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Commit Graph

181 Commits

Author SHA1 Message Date
Duncan Sands
5aeb9b727a Generalize some alias analysis logic from atomic
intrinsics to any IntrWriteArgMem intrinsics.

llvm-svn: 64551
2009-02-14 10:56:35 +00:00
Nick Lewycky
f6c8dc0825 BasicAA was making the assumption that a local allocation which hadn't escaped
couldn't ever be the return of call instruction. However, it's quite possible
that said local allocation is itself the return of a function call. That's
what malloc and calloc are for, actually.

llvm-svn: 64442
2009-02-13 07:06:27 +00:00
Owen Anderson
acbec98578 Refactor my previous change to maintain the distinction between AliasAnalysis and BasicAliasAnalysis. This involves some wider changes because it
folds away some never-used methods.

llvm-svn: 63900
2009-02-05 23:36:27 +00:00
Owen Anderson
c418b82207 Finish making AliasAnalysis aware of the fact that most atomic intrinsics only dereference their arguments, and enhance
BasicAA to make use of this fact when computing ModRef info.

llvm-svn: 63718
2009-02-04 05:16:46 +00:00
Dan Gohman
bf5427a7f0 Move isIdentifiedObject and isNoAliasCall into AliasAnalysis.cpp since
they are useful to analyses other than BasicAliasAnalysis.cpp. Include
the full comment for isIdentifiedObject in the header file. Thanks to
Chris for suggeseting this.

llvm-svn: 63589
2009-02-03 01:28:32 +00:00
Dan Gohman
50283ce80b Fix a post-RA scheduling dependency bug.
If a MachineInstr doesn't have a memoperand but has an opcode that
is known to load or store, assume its memory reference may alias
*anything*, including stack slots which the compiler completely
controls.

To partially compensate for this, teach the ScheduleDAG building
code to do basic getUnderlyingValue analysis. This greatly
reduces the number of instructions that require restrictive
dependencies. This code will need to be revisited when we start
doing real alias analysis, but it should suffice for now.

llvm-svn: 63370
2009-01-30 02:49:14 +00:00
Duncan Sands
ddfeabbab7 BasicAliasAnalysis and FunctionAttrs were both
doing very similar pointer capture analysis.
Factor out the common logic.  The new version
is from FunctionAttrs since it does a better
job than the version in BasicAliasAnalysis

llvm-svn: 62461
2009-01-18 12:19:30 +00:00
Gabor Greif
6a02ecbd29 add a comment
llvm-svn: 62436
2009-01-18 00:27:21 +00:00
Duncan Sands
bcdbfb63dc Rename getABITypeSize to getTypePaddedSize, as
suggested by Chris.

llvm-svn: 62099
2009-01-12 20:38:59 +00:00
Chris Lattner
ed4ee47a0d make tblgen autogenerate the nocapture intrinsics for
llvm.memcpy/memset/memmove.  This allows removal of some 
hackish code from basicaa.

llvm-svn: 62071
2009-01-12 02:41:37 +00:00
Duncan Sands
4e1ee2698f When checking if an Argument escapes, check if
the argument is marked nocapture - no need to
analyze the argument if the answer is already
known!

llvm-svn: 61753
2009-01-05 21:19:53 +00:00
Nick Lewycky
8f96b51785 Resubmit support for the 'nocapture' attribute.
The problematic part of this patch is that we were out of attribute bits,
requiring some fancy bit hacking to make it fit (by shrinking alignment)
without breaking existing users or the file format.

This change will require users to rebuild llvm-gcc to match llvm.

llvm-svn: 61239
2008-12-19 06:39:12 +00:00
Bill Wendling
f807a68f2e Temporarily revert r61019, r61030, and r61040. These were breaking LLVM Release
builds.

llvm-svn: 61094
2008-12-16 19:06:48 +00:00
Chris Lattner
0e79aa6595 Teach basicaa to use the nocapture attribute when possible. When the
intrinsics are properly marked nocapture, the fixme should be addressed.

llvm-svn: 61040
2008-12-15 18:59:22 +00:00
Chris Lattner
e2b5854e41 Allow basicaa to walk through geps with identical indices in
parallel, allowing it to decide that P/Q must alias if A/B
must alias in things like:
 P = gep A, 0, i, 1
 Q = gep B, 0, i, 1

This allows GVN to delete 62 more instructions out of 403.gcc.

llvm-svn: 60820
2008-12-10 01:04:47 +00:00
Chris Lattner
6a5e9eaa36 Teach BasicAA::getModRefInfo(CallSite, CallSite) some
tricks based on readnone/readonly functions.

Teach memdep to look past readonly calls when analyzing
deps for a readonly call.  This allows elimination of a
few more calls from 403.gcc:

before:
     63 gvn    - Number of instructions PRE'd
 153986 gvn    - Number of instructions deleted
  50069 gvn    - Number of loads deleted

after:
     63 gvn    - Number of instructions PRE'd
 153991 gvn    - Number of instructions deleted
  50069 gvn    - Number of loads deleted

5 calls isn't much, but this adds plumbing for the next change.

llvm-svn: 60794
2008-12-09 21:19:42 +00:00
Duncan Sands
982c6ed1d9 Fix comment typo.
llvm-svn: 60697
2008-12-08 14:01:59 +00:00
Chris Lattner
494eb47570 Some minor optimizations for isObjectSmallerThan.
llvm-svn: 60687
2008-12-08 06:28:54 +00:00
Nick Lewycky
b8b082166a Seriously strengthen the guarantee offered by noalias on a function's return
value. It must now be as if the pointer were allocated and has not escaped to
the caller. Thanks to Dan Gohman for pointing out the error in the original
and helping devise this definition.

llvm-svn: 59940
2008-11-24 05:00:44 +00:00
Nick Lewycky
47fa9bd187 Extend the 'noalias' attribute to function return values. This is intended to
indicate functions that allocate, such as operator new, or list::insert. The
actual definition is slightly less strict (for now).

No changes to the bitcode reader/writer, asm printer or verifier were needed.

llvm-svn: 59934
2008-11-24 03:41:24 +00:00
Duncan Sands
88d8323743 Factorize code: remove variants of "strip off
pointer bitcasts and GEP's", and centralize the
logic in Value::getUnderlyingObject.  The
difference with stripPointerCasts is that
stripPointerCasts only strips GEPs if all
indices are zero, while getUnderlyingObject
strips GEPs no matter what the indices are.

llvm-svn: 56922
2008-10-01 15:25:41 +00:00
Devang Patel
a3e9bf1bca s/ParameterAttributes/Attributes/g
llvm-svn: 56513
2008-09-23 23:03:40 +00:00
Dan Gohman
e1f9be27bc Tidy up several unbeseeming casts from pointer to intptr_t.
llvm-svn: 55779
2008-09-04 17:05:41 +00:00
Chris Lattner
0bc9e4aa8f simplify some code by using a helper function. This really really
wants a 'nocapture' predicate.

llvm-svn: 52304
2008-06-16 06:38:26 +00:00
Chris Lattner
35be1f6c83 move a bunch of predicates up into their own section
in this file, no other changes.

llvm-svn: 52303
2008-06-16 06:30:22 +00:00
Chris Lattner
12453dd555 Other parts of this code treat noalias arguments as objects for
the purposes of escape analysis.

llvm-svn: 52302
2008-06-16 06:28:01 +00:00
Chris Lattner
e987a3bdd1 If we are checking to see if the result of a call aliases a
pointer derived from a local allocation, if the local allocation
never escapes, the pointers can't alias.  This implements PR2436

llvm-svn: 52301
2008-06-16 06:19:11 +00:00
Chris Lattner
4e38446b34 Refactor basicaa's main alias function somethin' fierce.
This fixes several minor bugs (such as returning noalias
for comparisons between external weak functions an null) but
is mostly a cleanup.

llvm-svn: 52299
2008-06-16 06:10:11 +00:00
Wojciech Matyjewicz
06e4c8a420 Fixes PR2395. Looking for a constant in a GEP tail (when the first GEP
is longer than the second one) should stop after finding one. Added break 
instruction guarantees it. It also changes difference between offsets to 
absolute value of this difference in the condition.

llvm-svn: 51875
2008-06-02 17:26:12 +00:00
Dan Gohman
bab18cae46 Clean up the use of static and anonymous namespaces. This turned up
several things that were neither in an anonymous namespace nor static
but not intended to be global.

llvm-svn: 51017
2008-05-13 00:00:25 +00:00
Duncan Sands
79654e36ce Fix a "large integer implicitly truncated to unsigned type"
warning.

llvm-svn: 50033
2008-04-21 07:35:28 +00:00
Dale Johannesen
45e14f7753 Don't assume a tail call can't reference a byval
argument to the outer function, this isn't correct.

llvm-svn: 49731
2008-04-15 17:41:34 +00:00
Devang Patel
f15fe34521 Restore isCFGOnly property of various analysis passes.
llvm-svn: 48579
2008-03-20 02:25:21 +00:00
Devang Patel
5e8cbbea65 PassInfo keep tracks whether a pass is an analysis pass or not.
llvm-svn: 48554
2008-03-19 21:56:59 +00:00
Duncan Sands
1bba49ca55 Fix a compiler warning.
llvm-svn: 47328
2008-02-19 09:28:48 +00:00
Owen Anderson
3efff61819 In addition to arguments passed to it, memcpy (and all other calls) can ModRef pointers that alias their arguments as well. This fixes PR2057.
llvm-svn: 47317
2008-02-19 06:47:18 +00:00
Chris Lattner
57eff5b5f5 don't bother calling getUnderlyingObject for non-pointers.
llvm-svn: 47272
2008-02-18 17:28:21 +00:00
Owen Anderson
f3107c8546 Since we're not checking for the more general AllocationInst first, we need to explicitly check
that Object is an Argument before casting it to one.

llvm-svn: 47268
2008-02-18 10:11:00 +00:00
Owen Anderson
1b743c32fd This check is not correct for mallocs, so exclude them earlier.
llvm-svn: 47263
2008-02-18 09:11:02 +00:00
Owen Anderson
b0891af18b Fix a comment, and a bug where we weren't applying the tail call logic in cases that failed the first test.
llvm-svn: 47253
2008-02-18 03:52:21 +00:00
Owen Anderson
0ef73a5d06 Fix bugs that Chris noticed in my last patch.
llvm-svn: 47252
2008-02-18 02:31:23 +00:00
Chris Lattner
d5885d43ef bitcasts of pointers are always pointers.
If we see a memcpy of a pointer, make sure to check later
uses of the pointer as well.

llvm-svn: 47250
2008-02-18 02:11:28 +00:00
Owen Anderson
884f6801df Teach getModRefInfo that memcpy, memmove, and memset don't "capture" memory addresses.
Also, noalias arguments are be considered "like" stack allocated ones for this purpose, because
the only way they can be modref'ed is if they escape somewhere in the current function.

llvm-svn: 47247
2008-02-17 21:29:08 +00:00
Chris Lattner
2c3646ea4a getUnderlyingObject can return null, handle this.
llvm-svn: 46318
2008-01-24 19:07:10 +00:00
Chris Lattner
cd5013eb2f Teach basicaa that 'byval' arguments define a new memory location that
can't be aliased to other known objects.  This allows us to know that byval 
pointer args don't alias globals, etc.

llvm-svn: 46315
2008-01-24 18:00:32 +00:00
Chris Lattner
ad9a6ccb83 Remove attribution from file headers, per discussion on llvmdev.
llvm-svn: 45418
2007-12-29 20:36:04 +00:00
Wojciech Matyjewicz
d76f256282 Make these loops follow GetGEPOperands() behavior.
Let: %q = GEP %p, X, ...
If %p is a GEP, we can chase baseptr further, only if X==0.

llvm-svn: 44999
2007-12-13 16:22:58 +00:00
Chris Lattner
95f9743c43 Fix PR1782, patch by Wojtek Matyjewicz!
llvm-svn: 44733
2007-12-09 07:35:13 +00:00
Duncan Sands
1e2e4972ff Rather than having special rules like "intrinsics cannot
throw exceptions", just mark intrinsics with the nounwind
attribute.  Likewise, mark intrinsics as readnone/readonly
and get rid of special aliasing logic (which didn't use
anything more than this anyway).

llvm-svn: 44544
2007-12-03 20:06:50 +00:00
Duncan Sands
14f11d6836 Integrate the readonly/readnone logic more deeply
into alias analysis.  This meant updating the API
which now has versions of the getModRefBehavior,
doesNotAccessMemory and onlyReadsMemory methods
which take a callsite parameter.  These should be
used unless the callsite is not known, since in
general they can do a better job than the versions
that take a function.  Also, users should no longer
call the version of getModRefBehavior that takes
both a function and a callsite.  To reduce the
chance of misuse it is now protected.

llvm-svn: 44487
2007-12-01 07:51:45 +00:00