Add support for `kIROp_FloatCast` (#2824)

* Add support for `kIROp_FloatCast`

* Update float-cast.slang

* Added flag to d3d options

1 files changed, 19 insertions, 0 deletions

diff --git a/source/slang/slang-ir-autodiff-transpose.h b/source/slang/slang-ir-autodiff-transpose.h
index c7ac8c357..55f042352 100644
--- a/source/slang/slang-ir-autodiff-transpose.h
+++ b/source/slang/slang-ir-autodiff-transpose.h
@@ -1744,6 +1744,9 @@ struct DiffTransposePass
             case kIROp_UpdateElement:
                 return transposeUpdateElement(builder, fwdInst, revValue);
 
+            case kIROp_FloatCast:
+                return transposeFloatCast(builder, fwdInst, revValue);
+
             case kIROp_LoadReverseGradient:
             case kIROp_ReverseGradientDiffPairRef:
             case kIROp_DefaultConstruct:
@@ -2228,6 +2231,22 @@ struct DiffTransposePass
         return TranspositionResult(gradients);
     }
 
+    TranspositionResult transposeFloatCast(IRBuilder* builder, IRInst* fwdInst, IRInst* revValue)
+    {
+        // (A = cast<T, U>(B)) -> (dB += cast<U, T>(dA))
+        return TranspositionResult(
+            List<RevGradient>(
+                RevGradient(
+                    RevGradient::Flavor::Simple,
+                    fwdInst->getOperand(0),
+                    builder->emitIntrinsicInst(
+                        fwdInst->getOperand(0)->getDataType(),
+                        kIROp_FloatCast,
+                        1,
+                        &revValue),
+                    fwdInst)));
+    }
+
     // Gather all reverse-mode gradients for a Load inst, aggregate them and store them in the ptr.
     // 
     void accumulateGradientsForLoad(IRBuilder* builder, IRLoad* revLoad)