From: Vineet Gupta <vineetg@rivosinc.com>
To: Jeff Law <jeffreyalaw@gmail.com>,
Philipp Tomsich <philipp.tomsich@vrull.eu>
Cc: Manolis Tsamis <manolis.tsamis@vrull.eu>,
Jivan Hakobyan <jivanhakobyan9@gmail.com>,
gcc-patches@gcc.gnu.org
Subject: Re: RISC-V: Folding memory for FP + constant case
Date: Tue, 1 Aug 2023 16:38:13 -0700 [thread overview]
Message-ID: <ff7259a2-1298-19c7-f385-597a4c75c546@rivosinc.com> (raw)
In-Reply-To: <40176a5c-382d-809d-a4b1-06c6541c3670@gmail.com>
On 8/1/23 16:27, Jeff Law wrote:
>
>
> On 8/1/23 17:13, Vineet Gupta wrote:
>>
>> On 8/1/23 16:06, Philipp Tomsich wrote:
>>> Very helpful! Looks as if regprop for stack_pointer is now either too
>>> conservative — or one of our patches is missing in everyone's test
>>> setup; we'll take a closer look.
>>
>> FWIW, all 5 of them involve a SH2ADD have SP as source in the fold FP
>> case which f-m-o seems to be generating a MV for.
> To clarify f-m-o isn't generating the mv. It's simplifying a sequence
> by pushing the constant in an addi instruction into the memory
> reference. As a result the addi simplifies into a sp->reg copy that
> is supposed to then be propagated away.
Yep, that's clear.
>
> Also note that getting FP out of the shift-add sequences is the other
> key goal of Jivan's work. FP elimination always results in a
> spill/reload if we have a shift-add insn where one operand is FP.
Hmm, are you saying it should NOT be generating shift-add with SP as
src, because currently thats exactly what fold FP offset *is* doing and
is the reason it has 5 less insns.
-Vineet
next prev parent reply other threads:[~2023-08-01 23:38 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-07-12 20:59 Jivan Hakobyan
2023-07-15 6:16 ` Jeff Law
2023-07-25 11:24 ` Jivan Hakobyan
2023-07-26 3:31 ` Jeff Law
2023-08-01 19:14 ` Vineet Gupta
2023-08-01 20:16 ` Jivan Hakobyan
2023-08-01 21:55 ` Jeff Law
2023-08-01 22:07 ` Philipp Tomsich
2023-08-01 23:03 ` Vineet Gupta
2023-08-01 23:06 ` Philipp Tomsich
2023-08-01 23:13 ` Vineet Gupta
2023-08-01 23:27 ` Jeff Law
2023-08-01 23:38 ` Vineet Gupta [this message]
2023-08-01 23:52 ` Jeff Law
2023-08-04 9:52 ` Manolis Tsamis
2023-08-04 16:23 ` Jeff Law
2023-08-05 9:27 ` Manolis Tsamis
2023-08-01 23:22 ` Jeff Law
2023-08-01 23:28 ` Vineet Gupta
2023-08-01 23:21 ` Jeff Law
2023-08-09 19:31 ` Jeff Law
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