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* Revert r368339 "[MBP] Disable aggressive loop rotate in plain mode"Hans Wennborg2019-08-121-4/+4
| | | | | | | | | | | | | | | | | | It caused assertions to fire when building Chromium: lib/CodeGen/LiveDebugValues.cpp:331: bool {anonymous}::LiveDebugValues::OpenRangesSet::empty() const: Assertion `Vars.empty() == VarLocs.empty() && "open ranges are inconsistent"' failed. See https://crbug.com/992871#c3 for how to reproduce. > Patch https://reviews.llvm.org/D43256 introduced more aggressive loop layout optimization which depends on profile information. If profile information is not available, the statically estimated profile information(generated by BranchProbabilityInfo.cpp) is used. If user program doesn't behave as BranchProbabilityInfo.cpp expected, the layout may be worse. > > To be conservative this patch restores the original layout algorithm in plain mode. But user can still try the aggressive layout optimization with -force-precise-rotation-cost=true. > > Differential Revision: https://reviews.llvm.org/D65673 llvm-svn: 368579
* [MBP] Disable aggressive loop rotate in plain modeGuozhi Wei2019-08-081-4/+4
| | | | | | | | | | Patch https://reviews.llvm.org/D43256 introduced more aggressive loop layout optimization which depends on profile information. If profile information is not available, the statically estimated profile information(generated by BranchProbabilityInfo.cpp) is used. If user program doesn't behave as BranchProbabilityInfo.cpp expected, the layout may be worse. To be conservative this patch restores the original layout algorithm in plain mode. But user can still try the aggressive layout optimization with -force-precise-rotation-cost=true. Differential Revision: https://reviews.llvm.org/D65673 llvm-svn: 368339
* [MBP] Move a latch block with conditional exit and multi predecessors to top ↵Guozhi Wei2019-06-141-7/+7
| | | | | | | | | | | | | | | | of loop Current findBestLoopTop can find and move one kind of block to top, a latch block has one successor. Another common case is: * a latch block * it has two successors, one is loop header, another is exit * it has more than one predecessors If it is below one of its predecessors P, only P can fall through to it, all other predecessors need a jump to it, and another conditional jump to loop header. If it is moved before loop header, all its predecessors jump to it, then fall through to loop header. So all its predecessors except P can reduce one taken branch. Differential Revision: https://reviews.llvm.org/D43256 llvm-svn: 363471
* [LLVM] Remove unwanted --check-prefix=CHECK from unit tests. NFC.Mandeep Singh Grang2016-04-191-1/+1
| | | | | | | | | | | | Summary: Removed unwanted --check-prefix=CHECK from numerous unit tests. Reviewers: t.p.northover, dblaikie, uweigand, MatzeB, tstellarAMD, mcrosier Subscribers: mcrosier, dsanders Differential Revision: http://reviews.llvm.org/D19279 llvm-svn: 266834
* Enhance loop rotation with existence of profile data in ↵Cong Hou2015-10-191-0/+122
MachineBlockPlacement pass. Currently, in MachineBlockPlacement pass the loop is rotated to let the best exit to be the last BB in the loop chain, to maximize the fall-through from the loop to outside. With profile data, we can determine the cost in terms of missed fall through opportunities when rotating a loop chain and select the best rotation. Basically, there are three kinds of cost to consider for each rotation: 1. The possibly missed fall through edge (if it exists) from BB out of the loop to the loop header. 2. The possibly missed fall through edges (if they exist) from the loop exits to BB out of the loop. 3. The missed fall through edge (if it exists) from the last BB to the first BB in the loop chain. Therefore, the cost for a given rotation is the sum of costs listed above. We select the best rotation with the smallest cost. This is only for PGO mode when we have more precise edge frequencies. Differential revision: http://reviews.llvm.org/D10717 llvm-svn: 250754
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