diff --git a/compiler-rt/lib/asan/asan_mapping.h b/compiler-rt/lib/asan/asan_mapping.h
--- a/compiler-rt/lib/asan/asan_mapping.h
+++ b/compiler-rt/lib/asan/asan_mapping.h
@@ -13,8 +13,6 @@
 #ifndef ASAN_MAPPING_H
 #define ASAN_MAPPING_H
 
-#include "asan_internal.h"
-
 // The full explanation of the memory mapping could be found here:
 // https://github.com/google/sanitizers/wiki/AddressSanitizerAlgorithm
 //
@@ -153,8 +151,6 @@
 
 #define ASAN_SHADOW_SCALE 3
 
-static const u64 kDefaultShadowSentinel = ~(uptr)0;
-
 #if SANITIZER_FUCHSIA
 #  define ASAN_SHADOW_OFFSET_CONST (0)
 #elif SANITIZER_WORDSIZE == 32
@@ -199,91 +195,99 @@
 #  elif SANITIZER_WINDOWS64
 #    define ASAN_SHADOW_OFFSET_DYNAMIC
 #  else
-#    define ASAN_SHADOW_OFFSET_CONST \
-      0x000000007FFFFFFF & (~0xFFFULL << ASAN_SHADOW_SCALE)
+#    if ASAN_SHADOW_SCALE != 3
+#      error "Value below is based on shadow scale = 3."
+#      error "Original formula was: 0x7FFFFFFF & (~0xFFFULL << SHADOW_SCALE)."
+#    endif
+#    define ASAN_SHADOW_OFFSET_CONST 0x000000007fff8000
 #  endif
 #endif
 
-#if defined(ASAN_SHADOW_OFFSET_CONST)
+#if defined(__cplusplus)
+#  include "asan_internal.h"
+
+static const u64 kDefaultShadowSentinel = ~(uptr)0;
+
+#  if defined(ASAN_SHADOW_OFFSET_CONST)
 static const u64 kConstShadowOffset = ASAN_SHADOW_OFFSET_CONST;
-#  define ASAN_SHADOW_OFFSET kConstShadowOffset
-#elif defined(ASAN_SHADOW_OFFSET_DYNAMIC)
-#  define ASAN_SHADOW_OFFSET __asan_shadow_memory_dynamic_address
-#else
-#  error "ASAN_SHADOW_OFFSET can't be determined."
-#endif
+#    define ASAN_SHADOW_OFFSET kConstShadowOffset
+#  elif defined(ASAN_SHADOW_OFFSET_DYNAMIC)
+#    define ASAN_SHADOW_OFFSET __asan_shadow_memory_dynamic_address
+#  else
+#    error "ASAN_SHADOW_OFFSET can't be determined."
+#  endif
 
-#if SANITIZER_ANDROID && defined(__arm__)
-#  define ASAN_PREMAP_SHADOW 1
-#else
-#  define ASAN_PREMAP_SHADOW 0
-#endif
+#  if SANITIZER_ANDROID && defined(__arm__)
+#    define ASAN_PREMAP_SHADOW 1
+#  else
+#    define ASAN_PREMAP_SHADOW 0
+#  endif
 
-#define ASAN_SHADOW_GRANULARITY (1ULL << ASAN_SHADOW_SCALE)
+#  define ASAN_SHADOW_GRANULARITY (1ULL << ASAN_SHADOW_SCALE)
 
-#define DO_ASAN_MAPPING_PROFILE 0  // Set to 1 to profile the functions below.
+#  define DO_ASAN_MAPPING_PROFILE 0  // Set to 1 to profile the functions below.
 
-#if DO_ASAN_MAPPING_PROFILE
-#  define PROFILE_ASAN_MAPPING() AsanMappingProfile[__LINE__]++;
-#else
-#  define PROFILE_ASAN_MAPPING()
-#endif
+#  if DO_ASAN_MAPPING_PROFILE
+#    define PROFILE_ASAN_MAPPING() AsanMappingProfile[__LINE__]++;
+#  else
+#    define PROFILE_ASAN_MAPPING()
+#  endif
 
 // If 1, all shadow boundaries are constants.
 // Don't set to 1 other than for testing.
-#define ASAN_FIXED_MAPPING 0
+#  define ASAN_FIXED_MAPPING 0
 
 namespace __asan {
 
 extern uptr AsanMappingProfile[];
 
-#if ASAN_FIXED_MAPPING
+#  if ASAN_FIXED_MAPPING
 // Fixed mapping for 64-bit Linux. Mostly used for performance comparison
 // with non-fixed mapping. As of r175253 (Feb 2013) the performance
 // difference between fixed and non-fixed mapping is below the noise level.
 static uptr kHighMemEnd = 0x7fffffffffffULL;
 static uptr kMidMemBeg = 0x3000000000ULL;
 static uptr kMidMemEnd = 0x4fffffffffULL;
-#else
+#  else
 extern uptr kHighMemEnd, kMidMemBeg, kMidMemEnd;  // Initialized in __asan_init.
-#endif
+#  endif
 
 }  // namespace __asan
 
-#if defined(__sparc__) && SANITIZER_WORDSIZE == 64
-#  include "asan_mapping_sparc64.h"
-#else
-#  define MEM_TO_SHADOW(mem) \
-    (((mem) >> ASAN_SHADOW_SCALE) + (ASAN_SHADOW_OFFSET))
+#  if defined(__sparc__) && SANITIZER_WORDSIZE == 64
+#    include "asan_mapping_sparc64.h"
+#  else
+#    define MEM_TO_SHADOW(mem) \
+      (((mem) >> ASAN_SHADOW_SCALE) + (ASAN_SHADOW_OFFSET))
 
-#  define kLowMemBeg 0
-#  define kLowMemEnd (ASAN_SHADOW_OFFSET ? ASAN_SHADOW_OFFSET - 1 : 0)
+#    define kLowMemBeg 0
+#    define kLowMemEnd (ASAN_SHADOW_OFFSET ? ASAN_SHADOW_OFFSET - 1 : 0)
 
-#  define kLowShadowBeg ASAN_SHADOW_OFFSET
-#  define kLowShadowEnd MEM_TO_SHADOW(kLowMemEnd)
+#    define kLowShadowBeg ASAN_SHADOW_OFFSET
+#    define kLowShadowEnd MEM_TO_SHADOW(kLowMemEnd)
 
-#  define kHighMemBeg (MEM_TO_SHADOW(kHighMemEnd) + 1)
+#    define kHighMemBeg (MEM_TO_SHADOW(kHighMemEnd) + 1)
 
-#  define kHighShadowBeg MEM_TO_SHADOW(kHighMemBeg)
-#  define kHighShadowEnd MEM_TO_SHADOW(kHighMemEnd)
+#    define kHighShadowBeg MEM_TO_SHADOW(kHighMemBeg)
+#    define kHighShadowEnd MEM_TO_SHADOW(kHighMemEnd)
 
-#  define kMidShadowBeg MEM_TO_SHADOW(kMidMemBeg)
-#  define kMidShadowEnd MEM_TO_SHADOW(kMidMemEnd)
+#    define kMidShadowBeg MEM_TO_SHADOW(kMidMemBeg)
+#    define kMidShadowEnd MEM_TO_SHADOW(kMidMemEnd)
 
 // With the zero shadow base we can not actually map pages starting from 0.
 // This constant is somewhat arbitrary.
-#  define kZeroBaseShadowStart 0
-#  define kZeroBaseMaxShadowStart (1 << 18)
+#    define kZeroBaseShadowStart 0
+#    define kZeroBaseMaxShadowStart (1 << 18)
 
-#  define kShadowGapBeg \
-    (kLowShadowEnd ? kLowShadowEnd + 1 : kZeroBaseShadowStart)
-#  define kShadowGapEnd ((kMidMemBeg ? kMidShadowBeg : kHighShadowBeg) - 1)
+#    define kShadowGapBeg \
+      (kLowShadowEnd ? kLowShadowEnd + 1 : kZeroBaseShadowStart)
+#    define kShadowGapEnd ((kMidMemBeg ? kMidShadowBeg : kHighShadowBeg) - 1)
 
-#  define kShadowGap2Beg (kMidMemBeg ? kMidShadowEnd + 1 : 0)
-#  define kShadowGap2End (kMidMemBeg ? kMidMemBeg - 1 : 0)
+#    define kShadowGap2Beg (kMidMemBeg ? kMidShadowEnd + 1 : 0)
+#    define kShadowGap2End (kMidMemBeg ? kMidMemBeg - 1 : 0)
 
-#  define kShadowGap3Beg (kMidMemBeg ? kMidMemEnd + 1 : 0)
-#  define kShadowGap3End (kMidMemBeg ? kHighShadowBeg - 1 : 0)
+#    define kShadowGap3Beg (kMidMemBeg ? kMidMemEnd + 1 : 0)
+#    define kShadowGap3End (kMidMemBeg ? kHighShadowBeg - 1 : 0)
 
 namespace __asan {
 
@@ -334,7 +338,7 @@
 
 }  // namespace __asan
 
-#endif
+#  endif
 
 namespace __asan {
 
@@ -382,4 +386,6 @@
 
 }  // namespace __asan
 
+#endif  // __cplusplus
+
 #endif  // ASAN_MAPPING_H