, (end - ptr) >> SHADOW_SCALE_LOG2);
 }