[all-commits] [llvm/llvm-project] 2d1b02: [DSE][NFC] Need to be carefull mixing signed and u...

[ebrevnov via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 2d1b024d06b2a81f1c35193a998a864be09e2ae8
      https://github.com/llvm/llvm-project/commit/2d1b024d06b2a81f1c35193a998a864be09e2ae8
  Author: Evgeniy Brevnov <ybrevnov at azul.com>
  Date:   2020-12-08 (Tue, 08 Dec 2020)

  Changed paths:
    M llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp

  Log Message:
  -----------
  [DSE][NFC] Need to be carefull mixing signed and unsigned types

Currently in some places we use signed type to represent size of an access and put explicit casts from unsigned to signed.
For example: int64_t EarlierSize = int64_t(Loc.Size.getValue());

Even though it doesn't loos bits (immidiatly) it may overflow and we end up with negative size. Potentially that cause later code to work incorrectly. A simple expample is a check that size is not negative.

I think it would be safer and clearer if we use unsigned type for the size and handle it appropriately.

Reviewed By: fhahn

Differential Revision: https://reviews.llvm.org/D92648