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path: root/lib/CodeGen/RegAllocGreedy.cpp
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2011-04-26Add a safe-guard against repeated splitting for some rare cases.Jakob Stoklund Olesen
The number of blocks covered by a live range must be strictly decreasing when splitting, otherwise we can't allow repeated splitting. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@130249 91177308-0d34-0410-b5e6-96231b3b80d8
2011-04-22Always compare the cost of region splitting with the cost of per-block ↵Jakob Stoklund Olesen
splitting. Sometimes it is better to split per block, and we missed those cases. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@130025 91177308-0d34-0410-b5e6-96231b3b80d8
2011-04-21Allow allocatable ranges from global live range splitting to be split again.Jakob Stoklund Olesen
These intervals are allocatable immediately after splitting, but they may be evicted because of later splitting. This is rare, but when it happens they should be split again. The remainder intervals that cannot be allocated after splitting still move directly to spilling. SplitEditor::finish can optionally provide a mapping from new live intervals back to the original interval indexes returned by openIntv(). Each original interval index can map to multiple new intervals after connected components have been separated. Dead code elimination may also add existing intervals to the list. The reverse mapping allows the SplitEditor client to treat the new intervals differently depending on the split region they came from. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129925 91177308-0d34-0410-b5e6-96231b3b80d8
2011-04-20Prefer cheap registers for busy live ranges.Jakob Stoklund Olesen
On the x86-64 and thumb2 targets, some registers are more expensive to encode than others in the same register class. Add a CostPerUse field to the TableGen register description, and make it available from TRI->getCostPerUse. This represents the cost of a REX prefix or a 32-bit instruction encoding required by choosing a high register. Teach the greedy register allocator to prefer cheap registers for busy live ranges (as indicated by spill weight). git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129864 91177308-0d34-0410-b5e6-96231b3b80d8
2011-04-13Stop using dead function.Jakob Stoklund Olesen
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129442 91177308-0d34-0410-b5e6-96231b3b80d8
2011-04-12SparseBitVector is SLOW.Jakob Stoklund Olesen
Use a Bitvector instead, we didn't need the smaller memory footprint anyway. This makes the greedy register allocator 10% faster. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129390 91177308-0d34-0410-b5e6-96231b3b80d8
2011-04-12Create new intervals for isolated blocks during region splitting.Jakob Stoklund Olesen
This merges the behavior of splitSingleBlocks into splitAroundRegion, so the RS_Region and RS_Block register stages can be coalesced. That means the leftover intervals after region splitting go directly to spilling instead of a second pass of per-block splitting. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129379 91177308-0d34-0410-b5e6-96231b3b80d8
2011-04-11Speed up eviction by stopping collectInterferingVRegs as soon as the spillJakob Stoklund Olesen
weight limit has been exceeded. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129305 91177308-0d34-0410-b5e6-96231b3b80d8
2011-04-09Build the Hopfield network incrementally when splitting global live ranges.Jakob Stoklund Olesen
It is common for large live ranges to have few basic blocks with register uses and many live-through blocks without any uses. This approach grows the Hopfield network incrementally around the use blocks, completely avoiding checking interference for some through blocks. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129188 91177308-0d34-0410-b5e6-96231b3b80d8
2011-04-07Extract SpillPlacement::addLinks for handling the special transparent blocks.Jakob Stoklund Olesen
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129079 91177308-0d34-0410-b5e6-96231b3b80d8
2011-04-06Also account for the spill code that would be inserted in live-through ↵Jakob Stoklund Olesen
blocks with interference. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129030 91177308-0d34-0410-b5e6-96231b3b80d8
2011-04-06Abort the constraint calculation early when all positive bias is lost.Jakob Stoklund Olesen
Without any positive bias, there is nothing for the spill placer to to. It will spill everywhere. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129029 91177308-0d34-0410-b5e6-96231b3b80d8
2011-04-06Keep track of the number of positively biased nodes when adding constraints.Jakob Stoklund Olesen
If there are no positive nodes, the algorithm can be aborted early. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129021 91177308-0d34-0410-b5e6-96231b3b80d8
2011-04-06Break the spill placement algorithm into three parts: prepare, ↵Jakob Stoklund Olesen
addConstraints, and finish. This will allow us to abort the algorithm early if it is determined to be futile. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129020 91177308-0d34-0410-b5e6-96231b3b80d8
2011-04-06Oops. Scary.Jakob Stoklund Olesen
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@128986 91177308-0d34-0410-b5e6-96231b3b80d8
2011-04-06Analyze blocks with uses separately from live-through blocks without uses.Jakob Stoklund Olesen
About 90% of the relevant blocks are live-through without uses, and the only information required about them is their number. This saves memory and enables later optimizations that need to look at only the use-blocks. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@128985 91177308-0d34-0410-b5e6-96231b3b80d8
2011-04-05Run LiveDebugVariables in RegAllocBasic and RegAllocGreedy.Jakob Stoklund Olesen
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@128935 91177308-0d34-0410-b5e6-96231b3b80d8
2011-04-05Stop precomputing last split points, query the SplitAnalysis cache on demand.Jakob Stoklund Olesen
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@128875 91177308-0d34-0410-b5e6-96231b3b80d8
2011-04-04Stop caching basic block index ranges now that SlotIndexes can keep up.Jakob Stoklund Olesen
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@128821 91177308-0d34-0410-b5e6-96231b3b80d8
2011-04-02Use InterferenceCache in RegAllocGreedy.Jakob Stoklund Olesen
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@128765 91177308-0d34-0410-b5e6-96231b3b80d8
2011-04-02Add an InterferenceCache class for caching per-block interference ranges.Jakob Stoklund Olesen
When the greedy register allocator is splitting multiple global live ranges, it tends to look at the same interference data many times. The InterferenceCache class caches queries for unaltered LiveIntervalUnions. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@128764 91177308-0d34-0410-b5e6-96231b3b80d8
2011-03-30Treat clones the same as their origin.Jakob Stoklund Olesen
When DCE clones a live range because it separates into connected components, make sure that the clones enter the same register allocator stage as the register they were cloned from. For instance, clones may be split even when they where created during spilling. Other registers created during spilling are not candidates for splitting or even (re-)spilling. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@128524 91177308-0d34-0410-b5e6-96231b3b80d8
2011-03-29Recompute register class and hint for registers created during spilling.Jakob Stoklund Olesen
The spill weight is not recomputed for an unspillable register - it stays infinite. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@128490 91177308-0d34-0410-b5e6-96231b3b80d8
2011-03-27Drop interference reassignment in favor of eviction.Jakob Stoklund Olesen
The reassignment phase was able to move interference with a higher spill weight, but it didn't happen very often and it was fairly expensive. The existing interference eviction picks up the slack. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@128397 91177308-0d34-0410-b5e6-96231b3b80d8
2011-03-19Add debug output.Jakob Stoklund Olesen
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@127959 91177308-0d34-0410-b5e6-96231b3b80d8
2011-03-16Add a LiveRangeEdit delegate callback before shrinking a live range.Jakob Stoklund Olesen
The register allocator needs to adjust its live interval unions when that happens. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@127774 91177308-0d34-0410-b5e6-96231b3b80d8
2011-03-16Clarify debugging output.Jakob Stoklund Olesen
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@127771 91177308-0d34-0410-b5e6-96231b3b80d8
2011-03-13Tell the register allocator about new unused virtual registers.Jakob Stoklund Olesen
This allows the allocator to free any resources used by the virtual register, including physical register assignments. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@127560 91177308-0d34-0410-b5e6-96231b3b80d8
2011-03-10Change the Spiller interface to take a LiveRangeEdit reference.Jakob Stoklund Olesen
This makes it possible to register delegates and get callbacks when the spiller edits live ranges. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@127389 91177308-0d34-0410-b5e6-96231b3b80d8
2011-03-10Make SpillIs an optional pointer. Avoid creating a bunch of temporary ↵Jakob Stoklund Olesen
SmallVectors. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@127388 91177308-0d34-0410-b5e6-96231b3b80d8
2011-03-09Add a LiveRangeEdit::Delegate protocol.Jakob Stoklund Olesen
This will we used for keeping register allocator data structures up to date while LiveRangeEdit is trimming live intervals. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@127300 91177308-0d34-0410-b5e6-96231b3b80d8
2011-03-07Make the UselessRegs argument optional in the LiveRangeEdit constructor.Jakob Stoklund Olesen
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@127181 91177308-0d34-0410-b5e6-96231b3b80d8
2011-03-05Rework the global split cost calculation.Jakob Stoklund Olesen
The global cost is the sum of block frequencies for spill code that must be inserted because preferences weren't met. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@127062 91177308-0d34-0410-b5e6-96231b3b80d8
2011-03-05Compute the constraints for global live range splitting from an interference ↵Jakob Stoklund Olesen
pattern. This simplifies the code and makes it faster too. The interference patterns are saved for each candidate register. It will be reused for actually executing the split. Work in progress. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@127054 91177308-0d34-0410-b5e6-96231b3b80d8
2011-03-04Extract a method. No functional change.Jakob Stoklund Olesen
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@127040 91177308-0d34-0410-b5e6-96231b3b80d8
2011-03-04Go back to comparing spill weights when deciding if interference can be evicted.Jakob Stoklund Olesen
It gives better results. Sometimes, a live range can be large and still have high spill weight. Such a range should not be spilled. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@127036 91177308-0d34-0410-b5e6-96231b3b80d8
2011-03-04Tweak debug output. No functional changes.Jakob Stoklund Olesen
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@127006 91177308-0d34-0410-b5e6-96231b3b80d8
2011-03-04Precompute block frequencies, pow() isn't free.Jakob Stoklund Olesen
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@126975 91177308-0d34-0410-b5e6-96231b3b80d8
2011-03-03Cache basic block bounds instead of asking SlotIndexes::getMBBRange all the ↵Jakob Stoklund Olesen
time. This speeds up the greedy register allocator by 15%. DenseMap is not as fast as one might hope. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@126921 91177308-0d34-0410-b5e6-96231b3b80d8
2011-03-03Change the SplitEditor interface to a single instance can be shared for ↵Jakob Stoklund Olesen
multiple splits. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@126912 91177308-0d34-0410-b5e6-96231b3b80d8
2011-03-01Drop RAGreedy::trySpillInterferences().Jakob Stoklund Olesen
This is a waste of time since we already know how to evict all interferences which is a better approach anyway. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@126798 91177308-0d34-0410-b5e6-96231b3b80d8
2011-03-01Keep track of which stage produced a live range, and bypass earlier stages ↵Jakob Stoklund Olesen
when revisiting. This effectively disables the 'turbo' functionality of the greedy register allocator where all new live ranges created by splitting would be reconsidered as if they were originals. There are two reasons for doing this, 1. It guarantees that the algorithm terminates. Early versions were prone to infinite looping in certain corner cases. 2. It is a 2x speedup. We can skip a lot of unnecessary interference checks that won't lead to good splitting anyway. The problem is that region splitting only gets one shot, so it should probably be changed to target multiple physical registers at once. Local live range splitting is still 'turbo' enabled. It only accounts for a small fraction of compile time, so it is probably not necessary to do anything about that. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@126781 91177308-0d34-0410-b5e6-96231b3b80d8
2011-02-25Try harder to get the hint by preferring to evict hint interference.Jakob Stoklund Olesen
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@126463 91177308-0d34-0410-b5e6-96231b3b80d8
2011-02-24Tweak the register allocator priority queue some more.Jakob Stoklund Olesen
New live ranges are assigned in long -> short order, but live ranges that have been evicted at least once are deferred and assigned in short -> long order. Also disable splitting and spilling for live ranges seen for the first time. The intention is to create a realistic interference pattern from the heavy live ranges before starting splitting and spilling around it. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@126451 91177308-0d34-0410-b5e6-96231b3b80d8
2011-02-23Keep track of how many times a live range has been dequeued, and prioritize ↵Jakob Stoklund Olesen
new ranges. When a large live range is evicted, it will usually be split when it comes around again. By deferring evicted live ranges, the splitting happens at a time when the interference pattern is more realistic. This prevents repeated splitting and evictions. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@126282 91177308-0d34-0410-b5e6-96231b3b80d8
2011-02-23Fix a bug in determining if there is only a single interfering register.Jakob Stoklund Olesen
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@126277 91177308-0d34-0410-b5e6-96231b3b80d8
2011-02-23Be more aggressive about evicting interference.Jakob Stoklund Olesen
Use interval sizes instead of spill weights to determine if it is legal to evict interference. A smaller interval can evict interference if all interfering live ranges are larger. Allow multiple interferences to be evicted as along as they are all larger than the live range being allocated. Spill weights are still used to select the preferred eviction candidate. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@126276 91177308-0d34-0410-b5e6-96231b3b80d8
2011-02-22Change the RAGreedy register assignment order so large live ranges are ↵Jakob Stoklund Olesen
allocated first. This is based on the observation that long live ranges are more difficult to allocate, so there is a better chance of solving the puzzle by handling the big pieces first. The allocator will evict and split long alive ranges when they get in the way. RABasic is still using spill weights for its priority queue, so the interface to the queue has been virtualized. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@126259 91177308-0d34-0410-b5e6-96231b3b80d8
2011-02-21Add SplitKit::isOriginalEndpoint and use it to force live range splitting to ↵Jakob Stoklund Olesen
terminate. An original endpoint is an instruction that killed or defined the original live range before any live ranges were split. When splitting global live ranges, avoid creating local live ranges without any original endpoints. We may still create global live ranges without original endpoints, but such a range won't be split again, and live range splitting still terminates. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@126151 91177308-0d34-0410-b5e6-96231b3b80d8
2011-02-19Give SplitAnalysis a VRM member to access VirtRegMap::getOriginal().Jakob Stoklund Olesen
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@126005 91177308-0d34-0410-b5e6-96231b3b80d8
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