[all-commits] [llvm/llvm-project] 3bd33c: [NFC?][SCEV][LoopVectorize] Add datalayout to the ...

[Roman Lebedev via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 3bd33ccfdf2f5183062e775e99725930bb4e5403
      https://github.com/llvm/llvm-project/commit/3bd33ccfdf2f5183062e775e99725930bb4e5403
  Author: Roman Lebedev <lebedev.ri at gmail.com>
  Date:   2020-02-12 (Wed, 12 Feb 2020)

  Changed paths:
    M llvm/test/Transforms/LoopVectorize/X86/float-induction-x86.ll

  Log Message:
  -----------
  [NFC?][SCEV][LoopVectorize] Add datalayout to the X86/float-induction-x86.ll test

Summary:
Currently, `SCEVExpander::isHighCostExpansionHelper()` has the following logic:
```
  if (auto *UDivExpr = dyn_cast<SCEVUDivExpr>(S)) {
    // If the divisor is a power of two and the SCEV type fits in a native
    // integer (and the LHS not expensive), consider the division cheap
    // irrespective of whether it occurs in the user code since it can be
    // lowered into a right shift.
    if (auto *SC = dyn_cast<SCEVConstant>(UDivExpr->getRHS()))
      if (SC->getAPInt().isPowerOf2()) {
        if (isHighCostExpansionHelper(UDivExpr->getLHS(), L, At,
                                      BudgetRemaining, TTI, Processed))
          return true;
        const DataLayout &DL =
            L->getHeader()->getParent()->getParent()->getDataLayout();
        unsigned Width = cast<IntegerType>(UDivExpr->getType())->getBitWidth();
        return DL.isIllegalInteger(Width);
      }
```

Since this test does not have a datalayout specified,
`SCEVExpander::isHighCostExpansionHelper()` says that
`[[TMP2:%.*]] = lshr exact i64 [[TMP1]], 5` is high-cost, and didn't perform it.

But future patches will change that logic to solely rely on cost-model,
without any such datalayout checks, so i think it is best to show
that that change is ephemeral, and can already happen without costmodel changes.

Reviewers: reames, fhahn, sanjoy, craig.topper, RKSimon

Reviewed By: RKSimon

Subscribers: javed.absar, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D73717