[compiler-rt] Fix interception of memcpy/memmove on win64

[etienneb]

Summary

This patch is fixing running interception unittests for memcpy/memmove on
windows 64.

[rnk]

lgtm

lib/sanitizer_common/sanitizer_common_interceptors.inc

 #endif
 
 #if SANITIZER_INTERCEPT_MEMCHR
 INTERCEPTOR(void*, memchr, const void *s, int c, SIZE_T n) {
   if (COMMON_INTERCEPTOR_NOTHING_IS_INITIALIZED)
     return internal_memchr(s, c, n);
   void *ctx;
   COMMON_INTERCEPTOR_ENTER(ctx, memchr, s, c, n);
-  void *res = REAL(memchr)(s, c, n);
+  void *res;
+  if (REAL(memchr)) {
+    res = REAL(memchr)(s, c, n);
+  } else {
+    res = internal_memchr(s, c, n);
+  }
   uptr len = res ? (char *)res - (const char *)s + 1 : n;
   COMMON_INTERCEPTOR_READ_RANGE(ctx, s, len);
   return res;
 }
 
 #define INIT_MEMCHR COMMON_INTERCEPT_FUNCTION(memchr)
 #else
 #define INIT_MEMCHR

lib/sanitizer_common/sanitizer_platform_interceptors.h

 #define SANITIZER_INTERCEPT_TEXTDOMAIN SI_LINUX_NOT_ANDROID
 #define SANITIZER_INTERCEPT_STRCASECMP SI_NOT_WINDOWS
 #define SANITIZER_INTERCEPT_MEMSET 1
 #define SANITIZER_INTERCEPT_MEMMOVE 1
 #define SANITIZER_INTERCEPT_MEMCPY 1
 #define SANITIZER_INTERCEPT_MEMCMP 1
 // FIXME: enable memmem on Windows.
 #define SANITIZER_INTERCEPT_MEMMEM SI_NOT_WINDOWS
-// The function memchr() contains a jump in the first 6 bytes
-// that is problematic to intercept correctly on Win64.
-// Disable memchr() interception for Win64.
-#if SANITIZER_WINDOWS64
-#define SANITIZER_INTERCEPT_MEMCHR 0
-#else
 #define SANITIZER_INTERCEPT_MEMCHR 1
-#endif
 #define SANITIZER_INTERCEPT_MEMRCHR SI_FREEBSD || SI_LINUX
 
 #define SANITIZER_INTERCEPT_READ   SI_NOT_WINDOWS
 #define SANITIZER_INTERCEPT_PREAD  SI_NOT_WINDOWS
 #define SANITIZER_INTERCEPT_WRITE  SI_NOT_WINDOWS
 #define SANITIZER_INTERCEPT_PWRITE SI_NOT_WINDOWS
 
 #define SANITIZER_INTERCEPT_PREAD64 SI_LINUX_NOT_ANDROID

test/asan/TestCases/Windows/intercept_memcpy.cc

if (buff1[2] != buff2[2])
     return 2;
   printf("Initial test OK\n");
   fflush(0);
 // CHECK: Initial test OK
 
   call_memcpy(&memcpy, buff2, buff1, 6);
 // CHECK: AddressSanitizer: stack-buffer-overflow on address [[ADDR:0x[0-9a-f]+]]
 // CHECK: WRITE of size 6 at [[ADDR]] thread T0
-// CHECK-NEXT:  __asan_{{.*}}memcpy
-// CHECK-NEXT:  call_memcpy
+// CHECK-NEXT:  __asan_{{.*}}mem{{.*}}
+// CHECK-NEXT:  call_mem{{.*}}
 // CHECK-NEXT:  main {{.*}}intercept_memcpy.cc:[[@LINE-5]]
 // CHECK: Address [[ADDR]] is located in stack of thread T0 at offset {{.*}} in frame
 // CHECK-NEXT:   #0 {{.*}} main
 // CHECK: 'buff2' <== Memory access at offset {{.*}} overflows this variable
 }