[all-commits] [llvm/llvm-project] 19f01a: [GVN] add early exit to ConstantFoldLoadThroughBit...

[Jameson Nash via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 19f01a484760d9a29f4f414b30da110dd6550191
      https://github.com/llvm/llvm-project/commit/19f01a484760d9a29f4f414b30da110dd6550191
  Author: Jameson Nash <vtjnash at gmail.com>
  Date:   2020-07-13 (Mon, 13 Jul 2020)

  Changed paths:
    M llvm/lib/Analysis/ConstantFolding.cpp
    M llvm/test/Transforms/GVN/non-integral-pointers.ll
    M llvm/test/Transforms/GlobalOpt/evaluate-call-errors.ll

  Log Message:
  -----------
  [GVN] add early exit to ConstantFoldLoadThroughBitcast [NFC]

And adds some additional test coverage to ensure later commits don't
introduce regressions.

Differential Revision: https://reviews.llvm.org/D59730


  Commit: e244f86f4dfd9e8982940d09294af522d3809d7f
      https://github.com/llvm/llvm-project/commit/e244f86f4dfd9e8982940d09294af522d3809d7f
  Author: Jameson Nash <vtjnash at gmail.com>
  Date:   2020-07-13 (Mon, 13 Jul 2020)

  Changed paths:
    M llvm/lib/Transforms/Utils/VNCoercion.cpp

  Log Message:
  -----------
  [VNCoercion] avoid creating bitcast for zero offsets [NFCI]

This could previously make it more complicated for ConstantFolding
later, leading to a higher likelyhood it would have to reject the
expression, even though zero seems like probably the common case here.

Differential Revision: https://reviews.llvm.org/D59730


  Commit: 2c7a07b59d5da54eba8e3e030e1cc040a88ecf58
      https://github.com/llvm/llvm-project/commit/2c7a07b59d5da54eba8e3e030e1cc040a88ecf58
  Author: Jameson Nash <vtjnash at gmail.com>
  Date:   2020-07-13 (Mon, 13 Jul 2020)

  Changed paths:
    M llvm/lib/Analysis/ConstantFolding.cpp
    M llvm/lib/Transforms/Utils/VNCoercion.cpp
    M llvm/test/Transforms/GVN/non-integral-pointers.ll

  Log Message:
  -----------
  [GVN] teach ConstantFolding correct handling of non-integral addrspace casts

Here we teach the ConstantFolding analysis pass that it is not legal to
replace a load of a bitcast constant (having a non-integral addrspace)
with a bitcast of the value of that constant (with a different
non-integral addrspace).

But also teach it that certain bit patterns are always known and
convertable (a fact it already uses elsewhere). This required us to also
fix a globalopt test, since, after this change, LLVM is able to realize
that the test actually is a valid transform (NULL is always a known
bit-pattern) and so it doesn't need to emit the failure remarks for it.

Also simplify some of the negative tests for transforms by avoiding a
type change in their bitcast, and add positive versions of the same
tests, to show that they otherwise should work.

Differential Revision: https://reviews.llvm.org/D59730


Compare: https://github.com/llvm/llvm-project/compare/fefe6a6642e4...2c7a07b59d5d