Commit Graph

28 Commits

Author SHA1 Message Date
Chandler Carruth
8677f2ff9a [Modules] Remove potential ODR violations by sinking the DEBUG_TYPE
define below all header includes in the lib/CodeGen/... tree. While the
current modules implementation doesn't check for this kind of ODR
violation yet, it is likely to grow support for it in the future. It
also removes one layer of macro pollution across all the included
headers.

Other sub-trees will follow.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206837 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-22 02:02:50 +00:00
Craig Topper
4ba844388c [C++11] More 'nullptr' conversion. In some cases just using a boolean check instead of comparing to nullptr.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206142 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-14 00:51:57 +00:00
Duncan P. N. Exon Smith
861e4db905 RegAlloc: Account for a variable entry block frequency
Until r197284, the entry frequency was constant -- i.e., set to 2^14.
Although current ToT still has a constant entry frequency, since r197284
that has been an implementation detail (which is soon going to change).

  - r204690 made the wrong assumption for the CSRCost metric.  Adjust
    callee-saved register cost based on entry frequency.

  - r185393 made the wrong assumption (although it was valid at the
    time).  Update SpillPlacement.cpp::Threshold to be relative to the
    entry frequency.

Since ToT still has 2^14 entry frequency, this should have no observable
functionality change.

<rdar://problem/14292693>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205789 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-08 19:18:56 +00:00
Benjamin Kramer
d628f19f5d [C++11] Replace llvm::next and llvm::prior with std::next and std::prev.
Remove the old functions.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@202636 91177308-0d34-0410-b5e6-96231b3b80d8
2014-03-02 12:27:27 +00:00
Manman Ren
5de5680689 SpillPlacement: fix a bug in iterate.
Inside iterate, we scan backwards then scan forwards in a loop. When iteration
is not zero, the last node was just updated so we can skip it. But when
iteration is zero, we can't skip the last node.

For the testing case, fixing this will save a spill and move register copies
from hot path to cold path.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@202557 91177308-0d34-0410-b5e6-96231b3b80d8
2014-02-28 23:05:31 +00:00
Michael Gottesman
523823b897 [block-freq] Rename getEntryFrequency() -> getEntryFreq() to match getBlockFreq() in all *BlockFrequencyInfo*.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@197304 91177308-0d34-0410-b5e6-96231b3b80d8
2013-12-14 02:37:38 +00:00
Michael Gottesman
1a938c2beb [block-freq] Store MBFI as a field on SpillPlacement so we can access it to get the entry frequency while processing data.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@197291 91177308-0d34-0410-b5e6-96231b3b80d8
2013-12-14 00:25:47 +00:00
Jakob Stoklund Olesen
6d9fe79afe Reapply r185393.
Original commit message:

Remove floating point computations from SpillPlacement.cpp.

Patch by Benjamin Kramer!

Use the BlockFrequency class instead of floats in the Hopfield network
computations. This rescales the node Bias field from a [-2;2] float
range to two block frequencies BiasN and BiasP pulling in opposite
directions. This construct has a more predictable behavior when block
frequencies saturate.

The per-node scaling factors are no longer necessary, assuming the block
frequencies around a bundle are consistent.

This patch can cause the register allocator to make different spilling
decisions. The differences should be small.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186434 91177308-0d34-0410-b5e6-96231b3b80d8
2013-07-16 18:26:15 +00:00
Jakob Stoklund Olesen
92879a8cb1 Revert (most of) r185393 and r185395.
"Remove floating point computations form SpillPlacement.cpp."

These commits caused test failures in lencod on clang-native-arm-lnt.

I suspect these changes are only exposing an existing issue, but
reverting anyway to keep the bots passing while we investigate.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@185447 91177308-0d34-0410-b5e6-96231b3b80d8
2013-07-02 17:31:58 +00:00
Jakob Stoklund Olesen
7babb052a6 Tweak some comments that referred to the old bias computations.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@185395 91177308-0d34-0410-b5e6-96231b3b80d8
2013-07-01 23:36:37 +00:00
Jakob Stoklund Olesen
74d2a3e1a0 Remove floating point computations form SpillPlacement.cpp.
Patch by Benjamin Kramer!

Use the BlockFrequency class instead of floats in the Hopfield network
computations. This rescales the node Bias field from a [-2;2] float
range to two block frequencies BiasN and BiasP pulling in opposite
directions. This construct has a more predictable behavior when block
frequencies saturate.

The per-node scaling factors are no longer necessary, assuming the block
frequencies around a bundle are consistent.

This patch can cause the register allocator to make different spilling
decisions. The differences should be small.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@185393 91177308-0d34-0410-b5e6-96231b3b80d8
2013-07-01 23:19:39 +00:00
Benjamin Kramer
4eed756153 Switch spill weights from a basic loop depth estimation to BlockFrequencyInfo.
The main advantages here are way better heuristics, taking into account not
just loop depth but also __builtin_expect and other static heuristics and will
eventually learn how to use profile info. Most of the work in this patch is
pushing the MachineBlockFrequencyInfo analysis into the right places.

This is good for a 5% speedup on zlib's deflate (x86_64), there were some very
unfortunate spilling decisions in its hottest loop in longest_match(). Other
benchmarks I tried were mostly neutral.

This changes register allocation in subtle ways, update the tests for it.
2012-02-20-MachineCPBug.ll was deleted as it's very fragile and the instruction
it looked for was gone already (but the FileCheck pattern picked up unrelated
stuff).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@184105 91177308-0d34-0410-b5e6-96231b3b80d8
2013-06-17 19:00:36 +00:00
Jakub Staszak
f31034db8c Move #include of BitVector from .h to .cpp file.
Also remove unneeded #include and forward declaration.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@177357 91177308-0d34-0410-b5e6-96231b3b80d8
2013-03-18 23:45:45 +00:00
Jakob Stoklund Olesen
1dc12aa148 Give a small negative bias to giant edge bundles.
This helps compile time when the greedy register allocator splits live
ranges in giant functions. Without the bias, we would try to grow
regions through the giant edge bundles, usually to find out that the
region became too big and expensive.

If a live range has many uses in blocks near the giant bundle, the small
negative bias doesn't make a big difference, and we still consider
regions including the giant edge bundle.

Giant edge bundles are usually connected to landing pads or indirect
branches.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@157174 91177308-0d34-0410-b5e6-96231b3b80d8
2012-05-21 03:11:23 +00:00
Jakob Stoklund Olesen
b87f91b063 Be more conservative when forming compact regions.
Apply twice the negative bias on transparent blocks when computing the
compact regions. This excludes loop backedges from the region when only
one of the loop blocks uses the register.

Previously, we would include the backedge in the region if the loop
preheader and the loop latch both used the register, but the loop header
didn't.

When both the header and latch blocks use the register, we still keep it
live on the backedge.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@136832 91177308-0d34-0410-b5e6-96231b3b80d8
2011-08-03 23:09:38 +00:00
Jakob Stoklund Olesen
0e0a8806d4 Extend the SpillPlacement interface with two new features.
The PrefBoth constraint is used for blocks that ideally want a live-in
value both on the stack and in a register. This would be used by a block
that has a use before interference forces a spill.

Secondly, add the ChangesValue flag to BlockConstraint. This tells
SpillPlacement if a live-in value on the stack can be reused as a
live-out stack value for free. If the block redefines the virtual
register, a spill would be required for that.

This extra information will be used by SpillPlacement to more accurately
calculate spill costs when a value can exist both on the stack and in a
register.

The simplest example is a basic block that reads the virtual register,
but doesn't change its value. Spilling around such a block requires a
reload, but no spill in the block.

The spiller already knows this, but the spill placer doesn't. That can
sometimes lead to suboptimal regions.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@136731 91177308-0d34-0410-b5e6-96231b3b80d8
2011-08-02 21:53:03 +00:00
Jakob Stoklund Olesen
e60f103d2d Add a simple method for marking blocks with interference in and out.
This method matches addLinks - All the listed blocks are considered to
have interference, so they add a negative bias to their bundles.

This could also be done by addConstraints, but that requires building a
separate BlockConstraint array.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@135844 91177308-0d34-0410-b5e6-96231b3b80d8
2011-07-23 03:10:19 +00:00
Jakob Stoklund Olesen
f4afdfc501 Build the Hopfield network incrementally when splitting global live ranges.
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
2011-04-09 02:59:09 +00:00
Jakob Stoklund Olesen
0bd2bd9ecc Prefer multiplications to divisions.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129080 91177308-0d34-0410-b5e6-96231b3b80d8
2011-04-07 17:27:48 +00:00
Jakob Stoklund Olesen
7b41fbe872 Extract SpillPlacement::addLinks for handling the special transparent blocks.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129079 91177308-0d34-0410-b5e6-96231b3b80d8
2011-04-07 17:27:46 +00:00
Jakob Stoklund Olesen
70d4370b47 Keep track of the number of positively biased nodes when adding constraints.
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
2011-04-06 19:14:00 +00:00
Jakob Stoklund Olesen
9efa2a263e Break the spill placement algorithm into three parts: prepare, 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
2011-04-06 19:13:57 +00:00
Jakob Stoklund Olesen
40a42a2cca Precompute block frequencies, pow() isn't free.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@126975 91177308-0d34-0410-b5e6-96231b3b80d8
2011-03-04 00:58:40 +00:00
Jakob Stoklund Olesen
febb0bd0b9 Trim debugging output.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@125802 91177308-0d34-0410-b5e6-96231b3b80d8
2011-02-18 00:32:47 +00:00
Jakob Stoklund Olesen
9590c7fbca Silence an MSVC warning
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@124798 91177308-0d34-0410-b5e6-96231b3b80d8
2011-02-03 17:04:12 +00:00
Jakob Stoklund Olesen
fc7d775178 Divert Hopfield network debug output. It is very noisy.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123859 91177308-0d34-0410-b5e6-96231b3b80d8
2011-01-19 23:14:59 +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
Jakob Stoklund Olesen
8bfe50871f Add the SpillPlacement analysis pass.
This pass precomputes CFG block frequency information that can be used by the
register allocator to find optimal spill code placement.

Given an interference pattern, placeSpills() will compute which basic blocks
should have the current variable enter or exit in a register, and which blocks
prefer the stack.

The algorithm is ready to consume block frequencies from profiling data, but for
now it gets by with the static estimates used for spill weights.

This is a work in progress and still not hooked up to RegAllocGreedy.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122938 91177308-0d34-0410-b5e6-96231b3b80d8
2011-01-06 01:21:53 +00:00