[Switch] Fix OOB in Initialize compute (#261)

* Fix OOB

See original experiment dfe52ee

* *Update changelog.md

* Minor refactor of dichotomy code

- Address this issue : Fix https://github.cds.internal.unity3d.com/unity/vfx-graphics/pull/261#discussion_r159944
- I checked the generated code from ilassembly : http://shader-playground.timjones.io/52be834b8d455f3240051c5f7eebee5d
- Run locally URP graphicTest in playmode :green: (TODO : verify on switch)

Author: PaulDemeulenaere

com.unity.visualeffectgraph/CHANGELOG.md

@@ -73,6 +73,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Fix IsFrontFace shader graph node for VFX.
 - Fix crash when loading SDF Baker settings holding a mesh prefab [Case 1343898](https://issuetracker.unity3d.com/product/unity/issues/guid/1343898/)
 - Exception using gizmo on exposed properties [Case 1340818](https://issuetracker.unity3d.com/product/unity/issues/guid/1340818/)
+- GPU hang on some initialize dispatch during dichotomy (platform specific)
 
 ## [11.0.0] - 2020-10-21
 ### Added

com.unity.visualeffectgraph/Shaders/VFXInit.template

@@ -108,13 +108,16 @@ void CSMain(uint3 groupId          : SV_GroupID,
             while (left <= right)
             {
                 sourceIndex = (int)((left + right) / 2);
-                if (id < prefixSumSpawnCount[sourceIndex] && (sourceIndex == 0 || id >= prefixSumSpawnCount[sourceIndex-1]))
-                    break;
-
-                if (id < prefixSumSpawnCount[sourceIndex])
+                if (id.x < prefixSumSpawnCount[sourceIndex])
+                {
+                    if (sourceIndex == 0 || id.x >= prefixSumSpawnCount[max(sourceIndex - 1, 0)])
+                        break;
                     right = sourceIndex - 1;
+                }
                 else
+                {
                     left = sourceIndex + 1;
+                }
             }
         #endif
 #endif