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using Ryujinx.Graphics.Shader.IntermediateRepresentation;
using Ryujinx.Graphics.Shader.Translation;
using System.Collections.Generic;
using System.Linq;
using static Ryujinx.Graphics.Shader.StructuredIr.AstHelper;
namespace Ryujinx.Graphics.Shader.StructuredIr
{
static class AstOptimizer
{
public static void Optimize(StructuredProgramContext context)
{
AstBlock mainBlock = context.CurrentFunction.MainBlock;
// When debug mode is enabled, we disable expression propagation
// (this makes comparison with the disassembly easier).
if (!context.Config.Options.Flags.HasFlag(TranslationFlags.DebugMode))
{
AstBlockVisitor visitor = new AstBlockVisitor(mainBlock);
foreach (IAstNode node in visitor.Visit())
{
if (node is AstAssignment assignment && assignment.Destination is AstOperand propVar)
{
bool isWorthPropagating = propVar.Uses.Count == 1 || IsWorthPropagating(assignment.Source);
if (propVar.Defs.Count == 1 && isWorthPropagating)
{
PropagateExpression(propVar, assignment.Source);
}
if (propVar.Type == OperandType.LocalVariable && propVar.Uses.Count == 0)
{
visitor.Block.Remove(assignment);
context.CurrentFunction.Locals.Remove(propVar);
}
}
}
}
RemoveEmptyBlocks(mainBlock);
}
private static bool IsWorthPropagating(IAstNode source)
{
if (!(source is AstOperation srcOp))
{
return false;
}
if (!InstructionInfo.IsUnary(srcOp.Inst))
{
return false;
}
return srcOp.GetSource(0) is AstOperand || srcOp.Inst == Instruction.Copy;
}
private static void PropagateExpression(AstOperand propVar, IAstNode source)
{
IAstNode[] uses = propVar.Uses.ToArray();
foreach (IAstNode useNode in uses)
{
if (useNode is AstBlock useBlock)
{
useBlock.Condition = source;
}
else if (useNode is AstOperation useOperation)
{
for (int srcIndex = 0; srcIndex < useOperation.SourcesCount; srcIndex++)
{
if (useOperation.GetSource(srcIndex) == propVar)
{
useOperation.SetSource(srcIndex, source);
}
}
}
else if (useNode is AstAssignment useAssignment)
{
useAssignment.Source = source;
}
}
}
private static void RemoveEmptyBlocks(AstBlock mainBlock)
{
Queue<AstBlock> pending = new Queue<AstBlock>();
pending.Enqueue(mainBlock);
while (pending.TryDequeue(out AstBlock block))
{
foreach (IAstNode node in block)
{
if (node is AstBlock childBlock)
{
pending.Enqueue(childBlock);
}
}
AstBlock parent = block.Parent;
if (parent == null)
{
continue;
}
AstBlock nextBlock = Next(block) as AstBlock;
bool hasElse = nextBlock != null && nextBlock.Type == AstBlockType.Else;
bool isIf = block.Type == AstBlockType.If;
if (block.Count == 0)
{
if (isIf)
{
if (hasElse)
{
nextBlock.TurnIntoIf(InverseCond(block.Condition));
}
parent.Remove(block);
}
else if (block.Type == AstBlockType.Else)
{
parent.Remove(block);
}
}
else if (isIf && parent.Type == AstBlockType.Else && parent.Count == (hasElse ? 2 : 1))
{
AstBlock parentOfParent = parent.Parent;
parent.Remove(block);
parentOfParent.AddAfter(parent, block);
if (hasElse)
{
parent.Remove(nextBlock);
parentOfParent.AddAfter(block, nextBlock);
}
parentOfParent.Remove(parent);
block.TurnIntoElseIf();
}
}
}
}
}
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