Commit Graph

165 Commits

Author SHA1 Message Date
Jakob Stoklund Olesen
22a1df6bf2 Keep track of which stage produced a live range, and bypass earlier stages 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
2011-03-01 21:10:07 +00:00
Jakob Stoklund Olesen
57f1e2cee0 Try harder to get the hint by preferring to evict hint interference.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@126463 91177308-0d34-0410-b5e6-96231b3b80d8
2011-02-25 01:04:22 +00:00
Jakob Stoklund Olesen
107d366df7 Tweak the register allocator priority queue some more.
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
2011-02-24 23:21:36 +00:00
Jakob Stoklund Olesen
d2a5073423 Keep track of how many times a live range has been dequeued, and prioritize 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
2011-02-23 00:56:56 +00:00
Jakob Stoklund Olesen
417df01291 Fix a bug in determining if there is only a single interfering register.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@126277 91177308-0d34-0410-b5e6-96231b3b80d8
2011-02-23 00:29:55 +00:00
Jakob Stoklund Olesen
98c8141b6d Be more aggressive about evicting interference.
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
2011-02-23 00:29:52 +00:00
Jakob Stoklund Olesen
98d9648de7 Change the RAGreedy register assignment order so large live ranges are 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
2011-02-22 23:01:52 +00:00
Jakob Stoklund Olesen
06c0f25499 Add SplitKit::isOriginalEndpoint and use it to force live range splitting to 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
2011-02-21 23:09:46 +00:00
Jakob Stoklund Olesen
1b847deb26 Give SplitAnalysis a VRM member to access VirtRegMap::getOriginal().
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@126005 91177308-0d34-0410-b5e6-96231b3b80d8
2011-02-19 00:53:42 +00:00
Jakob Stoklund Olesen
a2ebf60ef2 Separate timers for local and global splitting.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@126001 91177308-0d34-0410-b5e6-96231b3b80d8
2011-02-19 00:38:40 +00:00
Jakob Stoklund Olesen
ba05c01dab Add VirtRegMap::rewrite() and use it in the new register allocators.
The rewriter works almost identically to -rewriter=trivial, except it also
eliminates any identity copies.

This makes the new register allocators independent of VirtRegRewriter.cpp which
will be going away at the same time as RegAllocLinearScan.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@125967 91177308-0d34-0410-b5e6-96231b3b80d8
2011-02-18 22:03:18 +00:00
Jakob Stoklund Olesen
0db841f9c2 Add basic register allocator statistics.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@125789 91177308-0d34-0410-b5e6-96231b3b80d8
2011-02-17 22:53:48 +00:00
Jakob Stoklund Olesen
034a80d065 Split local live ranges.
A local live range is live in a single basic block. If such a range fails to
allocate, try to find a sub-range that would get a larger spill weight than its
interference.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@125764 91177308-0d34-0410-b5e6-96231b3b80d8
2011-02-17 19:13:53 +00:00
Jakob Stoklund Olesen
23cd57c299 Simplify using the new leaveIntvBefore()
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@125238 91177308-0d34-0410-b5e6-96231b3b80d8
2011-02-09 23:33:02 +00:00
Jakob Stoklund Olesen
f0ac26c511 Move calcLiveBlockInfo() and the BlockInfo struct into SplitAnalysis.
No functional changes intended.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@125231 91177308-0d34-0410-b5e6-96231b3b80d8
2011-02-09 22:50:26 +00:00
Jakob Stoklund Olesen
2710638db2 Evict a lighter single interference before attempting to split a live range.
Registers are not allocated strictly in spill weight order when live range
splitting and spilling has created new shorter intervals with higher spill
weights.

When one of the new heavy intervals conflicts with a single lighter interval,
simply evict the old interval instead of trying to split the heavy one.

The lighter interval is a better candidate for splitting, it has a smaller use
density.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@125151 91177308-0d34-0410-b5e6-96231b3b80d8
2011-02-09 01:14:03 +00:00
Jakob Stoklund Olesen
8a2bbdeee2 Fix one more case of splitting after the last split point.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@125137 91177308-0d34-0410-b5e6-96231b3b80d8
2011-02-08 23:26:48 +00:00
Jakob Stoklund Olesen
a50c539b7a Reorganize interference code to check LastSplitPoint first.
The last split point can be anywhere in the block, so it interferes with the
strictly monotonic requirements of advanceTo().

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@125132 91177308-0d34-0410-b5e6-96231b3b80d8
2011-02-08 23:02:58 +00:00
Jakob Stoklund Olesen
d08d77318a Also handle the situation where an indirect branch is the first (and last)
instruction in a basic block.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@125116 91177308-0d34-0410-b5e6-96231b3b80d8
2011-02-08 21:46:11 +00:00
Jakob Stoklund Olesen
8a61da8a68 Add LiveIntervals::addKillFlags() to recompute kill flags after register allocation.
This is a lot easier than trying to get kill flags right during live range
splitting and rematerialization.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@125113 91177308-0d34-0410-b5e6-96231b3b80d8
2011-02-08 21:13:03 +00:00
Jakob Stoklund Olesen
124e423cce Trim debug spew
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@125109 91177308-0d34-0410-b5e6-96231b3b80d8
2011-02-08 19:33:58 +00:00
Jakob Stoklund Olesen
5c716bdccc Add SplitEditor::overlapIntv() to create small ranges where both registers are live.
If a live range is used by a terminator instruction, and that live range needs
to leave the block on the stack or in a different register, it can be necessary
to have both sides of the split live at the terminator instruction.

Example:

  %vreg2 = COPY %vreg1
  JMP %vreg1

Becomes after spilling %vreg2:

  SPILL %vreg1
  JMP %vreg1

The spill doesn't kill the register as is normally the case.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@125102 91177308-0d34-0410-b5e6-96231b3b80d8
2011-02-08 18:50:21 +00:00
Jakob Stoklund Olesen
fe3f99f95c Be more strict about the first/last interference-free use.
If the interference overlaps the instruction, we cannot separate it.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@124918 91177308-0d34-0410-b5e6-96231b3b80d8
2011-02-05 01:06:39 +00:00
Jakob Stoklund Olesen
de71095a1a Add assertions to verify that the new interval is clear of the interference.
If these inequalities don't hold, we are creating a live range split that won't
allocate.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@124917 91177308-0d34-0410-b5e6-96231b3b80d8
2011-02-05 01:06:36 +00:00
Jakob Stoklund Olesen
63935420ef Be more accurate about live range splitting at the end of blocks.
If interference reaches the last split point, it is effectively live out and
should be marked as 'MustSpill'.

This can make a difference when the terminator uses a register. There is no way
that register can be reused in the outgoing CFG bundle, even if it isn't live
out.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@124900 91177308-0d34-0410-b5e6-96231b3b80d8
2011-02-04 21:42:06 +00:00
Jakob Stoklund Olesen
9b3d24bf3d Verify that one of the ranges produced by region splitting is allocatable.
We should not be attempting a region split if it won't lead to at least one
directly allocatable interval. That could cause infinite splitting loops.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@124893 91177308-0d34-0410-b5e6-96231b3b80d8
2011-02-04 19:33:07 +00:00
Jakob Stoklund Olesen
45139874a7 Also compute interference intervals for blocks with no uses.
When the live range is live through a block that doesn't use the register, but
that has interference, region splitting wants to split at the top and bottom of
the basic block.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@124839 91177308-0d34-0410-b5e6-96231b3b80d8
2011-02-04 00:39:20 +00:00
Jakob Stoklund Olesen
2dfbb3e912 Ensure that the computed interference intervals actually overlap their basic blocks.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@124815 91177308-0d34-0410-b5e6-96231b3b80d8
2011-02-03 20:29:43 +00:00
Jakob Stoklund Olesen
207c868c92 Return live range end points from SplitEditor::enter*/leave*.
These end points come from the inserted copies, and can be passed directly to
useIntv. This simplifies the coloring code.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@124799 91177308-0d34-0410-b5e6-96231b3b80d8
2011-02-03 17:04:16 +00:00
Eric Christopher
0f43811903 Reapply this.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@124779 91177308-0d34-0410-b5e6-96231b3b80d8
2011-02-03 06:18:29 +00:00
Eric Christopher
463a2977b1 Temporarily revert 124765 in an attempt to find the cycle breaking bootstrap.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@124778 91177308-0d34-0410-b5e6-96231b3b80d8
2011-02-03 05:40:54 +00:00
Jakob Stoklund Olesen
2cd2111959 Defer SplitKit value mapping until all defs are available.
The greedy register allocator revealed some problems with the value mapping in
SplitKit. We would sometimes start mapping values before all defs were known,
and that could change a value from a simple 1-1 mapping to a multi-def mapping
that requires ssa update.

The new approach collects all defs and register assignments first without
filling in any live intervals. Only when finish() is called, do we compute
liveness and mapped values. At this time we know with certainty which values map
to multiple values in a split range.

This also has the advantage that we can compute live ranges based on the
remaining uses after rematerializing at split points.

The current implementation has many opportunities for compile time optimization.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@124765 91177308-0d34-0410-b5e6-96231b3b80d8
2011-02-03 00:54:23 +00:00
Jakob Stoklund Olesen
c0de995712 SplitKit requires that all defs are in place before calling useIntv().
The value mapping gets confused about which original values have multiple new
definitions so they may need phi insertions.

This could probably be simplified by letting enterIntvBefore() take a live range
to be added following the instruction. As long as the range stays inside the
same basic block, value mapping shouldn't be a problem.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123926 91177308-0d34-0410-b5e6-96231b3b80d8
2011-01-20 17:45:23 +00:00
Jakob Stoklund Olesen
92e6939d29 Don't accidentally leave small gaps in the live ranges when leaving the active
interval after an instruction. The leaveIntvAfter() method only adds liveness
from the instruction's boundary index to the inserted copy.

Ideally, SplitKit should be smarter about this, perhaps by combining useIntv()
and leaveIntvAfter() into one method that guarantees continuity.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123858 91177308-0d34-0410-b5e6-96231b3b80d8
2011-01-19 23:14:56 +00:00
Jakob Stoklund Olesen
ccdb3fcef9 Implement RAGreedy::splitAroundRegion and remove loop splitting.
Region splitting includes loop splitting as a subset, and it is more generic.
The splitting heuristics for variables that are live in more than one block are
now:

1. Try to create a region that covers multiple basic blocks.
2. Try to create a new live range for each block with multiple uses.
3. Spill.

Steps 2 and 3 are similar to what the standard spiller is doing.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123853 91177308-0d34-0410-b5e6-96231b3b80d8
2011-01-19 22:11:48 +00:00
Jakob Stoklund Olesen
b5fa933343 Add RAGreedy methods for splitting live ranges around regions.
Analyze the live range's behavior entering and leaving basic blocks. Compute an
interference pattern for each allocation candidate, and use SpillPlacement to
find an optimal region where that register can be live.

This code is still not enabled.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123774 91177308-0d34-0410-b5e6-96231b3b80d8
2011-01-18 21:13:27 +00:00
Duncan Sands
2aea490e16 Pacify the compiler. BestWeight cannot in fact be used uninitialized
in this function, but the compiler was warning that it might be when
doing a release build.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122595 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-28 10:07:15 +00:00
Jakob Stoklund Olesen
770d42de3b When RegAllocGreedy decides to spill the interferences of the current register,
pick the victim with the lowest total spill weight.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122445 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-22 22:01:30 +00:00
Jakob Stoklund Olesen
87c6d25c71 Tweak debug spew.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122132 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-18 03:04:11 +00:00
Nick Lewycky
bb1744ec15 Fix GCC warning:
lib/CodeGen/RegAllocGreedy.cpp:311: error: unused variable 'PhysReg' [-Wunused-variable]


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122122 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-18 01:05:55 +00:00
Jakob Stoklund Olesen
89cab93fe9 Pass a Banner argument to the machine code verifier both from
createMachineVerifierPass and MachineFunction::verify.

The banner is printed before the machine code dump, just like the printer pass.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122113 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-18 00:06:56 +00:00
Jakob Stoklund Olesen
af24964251 Make the -verify-regalloc command line option available to base classes as
RegAllocBase::VerifyEnabled.

Run the machine code verifier in a few interesting places during RegAllocGreedy.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122107 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-17 23:16:35 +00:00
Jakob Stoklund Olesen
f428eb6c1b Enable loop splitting in RegAllocGreedy.
The heuristics split around the largest loop where the current register may be
allocated without interference.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122106 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-17 23:16:32 +00:00
Jakob Stoklund Olesen
d0bb5e2ca0 Start using SplitKit and MachineLoopRanges in RegAllocGreedy in preparation of
live range splitting around loops guided by register pressure.

So far, trySplit() simply prints a lot of debug output.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121918 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-15 23:46:13 +00:00
Jakob Stoklund Olesen
257c556d85 Simplify RegAllocGreedy's use of register aliases.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121807 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-14 23:38:19 +00:00
Matt Beaumont-Gay
3ef9f3da39 Move debugging code entirely within DEBUG(). Silences an unused variable
warning in the opt build.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121791 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-14 21:14:55 +00:00
Jakob Stoklund Olesen
bfce678de7 Add LiveIntervalUnion print methods, RegAllocGreedy::trySplit debug spew.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121783 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-14 19:38:49 +00:00
Jakob Stoklund Olesen
d84de8cf62 Q.seenAllInterferences() must be called after Q.collectInterferingVRegs().
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121774 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-14 17:47:36 +00:00
Jakob Stoklund Olesen
885b3283ea Remove unused vector.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121741 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-14 00:58:47 +00:00
Jakob Stoklund Olesen
46c83c80c5 Try reassigning all virtual register interferences, not just those with lower
spill weight. Filter out fixed registers instead.

Add support for reassigning an interference that was assigned to an alias.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121737 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-14 00:37:49 +00:00
Jakob Stoklund Olesen
b64d92e29f Add stub for RAGreedy::trySplit.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121736 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-14 00:37:44 +00:00
Jakob Stoklund Olesen
533f58ecdd Add named timer groups for the different stages of register allocation.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121604 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-11 00:19:56 +00:00
Jakob Stoklund Olesen
4680dec5fb Move MRI into RegAllocBase. Clean up debug output a bit.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121599 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-10 23:49:00 +00:00
Nick Lewycky
a0bb037283 Remove extraneous close parenthesis.
Fix build breakage.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121596 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-10 23:14:35 +00:00
Nick Lewycky
5a4308bca8 Move variable that's unused in an NDEBUG build inside the DEBUG() macro, fixing
lib/CodeGen/RegAllocGreedy.cpp:233: error: unused variable 'TRC' [-Wunused-variable]


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121594 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-10 23:05:10 +00:00
Jakob Stoklund Olesen
f6dff84d4e Force the greedy register allocator to always use the inline spiller.
Soon, RegAllocGreedy will start splitting live ranges, and then deferred
spilling won't work anyway.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121591 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-10 22:54:44 +00:00
Jakob Stoklund Olesen
dd479e9769 Use AllocationOrder in RegAllocGreedy, fix a bug in the hint calculation.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121584 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-10 22:21:05 +00:00
Jakob Stoklund Olesen
6ce219ec64 Fix miscompilation caused by trivial logic error in the reassignVReg()
interference check.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121519 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-10 20:45:04 +00:00
Jakob Stoklund Olesen
ff092faffb Remember to filter out reserved rergisters from the allocation order.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121411 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-09 21:20:46 +00:00
Andrew Trick
b853e6c370 Added register reassignment prototype to RAGreedy. It's a simple
heuristic to reshuffle register assignments when we can't find an
available reg.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121388 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-09 18:15:21 +00:00
Jakob Stoklund Olesen
9b0c4f8af3 Properly deal with empty intervals when checking for interference.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121319 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-08 23:51:35 +00:00
Jakob Stoklund Olesen
90c1d7ddfc Implement very primitive hinting support in RegAllocGreedy.
The hint is simply tried first and then forgotten if it couldn't be allocated
immediately.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121306 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-08 22:57:16 +00:00
Jakob Stoklund Olesen
d0bec3e62c Store (priority,regnum) pairs in the priority queue instead of providing an
abstract priority queue interface in subclasses that want to override the
priority calculations.

Subclasses must provide a getPriority() implementation instead.

This approach requires less code as long as priorities are expressable as simple
floats, and it avoids the dangers of defining potentially expensive priority
comparison functions.

It also should speed up priority_queue operations since they no longer have to
chase pointers when comparing registers. This is not measurable, though.

Preferably, we shouldn't use floats to guide code generation. The use of floats
here is derived from the use of floats for spill weights. Spill weights have a
dynamic range that doesn't lend itself easily to a fixpoint implementation.

When someone invents a stable spill weight representation, it can be reused for
allocation priorities.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121294 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-08 22:22:41 +00:00
Jakob Stoklund Olesen
753936602e Trim includes.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121283 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-08 21:12:00 +00:00
Jakob Stoklund Olesen
cba2e06d52 Stub out RegAllocGreedy.
This new register allocator is initially identical to RegAllocBasic, but it will
receive all of the tricks that RegAllocBasic won't get.

RegAllocGreedy will eventually replace linear scan.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121234 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-08 03:26:16 +00:00