From c1138e20c54c3abf786f984d8c27d722a323f7db Mon Sep 17 00:00:00 2001
From: baldurk <baldurk@baldurk.org>
Date: Tue, 29 Jul 2025 13:04:43 +0100
Subject: [PATCH] Handle debugging PS with unwritten inputs

* If a VS-PS declares a struct but there is an element which is declared but
  never written in the VS (and never read in the PS) then we can't read from it
  and must skip that element.
---
 renderdoc/driver/shaders/dxbc/dx_debug.cpp | 24 ++++++++++++++--------
 1 file changed, 16 insertions(+), 8 deletions(-)

diff --git a/renderdoc/driver/shaders/dxbc/dx_debug.cpp b/renderdoc/driver/shaders/dxbc/dx_debug.cpp
index 6deffb89e..df38db5ab 100644
--- a/renderdoc/driver/shaders/dxbc/dx_debug.cpp
+++ b/renderdoc/driver/shaders/dxbc/dx_debug.cpp
@@ -66,9 +66,13 @@ void GatherInputDataForInitialValues(const DXBC::DXBCContainer *dxbc, InputFetch
   nonfloatInputs.clear();
   inputVarNames.clear();
   fetcher.hlsl += "struct Inputs\n{\n";
-  rdcstr defines;
+  rdcstr defines, copyFunc;
   fetcher.laneDataBufferStride = 0;
 
+  copyFunc =
+      "void CopyInputs(out Inputs OUT, in Inputs IN) {\n"
+      "  OUT = (Inputs)0;\n";
+
   if(stageInputSig.empty() && dxbc->m_Type == DXBC::ShaderType::Pixel)
   {
     fetcher.hlsl += "float4 input_dummy : SV_Position;\n";
@@ -322,7 +326,7 @@ void GatherInputDataForInitialValues(const DXBC::DXBCContainer *dxbc, InputFetch
     if(arrayLength > 0)
       inputVarNames[i] += StringFormat::Fmt("[%d]", RDCMAX(0, arrayIndex));
 
-    if(included)
+    if(included && sig.channelUsedMask != 0)
     {
       rdcarray<rdcstr> &outArray = sig.varType == VarType::Float ? floatInputs : nonfloatInputs;
       if(arrayLength == 0)
@@ -334,6 +338,8 @@ void GatherInputDataForInitialValues(const DXBC::DXBCContainer *dxbc, InputFetch
         for(int a = 0; a < arrayLength; a++)
           outArray.push_back(inputName + "[" + ToStr(a) + "]");
       }
+
+      copyFunc += StringFormat::Fmt("  OUT.%s = IN.%s;\n", inputName.c_str(), inputName.c_str());
     }
 
     fetcher.hlsl += ";\n";
@@ -366,7 +372,9 @@ void GatherInputDataForInitialValues(const DXBC::DXBCContainer *dxbc, InputFetch
     }
   }
 
-  fetcher.hlsl += "};\n\n" + defines;
+  copyFunc += "\n};\n\n";
+
+  fetcher.hlsl += "};\n\n" + defines + "\n\n" + copyFunc;
 }
 
 void CreateLegacyInputFetcher(const DXBC::DXBCContainer *dxbc, const InputFetcherConfig &cfg,
@@ -532,10 +540,10 @@ void ExtractInputs(Inputs IN
 
   // start off with just copying all the inputs to all the quad. For float inputs or uints that may
   // vary across the quad we will quadSwizzle them
-  HitBuffer[idx].lanes[0].IN = IN;
-  HitBuffer[idx].lanes[1].IN = IN;
-  HitBuffer[idx].lanes[2].IN = IN;
-  HitBuffer[idx].lanes[3].IN = IN;
+  CopyInputs(HitBuffer[idx].lanes[0].IN, IN);
+  CopyInputs(HitBuffer[idx].lanes[1].IN, IN);
+  CopyInputs(HitBuffer[idx].lanes[2].IN, IN);
+  CopyInputs(HitBuffer[idx].lanes[3].IN, IN);
 )";
 
   for(int q = 0; q < 4; q++)
@@ -1042,7 +1050,7 @@ void ExtractInputs(Inputs IN
         LaneBuffer[idx*MAXWAVESIZE+laneIndex].vs = vs;
         LaneBuffer[idx*MAXWAVESIZE+laneIndex].ps = ps;
         LaneBuffer[idx*MAXWAVESIZE+laneIndex].cs = cs;
-        LaneBuffer[idx*MAXWAVESIZE+laneIndex].IN = IN;
+        CopyInputs(LaneBuffer[idx*MAXWAVESIZE+laneIndex].IN, IN);
       }
     }
   }