58 Commits

Author SHA1 Message Date
Duncan Sands
c7affb0a8f Load tracking means that the value analyzed may
not have pointer type.  In particular, it may
be the condition argument for a select or a GEP
index.  While I was unable to construct a testcase
for which some bits of the original pointer are
captured due to one of these, it's very very close
to being possible - so play safe and exclude these
possibilities.

llvm-svn: 61580
2009-01-02 15:16:38 +00:00
Duncan Sands
b193a37cd3 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.

llvm-svn: 61570
2009-01-02 11:54:37 +00:00
Duncan Sands
cefc8604aa Improve comments and reorganize a bit - no functionality
change.

llvm-svn: 61569
2009-01-02 11:46:24 +00:00
Nick Lewycky
7e82055e88 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.

llvm-svn: 61552
2009-01-02 03:46:56 +00:00
Duncan Sands
1f11d2bbc1 Mention that this pass does escape analysis in the
leading comments.

llvm-svn: 61548
2009-01-01 20:45:19 +00:00
Duncan Sands
163848021b Look through phi nodes and select instructions when
calculating nocapture attributes.

llvm-svn: 61535
2008-12-31 20:21:34 +00:00
Duncan Sands
df128eb477 Don't analyze arguments already marked 'nocapture'.
llvm-svn: 61532
2008-12-31 18:08:59 +00:00
Duncan Sands
44c8cd97a5 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'.

llvm-svn: 61525
2008-12-31 16:14:43 +00:00