[PATCH/middle-end 2/6] __builtin_thread_pointer and AARCH64 ILP32

[Chung-Lin Tang]

On 2014/2/25 上午 10:06, Andrew Pinski wrote:
> On Wed, Dec 4, 2013 at 9:42 AM, Yufeng Zhang <Yufeng.Zhang@arm.com> wrote:
>> On 12/03/13 21:24, Andrew Pinski wrote:
>>>
>>> Hi,
>>>    With ILP32 AARCH64, Pmode (DImode) != ptrmode (SImode) so the variable
>>> decl
>>> has a mode of SImode while the register is DImode.  So the target that
>>> gets
>>> passed down to expand_builtin_thread_pointer is NULL as expand does not
>>> know how to get a subreg for a pointer type.
>>>
>>> This fixes the problem by handling a NULL target like we are able to
>>> handle
>>> for a non register/correct mode target inside
>>> expand_builtin_thread_pointer.
>>>
>>> OK?  Build and tested for aarch64-elf with no regressions.
>>>
>>> Thanks,
>>> Andrew Pinski
>>>
>>>         * builtins.c (expand_builtin_thread_pointer): Create a new target
>>>         when the target is NULL.
>>> ---
>>>   gcc/ChangeLog  |    5 +++++
>>>   gcc/builtins.c |    2 +-
>>>   2 files changed, 6 insertions(+), 1 deletions(-)
>>>
>>> diff --git a/gcc/builtins.c b/gcc/builtins.c
>>> index 4f1c818..66797fa 100644
>>> --- a/gcc/builtins.c
>>> +++ b/gcc/builtins.c
>>> @@ -5699,7 +5699,7 @@ expand_builtin_thread_pointer (tree exp, rtx target)
>>>     if (icode != CODE_FOR_nothing)
>>>       {
>>>         struct expand_operand op;
>>> -      if (!REG_P (target) || GET_MODE (target) != Pmode)
>>> +      if (target == NULL_RTX || !REG_P (target) || GET_MODE (target) !=
>>> Pmode)
>>>         target = gen_reg_rtx (Pmode);
>>>         create_output_operand (&op, target, Pmode);
>>>         expand_insn (icode, 1,&op);
>>
>>
>> Shouldn't thread pointer have ptr_mode instead?  I'm aware that on AArch64
>> the thread pointer system register tpidr_el0 is 64-bit wide regardless of
>> ILP32 or not, but in the abstracted view of AArch64 ILP32 world, the thread
>> pointer shall be a 32-bit pointer; the OS should have taken care of the
>> hardware register tpidr_el0 by having its higher 32 bits cleared.  I think
>> expand_builtin_thread_pointer and expand_builtin_set_thread_pointer should
>> use ptr_mode instead.  Correct me if I missed anything.
>>
>> Add Chung-Lin Tang to the CC list; Chung-Lin wrote these builtins in r192364
> 
> Pmode seems more correct as the hardware mode is Pmode, having it
> ptr_mode would expose the C size of the pointer rather than the
> hardware size.
> 
> Thanks,
> Andrew Pinski

Don't have any approval powers, but the fix looks rather obvious.

Thanks,
Chung-Lin