Support `out` parameters in backward differentiation. (#2619)

* Support `out` parameters in backward differentiation.

* Fixes.

* Fix cleanup.

---------

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

1 files changed, 34 insertions, 0 deletions

diff --git a/source/slang/slang-ir-init-local-var.cpp b/source/slang/slang-ir-init-local-var.cpp
new file mode 100644
index 000000000..4b28db268
--- /dev/null
+++ b/source/slang/slang-ir-init-local-var.cpp
@@ -0,0 +1,34 @@
+// slang-ir-init-local-var.cpp
+#include "slang-ir-init-local-var.h"
+#include "slang-ir.h"
+#include "slang-ir-insts.h"
+
+namespace Slang
+{
+
+void initializeLocalVariables(SharedIRBuilder* sharedBuilder, IRGlobalValueWithCode* func)
+{
+    IRBuilder builder(sharedBuilder);
+    for (auto block : func->getBlocks())
+    {
+        for (auto inst : block->getChildren())
+        {
+            if (inst->getOp() == kIROp_Var)
+            {
+                auto firstUse = inst->firstUse;
+                bool initialized =
+                    (firstUse && firstUse->getUser()->getOp() == kIROp_Store &&
+                        firstUse->getUser()->getParent() == inst->getParent());
+                if (initialized)
+                    continue;
+                builder.setInsertAfter(inst);
+                builder.emitStore(
+                    inst,
+                    builder.emitDefaultConstruct(
+                        as<IRPtrTypeBase>(inst->getFullType())->getValueType()));
+            }
+        }
+    }
+}
+
+} // namespace Slang