diff options
| author | FICTURE7 <FICTURE7@gmail.com> | 2021-10-19 02:51:22 +0400 |
|---|---|---|
| committer | GitHub <noreply@github.com> | 2021-10-18 19:51:22 -0300 |
| commit | fbf40424f4d3a9aecc7fe528d7503619738ce542 (patch) | |
| tree | df9ba920add4d744fe527e78cc040ff4658a6d7e /ARMeilleure/CodeGen/Optimizations/TailMerge.cs | |
| parent | d512ce122cb1c9a7fe7cb40d3f85d642ee37f897 (diff) | |
Add an early `TailMerge` pass (#2721)
* Add an early `TailMerge` pass
Some translations can have a lot of guest calls and since for each guest
call there is a call guard which may return. This can produce a lot of
epilogue code for returns. This pass merges the epilogue into a single
block.
```
Using filter 'hcq'.
Using metric 'code size'.
Total diff: -1648111 (-7.19 %) (bytes):
Base: 22913847
Diff: 21265736
Improved: 4567, regressed: 14, unchanged: 144
```
* Set PTC version
* Address feedback
* Handle `void` returning functions
* Actually handle `void` returning functions
* Fix `RegisterToLocal` logging
Diffstat (limited to 'ARMeilleure/CodeGen/Optimizations/TailMerge.cs')
| -rw-r--r-- | ARMeilleure/CodeGen/Optimizations/TailMerge.cs | 83 |
1 files changed, 83 insertions, 0 deletions
diff --git a/ARMeilleure/CodeGen/Optimizations/TailMerge.cs b/ARMeilleure/CodeGen/Optimizations/TailMerge.cs new file mode 100644 index 00000000..f85b9c69 --- /dev/null +++ b/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) + { + 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; + } + } + } +} |