ryujinx/Ryujinx.Graphics.Shader/Translation/Optimizations/BranchElimination.cs
2020-01-09 02:13:00 +01:00

64 lines
1.8 KiB
C#

using Ryujinx.Graphics.Shader.IntermediateRepresentation;
using System;
namespace Ryujinx.Graphics.Shader.Translation.Optimizations
{
static class BranchElimination
{
public static bool RunPass(BasicBlock block)
{
if (block.HasBranch && IsRedundantBranch((Operation)block.GetLastOp(), Next(block)))
{
block.Branch = null;
return true;
}
return false;
}
private static bool IsRedundantBranch(Operation current, BasicBlock nextBlock)
{
// Here we check that:
// - The current block ends with a branch.
// - The next block only contains a branch.
// - The branch on the next block is unconditional.
// - Both branches are jumping to the same location.
// In this case, the branch on the current block can be removed,
// as the next block is going to jump to the same place anyway.
if (nextBlock == null)
{
return false;
}
if (!(nextBlock.Operations.First?.Value is Operation next))
{
return false;
}
if (next.Inst != Instruction.Branch)
{
return false;
}
return current.Dest == next.Dest;
}
private static BasicBlock Next(BasicBlock block)
{
block = block.Next;
while (block != null && block.Operations.Count == 0)
{
if (block.HasBranch)
{
throw new InvalidOperationException("Found a bogus empty block that \"ends with a branch\".");
}
block = block.Next;
}
return block;
}
}
}