[asan] Implemented getAddressSanitizerParams used by the ASan callback optimization code.

llvm/include/llvm/Transforms/Instrumentation/AddressSanitizerCommon.h

if (NumCoveredExits == ReachableRetVec.size()) {
       // We may have inserted untag outside of the lifetime interval.
       // Signal the caller to remove the lifetime end call for this alloca.
       return false;
     }
   }
   return true;
 }
 
+// Get AddressSanitizer parameters.
+void getAddressSanitizerParams(const Triple &TargetTriple, int LongSize,
+                               bool IsKasan, uint64_t *ShadowBase,
+                               int *MappingScale, bool *OrShadowOffset);
+
 } // namespace llvm
 
 #endif

llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp

struct ShadowMapping {
   int Scale;
   uint64_t Offset;
   bool OrShadowOffset;
   bool InGlobal;
 };
 
 } // end anonymous namespace
 
-static ShadowMapping getShadowMapping(Triple &TargetTriple, int LongSize,
+static ShadowMapping getShadowMapping(const Triple &TargetTriple, int LongSize,
                                       bool IsKasan) {
   bool IsAndroid = TargetTriple.isAndroid();
   bool IsIOS = TargetTriple.isiOS() || TargetTriple.isWatchOS();
   bool IsMacOS = TargetTriple.isMacOSX();
   bool IsFreeBSD = TargetTriple.isOSFreeBSD();
   bool IsNetBSD = TargetTriple.isOSNetBSD();
   bool IsPS4CPU = TargetTriple.isPS4CPU();
   bool IsLinux = TargetTriple.isOSLinux();
Mapping.OrShadowOffset = !IsAArch64 && !IsPPC64 && !IsSystemZ && !IsPS4CPU &&
                            Mapping.Offset != kDynamicShadowSentinel;
   bool IsAndroidWithIfuncSupport =
       IsAndroid && !TargetTriple.isAndroidVersionLT(21);
   Mapping.InGlobal = ClWithIfunc && IsAndroidWithIfuncSupport && IsArmOrThumb;
 
   return Mapping;
 }
 
+namespace llvm {
+void getAddressSanitizerParams(const Triple &TargetTriple, int LongSize,
+                               bool IsKasan, uint64_t *ShadowBase,
+                               int *MappingScale, bool *OrShadowOffset) {
+  auto Mapping = getShadowMapping(TargetTriple, LongSize, IsKasan);
+  *ShadowBase = Mapping.Offset;
+  *MappingScale = Mapping.Scale;
+  *OrShadowOffset = Mapping.OrShadowOffset;
+}
+} // namespace llvm
+
 static uint64_t getRedzoneSizeForScale(int MappingScale) {
   // Redzone used for stack and globals is at least 32 bytes.
   // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
   return std::max(32U, 1U << MappingScale);
 }
 
 static uint64_t GetCtorAndDtorPriority(Triple &TargetTriple) {
   if (TargetTriple.isOSEmscripten()) {