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

[Will Newton <will dot newton at linaro dot org>]

On 19 August 2014 03:37, Tony Wang <tony.wang@arm.com> wrote:
> Ping 2? Is this patch ok?

Looks ok to me (although I am not a maintainer).

> BR,
> Tony
>> -----Original Message-----
>> From: Tony Wang [mailto:tony.wang@arm.com]
>> Sent: Tuesday, August 12, 2014 10:25 AM
>> To: 'binutils@sourceware.org'
>> Cc: nickc@redhat.com
>> Subject: RE: [Patch, ARM]Enable veneer routine for R_ARM_THM_JUMP19
>>
>> 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



-- 
Will Newton
Toolchain Working Group, Linaro