Split bwd_diff op into separate ops for primal and propagate func. (#2582)

* Split bwd_diff op into separate ops for primal and propagate func.

* Fix.

* Download swiftshader with github actions instead of curl on linux.

* Fix github action.

Co-authored-by: Yong He <yhe@nvidia.com>

1 files changed, 82 insertions, 12 deletions

diff --git a/source/slang/slang-check-decl.cpp b/source/slang/slang-check-decl.cpp
index 80bf74e53..7c8e320c4 100644
--- a/source/slang/slang-check-decl.cpp
+++ b/source/slang/slang-check-decl.cpp
@@ -2665,10 +2665,28 @@ namespace Slang
             }
             else if (auto bwdReq = as<BackwardDerivativeRequirementDecl>(reqRefDecl->referencedDecl))
             {
-                BackwardDifferentiateVal* val = m_astBuilder->create<BackwardDifferentiateVal>();
+                DifferentiateVal* val = m_astBuilder->create<BackwardDifferentiateVal>();
                 val->func = satisfyingMemberDeclRef;
                 witnessTable->add(bwdReq, RequirementWitness(val));
             }
+            else if (auto primalReq = as<BackwardDerivativePrimalRequirementDecl>(reqRefDecl->referencedDecl))
+            {
+                DifferentiateVal* val = m_astBuilder->create<BackwardDifferentiatePrimalVal>();
+                val->func = satisfyingMemberDeclRef;
+                witnessTable->add(primalReq, RequirementWitness(val));
+            }
+            else if (auto propReq = as<BackwardDerivativePropagateRequirementDecl>(reqRefDecl->referencedDecl))
+            {
+                DifferentiateVal* val = m_astBuilder->create<BackwardDifferentiatePropagateVal>();
+                val->func = satisfyingMemberDeclRef;
+                witnessTable->add(propReq, RequirementWitness(val));
+            }
+            else if (auto itypeReq = as<BackwardDerivativeIntermediateTypeRequirementDecl>(reqRefDecl->referencedDecl))
+            {
+                DifferentiateVal* val = m_astBuilder->create<BackwardDifferentiateIntermediateTypeVal>();
+                val->func = satisfyingMemberDeclRef;
+                witnessTable->add(itypeReq, RequirementWitness(val));
+            }
         }
         witnessTable->add(requiredMemberDeclRef, RequirementWitness(satisfyingMemberDeclRef));
     }
@@ -5652,18 +5670,70 @@ namespace Slang
             }
             if (decl->hasModifier<BackwardDifferentiableAttribute>())
             {
-                auto reqDecl = m_astBuilder->create<BackwardDerivativeRequirementDecl>();
-                cloneModifiers(reqDecl, decl);
+                // Requirement for backward derivative.
                 auto declRef = DeclRef<CallableDecl>(decl, createDefaultSubstitutions(m_astBuilder, this, decl));
-                auto diffFuncType = getBackwardDiffFuncType(getFuncType(m_astBuilder, declRef));
-                setFuncTypeIntoRequirementDecl(reqDecl, as<FuncType>(diffFuncType));
-                interfaceDecl->members.add(reqDecl);
-                reqDecl->parentDecl = interfaceDecl;
-
-                auto reqRef = m_astBuilder->create<DerivativeRequirementReferenceDecl>();
-                reqRef->referencedDecl = reqDecl;
-                reqRef->parentDecl = decl;
-                decl->members.add(reqRef);
+                auto diffFuncType = as<FuncType>(getBackwardDiffFuncType(getFuncType(m_astBuilder, declRef)));
+                {
+                    auto reqDecl = m_astBuilder->create<BackwardDerivativeRequirementDecl>();
+                    cloneModifiers(reqDecl, decl);
+                    setFuncTypeIntoRequirementDecl(reqDecl, diffFuncType);
+                    interfaceDecl->members.add(reqDecl);
+                    reqDecl->parentDecl = interfaceDecl;
+
+                    auto reqRef = m_astBuilder->create<DerivativeRequirementReferenceDecl>();
+                    reqRef->referencedDecl = reqDecl;
+                    reqRef->parentDecl = decl;
+                    decl->members.add(reqRef);
+                }
+                // Requirement for backward derivative intermediate type.
+                auto intermediateTypeReqDecl = m_astBuilder->create<BackwardDerivativeIntermediateTypeRequirementDecl>();
+                auto intermediateType = m_astBuilder->getOrCreateDeclRefType(
+                    intermediateTypeReqDecl, createDefaultSubstitutions(m_astBuilder, this, decl));
+                {
+                    cloneModifiers(intermediateTypeReqDecl, decl);
+                    interfaceDecl->members.add(intermediateTypeReqDecl);
+                    intermediateTypeReqDecl->parentDecl = interfaceDecl;
+
+                    auto reqRef = m_astBuilder->create<DerivativeRequirementReferenceDecl>();
+                    reqRef->referencedDecl = intermediateTypeReqDecl;
+                    reqRef->parentDecl = decl;
+                    decl->members.add(reqRef);
+                }
+                // Requirement for backward derivative primal func.
+                {
+                    auto reqDecl = m_astBuilder->create<BackwardDerivativePrimalRequirementDecl>();
+                    cloneModifiers(reqDecl, decl);
+                    FuncType* primalFuncType = m_astBuilder->create<FuncType>();
+                    primalFuncType->resultType = diffFuncType->resultType;
+                    primalFuncType->paramTypes.addRange(diffFuncType->paramTypes);
+                    auto outType = m_astBuilder->getOutType(intermediateType);
+                    primalFuncType->paramTypes.add(outType);
+                    setFuncTypeIntoRequirementDecl(reqDecl, primalFuncType);
+                    interfaceDecl->members.add(reqDecl);
+                    reqDecl->parentDecl = interfaceDecl;
+
+                    auto reqRef = m_astBuilder->create<DerivativeRequirementReferenceDecl>();
+                    reqRef->referencedDecl = reqDecl;
+                    reqRef->parentDecl = decl;
+                    decl->members.add(reqRef);
+                }
+                // Requirement for backward derivative propagate func.
+                {
+                    auto reqDecl = m_astBuilder->create<BackwardDerivativePropagateRequirementDecl>();
+                    cloneModifiers(reqDecl, decl);
+                    interfaceDecl->members.add(reqDecl);
+                    reqDecl->parentDecl = interfaceDecl;
+                    FuncType* propagateFuncType = m_astBuilder->create<FuncType>();
+                    propagateFuncType->resultType = diffFuncType->resultType;
+                    propagateFuncType->paramTypes.addRange(diffFuncType->paramTypes);
+                    propagateFuncType->paramTypes.add(intermediateType);
+                    setFuncTypeIntoRequirementDecl(reqDecl, propagateFuncType);
+                    auto reqRef = m_astBuilder->create<DerivativeRequirementReferenceDecl>();
+                    reqRef->referencedDecl = reqDecl;
+                    reqRef->parentDecl = decl;
+                    decl->members.add(reqRef);
+                }
+                
                 isDiffFunc = true;
             }
             if (isDiffFunc)