[Torch] decompose AtenLerpTensorOp (#3251)

as title

lib/Dialect/Torch/Transforms/DecomposeComplexOps.cpp

@@ -2585,7 +2585,36 @@ public:
 
     auto weightedDelta =
         rewriter.create<AtenMulScalarOp>(loc, inputType, delta, op.getWeight());
-    auto lerp = rewriter.create<AtenAddTensorOp>(loc, inputType, start,
+    auto lerp = rewriter.create<AtenAddTensorOp>(loc, resType, start,
+                                                 weightedDelta, cstOne);
+    rewriter.replaceOp(op, lerp);
+    return success();
+  }
+};
+} // namespace
+
+namespace {
+class DecomposeAtenLerpTensorOp : public OpRewritePattern<AtenLerpTensorOp> {
+public:
+  using OpRewritePattern::OpRewritePattern;
+  LogicalResult matchAndRewrite(AtenLerpTensorOp op,
+                                PatternRewriter &rewriter) const override {
+    Location loc = op.getLoc();
+    auto resType = cast<BaseTensorType>(op.getType());
+    if (!resType.hasDtype()) {
+      return rewriter.notifyMatchFailure(op, "result should have dtype");
+    }
+    Value cstOne =
+        rewriter.create<ConstantIntOp>(loc, rewriter.getI64IntegerAttr(1));
+    auto start = op.getSelf();
+    auto inputType = cast<BaseTensorType>(start.getType());
+
+    auto delta = rewriter.create<AtenSubTensorOp>(loc, inputType, op.getEnd(),
+                                                  start, cstOne);
+
+    auto weightedDelta =
+        rewriter.create<AtenMulTensorOp>(loc, inputType, delta, op.getWeight());
+    auto lerp = rewriter.create<AtenAddTensorOp>(loc, resType, start,
                                                  weightedDelta, cstOne);
     rewriter.replaceOp(op, lerp);
     return success();
@@ -8114,6 +8143,7 @@ public:
     addPatternIfTargetOpIsIllegal<DecomposeAtenLeakyReluOp>(patterns);
     addPatternIfTargetOpIsIllegal<DecomposeAtenLeakyReluBackwardOp>(patterns);
     addPatternIfTargetOpIsIllegal<DecomposeAtenLerpScalarOp>(patterns);
+    addPatternIfTargetOpIsIllegal<DecomposeAtenLerpTensorOp>(patterns);
     addPatternIfTargetOpIsIllegal<DecomposeAtenNewEmptyStridedOp>(patterns);
     addPatternIfTargetOpIsIllegal<DecomposeAtenEmptyStridedOp>(patterns);
     addPatternIfTargetOpIsIllegal<DecomposeAtenBucketizeTensorOp>(patterns);

lib/Dialect/Torch/Transforms/LowerToBackendContract.cpp

@@ -507,6 +507,7 @@ static void markDecomposedOpsAsIllegal(MLIRContext *context,
   target.addIllegalOp<Aten_EmbeddingBagOp>();
   target.addIllegalOp<AtenLiftFreshCopyOp>();
   target.addIllegalOp<AtenLerpScalarOp>();
+  target.addIllegalOp<AtenLerpTensorOp>();
   target.addIllegalOp<AtenMseLossOp>();
   target.addIllegalOp<AtenRandintLowOp>();
   target.addIllegalOp<AtenRandintOp>();

projects/pt1/e2e_testing/xfail_sets.py

@@ -1020,6 +1020,7 @@ STABLEHLO_PASS_SET = {
     "ElementwiseSqrtModule_basic",
     "ElementwiseTanIntModule_basic",
     "ElementwiseTanModule_basic",
+    "ElementwiseTernaryStaticShapeModule_basic",
     "ElementwiseToDtypeF32ToI64Module_basic",
     "ElementwiseToDtypeI64ToI8Module_basic",
     "ElementwiseToDtypeIdentityModule_basic",
@@ -1475,6 +1476,7 @@ TOSA_PASS_SET = {
     "AtenDotModule_basic",
     "ElementwiseFloatTensorGtIntScalarModule_basic",
     "ElementwiseLogSigmoidModule_basic",
+    "ElementwiseTernaryStaticShapeModule_basic",
     "ElementwiseTruncModule_basic",
     "ElementwiseTruncIntModule_basic",
     "ElementwiseSgnModule_basic",

projects/pt1/python/torch_mlir_e2e_test/test_suite/elementwise.py

@@ -414,6 +414,31 @@ def ElementwiseTernaryModule_basic(module, tu: TestUtils):
 # ==============================================================================
 
 
+class ElementwiseTernaryStaticShapeModule(torch.nn.Module):
+    def __init__(self):
+        super().__init__()
+
+    @export
+    @annotate_args(
+        [
+            None,
+            ([5, 4, 3], torch.float32, True),
+            ([4, 3], torch.float32, True),
+            ([3], torch.float32, True),
+        ]
+    )
+    def forward(self, a, b, c):
+        return torch.lerp(a, b, c)
+
+
+@register_test_case(module_factory=lambda: ElementwiseTernaryStaticShapeModule())
+def ElementwiseTernaryStaticShapeModule_basic(module, tu: TestUtils):
+    module.forward(tu.rand(5, 4, 3), tu.rand(4, 3), tu.rand(3))
+
+
+# ==============================================================================
+
+
 class ElementwiseAtenWhereSelfModule(torch.nn.Module):
     def __init__(self):
         super().__init__()