From a3a0aae660ff69378a8ad68d241db147d9da5b4d Mon Sep 17 00:00:00 2001
From: baldurk <baldurk@baldurk.org>
Date: Mon, 19 Jul 2021 14:26:28 +0100
Subject: [PATCH] Handle fixed index lookups in array resources

---
 .../driver/d3d12/d3d12_shader_feedback.cpp    | 45 ++++++++++++-------
 .../demos/d3d12/d3d12_descriptor_indexing.cpp |  1 +
 .../tests/D3D12/D3D12_Descriptor_Indexing.py  |  3 +-
 3 files changed, 33 insertions(+), 16 deletions(-)

diff --git a/renderdoc/driver/d3d12/d3d12_shader_feedback.cpp b/renderdoc/driver/d3d12/d3d12_shader_feedback.cpp
index 4cd9548f1..ef812d8eb 100644
--- a/renderdoc/driver/d3d12/d3d12_shader_feedback.cpp
+++ b/renderdoc/driver/d3d12/d3d12_shader_feedback.cpp
@@ -110,10 +110,34 @@ static bool AnnotateShader(const DXBC::DXBCContainer *dxbc, uint32_t space,
       if(decl->operand.indices[1].index == decl->operand.indices[2].index)
         continue;
 
-      // the operand should be relative addressing like r0.x + 6 for a t6 resource being indexed
-      // with [r0.x]
-      RDCASSERT(operand.indices[1].relative &&
-                operand.indices[1].index == decl->operand.indices[1].index);
+      bool dynamic = operand.indices[1].relative;
+
+      Operand idx;
+
+      if(dynamic)
+      {
+        // the operand should be relative addressing like r0.x + 6 for a t6 resource being indexed
+        // with [r0.x]
+        RDCASSERT(operand.indices[1].index == decl->operand.indices[1].index);
+
+        idx = operand.indices[1].operand;
+
+        // should be getting a scalar index
+        if(idx.comps[1] != 0xff || idx.comps[2] != 0xff || idx.comps[3] != 0xff)
+        {
+          RDCERR("Unexpected vector index for resource: %s",
+                 operand.toString(dxbc->GetReflection(), ToString::None).c_str());
+          continue;
+        }
+      }
+      else
+      {
+        // shader could be indexing into an array with a fixed index. Handle that by subtracting the
+        // base manually
+        RDCASSERT(operand.indices[1].index >= decl->operand.indices[1].index);
+
+        idx = imm(uint32_t(operand.indices[1].index - decl->operand.indices[1].index));
+      }
 
       D3D12FeedbackKey key;
       key.type = operand.type;
@@ -129,21 +153,12 @@ static bool AnnotateShader(const DXBC::DXBCContainer *dxbc, uint32_t space,
         continue;
       }
 
-      // should be getting a scalar index
-      if(operand.indices[1].operand.comps[1] != 0xff ||
-         operand.indices[1].operand.comps[2] != 0xff || operand.indices[1].operand.comps[3] != 0xff)
-      {
-        RDCERR("Unexpected vector index for resource: %s",
-               operand.toString(dxbc->GetReflection(), ToString::None).c_str());
-        continue;
-      }
-
       if(u.first == ~0U && u.second == ~0U)
         u = editor.DeclareUAV(desc, space, 0, 0);
 
       // resource base plus index
-      editor.InsertOperation(i++, oper(OPCODE_IADD, {temp(t).swizzle(0), imm(it->second.Slot()),
-                                                     operand.indices[1].operand}));
+      editor.InsertOperation(i++,
+                             oper(OPCODE_IADD, {temp(t).swizzle(0), imm(it->second.Slot()), idx}));
       // multiply by 4 for byte index
       editor.InsertOperation(i++,
                              oper(OPCODE_ISHL, {temp(t).swizzle(0), temp(t).swizzle(0), imm(2)}));
diff --git a/util/test/demos/d3d12/d3d12_descriptor_indexing.cpp b/util/test/demos/d3d12/d3d12_descriptor_indexing.cpp
index 379802fd1..e17a9060d 100644
--- a/util/test/demos/d3d12/d3d12_descriptor_indexing.cpp
+++ b/util/test/demos/d3d12/d3d12_descriptor_indexing.cpp
@@ -114,6 +114,7 @@ float4 main(v2f IN) : SV_Target0
       {
         ret *= texArray2[t.binding].SampleLevel(s, uv.xy, 0);
         ret *= texArray2[t.binding+10].SampleLevel(s, uv.xy, 0);
+        ret *= texArray2[20].SampleLevel(s, uv.xy, 0);
       }
       else if(t.tex == 2)
       {
diff --git a/util/test/tests/D3D12/D3D12_Descriptor_Indexing.py b/util/test/tests/D3D12/D3D12_Descriptor_Indexing.py
index 645c21664..0da5b5a4b 100644
--- a/util/test/tests/D3D12/D3D12_Descriptor_Indexing.py
+++ b/util/test/tests/D3D12/D3D12_Descriptor_Indexing.py
@@ -53,10 +53,11 @@ class D3D12_Descriptor_Indexing(rdtest.TestCase):
             #     image 15 in root range 0 should also be statically used
             #   - images 19, 20, 21 in root range 1 should be used for the non-uniform index
             #     images 49 & 59 in root range 1 should be used for a second array in the same range
+            #     image 60 in root range 1 should be used for a fixed index in an array
             #     image 99 and 103 in root range 1 should be used
             bind_info = {
                 0: [8, 12],
-                1: [19, 20, 21, 49, 59, 99, 103],
+                1: [19, 20, 21, 49, 59, 60, 99, 103],
             }
 
             if len(pipe.rootElements) != 3: