Miscellaneous backward autodiff fixes. (#2665)

* Fix differentiable type registration

* Fix use of non-differentiable return value in a differentiable func.

* Fix use of primal inst that does not dominate the diff block.

* Fix primal inst hoisting, and add missing type legalization logic.

* Make `detach` defined on all differentiable T.

---------

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

1 files changed, 1 insertions, 10 deletions

diff --git a/source/slang/slang-check-stmt.cpp b/source/slang/slang-check-stmt.cpp
index 519ca91ff..bc89dc94e 100644
--- a/source/slang/slang-check-stmt.cpp
+++ b/source/slang/slang-check-stmt.cpp
@@ -585,6 +585,7 @@ namespace Slang
 
     void SemanticsStmtVisitor::checkLoopInDifferentiableFunc(Stmt* stmt)
     {
+        SLANG_UNUSED(stmt);
         if (getParentDifferentiableAttribute())
         {
             if (!getParentFunc())
@@ -601,16 +602,6 @@ namespace Slang
                 return;
             if (getParentFunc()->findModifier<BackwardDerivativeAttribute>())
                 return;
-
-            // For all ordinary differentiable functions, we require either a `[MaxIters]` attribute,
-            // or a `[ForceUnroll]` attribet on loops.
-            if (stmt->hasModifier<MaxItersAttribute>() || stmt->hasModifier<ForceUnrollAttribute>() || stmt->hasModifier<InferredMaxItersAttribute>())
-            {
-            }
-            else
-            {
-                getSink()->diagnose(stmt, Diagnostics::loopInDiffFuncRequireUnrollOrMaxIters);
-            }
         }
     }