[IR] Add Instruction::isLifetimeStartOrEnd, NFC

Instruction::isLifetimeStartOrEnd() checks whether an Instruction is an
llvm.lifetime.start or an llvm.lifetime.end intrinsic.

This was suggested as a cleanup in D55967.

Differential Revision: https://reviews.llvm.org/D56019

llvm-svn: 349964
diff --git a/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp b/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
index ef8e60d..f1558c7 100644
--- a/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
+++ b/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
@@ -1005,7 +1005,7 @@
     if (ID == Intrinsic::localescape) LocalEscapeCall = ⅈ
     if (!ASan.UseAfterScope)
       return;
-    if (ID != Intrinsic::lifetime_start && ID != Intrinsic::lifetime_end)
+    if (!II.isLifetimeStartOrEnd())
       return;
     // Found lifetime intrinsic, add ASan instrumentation if necessary.
     ConstantInt *Size = dyn_cast<ConstantInt>(II.getArgOperand(0));