Fix #31806: cycles crash rendering a particular node setup with multiple mix/add

shader nodes.

1 files changed, 11 insertions, 0 deletions

diff --git a/intern/cycles/render/svm.cpp b/intern/cycles/render/svm.cpp
index 844ce01569f..da287a10199 100644
--- a/intern/cycles/render/svm.cpp
+++ b/intern/cycles/render/svm.cpp
@@ -274,6 +274,17 @@ void SVMCompiler::stack_clear_users(ShaderNode *node, set<ShaderNode*>& done)
 
 				foreach(ShaderInput *in, output->links)
 					in->stack_offset = SVM_STACK_INVALID;
+
+				/* unmark any nodes that have no more valid outputs, see [#31806] */
+				if(done.find(output->parent) != done.end()) {
+					all_done = true;
+					foreach(ShaderOutput *pout, output->parent->outputs)
+						if(pout->stack_offset != SVM_STACK_INVALID)
+							all_done = false;
+
+					if(all_done)
+						done.erase(output->parent);
+				}
 			}
 		}
 	}