Commit Graph

2016 Commits

Author SHA1 Message Date
Andrew Trick
8b7036b0f4 Factor SCEV traversal code so I can use it elsewhere. No functionality.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160203 91177308-0d34-0410-b5e6-96231b3b80d8
2012-07-13 23:33:03 +00:00
Nuno Lopes
0dff532fce fold PHI nodes in SizeOffsetEvaluator whenever possible.
Unfortunately this change requires the cache map to hold WeakVHs instead

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@159667 91177308-0d34-0410-b5e6-96231b3b80d8
2012-07-03 17:13:25 +00:00
Chandler Carruth
06cb8ed006 Move llvm/Support/IRBuilder.h -> llvm/IRBuilder.h
This was always part of the VMCore library out of necessity -- it deals
entirely in the IR. The .cpp file in fact was already part of the VMCore
library. This is just a mechanical move.

I've tried to go through and re-apply the coding standard's preferred
header sort, but at 40-ish files, I may have gotten some wrong. Please
let me know if so.

I'll be committing the corresponding updates to Clang and Polly, and
Duncan has DragonEgg.

Thanks to Bill and Eric for giving the green light for this bit of cleanup.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@159421 91177308-0d34-0410-b5e6-96231b3b80d8
2012-06-29 12:38:19 +00:00
Bill Wendling
16eeb6f5eb The DIBuilder class is just a wrapper around debug info creation
(a.k.a. MDNodes). The module doesn't belong in Analysis. Move it to the VMCore
instead.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@159414 91177308-0d34-0410-b5e6-96231b3b80d8
2012-06-29 08:32:07 +00:00
Nuno Lopes
41a3f25134 MemoryBuiltins:
- recognize C++ new(std::nothrow) friends
 - ignore ExtractElement and ExtractValue instructions in size/offset analysis (all easy cases are probably folded away before we get here)
 - also recognize realloc as noalias

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@159356 91177308-0d34-0410-b5e6-96231b3b80d8
2012-06-28 16:34:03 +00:00
Bill Wendling
0bcbd1df7a Move lib/Analysis/DebugInfo.cpp to lib/VMCore/DebugInfo.cpp and
include/llvm/Analysis/DebugInfo.h to include/llvm/DebugInfo.h.

The reasoning is because the DebugInfo module is simply an interface to the
debug info MDNodes and has nothing to do with analysis.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@159312 91177308-0d34-0410-b5e6-96231b3b80d8
2012-06-28 00:05:13 +00:00
Bill Wendling
494f8c6cfa Revamp how debugging information is emitted for debug info objects.
It's not necessary for each DI class to have its own copy of `print' and
`dump'. Instead, just give DIDescriptor those methods and have it call the
appropriate debugging printing routine based on the type of the debug
information.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@159237 91177308-0d34-0410-b5e6-96231b3b80d8
2012-06-26 22:57:33 +00:00
Andrew Trick
c9b1e25493 Enable the new LoopInfo algorithm by default.
The primary advantage is that loop optimizations will be applied in a
stable order. This helps debugging and unit test creation. It is also
a better overall implementation without pathologically bad performance
on deep functions.

On large functions (llvm-stress --size=200000 | opt -loops)
Before: 0.1263s
After:  0.0225s

On deep functions (after tweaking llvm-stress, thanks Nadav):
Before: 0.2281s
After:  0.0227s

See r158790 for more comments.

The loop tree is now consistently generated in forward order, but loop
passes are applied in reverse order over the program. If we have a
loop optimization that prefers forward order, that can easily be
achieved by adding a different type of LoopPassManager.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@159183 91177308-0d34-0410-b5e6-96231b3b80d8
2012-06-26 04:11:38 +00:00
Nuno Lopes
eb7c6865cd remove extractMallocCallFromBitCast, since it was tailor maded for its sole user. Update GlobalOpt accordingly.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@158952 91177308-0d34-0410-b5e6-96231b3b80d8
2012-06-22 00:25:01 +00:00
Nuno Lopes
2b3e958053 Add support for invoke to the MemoryBuiltin analysid.
Update comments accordingly.

Make instcombine remove useless invokes to C++'s 'new' allocation function (test attached).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@158937 91177308-0d34-0410-b5e6-96231b3b80d8
2012-06-21 21:25:05 +00:00
Nuno Lopes
10cefaab3f move some typedefs so that we don't polute the llvm namespace. this should appease the GCC buildbots
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@158924 91177308-0d34-0410-b5e6-96231b3b80d8
2012-06-21 16:58:41 +00:00
Nuno Lopes
9e72a79ef4 refactor the MemoryBuiltin analysis:
- provide more extensive set of functions to detect library allocation functions (e.g., malloc, calloc, strdup, etc)
 - provide an API to compute the size and offset of an object pointed by

Move a few clients (GVN, AA, instcombine, ...) to the new API.
This implementation is a lot more aggressive than each of the custom implementations being replaced.

Patch reviewed by Nick Lewycky and Chandler Carruth, thanks.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@158919 91177308-0d34-0410-b5e6-96231b3b80d8
2012-06-21 15:45:28 +00:00
Andrew Trick
b9598e41bc Restructure PopulateLoopsDFS::insertIntoLoop.
As Nadav pointed out the first implementation was obscure.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@158862 91177308-0d34-0410-b5e6-96231b3b80d8
2012-06-20 22:18:33 +00:00
Andrew Trick
60c7d5bc2c Add "extern template" declarations now that we use explicit instantiation.
This is supported by gcc and clang, but guarded by a macro for MSVC 2008.

The extern template declaration is not necessary but generally good
form. It can avoid extra instantiations of the template methods
defined inline.

The EXTERN_TEMPLATE_INSTANTIATION macro could probably be generalized to
handle multiple template parameters if someone thinks it's worthwhile.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@158840 91177308-0d34-0410-b5e6-96231b3b80d8
2012-06-20 20:17:20 +00:00
Chandler Carruth
305b515c27 Remove 'static' from inline functions defined in header files.
There is a pretty staggering amount of this in LLVM's header files, this
is not all of the instances I'm afraid. These include all of the
functions that (in my build) are used by a non-static inline (or
external) function. Specifically, these issues were caught by the new
'-Winternal-linkage-in-inline' warning.

I'll try to just clean up the remainder of the clearly redundant "static
inline" cases on functions (not methods!) defined within headers if
I can do so in a reliable way.

There were even several cases of a missing 'inline' altogether, or my
personal favorite "static bool inline". Go figure. ;]

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@158800 91177308-0d34-0410-b5e6-96231b3b80d8
2012-06-20 08:39:33 +00:00
Andrew Trick
37aa33bc11 A new algorithm for computing LoopInfo. Temporarily disabled.
-stable-loops enables a new algorithm for generating the Loop
forest. It differs from the original algorithm in a few respects:

- Not determined by use-list order.
- Initially guarantees RPO order of block and subloops.
- Linear in the number of CFG edges.
- Nonrecursive.

I didn't want to change the LoopInfo API yet, so the block lists are
still inclusive. This seems strange to me, and it means that building
LoopInfo is not strictly linear, but it may not be a problem in
practice. At least the block lists start out in RPO order now. In the
future we may add an attribute or wrapper analysis that allows other
passes to assume RPO order.

The primary motivation of this work was not to optimize LoopInfo, but
to allow reproducing performance issues by decomposing the compilation
stages. I'm often unable to do this with the current LoopInfo, because
the loop tree order determines Loop pass order. Serializing the IR
tends to invert the order, which reverses the optimization order. This
makes it nearly impossible to debug interdependent loop optimizations
such as LSR.

I also believe this will provide more stable performance results across time.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@158790 91177308-0d34-0410-b5e6-96231b3b80d8
2012-06-20 05:23:33 +00:00
Andrew Trick
cbf24b4e58 Move the implementation of LoopInfo into LoopInfoImpl.h.
The implementation only needs inclusion from LoopInfo.cpp and
MachineLoopInfo.cpp. Clients of the interface should only include the
interface. This makes the interface readable and speeds up rebuilds
after modifying the implementation.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@158787 91177308-0d34-0410-b5e6-96231b3b80d8
2012-06-20 03:42:09 +00:00
Benjamin Kramer
95a9d93772 Round 2 of dead private variable removal.
LLVM is now -Wunused-private-field clean except for
- lib/MC/MCDisassembler/Disassembler.h. Not sure why it keeps all those unaccessible fields.
- gtest.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@158096 91177308-0d34-0410-b5e6-96231b3b80d8
2012-06-06 19:47:08 +00:00
Benjamin Kramer
d9b0b02561 Fix typos found by http://github.com/lyda/misspell-check
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@157885 91177308-0d34-0410-b5e6-96231b3b80d8
2012-06-02 10:20:22 +00:00
Eric Christopher
fc4199bf4a Add support for enum forward declarations.
Part of rdar://11570854

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@157786 91177308-0d34-0410-b5e6-96231b3b80d8
2012-06-01 00:22:32 +00:00
Benjamin Kramer
6cf07a80ff Teach SCEV's icmp simplification logic that a-b == 0 is equivalent to a == b.
This also required making recursive simplifications until
nothing changes or a hard limit (currently 3) is hit.

With the simplification in place indvars can canonicalize
loops of the form
for (unsigned i = 0; i < a-b; ++i)
into
for (unsigned i = 0; i != a-b; ++i)
which used to fail because SCEV created a weird umax expr
for the backedge taken count.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@157701 91177308-0d34-0410-b5e6-96231b3b80d8
2012-05-30 18:32:23 +00:00
Eric Christopher
bb0f6eac1f Add support for C++11 enum classes in llvm.
Part of rdar://11496790

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@157303 91177308-0d34-0410-b5e6-96231b3b80d8
2012-05-23 00:09:20 +00:00
Eric Christopher
791e629dee Actually support DW_TAG_rvalue_reference_type that we were trying
to generate out of the front end.

rdar://11479676

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@157094 91177308-0d34-0410-b5e6-96231b3b80d8
2012-05-19 01:36:37 +00:00
Andrew Trick
8aa22019ca SCEV: Add MarkPendingLoopPredicates to avoid recursive isImpliedCond.
getUDivExpr attempts to simplify by checking for overflow.
isLoopEntryGuardedByCond then evaluates the loop predicate which
may lead to the same getUDivExpr causing endless recursion.

Fixes PR12868: clang 3.2 segmentation fault.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@157092 91177308-0d34-0410-b5e6-96231b3b80d8
2012-05-19 00:48:25 +00:00
Chad Rosier
3a884f5c17 Move the capture analysis from MemoryDependencyAnalysis to a more general place
so that it can be reused in MemCpyOptimizer.  This analysis is needed to remove
an unnecessary memcpy when returning a struct into a local variable.
rdar://11341081
PR12686


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@156776 91177308-0d34-0410-b5e6-96231b3b80d8
2012-05-14 20:35:04 +00:00
Dan Gohman
b401e3bd16 Teach DeadStoreElimination to eliminate exit-block stores with phi addresses.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@156558 91177308-0d34-0410-b5e6-96231b3b80d8
2012-05-10 18:57:38 +00:00
Eric Christopher
599da5ec01 Update comment.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@156404 91177308-0d34-0410-b5e6-96231b3b80d8
2012-05-08 18:55:57 +00:00
Chandler Carruth
7c52c97a22 Rename the Region::block_iterator to Region::block_node_iterator, and
add a new Region::block_iterator which actually iterates over the basic
blocks of the region.

The old iterator, now call 'block_node_iterator' iterates over
RegionNodes which contain a single basic block. This works well with the
GraphTraits-based iterator design, however most users actually want an
iterator over the BasicBlocks inside these RegionNodes. Now the
'block_iterator' is a wrapper which exposes exactly this interface.
Internally it uses the block_node_iterator to walk all nodes which are
single basic blocks, but transparently unwraps the basic block to make
user code simpler.

While this patch is a bit of a wash, most of the updates are to internal
users, not external users of the RegionInfo. I have an accompanying
patch to Polly that is a strict simplification of every user of this
interface, and I'm working on a pass that also wants the same simplified
interface.

This patch alone should have no functional impact.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@156202 91177308-0d34-0410-b5e6-96231b3b80d8
2012-05-04 20:55:23 +00:00
Chandler Carruth
d5003cafd6 A pile of long over-due refactorings here. There are some very, *very*
minor behavior changes with this, but nothing I have seen evidence of in
the wild or expect to be meaningful. The real goal is unifying our logic
and simplifying the interfaces. A summary of the changes follows:

- Make 'callIsSmall' actually accept a callsite so it can handle
  intrinsics, and simplify callers appropriately.
- Nuke a completely bogus declaration of 'callIsSmall' that was still
  lurking in InlineCost.h... No idea how this got missed.
- Teach the 'isInstructionFree' about the various more intelligent
  'free' heuristics that got added to the inline cost analysis during
  review and testing. This mostly surrounds int->ptr and ptr->int casts.
- Switch most of the interesting parts of the inline cost analysis that
  were essentially computing 'is this instruction free?' to use the code
  metrics routine instead. This way we won't keep duplicating logic.

All of this is motivated by the desire to allow other passes to compute
a roughly equivalent 'cost' metric for a particular basic block as the
inline cost analysis. Sadly, re-using the same analysis for both is
really messy because only the actual inline cost analysis is ever going
to go to the contortions required for simplification, SROA analysis,
etc.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@156140 91177308-0d34-0410-b5e6-96231b3b80d8
2012-05-04 00:58:03 +00:00
Nuno Lopes
252ef566e8 add support for calloc to objectsize lowering
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@156102 91177308-0d34-0410-b5e6-96231b3b80d8
2012-05-03 21:19:58 +00:00
Eric Christopher
216432df5a Allow forward declarations to take a context. This helps the debugger
find forward declarations in the context that the actual definition
will occur.

rdar://11291658

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@155380 91177308-0d34-0410-b5e6-96231b3b80d8
2012-04-23 19:00:11 +00:00
Dan Gohman
558ece284c Add forms of dominates and isReachableFromEntry that accept a Use
directly instead of a user Instruction. This allows them to test
whether a def dominates a particular operand if the user instruction
is a PHI.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@154631 91177308-0d34-0410-b5e6-96231b3b80d8
2012-04-12 23:31:46 +00:00
Benjamin Kramer
f7c3e5f051 FoldingSet: Push the hash through FoldingSetTraits::Equals, so clients can use it.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@154496 91177308-0d34-0410-b5e6-96231b3b80d8
2012-04-11 14:06:47 +00:00
Andrew Trick
d9fc1ce809 Fix 12513: Loop unrolling breaks with indirect branches.
Take this opportunity to generalize the indirectbr bailout logic for
loop transformations. CFG transformations will never get indirectbr
right, and there's no point trying.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@154386 91177308-0d34-0410-b5e6-96231b3b80d8
2012-04-10 05:14:42 +00:00
David Chisnall
b381578fcb Reintroduce InlineCostAnalyzer::getInlineCost() variant with explicit callee
parameter until we have a more sensible API for doing the same thing.

Reviewed by Chandler.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@154180 91177308-0d34-0410-b5e6-96231b3b80d8
2012-04-06 17:27:41 +00:00
Rafael Espindola
26c8dcc692 Always compute all the bits in ComputeMaskedBits.
This allows us to keep passing reduced masks to SimplifyDemandedBits, but
know about all the bits if SimplifyDemandedBits fails. This allows instcombine
to simplify cases like the one in the included testcase.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@154011 91177308-0d34-0410-b5e6-96231b3b80d8
2012-04-04 12:51:34 +00:00
Eric Christopher
6126a1e189 Add a line number for the scope of the function (starting at the first
brace) so that we get more accurate line number information about the
declaration of a given function and the line where the function
first starts.

Part of rdar://11026482

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@153916 91177308-0d34-0410-b5e6-96231b3b80d8
2012-04-03 00:43:49 +00:00
Rafael Espindola
1c8cf21d0c Make dominatedBySlowTreeWalk private and assert cases handled by the caller.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@153905 91177308-0d34-0410-b5e6-96231b3b80d8
2012-04-02 22:37:54 +00:00
Rafael Espindola
5004e9849a Add missing 'd'.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@153872 91177308-0d34-0410-b5e6-96231b3b80d8
2012-04-02 13:02:57 +00:00
Chandler Carruth
caa2c40a57 Start cleaning up the InlineCost class. This switches to sentinel values
rather than a bitfield, a great suggestion by Chris during code review.

There is still quite a bit of cruft in the interface, but that requires
sorting out some awkward uses of the cost inside the actual inliner.

No functionality changed intended here.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@153853 91177308-0d34-0410-b5e6-96231b3b80d8
2012-04-01 22:44:09 +00:00
Rafael Espindola
6226c49bde Add a workaround for building with old versions of clang.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@153820 91177308-0d34-0410-b5e6-96231b3b80d8
2012-03-31 21:54:20 +00:00
Rafael Espindola
95d594cac3 Teach CodeGen's version of computeMaskedBits to understand the range metadata.
This is the CodeGen equivalent of r153747. I tested that there is not noticeable
performance difference with any combination of -O0/-O2 /-g when compiling
gcc as a single compilation unit.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@153817 91177308-0d34-0410-b5e6-96231b3b80d8
2012-03-31 18:14:00 +00:00
Chandler Carruth
45de584b4f Remove a bunch of empty, dead, and no-op methods from all of these
interfaces. These methods were used in the old inline cost system where
there was a persistent cache that had to be updated, invalidated, and
cleared. We're now doing more direct computations that don't require
this intricate dance. Even if we resume some level of caching, it would
almost certainly have a simpler and more narrow interface than this.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@153813 91177308-0d34-0410-b5e6-96231b3b80d8
2012-03-31 12:48:08 +00:00
Chandler Carruth
f2286b0152 Initial commit for the rewrite of the inline cost analysis to operate
on a per-callsite walk of the called function's instructions, in
breadth-first order over the potentially reachable set of basic blocks.

This is a major shift in how inline cost analysis works to improve the
accuracy and rationality of inlining decisions. A brief outline of the
algorithm this moves to:

- Build a simplification mapping based on the callsite arguments to the
  function arguments.
- Push the entry block onto a worklist of potentially-live basic blocks.
- Pop the first block off of the *front* of the worklist (for
  breadth-first ordering) and walk its instructions using a custom
  InstVisitor.
- For each instruction's operands, re-map them based on the
  simplification mappings available for the given callsite.
- Compute any simplification possible of the instruction after
  re-mapping, and store that back int othe simplification mapping.
- Compute any bonuses, costs, or other impacts of the instruction on the
  cost metric.
- When the terminator is reached, replace any conditional value in the
  terminator with any simplifications from the mapping we have, and add
  any successors which are not proven to be dead from these
  simplifications to the worklist.
- Pop the next block off of the front of the worklist, and repeat.
- As soon as the cost of inlining exceeds the threshold for the
  callsite, stop analyzing the function in order to bound cost.

The primary goal of this algorithm is to perfectly handle dead code
paths. We do not want any code in trivially dead code paths to impact
inlining decisions. The previous metric was *extremely* flawed here, and
would always subtract the average cost of two successors of
a conditional branch when it was proven to become an unconditional
branch at the callsite. There was no handling of wildly different costs
between the two successors, which would cause inlining when the path
actually taken was too large, and no inlining when the path actually
taken was trivially simple. There was also no handling of the code
*path*, only the immediate successors. These problems vanish completely
now. See the added regression tests for the shiny new features -- we
skip recursive function calls, SROA-killing instructions, and high cost
complex CFG structures when dead at the callsite being analyzed.

Switching to this algorithm required refactoring the inline cost
interface to accept the actual threshold rather than simply returning
a single cost. The resulting interface is pretty bad, and I'm planning
to do lots of interface cleanup after this patch.

Several other refactorings fell out of this, but I've tried to minimize
them for this patch. =/ There is still more cleanup that can be done
here. Please point out anything that you see in review.

I've worked really hard to try to mirror at least the spirit of all of
the previous heuristics in the new model. It's not clear that they are
all correct any more, but I wanted to minimize the change in this single
patch, it's already a bit ridiculous. One heuristic that is *not* yet
mirrored is to allow inlining of functions with a dynamic alloca *if*
the caller has a dynamic alloca. I will add this back, but I think the
most reasonable way requires changes to the inliner itself rather than
just the cost metric, and so I've deferred this for a subsequent patch.
The test case is XFAIL-ed until then.

As mentioned in the review mail, this seems to make Clang run about 1%
to 2% faster in -O0, but makes its binary size grow by just under 4%.
I've looked into the 4% growth, and it can be fixed, but requires
changes to other parts of the inliner.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@153812 91177308-0d34-0410-b5e6-96231b3b80d8
2012-03-31 12:42:41 +00:00
Rafael Espindola
092c5ccf5b Handle unreachable code in the dominates functions. This changes users when
needed for correctness, but still doesn't clean up code that now unnecessary
checks for reachability.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@153755 91177308-0d34-0410-b5e6-96231b3b80d8
2012-03-30 16:46:21 +00:00
Eric Christopher
b8ca988743 Add support for objc property decls according to the page at:
http://llvm.org/docs/SourceLevelDebugging.html#objcproperty

including type and DECL. Expand the metadata needed accordingly.

rdar://11144023

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@153639 91177308-0d34-0410-b5e6-96231b3b80d8
2012-03-29 08:42:56 +00:00
Rafael Espindola
eede6c9075 Use the isReachableFromEntry method.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@153400 91177308-0d34-0410-b5e6-96231b3b80d8
2012-03-24 23:29:27 +00:00
Rafael Espindola
42c487d2e5 Avoid using dominatedBySlowTreeWalk.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@153398 91177308-0d34-0410-b5e6-96231b3b80d8
2012-03-24 22:52:25 +00:00
Chandler Carruth
6b980541df Refactor the interface to recursively simplifying instructions to be tad
bit simpler by handling a common case explicitly.

Also, refactor the implementation to use a worklist based walk of the
recursive users, rather than trying to use value handles to detect and
recover from RAUWs during the recursive descent. This fixes a very
subtle bug in the previous implementation where degenerate control flow
structures could cause mutually recursive instructions (PHI nodes) to
collapse in just such a way that From became equal to To after some
amount of recursion. At that point, we hit the inf-loop that the assert
at the top attempted to guard against. This problem is defined away when
not using value handles in this manner. There are lots of comments
claiming that the WeakVH will protect against just this sort of error,
but they're not accurate about the actual implementation of WeakVHs,
which do still track RAUWs.

I don't have any test case for the bug this fixes because it requires
running the recursive simplification on unreachable phi nodes. I've no
way to either run this or easily write an input that triggers it. It was
found when using instruction simplification inside the inliner when
running over the nightly test-suite.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@153393 91177308-0d34-0410-b5e6-96231b3b80d8
2012-03-24 21:11:24 +00:00
Andrew Trick
1508e5e049 Cleanup IVUsers::addUsersIfInteresting.
Keep the public interface clean, even though LLVM proper does not
currently use it.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@153263 91177308-0d34-0410-b5e6-96231b3b80d8
2012-03-22 17:47:33 +00:00