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namespace Ryujinx.Cpu.LightningJit.Graph
{
static class DataFlow
{
public static (RegisterMask[], RegisterMask[]) GetGlobalUses(IBlockList blocks)
{
// Compute local register inputs and outputs used inside blocks.
RegisterMask[] localInputs = new RegisterMask[blocks.Count];
RegisterMask[] localOutputs = new RegisterMask[blocks.Count];
for (int index = 0; index < blocks.Count; index++)
{
IBlock block = blocks[index];
RegisterUse use = block.ComputeUseMasks();
localInputs[block.Index] = use.Read;
localOutputs[block.Index] = use.Write;
}
// Compute global register inputs and outputs used across blocks.
RegisterMask[] globalInputs = new RegisterMask[blocks.Count];
RegisterMask[] globalOutputs = new RegisterMask[blocks.Count];
bool modified;
// Compute register outputs.
do
{
modified = false;
for (int index = 0; index < blocks.Count; index++)
{
IBlock block = blocks[index];
int firstPIndex = GetFirstPredecessorIndex(block);
if (firstPIndex >= 0)
{
IBlock predecessor = block.GetPredecessor(firstPIndex);
RegisterMask outputs = globalOutputs[predecessor.Index];
for (int pIndex = firstPIndex + 1; pIndex < block.PredecessorsCount; pIndex++)
{
predecessor = block.GetPredecessor(pIndex);
if (predecessor.EndsWithContextStore())
{
// If a block ended with a context store, then we don't need to care
// about any of it's outputs, as they have already been saved to the context.
// Common outputs must be reset as doing a context stores indicates we will
// do a function call and wipe all register values.
continue;
}
outputs |= globalOutputs[predecessor.Index];
}
outputs |= localOutputs[block.Index];
modified |= Exchange(globalOutputs, block.Index, globalOutputs[block.Index] | outputs);
}
else
{
modified |= Exchange(globalOutputs, block.Index, localOutputs[block.Index]);
}
}
}
while (modified);
// Compute register inputs.
do
{
modified = false;
for (int index = blocks.Count - 1; index >= 0; index--)
{
IBlock block = blocks[index];
RegisterMask cmnOutputs = RegisterMask.Zero;
RegisterMask allOutputs = RegisterMask.Zero;
int firstPIndex = GetFirstPredecessorIndex(block);
if (firstPIndex == 0)
{
IBlock predecessor = block.GetPredecessor(0);
// Assumes that block index 0 is the entry block.
cmnOutputs = block.Index != 0 ? globalOutputs[predecessor.Index] : RegisterMask.Zero;
allOutputs = globalOutputs[predecessor.Index];
for (int pIndex = 1; pIndex < block.PredecessorsCount; pIndex++)
{
predecessor = block.GetPredecessor(pIndex);
if (!predecessor.EndsWithContextStore())
{
RegisterMask outputs = globalOutputs[predecessor.Index];
cmnOutputs &= outputs;
allOutputs |= outputs;
}
else
{
cmnOutputs = RegisterMask.Zero;
}
}
}
else if (firstPIndex > 0)
{
IBlock predecessor = block.GetPredecessor(firstPIndex);
allOutputs = globalOutputs[predecessor.Index];
for (int pIndex = firstPIndex + 1; pIndex < block.PredecessorsCount; pIndex++)
{
predecessor = block.GetPredecessor(pIndex);
if (!predecessor.EndsWithContextStore())
{
allOutputs |= globalOutputs[predecessor.Index];
}
}
}
RegisterMask inputs = localInputs[block.Index];
// If this block will load from context at the end,
// we don't need to care about what comes next.
if (!block.EndsWithContextLoad())
{
for (int sIndex = 0; sIndex < block.SuccessorsCount; sIndex++)
{
inputs |= globalInputs[block.GetSuccessor(sIndex).Index] & ~localOutputs[block.Index];
}
}
inputs |= allOutputs & ~localOutputs[block.Index];
inputs &= ~cmnOutputs;
modified |= Exchange(globalInputs, block.Index, globalInputs[block.Index] | inputs);
}
}
while (modified);
return (globalInputs, globalOutputs);
}
private static bool Exchange(RegisterMask[] masks, int blkIndex, RegisterMask value)
{
ref RegisterMask curValue = ref masks[blkIndex];
bool changed = curValue != value;
curValue = value;
return changed;
}
private static int GetFirstPredecessorIndex(IBlock block)
{
for (int pIndex = 0; pIndex < block.PredecessorsCount; pIndex++)
{
if (!block.GetPredecessor(pIndex).EndsWithContextStore())
{
return pIndex;
}
}
return -1;
}
}
}
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