[PATCH] D128877: [LoopCacheAnalysis] Fix a type mismatch bug in cost calculation

[Congzhe Cao via Phabricator via llvm-commits]

congzhe created this revision.
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As reported in https://reviews.llvm.org/rGb941857b40edd7f3f3a9ec2ec85a26db24739774#1100674, there is a loop cache analysis bug exposed by the recent loop interchange new cost model patch. In `isConsecutive()` from LoopCacheAnalysis.cpp, sometimes the SCEV variables `Coeff` and `ElemSize` may not match, e.g., when there is no target datalayout provided in an IR. The mismatch would cause SCEV failures when multiplying `Coeff` with `ElemSize`.

The fix in this patch is to extend the type of both `Coeff` and `ElemSize` to whichever is wider in those two variables. The IR reported in https://reviews.llvm.org/rGb941857b40edd7f3f3a9ec2ec85a26db24739774#1100674 is added in loop cache analysis tests.

As a clean-up, the `Stride` variable in `computeRefCost()` has been already computed in `isConsecutive()`, so I remove the duplicate calculations of `Stride` which also helps this patch to be more compact.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D128877

Files:
  llvm/include/llvm/Analysis/LoopCacheAnalysis.h
  llvm/lib/Analysis/LoopCacheAnalysis.cpp
  llvm/test/Analysis/LoopCacheAnalysis/PowerPC/compute-cost.ll
  llvm/test/Analysis/LoopCacheAnalysis/compute-cost.ll

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