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From: Latchesar Ionkov <lucho@ionkov.net>
To: 9fans@cse.psu.edu
Subject: [9fans] 8a/8l bug
Date: Wed, 17 Dec 2003 12:59:58 -0500	[thread overview]
Message-ID: <20031217175958.GA6505@ionkov.net> (raw)

Hi,

I am working on making gcc to support the standard Plan9 object format. I
noticed something that IMO is a bug.

If I try to compile:

TEXT	main(SB), $0
	ADDL	$-1, AX
	ADCL	$-1, DX
	RET

the result from

	8l -a t.8
is:

001020  (1)	TEXT	main+0(SB),$0
001020 48	(2)	SUBL	$1, AX
001021 83d2ff	(3)	ADCL	$-1, DX

According to my ia32 instruction set reference 0x48 is
	DECL AX

not
	SUBL $1, AX

Unlike SUBL, DECL doesn't change CF flag, so the ADCL instruction is not
working correctly.

Where are these types of optimizations made? Is it possible to turn them off
completely?

Thanks,
	Lucho



             reply	other threads:[~2003-12-17 17:59 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2003-12-17 17:59 Latchesar Ionkov [this message]
2003-12-17 19:26 ` Latchesar Ionkov
2003-12-17 22:54   ` Russ Cox
2003-12-17 23:33     ` Latchesar Ionkov
2003-12-17 23:38       ` Russ Cox
2003-12-18  0:13         ` Latchesar Ionkov
2003-12-18  0:25         ` Charles Forsyth
2003-12-18  4:54   ` jmk

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