[all-commits] [llvm/llvm-project] 333246: Reapply [InstCombine] Switch foldOpIntoPhi() to us...

[Nikita Popov via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 333246b48ea4a70842e78c977cc92d365720465f
      https://github.com/llvm/llvm-project/commit/333246b48ea4a70842e78c977cc92d365720465f
  Author: Nikita Popov <npopov at redhat.com>
  Date:   2022-10-07 (Fri, 07 Oct 2022)

  Changed paths:
    M llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
    M llvm/test/Transforms/InstCombine/intptr1.ll
    M llvm/test/Transforms/InstCombine/intptr4.ll
    M llvm/test/Transforms/InstCombine/intptr5.ll
    M llvm/test/Transforms/InstCombine/intptr7.ll
    M llvm/test/Transforms/InstCombine/phi-select-constant.ll
    M llvm/test/Transforms/InstCombine/phi.ll
    M llvm/test/Transforms/InstCombine/recurrence.ll

  Log Message:
  -----------
  Reapply [InstCombine] Switch foldOpIntoPhi() to use InstSimplify

Relative to the previous attempt, this adjusts simplification to
use the correct context instruction: We need to use the terminator
of the incoming block, not the original instruction.

-----

foldOpIntoPhi() currently only folds operations into the phi if all
but one operands constant-fold. The two exceptions to this are freeze
and select, where we allow more general simplification.

This patch makes foldOpIntoPhi() generally simplification based and
removes all the instruction-specific logic. We just try to simplify
the instruction for each operand, and for the (potentially) one
non-simplified operand, we move it into the new block with adjusted
operands.

This fixes https://github.com/llvm/llvm-project/issues/57448, which
was my original motivation for the change.

Differential Revision: https://reviews.llvm.org/D134954