On Thu, Jun 19, 2025 at 05:59:04PM +0800, Yang Yujie wrote:
> For targets that treat small _BitInts like the fundamental
> integral types, we should allow their machine modes to be promoted
> in the same way.
>
> gcc/ChangeLog:
>
> * explow.cc (promote_function_mode): Add a case for
> small/medium _BitInts.
> (promote_mode): Same.
> ---
> gcc/explow.cc | 31 ++++++++++++++++++++++++++++++-
> 1 file changed, 30 insertions(+), 1 deletion(-)
>
> diff --git a/gcc/explow.cc b/gcc/explow.cc
> index 7799a98053b..00d0380c664 100644
> --- a/gcc/explow.cc
> +++ b/gcc/explow.cc
> @@ -856,7 +856,21 @@ promote_function_mode (const_tree type, machine_mode
> mode, int *punsignedp,
> {
> case INTEGER_TYPE: case ENUMERAL_TYPE: case BOOLEAN_TYPE:
> case REAL_TYPE: case OFFSET_TYPE: case FIXED_POINT_TYPE:
> - case POINTER_TYPE: case REFERENCE_TYPE:
> + case POINTER_TYPE: case REFERENCE_TYPE: case BITINT_TYPE:
> + /* Handle _BitInt(N) that does not require promotion. */
> + if (TREE_CODE (type) == BITINT_TYPE)
> + {
> + if (TYPE_MODE (type) == BLKmode)
> + return mode;
> +
> + struct bitint_info info;
> + bool ok = targetm.c.bitint_type_info (TYPE_PRECISION (type), &info);
> + gcc_assert (ok);
> +
> + if (!info.extended)
> + return mode;
> + }
> +
Having tons of case ...: followed by if is wasteful.
Instead, please do:
{
case BITINT_TYPE:
if (TYPE_MODE (type) == BLKmode)
return mode;
struct bitint_info info;
bool ok;
ok = targetm.c.bitint_type_info (TYPE_PRECISION (type), &info);
gcc_assert (ok);
if (!info.extended)
return mode;
/* FALLTHRU */
case INTEGER_TYPE: case ENUMERAL_TYPE: case BOOLEAN_TYPE:
case REAL_TYPE: case OFFSET_TYPE: case FIXED_POINT_TYPE:
case POINTER_TYPE: case REFERENCE_TYPE:
return targetm.calls.promote_function_mode (type, mode, punsignedp,
funtype,
for_return);
> @@ -895,6 +909,21 @@ promote_mode (const_tree type ATTRIBUTE_UNUSED,
> machine_mode mode,
> {
> case INTEGER_TYPE: case ENUMERAL_TYPE: case BOOLEAN_TYPE:
> case REAL_TYPE: case OFFSET_TYPE: case FIXED_POINT_TYPE:
> + case BITINT_TYPE:
> + /* Handle _BitInt(N) that does not require promotion. */
> + if (code == BITINT_TYPE)
> + {
> + if (TYPE_MODE (type) == BLKmode)
> + return mode;
> +
> + struct bitint_info info;
> + bool ok = targetm.c.bitint_type_info (TYPE_PRECISION (type), &info);
> + gcc_assert (ok);
> +
> + if (!info.extended)
> + return mode;
> + }
> +
> /* Values of these types always have scalar mode. */
> smode = as_a <scalar_mode> (mode);
> PROMOTE_MODE (smode, unsignedp, type);
And here similarly.
Jakub
