Commit Graph

10 Commits

Author SHA1 Message Date
Duncan Sands
1978426a94 Revert r70876 and add a testcase (@c7) showing the problem:
bits captured, but the pointer marked nocapture.  In fact
I now recall that this problem is why only readnone functions
returning void were considered before!  However keep a small
fix that was also in r70876: a readnone function returning
void can result in bits being captured if it unwinds, so
test for this.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@71168 91177308-0d34-0410-b5e6-96231b3b80d8
2009-05-07 18:08:34 +00:00
Duncan Sands
cfd0ebea27 Fix PR3754: don't mark functions that wrap MallocInst with
the readnone.  Since MallocInst is scheduled for deletion
it doesn't seem worth doing anything more subtle, such as
having mayWriteToMemory return true for MallocInst.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@71077 91177308-0d34-0410-b5e6-96231b3b80d8
2009-05-06 08:42:00 +00:00
Mike Stump
fe095f39e7 Restore minor deletion.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@70892 91177308-0d34-0410-b5e6-96231b3b80d8
2009-05-04 18:40:41 +00:00
Duncan Sands
b0cea8ff39 Remove alloca tracking from nocapture analysis. Not only
was it not very helpful, it was also wrong!  The problem
is shown in the testcase: the alloca might be passed to
a nocapture callee which dereferences it and returns the
original pointer.  But because it was a nocapture call we
think we don't need to track its uses, but we do.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@61876 91177308-0d34-0410-b5e6-96231b3b80d8
2009-01-07 19:39:06 +00:00
Duncan Sands
338cd6ba6e When calculating 'nocapture' argument attributes, allow
the argument to be stored to an alloca by tracking uses
of the alloca.  This occurs 4 times (out of 7121, 0.05%)
in MultiSource/Applications, so may not be worth it.  On
the other hand, it is easy to do and fairly cheap.  The
functions it helps are: W_addcom and W_addlit in spiff;
process_args (argv) in d (make_dparser); ercPixConcealIMB
in JM/ldecod.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@61570 91177308-0d34-0410-b5e6-96231b3b80d8
2009-01-02 11:54:37 +00:00
Nick Lewycky
8439653dfc Remove the cyclic part of this test, it was passing for the wrong
reason. Two functions which mutually require each other to be nocapture 
are not currently supported.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@61553 91177308-0d34-0410-b5e6-96231b3b80d8
2009-01-02 03:52:27 +00:00
Nick Lewycky
6b05686283 Make adding nocapture a bit stronger. FreeInst is nocapture. Also,
functions that don't write can't leak a pointer except through 
the return value, so a void readonly function is implicitly nocapture.

Test these, and add a test that verifies that f1 calling f2 with an 
otherwise dead pointer gets both of them marked nocapture.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@61552 91177308-0d34-0410-b5e6-96231b3b80d8
2009-01-02 03:46:56 +00:00
Duncan Sands
29ab02b2c2 Add tests for two types of traps that escape analysis
might one day fall into.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@61549 91177308-0d34-0410-b5e6-96231b3b80d8
2009-01-02 00:55:51 +00:00
Duncan Sands
1010941954 Look through phi nodes and select instructions when
calculating nocapture attributes.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@61535 91177308-0d34-0410-b5e6-96231b3b80d8
2008-12-31 20:21:34 +00:00
Duncan Sands
9e89ba31f1 Rename AddReadAttrs to FunctionAttrs, and teach it how
to work out (in a very simplistic way) which function
arguments (pointer arguments only) are only dereferenced
and so do not escape.  Mark such arguments 'nocapture'.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@61525 91177308-0d34-0410-b5e6-96231b3b80d8
2008-12-31 16:14:43 +00:00