[all-commits] [llvm/llvm-project] a09394: [ConstProp][JumpThreading] add more test coverage ...

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  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: a093942c287501484481384dd03686ffaa5fc98e
      https://github.com/llvm/llvm-project/commit/a093942c287501484481384dd03686ffaa5fc98e
  Author: Sanjay Patel <spatel at rotateright.com>
  Date:   2021-03-08 (Mon, 08 Mar 2021)

  Changed paths:
    M llvm/test/Transforms/InstSimplify/ConstProp/icmp-null.ll
    M llvm/test/Transforms/JumpThreading/thread-two-bbs.ll

  Log Message:
  -----------
  [ConstProp][JumpThreading] add more test coverage for potential nullptr folds; NFC

See D98150.


  Commit: f75b5305f4def4973027a9b96fb3f1e50ce056e3
      https://github.com/llvm/llvm-project/commit/f75b5305f4def4973027a9b96fb3f1e50ce056e3
  Author: Sanjay Patel <spatel at rotateright.com>
  Date:   2021-03-08 (Mon, 08 Mar 2021)

  Changed paths:
    M llvm/lib/IR/ConstantFold.cpp
    M llvm/test/CodeGen/PowerPC/pr46923.ll
    M llvm/test/Transforms/InstCombine/vector_gep1-inseltpoison.ll
    M llvm/test/Transforms/InstCombine/vector_gep1.ll
    M llvm/test/Transforms/InstSimplify/ConstProp/icmp-null.ll
    M llvm/test/Transforms/JumpThreading/thread-two-bbs.ll

  Log Message:
  -----------
  [ConstantFold] allow folding icmp of null and constexpr

I noticed that we were not folding expressions like this:
icmp ult (constexpr), null
in https://llvm.org/PR49355, so we end up with extremely large
icmp instructions as the constant expressions pile up on each other.

There is no potential to mis-fold an unsigned boundary condition
with a zero/null, so this is just falling through a crack in the
pattern matching.

The more general case of comparisons of non-zero constants and
constexpr are more tricky and may require the datalayout to know
how to cast to different types, etc. Negative tests verify that
we are only changing a subset of potential patterns.

Differential Revision: https://reviews.llvm.org/D98150


Compare: https://github.com/llvm/llvm-project/compare/b9f169fb7dcd...f75b5305f4de