On Fri, Jul 10, 2015 at 7:10 PM, H.J. Lu <hjl.to...@gmail.com> wrote:
> On Fri, Jul 10, 2015 at 9:30 AM, Uros Bizjak <ubiz...@gmail.com> wrote:
>> On Thu, Jul 9, 2015 at 12:54 PM, H.J. Lu <hjl.to...@gmail.com> wrote:
>>> Indirect sibcall with register arguments is OK when there is register
>>> available for argument passing.
>>>
>>> OK for trunk if there is no regression?
>>>
>>>
>>> H.J.
>>> ---
>>> gcc/
>>>
>>> PR target/66819
>>> * config/i386/i386.c (ix86_function_ok_for_sibcall): Allow
>>> indirect sibcall with register arguments if register available
>>> for argument passing.
>>> (init_cumulative_args): Set cfun->machine->arg_reg_available_p
>>> to cum->nregs != 0.
Please update the above entry for nregs > 0.
>>> (function_arg_advance_32): Set cfun->machine->arg_reg_available_p
>>> to 0 when setting cum->nregs = 0.
>>
>> Do we also need similar functionality for 64bit ABIs? What happens if
>> we are out of argument regs there?
>
> 64-bit is OK since we have rax, r10 and r11 as scratch registers which
> aren't used to pass arguments.
Maybe this fact should be added as a comment in some appropriate place.
>>> * config/i386/i386.h (machine_function): Add arg_reg_available_p.
>>>
>>> gcc/testsuite/
>>>
>>> PR target/66819
>>> * gcc.target/i386/pr66819-1.c: New test.
>>> * gcc.target/i386/pr66819-2.c: Likewise.
>>> * gcc.target/i386/pr66819-3.c: Likewise.
>>> * gcc.target/i386/pr66819-4.c: Likewise.
>>> * gcc.target/i386/pr66819-5.c: Likewise.
>>> ---
>>> gcc/config/i386/i386.c | 15 +++++++++------
>>> gcc/config/i386/i386.h | 3 +++
>>> gcc/testsuite/gcc.target/i386/pr66819-1.c | 8 ++++++++
>>> gcc/testsuite/gcc.target/i386/pr66819-2.c | 8 ++++++++
>>> gcc/testsuite/gcc.target/i386/pr66819-3.c | 10 ++++++++++
>>> gcc/testsuite/gcc.target/i386/pr66819-4.c | 12 ++++++++++++
>>> gcc/testsuite/gcc.target/i386/pr66819-5.c | 10 ++++++++++
>>> 7 files changed, 60 insertions(+), 6 deletions(-)
>>> create mode 100644 gcc/testsuite/gcc.target/i386/pr66819-1.c
>>> create mode 100644 gcc/testsuite/gcc.target/i386/pr66819-2.c
>>> create mode 100644 gcc/testsuite/gcc.target/i386/pr66819-3.c
>>> create mode 100644 gcc/testsuite/gcc.target/i386/pr66819-4.c
>>> create mode 100644 gcc/testsuite/gcc.target/i386/pr66819-5.c
>>>
>>> diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
>>> index 54ee6f3..85e59a8 100644
>>> --- a/gcc/config/i386/i386.c
>>> +++ b/gcc/config/i386/i386.c
>>> @@ -5628,12 +5628,12 @@ ix86_function_ok_for_sibcall (tree decl, tree exp)
>>> if (!decl
>>> || (TARGET_DLLIMPORT_DECL_ATTRIBUTES && DECL_DLLIMPORT_P (decl)))
>>> {
>>> - if (ix86_function_regparm (type, NULL) >= 3)
>>> - {
>>> - /* ??? Need to count the actual number of registers to be
>>> used,
>>> - not the possible number of registers. Fix later. */
>>> - return false;
>>> - }
>>> + /* FIXME: The symbol indirect call doesn't need a
>>> + call-clobbered register. But we don't know if
>>> + this is a symbol indirect call or not here. */
>>> + if (ix86_function_regparm (type, NULL) >= 3
>>> + && !cfun->machine->arg_reg_available_p)
>>
>> Isn't enough to look at arg_reg_available here?
>
> We need to check ix86_function_regparm since nregs is 0 if
> -mregparm=N isn't used and pr65753.c will fail.
OK. Please add this comment, is not that obvious.
>
>>> + return false;
>>> }
>>> }
>>>
>>> @@ -6567,6 +6567,7 @@ init_cumulative_args (CUMULATIVE_ARGS *cum, /*
>>> Argument info to initialize */
>>> ? X86_64_REGPARM_MAX
>>> : X86_64_MS_REGPARM_MAX);
>>> }
>>> + cfun->machine->arg_reg_available_p = cum->nregs != 0;
>>
>> false instead of 0. This is a boolean.
>
> Updated.
>
>>> if (TARGET_SSE)
>>> {
>>> cum->sse_nregs = SSE_REGPARM_MAX;
>>> @@ -6636,6 +6637,7 @@ init_cumulative_args (CUMULATIVE_ARGS *cum, /*
>>> Argument info to initialize */
>>> else
>>> cum->nregs = ix86_function_regparm (fntype, fndecl);
>>> }
>>> + cfun->machine->arg_reg_available_p = cum->nregs != 0;
>>
>> IMO, cum->nregs > 0 would be more descriptive.
>
> Updated.
>
>>> /* Set up the number of SSE registers used for passing SFmode
>>> and DFmode arguments. Warn for mismatching ABI. */
>>> @@ -7584,6 +7586,7 @@ pass_in_reg:
>>> {
>>> cum->nregs = 0;
>>> cum->regno = 0;
>>> + cfun->machine->arg_reg_available_p = 0;
>>> }
>>> break;
>>>
>>> diff --git a/gcc/config/i386/i386.h b/gcc/config/i386/i386.h
>>> index 74334ff..0b6e304 100644
>>> --- a/gcc/config/i386/i386.h
>>> +++ b/gcc/config/i386/i386.h
>>> @@ -2479,6 +2479,9 @@ struct GTY(()) machine_function {
>>> /* If true, it is safe to not save/restore DRAP register. */
>>> BOOL_BITFIELD no_drap_save_restore : 1;
>>>
>>> + /* If true, there is register available for argument passing. */
>>> + BOOL_BITFIELD arg_reg_available_p : 1;
>>
>> This is not a predicate, but a boolean flag. Please remove _p from the name.
>
> Updated.
>
> Here is the updated patch. OK for trunk?
OK with a small comment additions.
+ /* If true, there is register available for argument passing. */
+ BOOL_BITFIELD arg_reg_available : 1;
+
Please mention here that this is for 32bit targets only.
Thanks,
Uros.
