Shader cfg ssa (#707)

* [shader] add scalar control flow graph * [shader] add gen5 branch resolver * [shader] add scalar reaching definitions * [shader] add cfg and dataflow tests * [shader] guard descriptors from unresolved registers
2026-07-31 06:59:45 +08:00 · 2026-07-31 01:39:56 +03:00
parent 5864328e35
commit e7149bf41f
8 changed files with 1379 additions and 5 deletions
@@ -0,0 +1,168 @@
+// Copyright (C) 2026 SharpEmu Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+using System.Collections.Generic;
+using SharpEmu.ShaderCompiler;
+using SharpEmu.ShaderCompiler.Ir;
+using Xunit;
+
+namespace SharpEmu.ShaderCompiler.Tests;
+
+public sealed class Gen5ScalarSsaTests
+{
+    private static Gen5ShaderInstruction Mov(uint pc, uint destination, uint literal) =>
+        new(
+            pc,
+            Gen5ShaderEncoding.Sop1,
+            "SMov",
+            [0u],
+            [new Gen5Operand(Gen5OperandKind.LiteralConstant, literal)],
+            [Gen5Operand.Scalar(destination)],
+            null);
+
+    private static Gen5ShaderInstruction Nop(uint pc) =>
+        new(pc, Gen5ShaderEncoding.Sop1, "SNop", [0u], [], [], null);
+
+    private static Gen5ShaderInstruction Branch(uint pc, string opcode, short wordOffset) =>
+        new(
+            pc,
+            Gen5ShaderEncoding.Sopp,
+            opcode,
+            [unchecked((uint)(ushort)wordOffset)],
+            [],
+            [],
+            null);
+
+    [Fact]
+    public void StraightLineMovResolvesToAConstant()
+    {
+        List<Gen5ShaderInstruction> program =
+        [
+            Mov(0, destination: 8, literal: 0x1234),
+            Nop(4),
+        ];
+
+        var ssa = Gen5ScalarSsa.Build(program, userData: []);
+        var value = ssa.GetScalarAt(4, 8);
+
+        Assert.Equal(IrScalarState.Constant, value.State);
+        Assert.Equal(0x1234u, value.Constant);
+    }
+
+    [Fact]
+    public void UserDataSeedsTheEntryState()
+    {
+        List<Gen5ShaderInstruction> program = [Nop(0)];
+
+        var ssa = Gen5ScalarSsa.Build(program, userData: [0x40F55240, 0x00000004]);
+
+        Assert.Equal(IrScalarState.Constant, ssa.GetScalarAt(0, 0).State);
+        Assert.Equal(0x40F55240u, ssa.GetScalarAt(0, 0).Constant);
+        Assert.Equal(0x00000004u, ssa.GetScalarAt(0, 1).Constant);
+    }
+
+    [Fact]
+    public void ConflictingValuesFromTwoPathsBecomeMerged()
+    {
+        // if (cc) s8 = 0xAAAA else s8 = 0xBBBB; use s8
+        List<Gen5ShaderInstruction> program =
+        [
+            Branch(0, "SCbranchScc0", 2),
+            Mov(4, destination: 8, literal: 0xAAAA),
+            Branch(8, "SBranch", 1),
+            Mov(12, destination: 8, literal: 0xBBBB),
+            Nop(16),
+        ];
+
+        var ssa = Gen5ScalarSsa.Build(program, userData: []);
+
+        Assert.True(ssa.Graph.HasControlFlow);
+        Assert.Equal(IrScalarState.Merged, ssa.GetScalarAt(16, 8).State);
+    }
+
+    [Fact]
+    public void SameValueOnBothPathsStaysResolved()
+    {
+        List<Gen5ShaderInstruction> program =
+        [
+            Branch(0, "SCbranchScc0", 2),
+            Mov(4, destination: 8, literal: 0xCAFE),
+            Branch(8, "SBranch", 1),
+            Mov(12, destination: 8, literal: 0xCAFE),
+            Nop(16),
+        ];
+
+        var ssa = Gen5ScalarSsa.Build(program, userData: []);
+        var value = ssa.GetScalarAt(16, 8);
+
+        Assert.Equal(IrScalarState.Constant, value.State);
+        Assert.Equal(0xCAFEu, value.Constant);
+    }
+
+    [Fact]
+    public void RegisterWrittenOnOnlyOnePathIsMergedAtTheJoin()
+    {
+        List<Gen5ShaderInstruction> program =
+        [
+            Mov(0, destination: 8, literal: 0x1111),
+            Branch(4, "SCbranchScc0", 1),
+            Mov(8, destination: 8, literal: 0x2222),
+            Nop(12),
+        ];
+
+        var ssa = Gen5ScalarSsa.Build(program, userData: []);
+
+        Assert.Equal(IrScalarState.Merged, ssa.GetScalarAt(12, 8).State);
+    }
+
+    [Fact]
+    public void ValueBeforeTheBranchIsStillResolved()
+    {
+        List<Gen5ShaderInstruction> program =
+        [
+            Mov(0, destination: 8, literal: 0x1111),
+            Branch(4, "SCbranchScc0", 1),
+            Mov(8, destination: 8, literal: 0x2222),
+            Nop(12),
+        ];
+
+        var ssa = Gen5ScalarSsa.Build(program, userData: []);
+        var value = ssa.GetScalarAt(4, 8);
+
+        Assert.Equal(IrScalarState.Constant, value.State);
+        Assert.Equal(0x1111u, value.Constant);
+    }
+
+    [Fact]
+    public void MergeJoinIsReportedForDivergentBlocks()
+    {
+        List<Gen5ShaderInstruction> program =
+        [
+            Branch(0, "SCbranchScc0", 1),
+            Mov(4, destination: 8, literal: 1),
+            Nop(8),
+        ];
+
+        var ssa = Gen5ScalarSsa.Build(program, userData: []);
+
+        Assert.True(ssa.IsInsideDivergentMerge(8));
+        Assert.False(ssa.IsInsideDivergentMerge(0));
+    }
+
+    [Fact]
+    public void LoopDoesNotHangTheFixpoint()
+    {
+        List<Gen5ShaderInstruction> program =
+        [
+            Mov(0, destination: 8, literal: 1),
+            Nop(4),
+            Branch(8, "SCbranchScc1", -3),
+            Nop(12),
+        ];
+
+        var ssa = Gen5ScalarSsa.Build(program, userData: []);
+
+        Assert.NotEmpty(ssa.Graph.LoopHeaders);
+        Assert.Equal(IrScalarState.Constant, ssa.GetScalarAt(12, 8).State);
+    }
+}