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Re: Reload related segfaults
From: David Miller <email@example.com>
Date: Wed, 26 Oct 2011 23:07:11 -0400 (EDT)
> From: Alan Modra <firstname.lastname@example.org>
> Date: Thu, 27 Oct 2011 13:29:56 +1030
>> Some recent patch has exposed a reload bug. I'm seeing
> I think this might be a side effect or Eric's recent changes,
Eric, I'm seeing a similar segmentation fault in reload on sparc64.
But it's in a slightly different place than Alan's crash.
Simply compile gcc.target/ultrasp12.c with "-m64 -O2 -mcpu=ultrasparc -mvis"
to see this.
The crash is in find_valid_class() called from push_reload(), via this
code block around line 1184 of reload.c:
enum reg_class in_out_class
= find_valid_class (outmode, GET_MODE (SUBREG_REG (out)),
subreg_regno_offset (REGNO (SUBREG_REG (out)),
GET_MODE (SUBREG_REG (out)),
REGNO (SUBREG_REG (out)));
(subreg:DI (reg/v:V4QI 50 %f18 [orig:314 s2hi4_ ] ) 0)
so subreg_regno_offset() returns -1, and find_valid_class() isn't too happy
about getting "-1" for it's 'n' argument.
I suspect the test that you removed in order to fix rtl-optimization/46603
would guard against this happening.
And indeed, I confirmed that backing out the rtl-optimization/46603
fix makes the segmentation fault go away.