[mlir][TosaToLinalg] Exit after notifyMatchFailure (#132012)

This PR adds `return nullptr` when the shift value of `tosa.mul` is not
constant to prevent a crash. Fixes #131766.

Author: CoTinker

mlir/lib/Conversion/TosaToLinalg/TosaToLinalg.cpp

@@ -136,14 +136,14 @@ static Value createLinalgBodyCalculationForElementwiseOp(
 
   // tosa::MulOp
   if (isa<tosa::MulOp>(op)) {
-    auto shift_val = cast<tosa::MulOp>(op).getShift();
-    DenseElementsAttr shift_elem;
-    if (!shift_val.getImpl() ||
-        !matchPattern(shift_val, m_Constant(&shift_elem))) {
+    auto shiftVal = cast<tosa::MulOp>(op).getShift();
+    DenseElementsAttr shiftElem;
+    if (!matchPattern(shiftVal, m_Constant(&shiftElem))) {
       (void)rewriter.notifyMatchFailure(op, "shift value of mul not found");
+      return nullptr;
     }
 
-    int32_t shift = shift_elem.getValues<IntegerAttr>()[0].getInt();
+    int32_t shift = shiftElem.getValues<IntegerAttr>()[0].getInt();
 
     if (isa<FloatType>(elementTy)) {
       if (shift != 0) {

mlir/test/Conversion/TosaToLinalg/tosa-to-linalg-invalid.mlir

@@ -73,3 +73,11 @@ func.func @unranked_gather(%arg0: tensor<13x21x3xf32>, %arg1: tensor<13x26xi32>)
   %0 = tosa.gather %arg0, %arg1 : (tensor<13x21x3xf32>, tensor<13x26xi32>) -> tensor<*xf32>
   return %0 : tensor<*xf32>
 }
+
+// -----
+
+func.func @mul_no_const_shift(%arg0: tensor<2x3xi32>, %arg1: tensor<2x3xi32>, %arg2: tensor<1xi8>) -> tensor<2x3xi32> {
+  // expected-error@+1 {{failed to legalize operation 'tosa.mul'}}
+  %0 = tosa.mul %arg0, %arg1, %arg2 : (tensor<2x3xi32>, tensor<2x3xi32>, tensor<1xi8>) -> tensor<2x3xi32>
+  return %0 : tensor<2x3xi32>
+}