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To: "John David Anglin" <dave@hiauly1.hia.nrc.ca>
cc: roger@www.eyesopen.com, gcc-patches@gcc.gnu.org
Reply-To: law@redhat.com
Subject: Re: [PATCH] Fix RTL sharing problem in CSE 
In-Reply-To: Your message of "Fri, 17 Jan 2003 12:15:24 EST."
             <200301171715.h0HHFOL0006221@hiauly1.hia.nrc.ca> 
From: law@redhat.com
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Date: Fri, 17 Jan 2003 17:24:00 -0000
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In message <200301171715.h0HHFOL0006221@hiauly1.hia.nrc.ca>, "John David Anglin
" writes:
 >> > 2003-01-16  Roger Sayle  <roger@eyesopen.com>
 >> > 
 >> > 	* cse.c (cse_insn): Avoid RTL sharing when updating the RETVAL
 >> > 	insn's notes following a substitution inside a libcall.
 >> 
 >> This doesn't fix the hppa64 problem.  I will try to investigate further.
 >
 >This is the insn that causes the ICE:
 >
 >regclass.i.12.loop:
 >(insn 599 598 600 0000000000000000 (set (reg:DI 263)
 >        (mult:DI (zero_extend:DI (subreg:SI (reg:DI 262) 4))
 >	    (zero_extend:DI (subreg:SI (reg/v:DI 157) 4)))) -1 (nil)
 >	(nil))
 >
 >regclass.i.13.bypass:
 >(insn 599 598 600 21 0000000000000000 (set (reg:DI 263)
 >        (mult:DI (zero_extend:DI (subreg:SI (const_int -44 [0xffffffffffffffd
 >4]) 4))
 >	    (zero_extend:DI (subreg:SI (reg/v:DI 157) 4)))) -1 (nil)
 >	(nil))
 >
 >regclass.i.19.life:
 >(insn 599 598 600 18 0000000000000000 (set (reg:DI 263)
 >        (mult:DI (zero_extend:DI (subreg:SI (const_int -44 [0xffffffffffffffd
 >4]) 4))
 >	    (zero_extend:DI (subreg:SI (reg/v:DI 157) 4)))) -1 (nil)
 >    (expr_list:REG_DEAD (reg/v:DI 157)
 >	(nil)))
 >
 >The ICE occurs because combine tries to simplify it and it can't because
 >of the constant substitution in the regclass.i.13.bypass pass.  It would
 >seem to me that the subreg should be simplified when the substitution for
 >DI 262 is made.  After that, the mode information is lost.
Agreed.

jeff