From: Jeff Law <law@redhat.com>
To: Segher Boessenkool <segher@kernel.crashing.org>,
Steven Bosscher <stevenb.gcc@gmail.com>
Cc: GCC Patches <gcc-patches@gcc.gnu.org>,
Paolo Bonzini <bonzini@gnu.org>,
Seongbae Park <seongbae.park@gmail.com>,
Kenneth Zadeck <zadeck@naturalbridge.com>
Subject: Re: [PATCH] df: Keep return address register undefined until epilogue_completed
Date: Fri, 09 Sep 2016 22:51:00 -0000 [thread overview]
Message-ID: <c8fbb437-7211-f043-f52a-c61a7498592e@redhat.com> (raw)
In-Reply-To: <20160829204121.GB22842@gate.crashing.org>
On 08/29/2016 02:41 PM, Segher Boessenkool wrote:
> On Mon, Aug 29, 2016 at 10:19:25PM +0200, Steven Bosscher wrote:
>> On Mon, Aug 29, 2016 at 6:50 PM, Segher Boessenkool wrote:
>>> This patch changes that so that that def is only added after
>>> epilogue_completed.
>> ...
>>> Does this work on all other targets?
>>
>> Guessing: not for targets where INCOMING_RETURN_ADDR_RTX is the stack register?
>> That'd be at least h8300, rl78, and rx.
>
> The stack pointer is always added (earlier in this function):
>
> /* The always important stack pointer. */
> bitmap_set_bit (entry_block_defs, STACK_POINTER_REGNUM);
>
> so that isn't it.
>
> History suggests it was a fix (or workaround) for a problem on ia64,
> but I might well have that wrong.
It came in as part of a much larger change where Kenny was trying to
compute the correct set of registers that are live at function entry. I
believe this is the earliest draft of the function in question:
http://permalink.gmane.org/gmane.comp.gcc.devel/75329
Jeff
next prev parent reply other threads:[~2016-09-09 22:42 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-29 16:50 Segher Boessenkool
2016-08-29 20:20 ` Steven Bosscher
2016-08-29 20:41 ` Segher Boessenkool
2016-09-09 22:51 ` Jeff Law [this message]
2016-09-09 22:35 ` Jeff Law
2016-09-09 22:42 ` Jeff Law
2016-09-10 8:03 ` Segher Boessenkool
2016-09-12 16:33 ` Jeff Law
2016-09-14 12:46 ` Segher Boessenkool
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