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Re: [PATCH] ARM: Fix strcmp() for Thumb-1

On 05/28/2013 11:36 AM, Richard Earnshaw wrote:
On 27/05/13 07:59, Sebastian Huber wrote:
On 05/27/2013 04:18 AM, Bin.Cheng wrote:
Though I have no right to approve the patch, I would like to have below
UAL is generally preferred, thus you may handle armv6-m specially by
keeping UAL for it. For example,

#if (defined(__thumb__) && defined(__ARM_ARCH_6M__))

Which problem does this additional pre-processor complexity solve?  The
generated machine code is the same.

I don't think either patch is correct.  Instead we should explicitly mark the
attributes in this case, probably as follows, but I've only smoke tested this.

Sebastian, does this fix your problem?

This patches fixes my problem.  I get now this:

readelf -A ./arm-rtems4.11/thumb/newlib/libc/machine/arm/lib_a-strcmp.o
Attribute Section: aeabi
File Attributes
  Tag_CPU_name: "4T"
  Tag_CPU_arch: v4T
  Tag_THUMB_ISA_use: Thumb-1
  Tag_also_compatible_with: v6-M

The application link process yields now an ARMv4T executable. Without the patch I had "blx" instructions in the executable which are not supported on ARM7TDMI-S processors.

Sebastian Huber, embedded brains GmbH

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