Re: [RFA/ARM] Fix handling of Tag_DIV_use

[Richard Earnshaw <rearnsha at arm dot com>]

On 15/03/12 16:55, Matthew Gretton-Dann wrote:
> Hi,
> 
> The attached patch fixes how we use Tag_DIV_use in binutils to be in
> line with the meaning of the ARM ABI.
> 
> Tag_DIV_use has three values, 0, 1, or 2, which we have historically
> treated as:
>  0: Divide instruction permitted in Thumb state.  Emitted for v7M and
>     v7R.
>  1: Divide instruction not permitted.  Emitted for all architectures
>     which don't have a divide instruction (all v6 and before, v7A).
>  2: Divide instruction permitted in ARM state (emitted for v7A+idiv).
> 
> The value of 1 is actually meant to be read that the user did not intend
> for divide instructions to be used in the image (even if present in the
> architecture).  Similarly the value of 0 should be interpreted as the
> divide instruction was permitted as allowed by the architecture (see
> Tag_CPU_arch and Tag_CPU_arch_profile) - value 0 also maps to 'no info
> available'.
> 
> The attached patch changes the behaviour of binutils to match these
> clarified interpretations.
> 
> Gas currently does not provide any way on the command line to indicate
> the user intention that divide instructions should not be used.
> 
> Thanks,
> 
> Matt
> 
> bfd/ChangeLog:
> 
> 2012-03-15  Matthew Gretton-Dann  <matthew.gretton-dann@arm.com>
> 
> 	* elf32-arm.c (elf32_arm_attributes_accept_div): New function.
> 	(elf32_arm_attributes_forbid_div): Likewise.
> 	(elf32_arm_merge_eabi_attributes): Correct handling of
> 	Tag_DIV_use.
> 
> gas/ChangeLog:
> 
> 2012-03-15  Matthew Gretton-Dann  <matthew.gretton-dann@arm.com>
> 
> 	* config/tc-arm.c (aeabi_set_public_attributes): Correct
> 	handling of Tag_DIV_use.
> 
> gas/testsuite/ChangeLog:
> 
> 2012-03-15  Matthew Gretton-Dann  <matther.gretton-dann@arm.com>
> 
> 	* gas/testsuite/gas/arm/any-idiv.d: New testcase.
> 	* gas/testsuite/gas/arm/any-idiv.s: Likewise.
> 	* gas/arm/attr-any-armv4t.d: Update expected output.
> 	* gas/arm/attr-any-thumbv6.d: Likewise.
> 	* gas/arm/attr-cpu-directive.d: Likewise.
> 	* gas/arm/attr-default.d: Likewise.
> 	* gas/arm/attr-march-armv1.d: Likewise.
> 	* gas/arm/attr-march-armv2.d: Likewise.
> 	* gas/arm/attr-march-armv2a.d: Likewise.
> 	* gas/arm/attr-march-armv2s.d: Likewise.
> 	* gas/arm/attr-march-armv3.d: Likewise.
> 	* gas/arm/attr-march-armv3m.d: Likewise.
> 	* gas/arm/attr-march-armv4.d: Likewise.
> 	* gas/arm/attr-march-armv4t.d: Likewise.
> 	* gas/arm/attr-march-armv4txm.d: Likewise.
> 	* gas/arm/attr-march-armv4xm.d: Likewise.
> 	* gas/arm/attr-march-armv5.d: Likewise.
> 	* gas/arm/attr-march-armv5t.d: Likewise.
> 	* gas/arm/attr-march-armv5te.d: Likewise.
> 	* gas/arm/attr-march-armv5tej.d: Likewise.
> 	* gas/arm/attr-march-armv5texp.d: Likewise.
> 	* gas/arm/attr-march-armv5txm.d: Likewise.
> 	* gas/arm/attr-march-armv6-m+os.d: Likewise.
> 	* gas/arm/attr-march-armv6-m.d: Likewise.
> 	* gas/arm/attr-march-armv6.d: Likewise.
> 	* gas/arm/attr-march-armv6j.d: Likewise.
> 	* gas/arm/attr-march-armv6k+sec.d: Likewise.
> 	* gas/arm/attr-march-armv6k.d: Likewise.
> 	* gas/arm/attr-march-armv6kt2.d: Likewise.
> 	* gas/arm/attr-march-armv6s-m.d: Likewise.
> 	* gas/arm/attr-march-armv6t2.d: Likewise.
> 	* gas/arm/attr-march-armv6z.d: Likewise.
> 	* gas/arm/attr-march-armv6zk.d: Likewise.
> 	* gas/arm/attr-march-armv6zkt2.d: Likewise.
> 	* gas/arm/attr-march-armv6zt2.d: Likewise.
> 	* gas/arm/attr-march-armv7-a+mp.d: Likewise.
> 	* gas/arm/attr-march-armv7-a+sec.d: Likewise.
> 	* gas/arm/attr-march-armv7-a.d: Likewise.
> 	* gas/arm/attr-march-armv7.d: Likewise.
> 	* gas/arm/attr-march-armv7a.d: Likewise.
> 	* gas/arm/attr-march-iwmmxt.d: Likewise.
> 	* gas/arm/attr-march-iwmmxt2.d: Likewise.
> 	* gas/arm/attr-march-xscale.d: Likewise.
> 	* gas/arm/attr-mcpu.d: Likewise.
> 	* gas/arm/attr-mfpu-arm1020e.d: Likewise.
> 	* gas/arm/attr-mfpu-arm1020t.d: Likewise.
> 	* gas/arm/attr-mfpu-arm1136jf-s.d: Likewise.
> 	* gas/arm/attr-mfpu-arm1136jfs.d: Likewise.
> 	* gas/arm/attr-mfpu-arm7500fe.d: Likewise.
> 	* gas/arm/attr-mfpu-fpa.d: Likewise.
> 	* gas/arm/attr-mfpu-fpa10.d: Likewise.
> 	* gas/arm/attr-mfpu-fpa11.d: Likewise.
> 	* gas/arm/attr-mfpu-fpe.d: Likewise.
> 	* gas/arm/attr-mfpu-fpe2.d: Likewise.
> 	* gas/arm/attr-mfpu-fpe3.d: Likewise.
> 	* gas/arm/attr-mfpu-maverick.d: Likewise.
> 	* gas/arm/attr-mfpu-neon-fp16.d: Likewise.
> 	* gas/arm/attr-mfpu-neon.d: Likewise.
> 	* gas/arm/attr-mfpu-softfpa.d: Likewise.
> 	* gas/arm/attr-mfpu-softvfp+vfp.d: Likewise.
> 	* gas/arm/attr-mfpu-softvfp.d: Likewise.
> 	* gas/arm/attr-mfpu-vfp.d: Likewise.
> 	* gas/arm/attr-mfpu-vfp10-r0.d: Likewise.
> 	* gas/arm/attr-mfpu-vfp10.d: Likewise.
> 	* gas/arm/attr-mfpu-vfp3.d: Likewise.
> 	* gas/arm/attr-mfpu-vfp9.d: Likewise.
> 	* gas/arm/attr-mfpu-vfpv2.d: Likewise.
> 	* gas/arm/attr-mfpu-vfpv3-d16.d: Likewise.
> 	* gas/arm/attr-mfpu-vfpv3.d: Likewise.
> 	* gas/arm/attr-mfpu-vfpv4-d16.d: Likewise.
> 	* gas/arm/attr-mfpu-vfpv4.d: Likewise.
> 	* gas/arm/attr-mfpu-vfpxd.d: Likewise.
> 	* gas/arm/attr-order.d: Likewise.
> 	* gas/arm/attr-override-cpu-directive.d: Likewise.
> 	* gas/arm/attr-override-mcpu.d: Likewise.
> 	* gas/arm/eabi_attr_1.d: Likewise.
> 	* gas/arm/mov-highregs-any.d: Likewise.
> 	* gas/arm/mov-lowregs-any.d: Likewise.
> 	* gas/arm/pr12198-1.d: Likewise.
> 	* gas/arm/pr12198-2.d: Likewise.
> 
> ld/testsuite/ChangeLog:
> 
> 2012-03-15  Matthew Gretton-Dann  <matthew.gretton-dann@arm.com>
> 
> 	* ld-arm/arm-elf.exp: Add new testcases.
> 	* ld-arm/attr-merge-2.attr: Update ouput.
> 	* ld-arm/attr-merge-2a.s: Remove Tag_DIV_use test.
> 	* ld-arm/attr-merge-2b.s: Likewise.
> 	* ld-arm/attr-merge-3.attr: Updated expected output.
> 	* ld-arm/attr-merge-4.attr: Likewise.
> 	* ld-arm/attr-merge-5.attr: Likewise.
> 	* ld-arm/attr-merge-6.attr: Likewise.
> 	* ld-arm/attr-merge-7.attr: Likewise.
> 	* ld-arm/attr-merge-arch-1.attr: Likewise.
> 	* ld-arm/attr-merge-arch-2.attr: Likewise.
> 	* ld-arm/attr-merge-unknown-2.d: Likewise.
> 	* ld-arm/attr-merge-unknown-2r.d: Likewise.
> 	* ld-arm/attr-merge-unknown-3.d: Likewise.
> 	* ld-arm/attr-merge-vfp-1.d: Likewise.
> 	* ld-arm/attr-merge-vfp-1r.d: Likewise.
> 	* ld-arm/attr-merge-vfp-2.d: Likewise.
> 	* ld-arm/attr-merge-vfp-2r.d: Likewise.
> 	* ld-arm/attr-merge-vfp-3.d: Likewise.
> 	* ld-arm/attr-merge-vfp-3r.d: Likewise.
> 	* ld-arm/attr-merge-vfp-4.d: Likewise.
> 	* ld-arm/attr-merge-vfp-4r.d: Likewise.
> 	* ld-arm/attr-merge-vfp-5.d: Likewise.
> 	* ld-arm/attr-merge-vfp-5r.d: Likewise.
> 	* ld-arm/attr-merge-vfp-6.d: Likewise.
> 	* ld-arm/attr-merge-vfp-6r.d: Likewise.
> 	* ld-arm/attr-merge-wchar-00-nowarn.d: Likewise.
> 	* ld-arm/attr-merge-wchar-00.d: Likewise.
> 	* ld-arm/attr-merge-wchar-02-nowarn.d: Likewise.
> 	* ld-arm/attr-merge-wchar-02.d: Likewise.
> 	* ld-arm/attr-merge-wchar-04-nowarn.d: Likewise.
> 	* ld-arm/attr-merge-wchar-04.d: Likewise.
> 	* ld-arm/attr-merge-wchar-20-nowarn.d: Likewise.
> 	* ld-arm/attr-merge-wchar-20.d: Likewise.
> 	* ld-arm/attr-merge-wchar-22-nowarn.d: Likewise.
> 	* ld-arm/attr-merge-wchar-22.d: Likewise.
> 	* ld-arm/attr-merge-wchar-24-nowarn.d: Likewise.
> 	* ld-arm/attr-merge-wchar-40-nowarn.d: Likewise.
> 	* ld-arm/attr-merge-wchar-40.d: Likewise.
> 	* ld-arm/attr-merge-wchar-42-nowarn.d: Likewise.
> 	* ld-arm/attr-merge-wchar-44-nowarn.d: Likewise.
> 	* ld-arm/attr-merge-wchar-44.d: Likewise.
> 	* ld-arm/attr-merge.attr: Likewise.
> 	* ld-arm/attr-merge-div-0.s: New testcase.
> 	* ld-arm/attr-merge-div-00.d: Likewise.
> 	* ld-arm/attr-merge-div-01-m3.d: Likewise.
> 	* ld-arm/attr-merge-div-01.d: Likewise.
> 	* ld-arm/attr-merge-div-02.d: Likewise.
> 	* ld-arm/attr-merge-div-1.s: Likewise.
> 	* ld-arm/attr-merge-div-10-m3.d: Likewise.
> 	* ld-arm/attr-merge-div-10.d: Likewise.
> 	* ld-arm/attr-merge-div-11.d: Likewise.
> 	* ld-arm/attr-merge-div-12.d: Likewise.
> 	* ld-arm/attr-merge-div-120.d: Likewise.
> 	* ld-arm/attr-merge-div-2.s: Likewise.
> 	* ld-arm/attr-merge-div-20.d: Likewise.
> 	* ld-arm/attr-merge-div-21.d: Likewise.
> 	* ld-arm/attr-merge-div-22.d: Likewise.
> 
> 
> 

OK

R.