On 7/7/21 1:38 AM, Richard Biener wrote:
On Tue, Jul 6, 2021 at 5:47 PM Martin Sebor via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
Ping: https://gcc.gnu.org/pipermail/gcc-patches/2021-June/573349.html
+ if (TREE_CODE (axstype) != UNION_TYPE)
what about QUAL_UNION_TYPE? (why constrain union type accesses
here - note you don't seem to constrain accesses of union members here)
I didn't know a QUAL_UNION_TYPE was a thing. Removing the test
doesn't seem to cause any regressions so let me do that in a followup.
+ if (tree access_size = TYPE_SIZE_UNIT (axstype))
+ /* The byte size of the array has already been determined above
+ based on a pointer ARG. Set ELTSIZE to the size of the type
+ it points to and REFTYPE to the array with the size, rounded
+ down as necessary. */
+ if (POINTER_TYPE_P (reftype))
+ reftype = TREE_TYPE (reftype);
+ if (TREE_CODE (reftype) == ARRAY_TYPE)
+ reftype = TREE_TYPE (reftype);
+ if (tree refsize = TYPE_SIZE_UNIT (reftype))
+ if (TREE_CODE (refsize) == INTEGER_CST)
+ eltsize = wi::to_offset (refsize);
probably pre-existing but the pointer indirection is definitely confusing
me again and again given the variable is named 'reftype' - obviously
an access to a pointer does not have any element size. Possibly the
paths arriving here ensure somehow that the only case is when
reftype is not the access type but a pointer to the accessed memory.
"jump-threading" the source might help me avoiding to trip over this
again and again ...
I agree (it is confusing). There's more to simplify here. It's on
my to do list so let me see about this piece of code then.
The patch removes a lot of odd code, I like that. You know this code best
and it's hard to spot errors.
So OK, you'll deal with the fallout.
I certainly will. Pushed in r12-2132.
Thanks
Martin
Thanks,
Richard.
On 6/28/21 1:33 PM, Martin Sebor wrote:
Ping: https://gcc.gnu.org/pipermail/gcc-patches/2021-June/573349.html
On 6/21/21 4:25 PM, Martin Sebor wrote:
-Warray-bounds relies on similar logic as -Wstringop-overflow et al.,
but using its own algorithm, including its own bugs such as PR 100137.
The attached patch takes the first step toward unifying the logic
between the warnings. It changes a subset of -Warray-bounds to call
compute_objsize() to detect out-of-bounds indices. Besides fixing
the bug this also nicely simplifies the code and improves
the consistency between the informational messages printed by both
classes of warnings.
The changes to the test suite are extensive mainly because of
the different format of the diagnostics resulting from slightly
tighter bounds of offsets computed by the new algorithm, and in
smaller part because the change lets -Warray-bounds diagnose some
problems it previously missed due to the limitations of its own
solution.
The false positive reported in PR 100137 is a 10/11/12 regression
but this change is too intrusive to backport. I have a smaller
and more targeted patch I plan to backport in its stead.
Tested on x86_64-linux.
Martin
