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Add support for non-differentiable attribute in reverse mode
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MihailMihov committed Jul 6, 2024
1 parent 0ed5f1a commit 7b63512
Showing 2 changed files with 44 additions and 17 deletions.
53 changes: 40 additions & 13 deletions lib/Differentiator/ReverseModeVisitor.cpp
Original file line number Diff line number Diff line change
@@ -1369,6 +1369,27 @@ Expr* getArraySizeExpr(const ArrayType* AT, ASTContext& context,
return StmtDiff(Clone(CE));
}

SourceLocation validLoc{CE->getBeginLoc()};

// If the function is non_differentiable, return zero derivative.
if (clad::utils::hasNonDifferentiableAttribute(CE)) {
// Calling the function without computing derivatives
llvm::SmallVector<Expr*, 4> ClonedArgs;
for (unsigned i = 0, e = CE->getNumArgs(); i < e; ++i)
ClonedArgs.push_back(Clone(CE->getArg(i)));

Expr* Call = m_Sema
.ActOnCallExpr(getCurrentScope(), Clone(CE->getCallee()),
validLoc, ClonedArgs, validLoc)
.get();
// Creating a zero derivative
auto* zero = ConstantFolder::synthesizeLiteral(m_Context.IntTy, m_Context,
/*val=*/0);

// Returning the function call and zero derivative
return StmtDiff(Call, zero);
}

auto NArgs = FD->getNumParams();
// If the function has no args and is not a member function call then we
// assume that it is not related to independent variables and does not
@@ -2755,19 +2776,21 @@ Expr* getArraySizeExpr(const ArrayType* AT, ASTContext& context,
if (declsBegin != DS->decls().end() && isa<VarDecl>(*declsBegin)) {
auto* VD = dyn_cast<VarDecl>(*declsBegin);
QualType QT = VD->getType();
if (!QT->isPointerType()) {
auto* typeDecl = QT->getAsCXXRecordDecl();
// We should also simply copy the original lambda. The differentiation
// of lambdas is happening in the `VisitCallExpr`. For now, only the
// declarations with lambda expressions without captures are supported.
isLambda = typeDecl && typeDecl->isLambda();
if (isLambda) {
for (auto* D : DS->decls())
if (auto* VD = dyn_cast<VarDecl>(D))
decls.push_back(VD);
Stmt* DSClone = BuildDeclStmt(decls);
return StmtDiff(DSClone, nullptr);
}
if (QT->isPointerType())
QT = QT->getPointeeType();

auto* typeDecl = QT->getAsCXXRecordDecl();
// We should also simply copy the original lambda. The differentiation
// of lambdas is happening in the `VisitCallExpr`. For now, only the
// declarations with lambda expressions without captures are supported.
isLambda = typeDecl && typeDecl->isLambda();
if (isLambda ||
(typeDecl && clad::utils::hasNonDifferentiableAttribute(typeDecl))) {
for (auto* D : DS->decls())
if (auto* VD = dyn_cast<VarDecl>(D))
decls.push_back(VD);
Stmt* DSClone = BuildDeclStmt(decls);
return StmtDiff(DSClone, nullptr);
}
}

@@ -2954,6 +2977,10 @@ Expr* getArraySizeExpr(const ArrayType* AT, ASTContext& context,
"CXXMethodDecl nodes not supported yet!");
MemberExpr* clonedME = utils::BuildMemberExpr(
m_Sema, getCurrentScope(), baseDiff.getExpr(), field->getName());
auto* zero = ConstantFolder::synthesizeLiteral(m_Context.DoubleTy,
m_Context, /*val=*/0);
if (clad::utils::hasNonDifferentiableAttribute(ME))
return {clonedME, zero};
if (!baseDiff.getExpr_dx())
return {clonedME, nullptr};
MemberExpr* derivedME = utils::BuildMemberExpr(
8 changes: 4 additions & 4 deletions test/Gradient/NonDifferentiable.C
Original file line number Diff line number Diff line change
@@ -74,15 +74,15 @@ double fn_s2_operator(double i, double j) {

#define TEST_CLASS(classname, name, i, j) \
auto d_##name = clad::gradient(&classname::name); \
double result_##name[2] = {}; \
double result_##name[2]; \
d_##name.execute(expr_1, i, j, &result_##name[0], &result_##name[1]); \
printf("%.2f %.2f\n", result_##name[0], result_##name[1]);
printf("%.2f %.2f\n\n", result_##name[0], result_##name[1]);

#define TEST_FUNC(name, i, j) \
auto d_##name = clad::gradient(&name); \
double result_##name[2] = {}; \
double result_##name[2]; \
d_##name.execute(i, j, &result_##name[0], &result_##name[1]); \
printf("%.2f\n", result_##name[0], result_##name[1]);
printf("%.2f %.2f\n\n", result_##name[0], result_##name[1]);

int main() {
// FIXME: The parts of this test that are commented out are currently not working, due to bugs

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