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From: linux@arm.linux.org.uk (Russell King - ARM Linux)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] ARM: vfp: Fix up exception location in Thumb mode
Date: Sun, 23 Jan 2011 15:51:57 +0000	[thread overview]
Message-ID: <20110123155157.GD30094@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <AANLkTikY46rXDBzgKM=9zwAda4=bhRCXDKJM6UA0yyLU@mail.gmail.com>

On Sun, Jan 16, 2011 at 11:49:21AM +0000, Catalin Marinas wrote:
> On Saturday, 15 January 2011, Russell King - ARM Linux
> <linux@arm.linux.org.uk> wrote:
> > It's a reveq, so I thought we should cover all the instructions with
> > an 'eq' conditional for thumb.
> 
> If the it instruction doesn't cover all instructions, gas generates
> some more its. But in this case, for little endian, the it instruction
> covers more since reveq isn't included and having the beq not last in
> the block I think is unpredictable. If you really want to optimise the
> big endian case not to have an additional it generated by gas, you can
> write ittt so that beq is included with little endian but not with big
> endian. I wouldn't bother much for an extra it anyway.

I think the itttt is correct.  Unless you wish to illustrate why you
think it's wrong by pasting the code and showing why you think the
beq isn't the last instruction...

> > ?? ? ? ?tst ? ? r3, #PSR_T_BIT
> > ?? ? ? ?subeq ? r4, r2, #4
> > 1: ? ? ?ldreqt ?r0, [r4]
> > ?? ? ? ?reveq ? r0, r0
> > ?? ? ? ?beq ? ? call_fpe
> 
> You can have the T bit set but the instruction a 32-bit Thumb in which
> case r2 is in the middle of such instruction rather than the next.
> Unless you only refer to the ARM mode, in which case the comment is
> fine.

So?  I'm confused why you're making a mountain out of apparantly
nothing.

  reply	other threads:[~2011-01-23 15:51 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-01-14  7:42 [PATCH] ARM: vfp: Fix up exception location in Thumb mode Colin Cross
2011-01-14 11:43 ` Catalin Marinas
2011-01-14 12:02   ` Russell King - ARM Linux
2011-01-14 14:10     ` Catalin Marinas
2011-01-14 15:49       ` Russell King - ARM Linux
2011-01-14 16:23         ` Catalin Marinas
2011-01-14 16:35           ` Russell King - ARM Linux
2011-01-14 16:58             ` Catalin Marinas
2011-01-14 17:30               ` Russell King - ARM Linux
2011-01-14 18:47                 ` Russell King - ARM Linux
2011-01-14 19:23                   ` Colin Cross
2011-01-14 19:51                     ` Colin Cross
2011-01-14 21:24                       ` Russell King - ARM Linux
2011-01-25 23:33                       ` Colin Cross
2011-01-26 11:26                         ` Russell King - ARM Linux
2011-01-27  6:11                           ` Colin Cross
2011-01-27  6:35                             ` Colin Cross
2011-01-27  7:30                               ` Colin Cross
2011-02-09 18:12                                 ` Colin Cross
2011-01-15 15:38                   ` Catalin Marinas
2011-01-15 15:43                     ` Russell King - ARM Linux
2011-01-16 11:51                       ` Catalin Marinas
2011-01-15 15:31                 ` Catalin Marinas
2011-01-15 15:40                   ` Russell King - ARM Linux
2011-01-16 11:49                     ` Catalin Marinas
2011-01-23 15:51                       ` Russell King - ARM Linux [this message]
2011-01-25 13:19                         ` Catalin Marinas
2011-01-16 21:25                     ` Catalin Marinas
2011-01-23 15:46                       ` Russell King - ARM Linux
2011-01-25 13:45                         ` Catalin Marinas
2011-01-14 16:24       ` Dave Martin
2011-01-14 16:52         ` Russell King - ARM Linux

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