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Re: [PATCH][ARM] Fix broken shift patterns
- From: Paul Brook <paul at codesourcery dot com>
- To: Andrew Stubbs <ams at codesourcery dot com>
- Cc: "gcc-patches at gcc dot gnu dot org" <gcc-patches at gcc dot gnu dot org>, richard dot sandiford at linaro dot org
- Date: Fri, 7 Oct 2011 13:12:08 +0100
- Subject: Re: [PATCH][ARM] Fix broken shift patterns
- References: <4E8DC2C1.firstname.lastname@example.org> <4E8EE3F2.email@example.com>
> Oh, I forgot to say, I don't understand why the "rotate" operator is
> special cased?
> If I understand it correctly, the effect of the (existing) rotate is
> both to check the constant range, AND to disallow registers as the shift
> amount. This difference has no effect on Thumb, but might cause ARM mode
> some troubles?
> Is this likely to be deliberate, or an oversight? I can't see any reason
> in the ARM ARM why this should be the case.
Deliberate. ARM only has rotatert (which for immediate operands can be
substituted at assembly generation time).