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path: root/lib/CodeGen/SpillPlacement.h
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* Revert "Give internal classes hidden visibility."Benjamin Kramer2013-09-11
| | | | | | | It works with clang, but GCC has different rules so we can't make all of those hidden. This reverts commit r190534. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@190536 91177308-0d34-0410-b5e6-96231b3b80d8
* Give internal classes hidden visibility.Benjamin Kramer2013-09-11
| | | | | | Worth 100k on a linux/x86_64 Release+Asserts clang. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@190534 91177308-0d34-0410-b5e6-96231b3b80d8
* Remove floats from live range splitting costs.Jakob Stoklund Olesen2013-07-16
| | | | | | | | | | These floats all represented block frequencies anyway, so just use the BlockFrequency class directly. Some floating point computations remain in tryLocalSplit(). They are estimating spill weights which are still floats. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186435 91177308-0d34-0410-b5e6-96231b3b80d8
* Reapply r185393.Jakob Stoklund Olesen2013-07-16
| | | | | | | | | | | | | | | | | | | | | | 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
* Revert (most of) r185393 and r185395.Jakob Stoklund Olesen2013-07-02
| | | | | | | | | | | "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
* Remove floating point computations form SpillPlacement.cpp.Jakob Stoklund Olesen2013-07-01
| | | | | | | | | | | | | | | | | | 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
* Be more conservative when forming compact regions.Jakob Stoklund Olesen2011-08-03
| | | | | | | | | | | | | | | 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
* Extend the SpillPlacement interface with two new features.Jakob Stoklund Olesen2011-08-02
| | | | | | | | | | | | | | | | | | | | | | | | 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
* Add a simple method for marking blocks with interference in and out.Jakob Stoklund Olesen2011-07-23
| | | | | | | | | | 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
* Build the Hopfield network incrementally when splitting global live ranges.Jakob Stoklund Olesen2011-04-09
| | | | | | | | | 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
* Extract SpillPlacement::addLinks for handling the special transparent blocks.Jakob Stoklund Olesen2011-04-07
| | | | git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129079 91177308-0d34-0410-b5e6-96231b3b80d8
* Keep track of the number of positively biased nodes when adding constraints.Jakob Stoklund Olesen2011-04-06
| | | | | | 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
* Break the spill placement algorithm into three parts: prepare, ↵Jakob Stoklund Olesen2011-04-06
| | | | | | | | 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
* Precompute block frequencies, pow() isn't free.Jakob Stoklund Olesen2011-03-04
| | | | git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@126975 91177308-0d34-0410-b5e6-96231b3b80d8
* Add RAGreedy methods for splitting live ranges around regions.Jakob Stoklund Olesen2011-01-18
| | | | | | | | | | 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
* Add the SpillPlacement analysis pass.Jakob Stoklund Olesen2011-01-06
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