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Re: [PATCH, obvious?] Some minor nits in string folding functions
On 07/19/18 20:11, Jeff Law wrote:
> On 07/19/2018 12:04 PM, Bernd Edlinger wrote:
>> this fixes a few minor nits, which I spotted while
>> looking at the string folding functions:
>> string_constant: Remove impossible check: TREE_CODE (arg)
>> can't be COMPONENT_REF and MEM_REF at the same time.
> Shouldn't they all be != tests? Though clearly this code isn't being
> tested by anything.
I think a COMPONENT_REF would be possible for strlen(&a.b).
It looks like that removing this check will be the best option.
Unless Martin has a different idea of course.
>> c_strlen: maxelts is (signed) HOST_WIDE_INT, therefore
>> use tree_to_shwi.
> One could argue maxelts should be unsigned.
I would agree, but a few lines later I see:
/* Offset from the beginning of the string in elements. */
/* We have a known offset into the string. Start searching there for
a null character if we can represent it as a single HOST_WIDE_INT. */
if (byteoff == 0)
eltoff = 0;
else if (! tree_fits_shwi_p (byteoff))
eltoff = -1;
eltoff = tree_to_shwi (byteoff) / eltsize;
/* If the offset is known to be out of bounds, warn, and call strlen at
if (eltoff < 0 || eltoff > maxelts)
This would be doing signed/unsigned comparisons then.
Maybe that is the reason why ?
>> c_getstr: tree_to_uhwi needs to be protected by
> Looks correct to me.
>> BTW: c_getstr uses string_constant which appears to be
>> able to extract wide char string initializers, but c_getstr
>> does not seem to be prepared for wide char strings:
>> else if (string[string_length - 1] != '\0')
>> /* Support only properly NUL-terminated strings but handle
>> consecutive strings within the same array, such as the six
>> substrings in "1\0002\0003". */
>> return NULL;
> Seems like a goof to me.
Well, maybe this could be a gcc_assert instead. Normal strings should always
be zero-terminated, even wide character strings.
Anyways probably for another time.