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Re: [PATCH] doc: document -ftree-scev-cprop
- From: Richard Sandiford <richard dot sandiford at arm dot com>
- To: Alexander Monakov <amonakov at ispras dot ru>
- Cc: gcc-patches at gcc dot gnu dot org
- Date: Tue, 28 Aug 2018 22:17:22 +0100
- Subject: Re: [PATCH] doc: document -ftree-scev-cprop
- References: <alpine.LNX.2.20.13.1808281712180.10521@monopod.intra.ispras.ru>
Alexander Monakov <amonakov@ispras.ru> writes:
> @@ -9120,6 +9121,15 @@ determining number of iterations requires complicated analysis. Later
> optimizations then may determine the number easily. Useful especially
> in connection with unrolling.
>
> +@item -ftree-scev-cprop
> +@opindex ftree-scev-cprop
> +Perform final value replacement. If a variable is modified in a loop
> +in a way that its value when exiting the loop can be determined using
"in such a way"
> +only its initial value and number of loop iterations, replace uses of
"and the number"
> +the final value by such computation, provided it is sufficiently cheap.
"by such a computation".
OK otherwise, thanks.
Richard
> +This reduces data dependencies and may allow further simplifications.
> +Enabled by default at @option{-O} and higher.