Correct IR generation for no-diff pointer type (#5976)

* Correct IR generation for no-diff pointer type

Close #5805 

There is an issue on checking whether a pointer type parameter
is no_diff, we should first check whether this parameter is
an Attribute type first, then check the data type.

In the back-propagate pass, for the pointer type parameter, we should
load this parameter to a temp variable, then pass it to the primal
function call. Otherwise, the temp variable will no be initialized,
which will cause the following calculation wrong.

1 files changed, 6 insertions, 5 deletions

diff --git a/source/slang/slang-ir-autodiff-rev.cpp b/source/slang/slang-ir-autodiff-rev.cpp
index f0ac428c7..36093518a 100644
--- a/source/slang/slang-ir-autodiff-rev.cpp
+++ b/source/slang/slang-ir-autodiff-rev.cpp
@@ -512,11 +512,12 @@ InstPair BackwardDiffTranscriber::transcribeFuncHeader(IRBuilder* inBuilder, IRF
             {
                 // If primal parameter is mutable, we need to pass in a temp var.
                 auto tempVar = builder.emitVar(primalParamPtrType->getValueType());
-                if (primalParamPtrType->getOp() == kIROp_InOutType)
-                {
-                    // If the primal parameter is inout, we need to set the initial value.
-                    builder.emitStore(tempVar, primalArg);
-                }
+
+                // We also need to setup the initial value of the temp var, otherwise
+                // the temp var will be uninitialized which could cause undefined behavior
+                // in the primal function.
+                builder.emitStore(tempVar, primalArg);
+
                 primalArgs.add(tempVar);
             }
             else