Hi!
On Tue, Sep 12, 2023 at 05:27:30PM +0000, Joseph Myers wrote:
> On Tue, 12 Sep 2023, Jakub Jelinek via Gcc-patches wrote:
>
> > And by ensuring we never create 1-bit signed BITINT_TYPE e.g. the backends
> > don't need to worry about them.
> >
> > But I admit I don't feel strongly about that.
> >
> > Joseph, what do you think about this?
>
> I think it's appropriate to avoid 1-bit signed BITINT_TYPE consistently.
Here is a patch which does that. In addition to the previously changed two
hunks it also adds a checking assertion that we don't create
signed _BitInt(0), unsigned _BitInt(0) or signed _BitInt(1) types.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
2023-09-18 Jakub Jelinek <ja...@redhat.com>
gcc/
* tree.cc (build_bitint_type): Assert precision is not 0, or
for signed types 1.
(signed_or_unsigned_type_for): Return INTEGER_TYPE for signed variant
of unsigned _BitInt(1).
gcc/c-family/
* c-common.cc (c_common_signed_or_unsigned_type): Return INTEGER_TYPE
for signed variant of unsigned _BitInt(1).
--- gcc/tree.cc.jj 2023-09-11 17:01:17.612714178 +0200
+++ gcc/tree.cc 2023-09-18 12:36:37.598912717 +0200
@@ -7179,6 +7179,8 @@ build_bitint_type (unsigned HOST_WIDE_IN
{
tree itype, ret;
+ gcc_checking_assert (precision >= 1 + !unsignedp);
+
if (unsignedp)
unsignedp = MAX_INT_CACHED_PREC + 1;
@@ -11096,7 +11098,7 @@ signed_or_unsigned_type_for (int unsigne
else
return NULL_TREE;
- if (TREE_CODE (type) == BITINT_TYPE)
+ if (TREE_CODE (type) == BITINT_TYPE && (unsignedp || bits > 1))
return build_bitint_type (bits, unsignedp);
return build_nonstandard_integer_type (bits, unsignedp);
}
--- gcc/c-family/c-common.cc.jj 2023-09-11 17:01:17.517715431 +0200
+++ gcc/c-family/c-common.cc 2023-09-18 12:35:06.829126858 +0200
@@ -2739,7 +2739,9 @@ c_common_signed_or_unsigned_type (int un
|| TYPE_UNSIGNED (type) == unsignedp)
return type;
- if (TREE_CODE (type) == BITINT_TYPE)
+ if (TREE_CODE (type) == BITINT_TYPE
+ /* signed _BitInt(1) is invalid, avoid creating that. */
+ && (unsignedp || TYPE_PRECISION (type) > 1))
return build_bitint_type (TYPE_PRECISION (type), unsignedp);
#define TYPE_OK(node) \
Jakub
