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TargetProperties.td had a few settings listed as signed integral values,
but the Target.cpp methods reading those values were reading them as
unsigned. e.g. target.max-memory-read-size, some accesses of
target.max-children-count, still today, previously
target.max-string-summary-length.
After Jonas' change to use templates to read these values in
https://reviews.llvm.org/D149774, when the code tried to fetch these
values, we'd eventually end up calling OptionValue::GetAsUInt64 which
checks that the value is actually a UInt64 before returning it; finding
that it was an SInt64, it would drop the user setting and return the
default value. This manifested as a bug that target.max-memory-read-size
is never used for memory read.
target.max-children-count is less straightforward, where one read of
that setting was fetching it as an int64_t, the other as a uint64_t.
I suspect all of these settings were originally marked as SInt64 so a
user could do -1 for "infinite", getting it static_cast to a UINT64_MAX
value along the way. I can't find any documentation for this behavior,
but it seems like something Greg would have done. We've partially lost
that behavior already via
https://github.com/llvm/llvm-project/pull/72233 for
target.max-string-summary-length, and this further removes it.
We're still fetching UInt64's and returning them as uint32_t's but I'm
not overly pressed about someone setting a count/size limit over 4GB.
I added a simple API test for the memory read setting limit.
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