[all-commits] [llvm/llvm-project] 930b5b: [ConstantHoisting] Add a TTI hook to prevent hoist...

[Paul Walker via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 930b5b52ffe699dbcf05eea32d12a2861dd2bdf6
      https://github.com/llvm/llvm-project/commit/930b5b52ffe699dbcf05eea32d12a2861dd2bdf6
  Author: Paul Walker <paul.walker at arm.com>
  Date:   2023-12-13 (Wed, 13 Dec 2023)

  Changed paths:
    M llvm/include/llvm/Analysis/TargetTransformInfo.h
    M llvm/include/llvm/Analysis/TargetTransformInfoImpl.h
    M llvm/include/llvm/CodeGen/BasicTTIImpl.h
    M llvm/lib/Analysis/TargetTransformInfo.cpp
    M llvm/lib/Transforms/Scalar/ConstantHoisting.cpp
    M llvm/test/Transforms/ConstantHoisting/AArch64/large-immediate.ll

  Log Message:
  -----------
  [ConstantHoisting] Add a TTI hook to prevent hoisting. (#69004)

Code generation can sometimes simplify expensive operations when
an operand is constant.  An example of this is divides on AArch64
where they can be rewritten using a cheaper sequence of multiplies
and subtracts.  Doing this is often better than hoisting expensive
constants which are likely to be hoisted by MachineLICM anyway.