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Re: optimization/8165: builtin string functions SEGV on alpha-pc-linux-gnu at -O2
- From: Glen Nakamura <glen at imodulo dot com>
- To: nobody at gcc dot gnu dot org
- Cc: gcc-prs at gcc dot gnu dot org,
- Date: 8 Oct 2002 01:26:01 -0000
- Subject: Re: optimization/8165: builtin string functions SEGV on alpha-pc-linux-gnu at -O2
- Reply-to: Glen Nakamura <glen at imodulo dot com>
The following reply was made to PR optimization/8165; it has been noted by GNATS.
From: Glen Nakamura <glen@imodulo.com>
To: gcc-gnats@gcc.gnu.org, gcc-bugs@gcc.gnu.org
Cc:
Subject: Re: optimization/8165: builtin string functions SEGV on alpha-pc-linux-gnu at -O2
Date: Mon, 7 Oct 2002 15:24:09 -1000
http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=8165
Okay, I think the problem is in the gcse pass.
When we replace a register, we don't completely replace its references
in the instruction's REG_EQUAL note. Specifically, we miss the case
where the register is referred to in a (lo_sum (reg) (symbol_ref)).
My proposed fix is to add this case to simplify_replace_rtx() which is
called by try_replace_reg() during the gcse pass.
2002-10-07 Glen Nakamura <glen@imodulo.com>
* simplify-rtx.c (simplify_replace_rtx): Added case to simplify
and replace LO_SUM expressions.
Index: gcc/simplify-rtx.c
===================================================================
RCS file: /cvsroot/gcc/gcc/gcc/simplify-rtx.c,v
retrieving revision 1.122
diff -c -5 -p -r1.122 simplify-rtx.c
*** gcc/simplify-rtx.c 27 Sep 2002 12:48:02 -0000 1.122
--- gcc/simplify-rtx.c 8 Oct 2002 00:41:55 -0000
*************** simplify_replace_rtx (x, old, new)
*** 339,348 ****
--- 339,364 ----
if (code == MEM)
return replace_equiv_address_nv (x,
simplify_replace_rtx (XEXP (x, 0),
old, new));
+ if (code == LO_SUM)
+ {
+ if (REG_P (old) && REG_P (XEXP (x, 0))
+ && REGNO (old) == REGNO (XEXP (x, 0)))
+ {
+ if (REG_P (new))
+ return gen_rtx_fmt_ee (code, mode, new, XEXP (x, 1));
+
+ /* (lo_sum (high X) X) is simply X. */
+ if (GET_CODE (new) == HIGH
+ && rtx_equal_p (XEXP (new, 0), XEXP (x, 1)))
+ return XEXP (x, 1);
+ }
+ return x;
+ }
+
if (REG_P (x) && REG_P (old) && REGNO (x) == REGNO (old))
return new;
return x;