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133502
2020 Mar 26
5
canonical form loops
Hello,
Quick question to see if I haven't missed anything: I would like convert counting down loops, i.e. loops with a constant -1 step value, to counting up loops, because the vectoriser is able to better deal with these loops (see e.g. D76838 that I was discussing today with Ayal). It looks like LoopSimplifyCFG and IndVarSimplify don't do this. So was just curious if I haven't
2020 Apr 01
2
canonical form loops
...ect: Re: [llvm-dev] canonical form loops
>
> The topic came up before, e.g. https://reviews.llvm.org/D60565#1484984
>
> > Some canonicalization passes are designed for this. In particular,
> IndVarSimplify used to make canonical loops (i.e. start at zero, increment by
> one). r133502 introduced -disable-iv-rewrite to rely more on ScalarEvolution
> instead of "opcode/pattern matching" (cite from the commit message). -
> enable-iv-rewrite=false was made the default in r139579 after finding that it
> slows down many benchmarks. It was completely removed in r1532...