diff options
| author | TSR Berry <20988865+TSRBerry@users.noreply.github.com> | 2023-04-08 01:22:00 +0200 |
|---|---|---|
| committer | Mary <thog@protonmail.com> | 2023-04-27 23:51:14 +0200 |
| commit | cee712105850ac3385cd0091a923438167433f9f (patch) | |
| tree | 4a5274b21d8b7f938c0d0ce18736d3f2993b11b1 /src/ARMeilleure/CodeGen/Optimizations/TailMerge.cs | |
| parent | cd124bda587ef09668a971fa1cac1c3f0cfc9f21 (diff) | |
Move solution and projects to src
Diffstat (limited to 'src/ARMeilleure/CodeGen/Optimizations/TailMerge.cs')
| -rw-r--r-- | src/ARMeilleure/CodeGen/Optimizations/TailMerge.cs | 83 |
1 files changed, 83 insertions, 0 deletions
diff --git a/src/ARMeilleure/CodeGen/Optimizations/TailMerge.cs b/src/ARMeilleure/CodeGen/Optimizations/TailMerge.cs new file mode 100644 index 00000000..e94df159 --- /dev/null +++ b/src/ARMeilleure/CodeGen/Optimizations/TailMerge.cs @@ -0,0 +1,83 @@ +using ARMeilleure.IntermediateRepresentation; +using ARMeilleure.Translation; +using static ARMeilleure.IntermediateRepresentation.Operation.Factory; + +namespace ARMeilleure.CodeGen.Optimizations +{ + static class TailMerge + { + public static void RunPass(in CompilerContext cctx) + { + ControlFlowGraph cfg = cctx.Cfg; + + BasicBlock mergedReturn = new(cfg.Blocks.Count); + + Operand returnValue; + Operation returnOp; + + if (cctx.FuncReturnType == OperandType.None) + { + returnValue = default; + returnOp = Operation(Instruction.Return, default); + } + else + { + returnValue = cfg.AllocateLocal(cctx.FuncReturnType); + returnOp = Operation(Instruction.Return, default, returnValue); + } + + mergedReturn.Frequency = BasicBlockFrequency.Cold; + mergedReturn.Operations.AddLast(returnOp); + + for (BasicBlock block = cfg.Blocks.First; block != null; block = block.ListNext) + { + Operation op = block.Operations.Last; + + if (op != default && op.Instruction == Instruction.Return) + { + block.Operations.Remove(op); + + if (cctx.FuncReturnType == OperandType.None) + { + PrepareMerge(block, mergedReturn); + } + else + { + Operation copyOp = Operation(Instruction.Copy, returnValue, op.GetSource(0)); + + PrepareMerge(block, mergedReturn).Append(copyOp); + } + } + } + + cfg.Blocks.AddLast(mergedReturn); + cfg.Update(); + } + + private static BasicBlock PrepareMerge(BasicBlock from, BasicBlock to) + { + BasicBlock fromPred = from.Predecessors.Count == 1 ? from.Predecessors[0] : null; + + // If the block is empty, we can try to append to the predecessor and avoid unnecessary jumps. + if (from.Operations.Count == 0 && fromPred != null && fromPred.SuccessorsCount == 1) + { + for (int i = 0; i < fromPred.SuccessorsCount; i++) + { + if (fromPred.GetSuccessor(i) == from) + { + fromPred.SetSuccessor(i, to); + } + } + + // NOTE: `from` becomes unreachable and the call to `cfg.Update()` will remove it. + return fromPred; + } + else + { + from.AddSuccessor(to); + + return from; + } + } + } +} |