I suppose that it is possible to check assembly.
Following is part of diff before and after my patch:
29,32c29,32
< sd $6,0($2)
< sd $7,8($2)
< sd $8,16($2)
< sd $9,24($2)
---
> sd $5,0($2)
> sd $6,8($2)
> sd $7,16($2)
> sd $8,24($2)
63,66c63,66
< sd $6,0($2)
< sd $7,8($2)
< sd $8,16($2)
< sd $9,24($2)
---
> sd $5,0($2)
> sd $6,8($2)
> sd $7,16($2)
> sd $8,24($2)
138,141c138,141
< ld $6,64($16)
< ld $7,72($16)
< ld $8,80($16)
< ld $9,88($16)
---
> ld $5,64($16)
> ld $6,72($16)
> ld $7,80($16)
> ld $8,88($16)
148,151c148,151
< ld $6,64($16)
< ld $7,72($16)
< ld $8,80($16)
< ld $9,88($16)
---
> ld $5,64($16)
> ld $6,72($16)
> ld $7,80($16)
> ld $8,88($16)
167,170c167,170
< ld $6,0($16)
< ld $7,8($16)
< ld $8,16($16)
< ld $9,24($16)
---
> ld $5,0($16)
> ld $6,8($16)
> ld $7,16($16)
> ld $8,24($16)
What my patch effectively does it rearranges the data in
registers when invoking a function. I don't know whether
writing this testcase as an assembly check would make sense,
because that would make the testcase much less readable.
________________________________________
From: YunQiang Su <wzss...@gmail.com>
Sent: Wednesday, May 31, 2023 12:05 PM
To: Jovan Dmitrovic
Cc: gcc-patches@gcc.gnu.org; Djordje Todorovic
Subject: Re: [PATCH] mips: Fix overaligned function arguments [PR109435]
Jovan Dmitrovic <jovan.dmitro...@syrmia.com> 于2023年5月29日周一 19:00写道：
>
> This patch changes alignment for typedef types when passed as
> arguments, making the alignment equal to the alignment of
> original (aliased) types.
>
> This change makes it impossible for a typedef type to have
> alignment that is less than its size.
>
> Signed-off-by: Jovan Dmitrovic <jovan.dmitro...@syrmia.com>
>
> gcc/ChangeLog:
> PR target/109435
> * config/mips/mips.cc (mips_function_arg_alignment): Returns
> the alignment of function argument. In case of typedef type,
> it returns the aligment of the aliased type.
> (mips_function_arg_boundary): Relocated calculation of the
> aligment of function arguments.
>
> gcc/testsuite/ChangeLog:
> PR target/109435
> * gcc.target/mips/align-1.c: New test.
> ---
> gcc/config/mips/mips.cc | 18 +++++++++++++-
> gcc/testsuite/gcc.target/mips/align-1.c | 33 +++++++++++++++++++++++++
> 2 files changed, 50 insertions(+), 1 deletion(-)
> create mode 100644 gcc/testsuite/gcc.target/mips/align-1.c
>
> diff --git a/gcc/config/mips/mips.cc b/gcc/config/mips/mips.cc
> index ca822758b41..2019b7cd7d9 100644
> --- a/gcc/config/mips/mips.cc
> +++ b/gcc/config/mips/mips.cc
> @@ -6190,6 +6190,22 @@ mips_arg_partial_bytes (cumulative_args_t cum, const
> function_arg_info &arg)
> return info.stack_words > 0 ? info.reg_words * UNITS_PER_WORD : 0;
> }
>
> +/* Given MODE and TYPE of a function argument, return the alignment in
> + bits. In case of typedef, alignment of its original type is
> + used. */
> +
> +static unsigned int
> +mips_function_arg_alignment (machine_mode mode, const_tree type)
> +{
> + if (!type)
> + return GET_MODE_ALIGNMENT (mode);
> +
> + if (is_typedef_decl (TYPE_NAME (type)))
> + type = DECL_ORIGINAL_TYPE (TYPE_NAME (type));
> +
> + return TYPE_ALIGN (type);
> +}
> +
> /* Implement TARGET_FUNCTION_ARG_BOUNDARY. Every parameter gets at
> least PARM_BOUNDARY bits of alignment, but will be given anything up
> to STACK_BOUNDARY bits if the type requires it. */
> @@ -6198,8 +6214,8 @@ static unsigned int
> mips_function_arg_boundary (machine_mode mode, const_tree type)
> {
> unsigned int alignment;
> + alignment = mips_function_arg_alignment (mode, type);
>
> - alignment = type ? TYPE_ALIGN (type) : GET_MODE_ALIGNMENT (mode);
> if (alignment < PARM_BOUNDARY)
> alignment = PARM_BOUNDARY;
> if (alignment > STACK_BOUNDARY)
> diff --git a/gcc/testsuite/gcc.target/mips/align-1.c
> b/gcc/testsuite/gcc.target/mips/align-1.c
> new file mode 100644
> index 00000000000..816751b8099
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/mips/align-1.c
> @@ -0,0 +1,33 @@
> +/* Check that typedef alignment does not affect passing of function
> + parameters. */
> +/* { dg-do run { target { "mips*-*-linux*" } } } */
Is it possible to check the result with something like
scan-assembler
scan-assembler-not
instead of real running?
> +
> +#include <assert.h>
> +
> +typedef struct ui8
> +{
> + unsigned v[8];
> +} uint8 __attribute__ ((aligned(64)));
> +
> +unsigned
> +callee (int x, uint8 a)
> +{
> + return a.v[0];
> +}
> +
> +uint8
> +identity (uint8 in)
> +{
> + return in;
> +}
> +
> +int
> +main (void)
> +{
> + uint8 vec = {{1, 2, 3, 4, 5, 6, 7, 8}};
> + uint8 temp = identity (vec);
> + unsigned temp2 = callee (1, identity (vec));
> + assert (callee (1, temp) == 1);
> + assert (temp2 == 1);
> + return 0;
> +}
> --
> 2.34.1
>
