[llvm] [ASAN] Make asan pass idempotent. (PR #99439)

[via llvm-commits]

================
@@ -0,0 +1,56 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --check-globals all --version 5
+; This test checks in the second run, function is not instrumented again.
+; RUN: opt < %s -passes=asan,asan -S | FileCheck %s
----------------
b-sumner wrote:

@vitalybuka  I think it's a good idea to make all sanitizers idempotent.  Your guidance on preferred approaches would be appreciated.  With separate compilation, runtime compilation, etc. it seems hard to always "make sure that pass is unique in the pipeline".

https://github.com/llvm/llvm-project/pull/99439