From: Robin Dapp <rdapp.gcc@gmail.com>
To: Jeff Law <jeffreyalaw@gmail.com>,
gcc-patches <gcc-patches@gcc.gnu.org>,
richard.sandiford@arm.com
Cc: rdapp.gcc@gmail.com
Subject: Re: [PATCH] fwprop: Allow UNARY_P and check register pressure.
Date: Tue, 5 Sep 2023 10:45:02 +0200 [thread overview]
Message-ID: <5e4a58e3-df61-31af-18a2-052b1a9605a3@gmail.com> (raw)
In-Reply-To: <mptpm2xt3p4.fsf@arm.com>
> I imagine doing it in reverse postorder would still make sense.
>
> But my point was that, for the current fwprop limitation of substituting
> into exactly one use of a register, we can check whether that use is
> the *only* use of register.
>
> I.e. if we substitute:
>
> A: (set (reg R1) (foo (reg R2)))
>
> into:
>
> B: (set ... (reg R1) ...)
>
> if R1 and R2 are likely to be in the same register class, and if B
> is the only user of R2, then we don't need to calculate register
> pressure. The change is either neutral (if R2 died in A) or an
> improvement (if R2 doesn't die in A, and so R1 and R2 were previously
> live at the same time).
Ah, understood, thanks. Sure, that one I can include.
Regards
Robin
next prev parent reply other threads:[~2023-09-05 8:45 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-07 10:26 Robin Dapp
2023-08-24 14:06 ` Robin Dapp
2023-08-28 23:33 ` Jeff Law
2023-08-29 11:40 ` Richard Sandiford
2023-09-05 6:53 ` Robin Dapp
2023-09-05 8:38 ` Richard Sandiford
2023-09-05 8:45 ` Robin Dapp [this message]
2023-09-06 11:22 ` Robin Dapp
2023-09-06 20:44 ` Richard Sandiford
2023-09-07 7:56 ` Robin Dapp
2023-09-07 13:42 ` Richard Sandiford
2023-09-07 14:25 ` Robin Dapp
2023-09-26 16:24 ` Richard Sandiford
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