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From: Segher Boessenkool <segher@kernel.crashing.org>
Subject: Re: V4L2: __ucmpdi2 undefined on ppc
Date: Sun, 2 Mar 2008 22:53:12 +0100
To: "Stephane Marchesin" <marchesin@icps.u-strasbg.fr>
Cc: linuxppc-dev@ozlabs.org, henrik.sorensen@gmail.com, paulus@samba.org,
	David Woodhouse <dwmw2@infradead.org>
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>> +/*
>> + * __ucmpdi2: 64-bit comparison
>> + *
>> + * R3/R4 has 64 bit value A
>> + * R5/R6 has 64 bit value B
>> + * result in R3: 0 for A < B
>> + *              1 for A == B
>> + *              2 for A > B
>> + */
>> +_GLOBAL(__ucmpdi2)
>> +       cmplw   r7,r3,r5        # compare high words
>> +       li      r3,0
>> +       blt     r7,2f           # a < b ... return 0
>> +       bgt     r7,1f           # a > b ... return 2
>> +       cmplw   r6,r4,r6        # compare low words
>> +       blt     r6,2f           # a < b ... return 0
>> +       li      r3,1
>> +       ble     r6,2f           # a = b ... return 1
>> +1:     li      r3,2
>> +2:     blr

Every occurrence of r7 here is wrong (and some of the r6).  Is there
any reason to do this in assembler code at all?


Segher