ryujinx/ARMeilleure/Translation/Dominance.cs
gdkchan e5f78fb1d4
Replace LinkedList by IntrusiveList to avoid allocations on JIT (#931)
* Replace LinkedList by IntrusiveList to avoid allocations on JIT

* Fix wrong replacements
2020-02-17 22:30:54 +01:00

95 lines
3.0 KiB
C#

using ARMeilleure.IntermediateRepresentation;
using System.Diagnostics;
namespace ARMeilleure.Translation
{
static class Dominance
{
// Those methods are an implementation of the algorithms on "A Simple, Fast Dominance Algorithm".
// https://www.cs.rice.edu/~keith/EMBED/dom.pdf
public static void FindDominators(ControlFlowGraph cfg)
{
BasicBlock Intersect(BasicBlock block1, BasicBlock block2)
{
while (block1 != block2)
{
while (cfg.PostOrderMap[block1.Index] < cfg.PostOrderMap[block2.Index])
{
block1 = block1.ImmediateDominator;
}
while (cfg.PostOrderMap[block2.Index] < cfg.PostOrderMap[block1.Index])
{
block2 = block2.ImmediateDominator;
}
}
return block1;
}
cfg.Entry.ImmediateDominator = cfg.Entry;
Debug.Assert(cfg.Entry == cfg.PostOrderBlocks[cfg.PostOrderBlocks.Length - 1]);
bool modified;
do
{
modified = false;
for (int blkIndex = cfg.PostOrderBlocks.Length - 2; blkIndex >= 0; blkIndex--)
{
BasicBlock block = cfg.PostOrderBlocks[blkIndex];
BasicBlock newIDom = null;
foreach (BasicBlock predecessor in block.Predecessors)
{
if (predecessor.ImmediateDominator != null)
{
if (newIDom != null)
{
newIDom = Intersect(predecessor, newIDom);
}
else
{
newIDom = predecessor;
}
}
}
if (block.ImmediateDominator != newIDom)
{
block.ImmediateDominator = newIDom;
modified = true;
}
}
}
while (modified);
}
public static void FindDominanceFrontiers(ControlFlowGraph cfg)
{
for (BasicBlock block = cfg.Blocks.First; block != null; block = block.ListNext)
{
if (block.Predecessors.Count < 2)
{
continue;
}
for (int pBlkIndex = 0; pBlkIndex < block.Predecessors.Count; pBlkIndex++)
{
BasicBlock current = block.Predecessors[pBlkIndex];
while (current != block.ImmediateDominator)
{
current.DominanceFrontiers.Add(block);
current = current.ImmediateDominator;
}
}
}
}
}
}