From bbd1e1786401bb88c34802b987d4da72e2364503 Mon Sep 17 00:00:00 2001
From: Yong He <yonghe@outlook.com>
Date: Wed, 1 Feb 2023 14:18:57 -0800
Subject: Support `out` parameters in backward differentiation. (#2619)

* Support `out` parameters in backward differentiation.

* Fixes.

* Fix cleanup.

---------

Co-authored-by: Yong He <yhe@nvidia.com>
---
 source/slang/slang-ir-check-differentiability.cpp | 30 +++--------------------
 1 file changed, 4 insertions(+), 26 deletions(-)

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

diff --git a/source/slang/slang-ir-check-differentiability.cpp b/source/slang/slang-ir-check-differentiability.cpp
index ce3e563f5..e7d5a0e5c 100644
--- a/source/slang/slang-ir-check-differentiability.cpp
+++ b/source/slang/slang-ir-check-differentiability.cpp
@@ -5,28 +5,6 @@
 
 namespace Slang
 {
-IRInst* getSpecializedVal(IRInst* inst)
-{
-    int loopLimit = 1024;
-    while (inst && inst->getOp() == kIROp_Specialize)
-    {
-        inst = as<IRSpecialize>(inst)->getBase();
-        loopLimit--;
-        if (loopLimit == 0)
-            return inst;
-    }
-    return inst;
-}
-
-IRInst* getLeafFunc(IRInst* func)
-{
-    func = getSpecializedVal(func);
-    if (!func)
-        return nullptr;
-    if (auto genericFunc = as<IRGeneric>(func))
-        return findInnerMostGenericReturnVal(genericFunc);
-    return func;
-}
 
 struct CheckDifferentiabilityPassContext : public InstPassBase
 {
@@ -47,7 +25,7 @@ public:
 
     bool _isFuncMarkedForAutoDiff(IRInst* func)
     {
-        func = getLeafFunc(func);
+        func = getResolvedInstForDecorations(func);
         if (!func)
             return false;
         for (auto decorations : func->getDecorations())
@@ -65,7 +43,7 @@ public:
 
     bool _isDifferentiableFuncImpl(IRInst* func, DifferentiableLevel level)
     {
-        func = getLeafFunc(func);
+        func = getResolvedInstForDecorations(func);
         if (!func)
             return false;
 
@@ -103,7 +81,7 @@ public:
             }
         }
 
-        func = getLeafFunc(func);
+        func = getResolvedInstForDecorations(func);
         if (!func)
             return false;
 
@@ -332,7 +310,7 @@ public:
                     sink->diagnose(
                         inst,
                         Diagnostics::lossOfDerivativeDueToCallOfNonDifferentiableFunction,
-                        getLeafFunc(call->getCallee()),
+                        getResolvedInstForDecorations(call->getCallee()),
                         requiredDiffLevel == DifferentiableLevel::Forward ? "forward" : "backward");
                 }
             }
-- 
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