Re: [AArch64][TLSLE][3/3] Implement local executable mode for all memory model

[Jiong Wang <jiong.wang@arm.com>]

Christophe Lyon writes:

> On 19 August 2015 at 16:21, Jiong Wang <jiong.wang@arm.com> wrote:
>>
>> Marcus Shawcroft writes:
>>
>>> On 21 May 2015 at 17:49, Jiong Wang <jiong.wang@arm.com> wrote:
>>>
>>>> 2015-05-14  Jiong Wang  <jiong.wang@arm.com>
>>>> gcc/
>>>>   * config/aarch64/aarch64.c (aarch64_print_operand): Support tls_size.
>>>>   * config/aarch64/aarch64.md (tlsle): Choose proper instruction
>>>>   sequences.
>>>>   (tlsle_<mode>): New define_insn.
>>>>   (tlsle_movsym_<mode>): Ditto.
>>>>   * config/aarch64/constraints.md (Uta): New constraint.
>>>>   (Utb): Ditto.
>>>>   (Utc): Ditto.
>>>>   (Utd): Ditto.
>>>>
>>>> gcc/testsuite/
>>>>   * gcc.target/aarch64/tlsle.c: New test source.
>>>>   * gcc.target/aarch64/tlsle12.c: New testcase.
>>>>   * gcc.target/aarch64/tlsle24.c: New testcase.
>>>>   * gcc.target/aarch64/tlsle32.c: New testcase.
>>>>
>>>
>>>
>>>   case SYMBOL_TLSLE:
>>> -  asm_fprintf (asm_out_file, ":tprel_lo12_nc:");
>>> +  if (aarch64_tls_size <= 12)
>>> +    /* Make sure TLS offset fit into 12bit.  */
>>> +    asm_fprintf (asm_out_file, ":tprel_lo12:");
>>> +  else
>>> +    asm_fprintf (asm_out_file, ":tprel_lo12_nc:");
>>>    break;
>>>
>>> Use the existing classify_symbol mechanism we use throughout the
>>> aarch64 backend.  Specifically rename SYMBOL_TLSLE as SYMBOL_TLSLE24
>>> and introduce the 3 missing flavours then use the symbol
>>> classification to control behaviour such as this modifier selection.
>>
>> Done.
>>
>> classified TLS symbol into the following sub-types according to the value of tls size.
>>
>>  SYMBOL_TLSLE12
>>  SYMBOL_TLSLE24
>>  SYMBOL_TLSLE32
>>  SYMBOL_TLSLE48
>>
>> And On AArch64, instruction sequence for TLS LE under -mtls-size=32 will
>> utilize the relocation modifier "tprel_g0_nc" together with MOVK, it's
>> only supported in binutils since 2015-03-04 as PR gas/17843. So I
>> adjusted tlsle32.c to make it robust by detecting whether there is such
>> binutils support.
>>
>
> Hi,
>
> I'm (still) using binutils-2.25, and I can see that 2 of these new
> tests (tlsle12_1.c and tlsle24_1.c) fail at execution time on
> aarch64*-none-elf targets.

Christophe,

Those relocation types required by tls-size 12 & 24 are supported by
binutils-2.25 already, and you have passed compilation and failed at
exectuion, so there do have something wrong I guess.

Either the generated instruction sequence or the bare-metal environment.

One thing strange to me is those testcases are guarded by:

  /* { dg-require-effective-target tls_native } */

while for bare-metal environment, normally you don't have tls_native
support right? then these testcases should have been marked as
unsupported otherwise they will generate native tls instruction
sequences while the bare-metal runtime environment may don't support
initialize tp register etc, thus caused the exectuion error.

Could you please double check this? thanks

Regards,
Jiong