From: Segher Boessenkool <segher@kernel.crashing.org>
To: liuhongt <hongtao.liu@intel.com>
Cc: gcc-patches@gcc.gnu.org, jakub@redhat.com,
richard.sandiford@arm.com, ubizjak@gmail.com
Subject: Re: [PATCH 1/2] CALL_INSN may not be a real function call.
Date: Mon, 5 Jul 2021 18:30:08 -0500 [thread overview]
Message-ID: <20210705233008.GJ1583@gate.crashing.org> (raw)
In-Reply-To: <20210603065408.47912-1-hongtao.liu@intel.com>
Hi!
I ran into this in shrink-wrap.c today.
On Thu, Jun 03, 2021 at 02:54:07PM +0800, liuhongt via Gcc-patches wrote:
> Use "used" flag for CALL_INSN to indicate it's a fake call. If it's a
> fake call, it won't have its own function stack.
Could you document somewhere what a "fake call" *is*? Including what
that means to RTL, how this is expected to be used, etc.? In rtl.h is
fine with me, but as it is, no one can know when to use this. What does
"its own function stack" mean in the description here? You can only put
FAKE_CALL on functions that do not have a stack frame? But that is
never true on x86, so that cannot be it, unless there isn't a call
instruction at all? But then, why use an RTL call insn for this?
Other targets simply do not use an RTL "call" when they want to hide
such an instruction, why can't you do that here, wouldn't that work much
better? There are many more insns that you may want to hide. The
traditional solution is to use unspecs, which very directly hides all
details.
Segher
next prev parent reply other threads:[~2021-07-05 23:31 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-13 9:23 [PATCH] [i386] Fix _mm256_zeroupper to notify LRA that vzeroupper will kill sse registers. [PR target/82735] Hongtao Liu
2021-05-13 9:40 ` Uros Bizjak
2021-05-13 9:43 ` Uros Bizjak
2021-05-13 9:54 ` Jakub Jelinek
2021-05-13 11:32 ` Richard Sandiford
2021-05-13 11:37 ` Jakub Jelinek
2021-05-13 11:52 ` Richard Sandiford
2021-05-14 2:27 ` Hongtao Liu
2021-05-17 8:44 ` Hongtao Liu
2021-05-17 9:56 ` Richard Sandiford
2021-05-18 13:12 ` Hongtao Liu
2021-05-18 15:18 ` Richard Sandiford
2021-05-25 6:04 ` Hongtao Liu
2021-05-25 6:30 ` Hongtao Liu
2021-05-27 5:07 ` Hongtao Liu
2021-05-27 7:05 ` Uros Bizjak
2021-06-01 2:24 ` Hongtao Liu
2021-06-03 6:54 ` [PATCH 1/2] CALL_INSN may not be a real function call liuhongt
2021-06-03 6:54 ` [PATCH 2/2] Fix _mm256_zeroupper by representing the instructions as call_insns in which the call has a special vzeroupper ABI liuhongt
2021-06-04 2:56 ` Hongtao Liu
2021-06-04 6:26 ` Uros Bizjak
2021-06-04 6:34 ` Hongtao Liu
2021-06-07 19:04 ` [PATCH] x86: Don't compile pr82735-[345].c for x32 H.J. Lu
2021-06-04 2:55 ` [PATCH 1/2] CALL_INSN may not be a real function call Hongtao Liu
2021-06-04 7:50 ` Jakub Jelinek
2021-07-05 23:30 ` Segher Boessenkool [this message]
2021-07-06 0:03 ` Jeff Law
2021-07-06 1:49 ` Hongtao Liu
2021-07-07 14:55 ` Segher Boessenkool
2021-07-07 17:56 ` Jeff Law
2021-07-06 1:37 ` Hongtao Liu
2021-07-07 2:44 ` Hongtao Liu
2021-07-07 8:15 ` Richard Biener
2021-07-07 14:52 ` Segher Boessenkool
2021-07-07 15:23 ` Hongtao Liu
2021-07-07 23:42 ` Segher Boessenkool
2021-07-08 4:14 ` Hongtao Liu
2021-07-07 15:32 ` Hongtao Liu
2021-07-07 23:54 ` Segher Boessenkool
2021-07-09 7:20 ` Hongtao Liu
2021-07-07 15:52 ` Hongtao Liu
2021-05-27 7:20 ` [PATCH] [i386] Fix _mm256_zeroupper to notify LRA that vzeroupper will kill sse registers. [PR target/82735] Jakub Jelinek
2021-05-27 10:50 ` Richard Sandiford
2021-06-01 2:22 ` Hongtao Liu
2021-06-01 2:25 ` Hongtao Liu
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