Better IPA shader instruction implementation (#1082)

* Fix varying interpolation on fragment shader

* Some nits

* Alignment

3 files changed, 65 insertions, 11 deletions

diff --git a/Ryujinx.Graphics.Shader/Translation/EmitterContext.cs b/Ryujinx.Graphics.Shader/Translation/EmitterContext.cs
index 7111196b..8044f074 100644
--- a/Ryujinx.Graphics.Shader/Translation/EmitterContext.cs
+++ b/Ryujinx.Graphics.Shader/Translation/EmitterContext.cs
@@ -76,7 +76,7 @@ namespace Ryujinx.Graphics.Shader.Translation
 
                 for (int attachment = 0; attachment < 8; attachment++)
                 {
-                    OutputMapTarget target = _config.OmapTargets[attachment];
+                    OmapTarget target = _config.OmapTargets[attachment];
 
                     for (int component = 0; component < 4; component++)
                     {
diff --git a/Ryujinx.Graphics.Shader/Translation/ShaderConfig.cs b/Ryujinx.Graphics.Shader/Translation/ShaderConfig.cs
index e3708b41..60660847 100644
--- a/Ryujinx.Graphics.Shader/Translation/ShaderConfig.cs
+++ b/Ryujinx.Graphics.Shader/Translation/ShaderConfig.cs
@@ -12,9 +12,11 @@ namespace Ryujinx.Graphics.Shader.Translation
 
         public int LocalMemorySize { get; }
 
-        public OutputMapTarget[] OmapTargets    { get; }
-        public bool              OmapSampleMask { get; }
-        public bool              OmapDepth      { get; }
+        public ImapPixelType[] ImapTypes { get; }
+
+        public OmapTarget[] OmapTargets    { get; }
+        public bool         OmapSampleMask { get; }
+        public bool         OmapDepth      { get; }
 
         public TranslationFlags Flags { get; }
 
@@ -26,6 +28,7 @@ namespace Ryujinx.Graphics.Shader.Translation
             OutputTopology    = OutputTopology.PointList;
             MaxOutputVertices = 0;
             LocalMemorySize   = 0;
+            ImapTypes         = null;
             OmapTargets       = null;
             OmapSampleMask    = false;
             OmapDepth         = false;
@@ -39,6 +42,7 @@ namespace Ryujinx.Graphics.Shader.Translation
             OutputTopology    = header.OutputTopology;
             MaxOutputVertices = header.MaxOutputVertexCount;
             LocalMemorySize   = header.ShaderLocalMemoryLowSize + header.ShaderLocalMemoryHighSize;
+            ImapTypes         = header.ImapTypes;
             OmapTargets       = header.OmapTargets;
             OmapSampleMask    = header.OmapSampleMask;
             OmapDepth         = header.OmapDepth;
diff --git a/Ryujinx.Graphics.Shader/Translation/ShaderHeader.cs b/Ryujinx.Graphics.Shader/Translation/ShaderHeader.cs
index 42701fbd..a3b861c9 100644
--- a/Ryujinx.Graphics.Shader/Translation/ShaderHeader.cs
+++ b/Ryujinx.Graphics.Shader/Translation/ShaderHeader.cs
@@ -4,7 +4,39 @@ using System.Runtime.InteropServices;
 
 namespace Ryujinx.Graphics.Shader.Translation
 {
-    struct OutputMapTarget
+    enum PixelImap
+    {
+        Unused = 0,
+        Constant = 1,
+        Perspective = 2,
+        ScreenLinear = 3
+    }
+
+    struct ImapPixelType
+    {
+        public PixelImap X { get; }
+        public PixelImap Y { get; }
+        public PixelImap Z { get; }
+        public PixelImap W { get; }
+
+        public ImapPixelType(PixelImap x, PixelImap y, PixelImap z, PixelImap w)
+        {
+            X = x;
+            Y = y;
+            Z = z;
+            W = w;
+        }
+
+        public PixelImap GetFirstUsedType()
+        {
+            if (X != PixelImap.Unused) return X;
+            if (Y != PixelImap.Unused) return Y;
+            if (Z != PixelImap.Unused) return Z;
+            return W;
+        }
+    }
+
+    struct OmapTarget
     {
         public bool Red   { get; }
         public bool Green { get; }
@@ -13,7 +45,7 @@ namespace Ryujinx.Graphics.Shader.Translation
 
         public bool Enabled => Red || Green || Blue || Alpha;
 
-        public OutputMapTarget(bool red, bool green, bool blue, bool alpha)
+        public OmapTarget(bool red, bool green, bool blue, bool alpha)
         {
             Red   = red;
             Green = green;
@@ -72,9 +104,11 @@ namespace Ryujinx.Graphics.Shader.Translation
         public int StoreReqStart { get; }
         public int StoreReqEnd   { get; }
 
-        public OutputMapTarget[] OmapTargets    { get; }
-        public bool              OmapSampleMask { get; }
-        public bool              OmapDepth      { get; }
+        public ImapPixelType[] ImapTypes { get; }
+
+        public OmapTarget[] OmapTargets    { get; }
+        public bool         OmapSampleMask { get; }
+        public bool         OmapDepth      { get; }
 
         public ShaderHeader(ReadOnlySpan<byte> code)
         {
@@ -127,14 +161,30 @@ namespace Ryujinx.Graphics.Shader.Translation
             StoreReqStart = commonWord4.Extract(12, 8);
             StoreReqEnd   = commonWord4.Extract(24, 8);
 
+            ImapTypes = new ImapPixelType[32];
+
+            for (int i = 0; i < 8; i++)
+            {
+                for (int j = 0; j < 4; j++)
+                {
+                    byte imap = (byte)(header[6 + i] >> (j * 8));
+
+                    ImapTypes[i * 4 + j] = new ImapPixelType(
+                        (PixelImap)((imap >> 0) & 3),
+                        (PixelImap)((imap >> 2) & 3),
+                        (PixelImap)((imap >> 4) & 3),
+                        (PixelImap)((imap >> 6) & 3));
+                }
+            }
+
             int type2OmapTarget = header[18];
             int type2Omap       = header[19];
 
-            OmapTargets = new OutputMapTarget[8];
+            OmapTargets = new OmapTarget[8];
 
             for (int offset = 0; offset < OmapTargets.Length * 4; offset += 4)
             {
-                OmapTargets[offset >> 2] = new OutputMapTarget(
+                OmapTargets[offset >> 2] = new OmapTarget(
                     type2OmapTarget.Extract(offset + 0),
                     type2OmapTarget.Extract(offset + 1),
                     type2OmapTarget.Extract(offset + 2),