From: Russell King - ARM Linux <linux@arm.linux.org.uk> To: Catalin Marinas <catalin.marinas@arm.com> Cc: Colin Cross <ccross@android.com>, "linux-arm-kernel@lists.infradead.org" <linux-arm-kernel@lists.infradead.org>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org> Subject: Re: [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.
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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.
next prev parent reply other threads:[~2011-01-23 15:52 UTC|newest] Thread overview: 64+ 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 7:42 ` Colin Cross 2011-01-14 11:43 ` Catalin Marinas 2011-01-14 11:43 ` Catalin Marinas 2011-01-14 12:02 ` Russell King - ARM Linux 2011-01-14 12:02 ` Russell King - ARM Linux 2011-01-14 14:10 ` Catalin Marinas 2011-01-14 14:10 ` Catalin Marinas 2011-01-14 15:49 ` Russell King - ARM Linux 2011-01-14 15:49 ` Russell King - ARM Linux 2011-01-14 16:23 ` Catalin Marinas 2011-01-14 16:23 ` Catalin Marinas 2011-01-14 16:35 ` Russell King - ARM Linux 2011-01-14 16:35 ` Russell King - ARM Linux 2011-01-14 16:58 ` Catalin Marinas 2011-01-14 16:58 ` Catalin Marinas 2011-01-14 17:30 ` Russell King - ARM Linux 2011-01-14 17:30 ` Russell King - ARM Linux 2011-01-14 18:47 ` Russell King - ARM Linux 2011-01-14 18:47 ` Russell King - ARM Linux 2011-01-14 19:23 ` Colin Cross 2011-01-14 19:23 ` Colin Cross 2011-01-14 19:51 ` Colin Cross 2011-01-14 19:51 ` Colin Cross 2011-01-14 21:24 ` Russell King - ARM Linux 2011-01-14 21:24 ` Russell King - ARM Linux 2011-01-25 23:33 ` Colin Cross 2011-01-25 23:33 ` Colin Cross 2011-01-26 11:26 ` Russell King - ARM Linux 2011-01-26 11:26 ` Russell King - ARM Linux 2011-01-27 6:11 ` Colin Cross 2011-01-27 6:11 ` Colin Cross 2011-01-27 6:35 ` Colin Cross 2011-01-27 6:35 ` Colin Cross 2011-01-27 7:30 ` Colin Cross 2011-01-27 7:30 ` Colin Cross 2011-02-09 18:12 ` Colin Cross 2011-02-09 18:12 ` Colin Cross 2011-01-15 15:38 ` Catalin Marinas 2011-01-15 15:38 ` Catalin Marinas 2011-01-15 15:43 ` Russell King - ARM Linux 2011-01-15 15:43 ` Russell King - ARM Linux 2011-01-16 11:51 ` Catalin Marinas 2011-01-16 11:51 ` Catalin Marinas 2011-01-15 15:31 ` Catalin Marinas 2011-01-15 15:31 ` Catalin Marinas 2011-01-15 15:40 ` Russell King - ARM Linux 2011-01-15 15:40 ` Russell King - ARM Linux 2011-01-16 11:49 ` Catalin Marinas 2011-01-16 11:49 ` Catalin Marinas 2011-01-23 15:51 ` Russell King - ARM Linux [this message] 2011-01-23 15:51 ` Russell King - ARM Linux 2011-01-25 13:19 ` Catalin Marinas 2011-01-25 13:19 ` Catalin Marinas 2011-01-16 21:25 ` Catalin Marinas 2011-01-16 21:25 ` Catalin Marinas 2011-01-23 15:46 ` Russell King - ARM Linux 2011-01-23 15:46 ` Russell King - ARM Linux 2011-01-25 13:45 ` Catalin Marinas 2011-01-25 13:45 ` Catalin Marinas 2011-01-14 16:24 ` Dave Martin 2011-01-14 16:24 ` Dave Martin 2011-01-14 16:52 ` Russell King - ARM Linux 2011-01-14 16:52 ` Russell King - ARM Linux
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