From 1093218d6f0e114eb9fa52d60ca525bf9dd9f98a Mon Sep 17 00:00:00 2001
From: Sai Praveen Bangaru <31557731+saipraveenb25@users.noreply.github.com>
Date: Thu, 20 Oct 2022 14:22:00 -0400
Subject: Modified the new type system to support generic differentiable types
 … (#2413)
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* Modified the new type system to support generic differentiable types and added support for differentiating overloaded functions.

* Changed a few asserts to release asserts to avoid unreferenced variable errors

* Fixed a naming issue with TypeWitnessBreadcumb::Flavor::Decl

* Added logic to avoid tracking differentiable types if the module does not use auto-diff or define differentiable types.

* Moved the auto-diff passes to after the specialization step, added a more complex generics test

* Added a generics stress test and fixed AST-side logic. IR side needs some more work

* Added differential getter and setter logic, fixed multiple issues with DifferentiableTypeDictionary, added support for loops and conditions

* Changed differential getters to use pointer types, added getter type checking

* Fixed some bugs related to diff type registration and differential getters

* Removed some superfluous code

* Removed some more unused code.

* Fixed an issue with witness substitution

* Minor fix

Co-authored-by: Yong He <yonghe@outlook.com>
---
 source/slang/slang-ast-val.cpp | 85 ++++++++++++++++++++++++++++++------------
 1 file changed, 61 insertions(+), 24 deletions(-)

(limited to 'source/slang/slang-ast-val.cpp')

diff --git a/source/slang/slang-ast-val.cpp b/source/slang/slang-ast-val.cpp
index 377dee350..a8ceaa716 100644
--- a/source/slang/slang-ast-val.cpp
+++ b/source/slang/slang-ast-val.cpp
@@ -283,7 +283,7 @@ Val* DeclaredSubtypeWitness::_substituteImplOverride(ASTBuilder* astBuilder, Sub
                     {
                         if (constraintParam == declRef.getDecl())
                         {
-                            found = true;
+                            found = true; 
                             break;
                         }
                         index++;
@@ -443,6 +443,66 @@ HashCode TransitiveSubtypeWitness::_getHashCodeOverride()
     return hash;
 }
 
+// !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! ExtractFromConjunctionSubtypeWitness !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+
+Val* ExtractFromConjunctionSubtypeWitness::_substituteImplOverride(ASTBuilder* astBuilder, SubstitutionSet subst, int * ioDiff)
+{
+    int diff = 0;
+
+    Type* substSub = as<Type>(sub->substituteImpl(astBuilder, subst, &diff));
+    Type* substSup = as<Type>(sup->substituteImpl(astBuilder, subst, &diff));
+    SubtypeWitness* substWitness = as<SubtypeWitness>(conjunctionWitness->substituteImpl(astBuilder, subst, &diff));
+
+    // If nothing changed, then we can bail out early.
+    if (!diff)
+        return this;
+
+    // Something changes, so let the caller know.
+    (*ioDiff)++;
+
+    // If the substituted witness is a conjunction, break it apart, but it's important to replace the
+    // sub and super types with the current ones since the conjunction witness will have an 
+    // 
+    if (auto substConjunctionWitness = as<ConjunctionSubtypeWitness>(substWitness))
+    {
+        if (indexInConjunction == 0)
+        {
+            auto witness = as<SubtypeWitness>(substConjunctionWitness->leftWitness);
+            SLANG_ASSERT(witness);
+
+            witness->sub = substSub;
+            witness->sup = substSup;
+            
+            return witness;
+        }
+        else if (indexInConjunction == 1)
+        {
+            auto witness = as<SubtypeWitness>(substConjunctionWitness->rightWitness);
+            SLANG_ASSERT(witness);
+            
+            witness->sub = substSub;
+            witness->sup = substSup;
+
+            return witness;
+        }
+        else
+        {
+            SLANG_UNIMPLEMENTED_X("conjunction index must be 0 or 1");
+        }
+    }
+    else
+    {
+        // In the simple case, we just construct a new conjunction subtype
+        // witness.
+        ExtractFromConjunctionSubtypeWitness* result = astBuilder->create<ExtractFromConjunctionSubtypeWitness>();
+        result->sub = substSub;
+        result->sup = substSup;
+        result->conjunctionWitness = substWitness;
+        result->indexInConjunction = indexInConjunction;
+        return result;
+    }
+}
+
 // !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! ExtractExistentialSubtypeWitness !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
 
 bool ExtractExistentialSubtypeWitness::_equalsValOverride(Val* val)
@@ -637,29 +697,6 @@ HashCode ExtractFromConjunctionSubtypeWitness::_getHashCodeOverride()
     return combineHash(indexInConjunction, conjunctionWitness ? conjunctionWitness->getHashCode() : 0);
 }
 
-Val* ExtractFromConjunctionSubtypeWitness::_substituteImplOverride(ASTBuilder* astBuilder, SubstitutionSet subst, int* ioDiff)
-{
-    int diff = 0;
-    Val* newConjunctionWitness = nullptr;
-
-    auto substSub = as<Type>(sub->substituteImpl(astBuilder, subst, &diff));
-    auto substSup = as<Type>(sup->substituteImpl(astBuilder, subst, &diff));
-
-    if (this->conjunctionWitness)
-        newConjunctionWitness = conjunctionWitness->substituteImpl(astBuilder, subst, &diff);
-    *ioDiff += diff;
-
-    if (diff)
-    {
-        auto result = astBuilder->create<ExtractFromConjunctionSubtypeWitness>();
-        result->conjunctionWitness = newConjunctionWitness;
-        result->sub = substSub;
-        result->sup = substSup;
-        return result;
-    }
-    return this;
-}
-
 // ModifierVal
 
 bool ModifierVal::_equalsValOverride(Val* val)
-- 
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