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https://github.com/c64scene-ar/llvm-6502.git
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dbaeb6e7cb
Runtime unrolling will create a prologue to execute the extra
iterations which is can't divided by the unroll factor. It
generates an if-then-else sequence to jump into a factor -1
times unrolled loop body, like
extraiters = tripcount % loopfactor
if (extraiters == 0) jump Loop:
if (extraiters == loopfactor) jump L1
if (extraiters == loopfactor-1) jump L2
...
L1: LoopBody;
L2: LoopBody;
...
if tripcount < loopfactor jump End
Loop:
...
End:
It means if the unroll factor is 4, the loop body will be 7
times unrolled, 3 are in loop prologue, and 4 are in the loop.
This commit is to use a loop to execute the extra iterations
in prologue, like
extraiters = tripcount % loopfactor
if (extraiters == 0) jump Loop:
else jump Prol
Prol: LoopBody;
extraiters -= 1 // Omitted if unroll factor is 2.
if (extraiters != 0) jump Prol: // Omitted if unroll factor is 2.
if (tripcount < loopfactor) jump End
Loop:
...
End:
Then when unroll factor is 4, the loop body will be copied by
only 5 times, 1 in the prologue loop, 4 in the original loop.
And if the unroll factor is 2, new loop won't be created, just
as the original solution.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218604 91177308-0d34-0410-b5e6-96231b3b80d8
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| .. | ||
| ADCE | ||
| AddDiscriminators | ||
| AlignmentFromAssumptions | ||
| ArgumentPromotion | ||
| AtomicExpand/ARM | ||
| BBVectorize | ||
| BranchFolding | ||
| CodeExtractor | ||
| CodeGenPrepare | ||
| ConstantHoisting | ||
| ConstantMerge | ||
| ConstProp | ||
| CorrelatedValuePropagation | ||
| DeadArgElim | ||
| DeadStoreElimination | ||
| DebugIR | ||
| EarlyCSE | ||
| FunctionAttrs | ||
| GCOVProfiling | ||
| GlobalDCE | ||
| GlobalOpt | ||
| GVN | ||
| IndVarSimplify | ||
| Inline | ||
| InstCombine | ||
| InstMerge | ||
| InstSimplify | ||
| Internalize | ||
| IPConstantProp | ||
| JumpThreading | ||
| LCSSA | ||
| LICM | ||
| LoadCombine | ||
| LoopDeletion | ||
| LoopIdiom | ||
| LoopReroll | ||
| LoopRotate | ||
| LoopSimplify | ||
| LoopStrengthReduce | ||
| LoopUnroll | ||
| LoopUnswitch | ||
| LoopVectorize | ||
| LowerAtomic | ||
| LowerExpectIntrinsic | ||
| LowerInvoke | ||
| LowerSwitch | ||
| Mem2Reg | ||
| MemCpyOpt | ||
| MergeFunc | ||
| MetaRenamer | ||
| ObjCARC | ||
| PartiallyInlineLibCalls | ||
| PhaseOrdering | ||
| PruneEH | ||
| Reassociate | ||
| Reg2Mem | ||
| SampleProfile | ||
| Scalarizer | ||
| ScalarRepl | ||
| SCCP | ||
| SeparateConstOffsetFromGEP/NVPTX | ||
| SimplifyCFG | ||
| Sink | ||
| SLPVectorizer | ||
| SROA | ||
| StripSymbols | ||
| StructurizeCFG | ||
| TailCallElim | ||
| TailDup | ||
| Util | ||