Daniel,
I'm not a GCC guru, so I had some problems picking up the restrict
qualifiers for argument types in llvm-gcc's type conversion routines.
It seems that for C the qualifier is kept with the argument type, but
in C++ it's only available in the declaration and is not kept with
the types. Is there a better/proper way to get access to these
qualifiers?
--
Chris
On Jul 31, 2007, at 8:27 AM, Daniel Berlin wrote:
On 7/31/07, Dan Gohman <[EMAIL PROTECTED]> wrote:
Log:
Teach BasicAA about noalias function parameters. Passes all of
DejaGNU and test-suite.
I just grepped through LLVM's test-suite and didn't find any uses
of the
restrict keyword though...
There are a few you could snag from GCC's testsuite, because we
started with an implementation that had the exact same problems you've
noted below.
So for an alias query where one of the two pointers is noalias and
the
other is not, and the non-noalias one doesn't have a base object that
basicaa can find, the answer should be MayAlias. A more advanced pass
could try to prove that the non-noalias pointer couldn't possibly be
"based on" the noalias one by examining all its uses, though the
specific
example here would defy such analysis.
This is also what we eventually did with GCC.
Note that your function call example is not just "not disallowed", it
is explicitly allowed. It is the one case you are allowed to carry
restricted pointers outside the block they are in.
See C99 6.7.3.1 #12
There is a weird issue in restrict where gcc doesn't "check for
correctness of input code", and i doubt LLVM can either (at least, not
easily). This is that block nesting can introduce valid restricted
pointers in the nested block that would have otherwise been invalid.
IIRC, anyway :)
We of course, eliminate lexical scoping. For safety sake, we just
assume that if they have come up with assignments between restricted
pointers, that they are legal.
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Christopher Lamb
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