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Date: Wed, 09 Mar 2005 01:47:00 -0000
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From: "jakub at redhat dot com" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug target/20126] [3.3/3.4/4.0/4.1 Regression] Inlined memcmp makes one argument null on entry
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------- Additional Comments From jakub at redhat dot com  2005-03-09 01:47 -------
Subject: Re: [PR target/20126, RFC] loop DEST_ADDR biv replacement may fail

On Mon, Mar 07, 2005 at 06:56:19PM -0300, Alexandre Oliva wrote:
> loop attempts to eliminate a biv represented by a pseudo in favor of a
> giv represented by (plus (reg) (const_int -1)).  Unfortunately, the
> biv pseudo appears in an insn that doesn't accept anything but a
> register, so validate_change fails and the error goes unnoticed.
> 
> The patch below fixes the problem and passed bootstrap on
> x86_64-linux-gnu (testing still pending), but I'm not very comfortable
> with the use of location for the assignment.  Is this a safe change?
> Any loop experts around willing to take a second look on this?  Thanks
> in advance,

Unfortunately, it seems to break ada bootstrap on at least x86-64 and i386:
../../gcc/ada/ali.adb: In function 'ALI.SCAN_ALI':
../../gcc/ada/ali.adb:2070: error: unrecognizable insn:
(insn:HI 5987 1558 1560 230 ../../gcc/ada/ali.adb:996 (set (plus:SI (reg:SI 2074)
            (symbol_ref:SI ("ali__cumulative_restrictions") [flags 0x2] <var_decl 0xb7e2b360 ali__cumulative_restrictions>))
        (plus:SI (reg:SI 2074)
            (symbol_ref:SI ("ali__cumulative_restrictions") [flags 0x2] <var_decl 0xb7e2b360 ali__cumulative_restrictions>))) -1 (nil)
    (nil))

../../gcc/ada/ali.adb: In function 'ALI.SCAN_ALI':
../../gcc/ada/ali.adb:2070: error: unrecognizable insn:
(insn:HI 6040 1461 1463 230 ../../gcc/ada/ali.adb:992 (set (plus:DI (plus:DI (reg:DI 2096)
                (reg/f:DI 726))
            (const_int 12 [0xc]))
        (plus:DI (reg:DI 2096)
            (const:DI (plus:DI (symbol_ref:DI ("ali__cumulative_restrictions") [flags 0x2] <var_decl 0x2a96136ea0 ali__cumulative_restrictions>)
                    (const_int 92 [0x5c]))))) -1 (nil)
    (nil))

	Jakub


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20126