[llvm] [LLVM][Instrumentation] Add numerical sanitizer (PR #85916)

[Fangrui Song via llvm-commits]

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@@ -0,0 +1,2191 @@
+//===-- NumericalStabilitySanitizer.cpp -----------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is a part of NumericalStabilitySanitizer.
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MaskRay wrote:

This is the main part of the instrumentation and deserves a more detailed comment.

https://github.com/llvm/llvm-project/pull/85916