From 46a4d98baa1d43b33717b4377aefeeaf46b9c2ff Mon Sep 17 00:00:00 2001
From: Yong He <yonghe@outlook.com>
Date: Mon, 23 Jan 2023 06:59:25 -0800
Subject: Full address insts elimination for backward autodiff. (#2604)

Co-authored-by: Yong He <yhe@nvidia.com>
---
 source/slang/slang-ir-check-differentiability.cpp | 82 +++++++++++++----------
 1 file changed, 45 insertions(+), 37 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 cb7290036..67b7e92b0 100644
--- a/source/slang/slang-ir-check-differentiability.cpp
+++ b/source/slang/slang-ir-check-differentiability.cpp
@@ -5,12 +5,45 @@
 
 namespace Slang
 {
+bool isDifferentiableType(DifferentiableTypeConformanceContext& context, IRInst* typeInst)
+{
+    HashSet<IRInst*> processedSet;
+    while (auto ptrType = as<IRPtrTypeBase>(typeInst))
+    {
+        typeInst = ptrType->getValueType();
+        if (!processedSet.Add(typeInst))
+            return false;
+    }
+    if (!typeInst)
+        return false;
+    switch (typeInst->getOp())
+    {
+    case kIROp_FloatType:
+    case kIROp_DifferentialPairType:
+        return true;
+    default:
+        break;
+    }
+    if (context.lookUpConformanceForType(typeInst))
+        return true;
+    // Look for equivalent types.
+    for (auto type : context.differentiableWitnessDictionary)
+    {
+        if (isTypeEqual(type.Key, (IRType*)typeInst))
+        {
+            context.differentiableWitnessDictionary[(IRType*)typeInst] = type.Value;
+            return true;
+        }
+    }
+    return false;
+}
 
 struct CheckDifferentiabilityPassContext : public InstPassBase
 {
 public:
     DiagnosticSink* sink;
     AutoDiffSharedContext sharedContext;
+    SharedIRBuilder* sharedBuilder;
 
     enum DifferentiableLevel
     {
@@ -18,8 +51,8 @@ public:
     };
     Dictionary<IRInst*, DifferentiableLevel> differentiableFunctions;
 
-    CheckDifferentiabilityPassContext(IRModule* inModule, DiagnosticSink* inSink)
-        : InstPassBase(inModule), sink(inSink), sharedContext(inModule->getModuleInst())
+    CheckDifferentiabilityPassContext(SharedIRBuilder* inSharedBuilder, IRModule* inModule, DiagnosticSink* inSink)
+        : InstPassBase(inModule), sharedBuilder(inSharedBuilder), sink(inSink), sharedContext(inModule->getModuleInst())
     {}
 
     IRInst* getSpecializedVal(IRInst* inst)
@@ -161,39 +194,6 @@ public:
         return false;
     }
 
-    bool isDifferentiableType(DifferentiableTypeConformanceContext& context, IRInst* typeInst)
-    {
-        HashSet<IRInst*> processedSet;
-        while (auto ptrType = as<IRPtrTypeBase>(typeInst))
-        {
-            typeInst = ptrType->getValueType();
-            if (!processedSet.Add(typeInst))
-                return false;
-        }
-        if (!typeInst)
-            return false;
-        switch (typeInst->getOp())
-        {
-        case kIROp_FloatType:
-        case kIROp_DifferentialPairType:
-            return true;
-        default:
-            break;
-        }
-        if (context.lookUpConformanceForType(typeInst))
-            return true;
-        // Look for equivalent types.
-        for (auto type : context.differentiableWitnessDictionary)
-        {
-            if (isTypeEqual(type.Key, (IRType*)typeInst))
-            {
-                context.differentiableWitnessDictionary[(IRType*)typeInst] = type.Value;
-                return true;
-            }
-        }
-        return false;
-    }
-
     int getParamIndexInBlock(IRParam* paramInst)
     {
         auto block = as<IRBlock>(paramInst->getParent());
@@ -228,6 +228,14 @@ public:
 
         DifferentiableTypeConformanceContext diffTypeContext(&sharedContext);
         diffTypeContext.setFunc(funcInst);
+        if (isBackwardDifferentiableFunc(funcInst) && !funcInst->findDecoration<IRUserDefinedBackwardDerivativeDecoration>())
+        {
+            if (auto func = as<IRFunc>(funcInst))
+            {
+                if (SLANG_FAILED(eliminateAddressInsts(sharedBuilder, diffTypeContext, func, sink)))
+                    return;
+            }
+        }
 
         HashSet<IRInst*> produceDiffSet;
         HashSet<IRInst*> expectDiffSet;
@@ -468,9 +476,9 @@ public:
     }
 };
 
-void checkAutoDiffUsages(IRModule* module, DiagnosticSink* sink)
+void checkAutoDiffUsages(SharedIRBuilder* sharedBuilder, IRModule* module, DiagnosticSink* sink)
 {
-    CheckDifferentiabilityPassContext context(module, sink);
+    CheckDifferentiabilityPassContext context(sharedBuilder, module, sink);
     context.processModule();
 }
 
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