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Date: Wed, 2 Sep 2015 14:53:59 -0400
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From: DJ Delorie <dj AT delorie DOT com>
To: djgpp AT delorie DOT com
In-reply-to: <837fo8byx8.fsf@gnu.org> (djgpp@delorie.com)
Subject: Re: different binary output with 32- and 64-bit hosted compilers
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> Could someone who feels more at home with assembly please take a look?
> DJ?

The difference is in GAS itself, which chooses a longer form of the JE
opcode here (and no, I can't think of a good reason why):

32:    21d3:	0f 84 47 00 00 00    	je     2220 <_fire_grenade2+0x270>
64:    21d3:	74 4b                	je     2220 <_fire_grenade2+0x270>

There are no other root differences - every other difference is due to
addresses being different, and even that is limited as an alignment
shortly after that resynchromizes everything.