Ryujinx/Ryujinx.Graphics/Shader/Translation/Optimizations/BranchElimination.cs

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New shader translator implementation (#654) * Start implementing a new shader translator * Fix shift instructions and a typo * Small refactoring on StructuredProgram, move RemovePhis method to a separate class * Initial geometry shader support * Implement TLD4 * Fix -- There's no negation on FMUL32I * Add constant folding and algebraic simplification optimizations, nits * Some leftovers from constant folding * Avoid cast for constant assignments * Add a branch elimination pass, and misc small fixes * Remove redundant branches, add expression propagation and other improvements on the code * Small leftovers -- add missing break and continue, remove unused properties, other improvements * Add null check to handle empty block cases on block visitor * Add HADD2 and HMUL2 half float shader instructions * Optimize pack/unpack sequences, some fixes related to half float instructions * Add TXQ, TLD, TLDS and TLD4S shader texture instructions, and some support for bindless textures, some refactoring on codegen * Fix copy paste mistake that caused RZ to be ignored on the AST instruction * Add workaround for conditional exit, and fix half float instruction with constant buffer * Add missing 0.0 source for TLDS.LZ variants * Simplify the switch for TLDS.LZ * Texture instructions related fixes * Implement the HFMA instruction, and some misc. fixes * Enable constant folding on UnpackHalf2x16 instructions * Refactor HFMA to use OpCode* for opcode decoding rather than on the helper methods * Remove the old shader translator * Remove ShaderDeclInfo and other unused things * Add dual vertex shader support * Add ShaderConfig, used to pass shader type and maximum cbuffer size * Move and rename some instruction enums * Move texture instructions into a separate file * Move operand GetExpression and locals management to OperandManager * Optimize opcode decoding using a simple list and binary search * Add missing condition for do-while on goto elimination * Misc. fixes on texture instructions * Simplify TLDS switch * Address PR feedback, and a nit
2019-04-17 23:57:08 +00:00
using Ryujinx.Graphics.Shader.IntermediateRepresentation;
using System;
namespace Ryujinx.Graphics.Shader.Translation.Optimizations
{
static class BranchElimination
{
public static bool Eliminate(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;
}
}
}