[PATCH] D73722: [SCEV] SCEVExpander::isHighCostExpansionHelper(): cost-model plain UDiv
Roman Lebedev via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Wed Feb 19 01:20:10 PST 2020
lebedev.ri marked an inline comment as done.
lebedev.ri added a comment.
@mkazantsev thank you for taking a look!
Please see inline reply :)
================
Comment at: llvm/test/Transforms/IndVarSimplify/exit_value_test2.ll:24
+; CHECK-NEXT: [[TMP1:%.*]] = udiv i32 [[TMP0]], 12
+; CHECK-NEXT: [[TMP2:%.*]] = mul i32 [[TMP1]], 12
; CHECK-NEXT: br label [[WHILE_BODY:%.*]]
----------------
mkazantsev wrote:
> Why do we need this change if it starts generating worse code?
We need this change because the goal of this patchset is to move
the *entirety* of SCEVExpander::isHighCostExpansionHelper()
to TTI cost-modelling. Entirety as in everything.
Also, please do see the patch's description:
> While that is the case, it is evident this is actually a regression
> due to the fact that cost-modelling is incomplete - we did not account
> for the add, mul costs yet. That is being addressed in D73728.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D73722/new/
https://reviews.llvm.org/D73722
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