RE: [Patch, ARM]Enable veneer routine for R_ARM_THM_JUMP19

["Tony Wang" <tony dot wang at arm dot com>]

Ping? Is it ok for trunk?

BR,
Tony
> -----Original Message-----
> From: Tony Wang [mailto:tony.wang@arm.com]
> Sent: Tuesday, August 05, 2014 9:46 AM
> To: 'Will Newton'; binutils@sourceware.org
> Cc: nickc@redhat.com
> Subject: RE: [Patch, ARM]Enable veneer routine for R_ARM_THM_JUMP19
> 
> New patch updated, fix Will's failure.
> 
> And it looks strange to me why binutils change the first branch instruction into a 32bit data, which introduced
> endian difference. Maybe anyone can help on me to understand why the first branch instruction is optimized
> out in some situation? However, as the jump24 is just doing the same thing, in this patch, I just keep conform
> with the old test case.
> 
> BR,
> Tony
> > -----Original Message-----
> > From: Will Newton [mailto:will.newton@linaro.org]
> > Sent: Monday, August 04, 2014 6:33 PM
> > To: Tony Wang
> > Cc: binutils@sourceware.org; nickc@redhat.com
> > Subject: Re: [Patch, ARM]Enable veneer routine for R_ARM_THM_JUMP19
> >
> > On 4 August 2014 11:27, Tony Wang <tony.wang@arm.com> wrote:
> > >> -----Original Message-----
> > >> From: Will Newton [mailto:will.newton@linaro.org]
> > >> Sent: Monday, August 04, 2014 5:50 PM
> > >> To: Tony Wang
> > >> Cc: binutils@sourceware.org; nickc@redhat.com
> > >> Subject: Re: [Patch, ARM]Enable veneer routine for R_ARM_THM_JUMP19
> > >>
> > >> On 4 August 2014 10:40, Tony Wang <tony.wang@arm.com> wrote:
> > >> >> -----Original Message-----
> > >> >> From: Will Newton [mailto:will.newton@linaro.org]
> > >> >> Sent: Monday, August 04, 2014 5:14 PM
> > >> >> To: Tony Wang
> > >> >> Cc: binutils@sourceware.org; nickc@redhat.com
> > >> >> Subject: Re: [Patch, ARM]Enable veneer routine for R_ARM_THM_JUMP19
> > >> >>
> > >> >> On 4 August 2014 05:40, Tony Wang <tony.wang@arm.com> wrote:
> > >> >> > Hi there,
> > >> >> >
> > >> >> > According to AAPCS-ELF specification R_ARM_THM_JUMP19 should
> > >> >> > also be veneered if the target is outside the addressable span
> > >> >> > of the branch instruction or where interworking happened.
> > >> >> >
> > >> >> > So the attached patch implements the veneer routine for
> > >> >> > R_ARM_THM_JUMP19, and two new macros
> > >> >> > THM2_MAX_FWD_COND_BRANCH_OFFSET
> > >> >> > and THM2_MAX_BWD_COND_BRANCH_OFFSET are introduced.
 > > >> >> > Also updated the
> > >> >> > conditional branch for both cases mentioned above.
> > >> >> >
> > >> >> > Tested with Binutils regression test, no new regressions. No
> > >> >> > regression on gcc trunk with target cortex m4
> > >> >> >
> > >> >> > Ok for the trunk?
> > >> >> >
> > >> >> > bfd/ChangeLog:
> > >> >> > 2014-08-4  Tony Wang <tony.wang@arm.com>
> > >> >> >
> > >> >> >      * elf32-arm.c (elf32_arm_final_link_relocate): Implement
> > >> >> > the veneer routine for R_ARM_THM_JUMP19.
> > >> >> >      (arm_type_of_stub): Add conditional clause for R_ARM_THM_JUMP19
> > >> >> >      (elf32_arm_size_stub): Ditto.
> > >> >> >
> > >> >> > ld/testsuite/ChangeLog:
> > >> >> > 2014-08-4  Tony Wang <tony.wang@arm.com>
> > >> >> >
> > >> >> >      * ld-arm/jump-reloc-veneers-cond.s: New test.
> > >> >> >      * ld-arm/farcall-cond-thumb-arm.s: Ditto.
> > >> >> >      * ld-arm/jump-reloc-veneers-cond-short.d: Expected output
> > >> >> > for target without a veneer generation.
> > >> >> >      * ld-arm/jump-reloc-veneers-cond-long.d: Expected output
> > >> >> > for target with a veneer generation.
> > >> >> >      * ld-arm/farcall-cond-thumb-arm.d: Expected output for
> > >> >> > inter working veneer generation.
> > >> >> >      * ld-arm/arm-elf.exp: Add tests for conditional branch veneer.
> > >> >>
> > >> >> Looks ok to me (although I am not a maintainer). Small details but
> > >> >> logical operations bind more loosely than almost every other
> > >> >> operator so in some cases you can drop the brackets around
> > >> >> assignments in conditionals and make them a bit easier to read.
> > >> >
> > >> > I agreed with your point.
> > >> >
> > >> >>Also the casts to unsigned int in
> > >> >> elf32_arm_size_stubs seem unnecessary.
> > >> >
> > >> > From my point of view, it might still needed here, as the enum type
> > >> > not always equals to unsigned int.
> > >>
> > >> Fair enough, its not a big issue.
> > >>
> > >> I also noticed a testsuite failure for armeb:
> > >>
> > >> /home/will/linaro/binutils-arm/ld/../binutils/objdump -d
> > >> tmpdir/jump-reloc- veneers-cond-long regexp_diff match failure
> > >> regexp "^    80..:      8002f040        .word   0x8002f040$"
> > >> line   "    8000:       f0408002        .word   0xf0408002"
> > >> FAIL: R_ARM_THM_JUMP19 Relocation veneers: Long
> > >>
> > >
> > > Hi Will,
> > > Thanks a lot for your report, and are you using the big endian toolchain? It
> > > looks like an endian issue. I only tested it with little endian toolchain.
> >
> > I configured binutils with --target=armeb-none-eabi, although I also
> > found that armeb EABI targets seem to be broken in general so I
> > submitted a patch to fix that.
> >
> > --
> > Will Newton
> > Toolchain Working Group, Linaro

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