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Re: [PATCH] ARM attributes and user intent
- From: Richard Earnshaw <rearnsha at arm dot com>
- To: Andrew Stubbs <ams at codesourcery dot com>
- Cc: binutils at sourceware dot org
- Date: Wed, 21 Jan 2009 16:32:44 +0000
- Subject: Re: [PATCH] ARM attributes and user intent
- References: <497701F4.1060008@codesourcery.com>
On Wed, 2009-01-21 at 11:07 +0000, Andrew Stubbs wrote:
> The patch adds a test case for every possible -march and -mfpu to ensure
> that the attributes are set correctly, and a number of test cases to
> ensure that the precedence rules above are obeyed. I have also updated
> the expected results for all affected existing tests.
>
> OK?
>
This looks good. However, if code is compiled/assembled without
interworking, then it seams a bit odd that the other instruction set is
still permitted.
Thus if the user compiles code with -mcpu=arm7tdmi -mno-thumb-interwork,
should the code be marked arm-only (ie permitted thumb use was none)?
Sadly, although gas has -mthumb-interwork, it doesn't have the inverse
(-mno-thumb-interwork). That's a bit unfortunate given that the new ABI
mandates interworking by default.
There are also technical difficulties for some thumb non-interworking
code that still uses the ARM instruction set internally (but in a way
that is not visible to the user). This is done, for example, in the
support code for soft-float in gcc.
R.