From e291f60c6b083eaa74aed5307a6e9461274c1642 Mon Sep 17 00:00:00 2001
From: Yong He <yonghe@outlook.com>
Date: Tue, 14 Mar 2023 09:31:51 -0700
Subject: Support `fwd_diff(bwd_diff(f))`. (#2697)

* Support `fwd_diff(bwd_diff(f))`.

* Fix.

---------

Co-authored-by: Yong He <yhe@nvidia.com>
---
 source/slang/slang-ir-validate.cpp | 6 ++++++
 1 file changed, 6 insertions(+)

(limited to 'source/slang/slang-ir-validate.cpp')

diff --git a/source/slang/slang-ir-validate.cpp b/source/slang/slang-ir-validate.cpp
index d5c0aa432..55e0f0168 100644
--- a/source/slang/slang-ir-validate.cpp
+++ b/source/slang/slang-ir-validate.cpp
@@ -208,6 +208,12 @@ namespace Slang
         if (allInGlobalScope)
             return;
 
+        // Allow exceptions.
+        switch (inst->getOp())
+        {
+        case kIROp_DifferentiableTypeDictionaryItem:
+            return;
+        }
         //
         // We failed to find `operandParent` while walking the ancestors of `inst`,
         // so something had gone wrong.
-- 
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