On Tue, 18 Aug 2020 at 05:38, qiaopeixin <qiaopei...@huawei.com> wrote:
>
> Hi Richard,
>
> Thanks for the review and explanation.
>
> The previous fix adding if condition of TARGET_FLOAT does crash glibc-2.29.
>
> I checked the past log of writing the function aarch64_init_cumulative_args,
> and did not find the reason why Alan Lawrence added TREE_PUBLIC (fndecl) as
> one condition for entering the function type check. Maybe Alan could clarify?
> I tried to delete TREE_PUBLIC (fndecl), which turns out could solve both the
> glibc problem and the previous ICE problem. A new fix is made as following,
> passed bootstrap and deja test. I believe this fix is reasonable, since the
> function type should be checked no matter if it has external linkage or not.
>
> The function aarch64_init_cumulative_args checks the function types and
> should catch the error that "-mgeneral-regs-only" is incompatible with the
> use of SIMD/FP registers. In the test case on PR96479, the function myfunc2
> returns one vector of 4 integers, while it is defined static type.
> TREE_PUBLIC (fndecl) is set as false and it prevents from entering if
> statement and checking function types. I delete "TREE_PUBLIC (fndecl)" so
> that gcc can catch the error through the function
> aarch64_init_cumulative_args now. The ICE on PR96479 can report the
> diagnostic error with this fix. The patch for the fix is attached as
> following:
>
> diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c
> index b7f5bc76f1b..9ce83dce131 100644
> --- a/gcc/config/aarch64/aarch64.c
> +++ b/gcc/config/aarch64/aarch64.c
> @@ -6017,7 +6017,7 @@ aarch64_init_cumulative_args (CUMULATIVE_ARGS *pcum,
>
> if (!silent_p
> && !TARGET_FLOAT
> - && fndecl && TREE_PUBLIC (fndecl)
> + && fndecl
> && fntype && fntype != error_mark_node)
> {
> const_tree type = TREE_TYPE (fntype);
>
> Christophe, thanks for your tests on glibc-2.29. With the above fix, I built
> glibc-2.29, and the previous error does not show up now. Could you please
> check if this fix works?
Hi,
I confirm this works OK for my testing (aarch64-linux-gnu and aarch64-elf)
Thanks,
Christophe
>
> Do you have any suggestions on this fix?
>
> All the best,
> Peixin
>
>
> -----Original Message-----
> From: Richard Sandiford [mailto:richard.sandif...@arm.com]
> Sent: Thursday, August 13, 2020 8:19 PM
> To: Christophe Lyon <christophe.l...@linaro.org>
> Cc: qiaopeixin <qiaopei...@huawei.com>; gcc-patches@gcc.gnu.org
> Subject: Re: [PATCH] AArch64: Add if condition in aarch64_function_value
> [PR96479]
>
> Christophe Lyon <christophe.l...@linaro.org> writes:
> > On Thu, 13 Aug 2020 at 03:54, qiaopeixin <qiaopei...@huawei.com> wrote:
> >>
> >> Thanks for the review and commit.
> >>
> >> All the best,
> >> Peixin
> >>
> >> -----Original Message-----
> >> From: Richard Sandiford [mailto:richard.sandif...@arm.com]
> >> Sent: 2020年8月13日 0:25
> >> To: qiaopeixin <qiaopei...@huawei.com>
> >> Cc: gcc-patches@gcc.gnu.org
> >> Subject: Re: [PATCH] AArch64: Add if condition in
> >> aarch64_function_value [PR96479]
> >>
> >> qiaopeixin <qiaopei...@huawei.com> writes:
> >> > Hi,
> >> >
> >> > The test case vector-subscript-2.c in the gcc testsuit will report an
> >> > ICE in the expand pass since '-mgeneral-regs-only' is incompatible with
> >> > the use of V4SI mode. I propose to report the diagnostic information
> >> > instead of ICE, and the problem has been discussed on PR 96479.
> >> >
> >> > I attached the patch to solve the problem. Bootstrapped and tested on
> >> > aarch64-linux-gnu. Any suggestions?
> >>
> >> Thanks, pushed. I was initially sceptical because raising an error here
> >> and in aarch64_layout_arg is a hack. Both functions are just query
> >> functions and shouldn't have any side effects.
> >>
> >> The approach we took for FP modes seemed better: we define the FP move
> >> patterns unconditionally, and raise an error if we try to emit an FP move
> >> with !TARGET_FLOAT. This defers any error reporting until we actually try
> >> to generate code that depends on TARGET_FLOAT.
> >>
> >> But I guess SIMD stuff is different. There's no reason in principle why
> >> you can't use:
> >>
> >> unsigned short __attribute__((vector_size(8)))
> >>
> >> *within* a function with -mgeneral-regs-only. It would just need to be
> >> emulated, in the same way as for:
> >>
> >> unsigned short __attribute__((vector_size(4)))
> >>
> >> So it would be wrong to define the SIMD move patterns unconditionally and
> >> raise an error there.
> >>
> >> So all in all, I agree this is the best we can do given the current
> >> infrastructure.
> >>
> >
> > Since this patch was committed my buildbot is broken for
> > aarch64-linux-gnu because it now fails to build glibc-2.29:
> > ../stdlib/bits/stdlib-float.h: In function 'atof':
> > ../stdlib/bits/stdlib-float.h:26:1: error: '-mgeneral-regs-only' is
> > incompatible with the use of floating-point types
>
> Thanks for the heads-up. I've reverted the patch for now.
>
> Looking more closely, it seems like aarch64_init_cumulative_args already
> tries to catch the problem that the patch was fixing:
>
> if (!silent_p
> && !TARGET_FLOAT
> && fndecl && TREE_PUBLIC (fndecl)
> && fntype && fntype != error_mark_node)
> {
> const_tree type = TREE_TYPE (fntype);
> machine_mode mode ATTRIBUTE_UNUSED; /* To pass pointer as argument. */
> int nregs ATTRIBUTE_UNUSED; /* Likewise. */
> if (aarch64_vfp_is_call_or_return_candidate (TYPE_MODE (type), type,
> &mode, &nregs, NULL,
> false))
> aarch64_err_no_fpadvsimd (TYPE_MODE (type));
> }
>
> The only reason it doesn't work for the testcase is that TREE_PUBLIC
> condition. TBH I'm not sure why it or the fndecl test is there:
> this is just as problematic when calling via a function pointer or when
> calling a static function.
>
> Richard
