[asan] Reapply: Switch to using dynamic shadow offset on iOS

The VM layout is not stable between iOS version releases, so switch to dynamic shadow offset.

This is the LLVM counterpart of https://reviews.llvm.org/D25218

Differential Revision: https://reviews.llvm.org/D25219

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@283376 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/Instrumentation/AddressSanitizer.cpp b/lib/Transforms/Instrumentation/AddressSanitizer.cpp
index 5442a09..f08672a 100644 (file)
--- a/lib/Transforms/Instrumentation/AddressSanitizer.cpp
+++ b/lib/Transforms/Instrumentation/AddressSanitizer.cpp
@@ -69,7 +69,6 @@ static const uint64_t kDefaultShadowOffset32 = 1ULL << 29;
 static const uint64_t kDefaultShadowOffset64 = 1ULL << 44;
 static const uint64_t kDynamicShadowSentinel = ~(uint64_t)0;
 static const uint64_t kIOSShadowOffset32 = 1ULL << 30;
-static const uint64_t kIOSShadowOffset64 = 0x120200000;
 static const uint64_t kIOSSimShadowOffset32 = 1ULL << 30;
 static const uint64_t kIOSSimShadowOffset64 = kDefaultShadowOffset64;
 static const uint64_t kSmallX86_64ShadowOffset = 0x7FFF8000;  // < 2G.
@@ -434,7 +433,9 @@ static ShadowMapping getShadowMapping(Triple &TargetTriple, int LongSize,
       Mapping.Offset = kMIPS64_ShadowOffset64;
     else if (IsIOS)
       // If we're targeting iOS and x86, the binary is built for iOS simulator.
-      Mapping.Offset = IsX86_64 ? kIOSSimShadowOffset64 : kIOSShadowOffset64;
+      // We are using dynamic shadow offset on the 64-bit devices.
+      Mapping.Offset =
+        IsX86_64 ? kIOSSimShadowOffset64 : kDynamicShadowSentinel;
     else if (IsAArch64)
       Mapping.Offset = kAArch64_ShadowOffset64;
     else