[asan] Fix shadow mapping on Android/AArch64.

Instrumentation and the runtime library were in disagreement about
ASan shadow offset on Android/AArch64.

This fixes a large number of existing tests on Android/AArch64.

llvm-svn: 242595

1 files changed, 6 insertions, 4 deletions

diff --git a/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp b/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
index a98439b6b39..52b2290a938 100644
--- a/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
+++ b/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
@@ -337,10 +337,12 @@ static ShadowMapping getShadowMapping(Triple &TargetTriple, int LongSize,
 
   ShadowMapping Mapping;
 
-  if (LongSize == 32) {
-    if (IsAndroid)
-      Mapping.Offset = 0;
-    else if (IsMIPS32)
+  if (IsAndroid) {
+    // Android is always PIE, which means that the beginning of the address
+    // space is always available.
+    Mapping.Offset = 0;
+  } else if (LongSize == 32) {
+    if (IsMIPS32)
       Mapping.Offset = kMIPS32_ShadowOffset32;
     else if (IsFreeBSD)
       Mapping.Offset = kFreeBSD_ShadowOffset32;