Support `constref` parameters passing. (#3249)

* Support `constref` parameters passing.

* Fix.

* Fix.

* Add test and diagnostic on mix use of __constref and no_diff.

* check for [constref] on differentiable member method.

---------

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

1 files changed, 3 insertions, 3 deletions

diff --git a/source/slang/slang-ir-autodiff-rev.cpp b/source/slang/slang-ir-autodiff-rev.cpp
index 335b6572e..ed70862d1 100644
--- a/source/slang/slang-ir-autodiff-rev.cpp
+++ b/source/slang/slang-ir-autodiff-rev.cpp
@@ -415,9 +415,9 @@ namespace Slang
 
                 // Fetch primal values to use as arguments in primal func call.
                 IRInst* primalArg = param;
-                if (!as<IROutType>(primalParamType))
+                if (!as<IROutType>(primalParamType) && !as<IRConstRefType>(primalParamType))
                 {
-                    // As long as the primal parameter is not an out type,
+                    // As long as the primal parameter is not an out or constref type,
                     // we need to fetch the primal value from the parameter.
                     if (as<IRPtrTypeBase>(propagateParamType))
                     {
@@ -428,7 +428,7 @@ namespace Slang
                         primalArg = builder.emitDifferentialPairGetPrimal(primalArg);
                     }
                 }
-                if (auto primalParamPtrType = as<IRPtrTypeBase>(primalParamType))
+                if (auto primalParamPtrType = isMutablePointerType(primalParamType))
                 {
                     // If primal parameter is mutable, we need to pass in a temp var.
                     auto tempVar = builder.emitVar(primalParamPtrType->getValueType());