On Thu, Jan 25, 2024 at 05:45:00PM +0000, Andre Vieira wrote:
>
> This patch ensures we use TARGET_ARRAY_MODE to determine the storage mode of
> large bitints that are represented as arrays in memory. This is required to
> support such bitints for aarch64 and potential other targets with similar
> bitint specifications. Existing tests like gcc.dg/torture/bitint-25.c are
> affected by this for aarch64 targets.
>
> gcc/ChangeLog:
> stor-layout.cc (layout_type): Use TARGET_ARRAY_MODE for large bitints
> for targets that implement it.
I thought this has been resolved by the r14-8275 change.
Do you really need it for something?
I've tried
make check-gcc -j32 -k GCC_TEST_RUN_EXPENSIVE=1
RUNTESTFLAGS="GCC_TEST_RUN_EXPENSIVE=1 dg.exp='*bitint* pr112673.c
builtin-stdc-bit-*.c pr112566-2.c pr112511.c' dg-torture.exp=*bitint*
dfp.exp=*bitint*"
in a x86_64 -> aarch64-linux cross with your other patch but not this one
and didn't see any ICEs (note, as I didn't have any aarch64 libc around,
all tests fail during linking).
I think BITINT_TYPE mode really should be that of a struct containing that
many limb elements rather than of an array and this patch doesn't match
that.
> diff --git a/gcc/stor-layout.cc b/gcc/stor-layout.cc
> index 4cf249133e9..31da2c123ab 100644
> --- a/gcc/stor-layout.cc
> +++ b/gcc/stor-layout.cc
> @@ -2427,8 +2427,16 @@ layout_type (tree type)
> }
> else
> {
> - SET_TYPE_MODE (type, BLKmode);
> cnt = CEIL (TYPE_PRECISION (type), GET_MODE_PRECISION (limb_mode));
> + machine_mode mode;
> + /* Some targets use TARGET_ARRAY_MODE to select the mode they use
> + for arrays with a specific element mode and a specific element
> + count and we should use this mode for large bitints that are
> + stored as such arrays. */
> + if (!targetm.array_mode (limb_mode, cnt).exists (&mode)
> + || !targetm.array_mode_supported_p (limb_mode, cnt))
> + mode = BLKmode;
> + SET_TYPE_MODE (type, mode);
> gcc_assert (info.abi_limb_mode == info.limb_mode
> || !info.big_endian == !WORDS_BIG_ENDIAN);
> }
Jakub
