[mlir][tosa] Fix ability to expand ranks with dynamic shape support (#128037)

- Fix ability to expand ranks with dynamic shape support
- Simplify the code

Signed-off-by: Suraj Sudhir <[email protected]>
Co-authored-by: Suraj Sudhir <[email protected]>

Author: Jerry-Ge

mlir/lib/Dialect/Tosa/Utils/ConversionUtils.cpp

@@ -77,24 +77,21 @@ computeReshapeOutput(ArrayRef<int64_t> higherRankShape,
   // Initialize new shapes with [1] * higherRank.
   int64_t higherRank = higherRankShape.size();
   int64_t lowerRank = lowerRankShape.size();
-
   reshapeOutputShape.assign(higherRank, 1);
 
   int64_t higherRankDim;
   int64_t lowerRankDim;
+  const int64_t rankDiff = higherRank - lowerRank;
+
+  for (int64_t i = lowerRank - 1; i >= 0; i--) {
+    higherRankDim = higherRankShape[i + rankDiff];
+    lowerRankDim = lowerRankShape[i];
 
-  for (int64_t i = higherRank - 1, j = lowerRank - 1; i >= 0 && j >= 0;
-       i--, j--) {
-    higherRankDim = higherRankShape[i];
-    lowerRankDim = lowerRankShape[j];
-
-    if (lowerRankDim == 1 && higherRankDim > 1)
-      reshapeOutputShape[i] = 1;
-    else if ((lowerRankDim > 1 && higherRankDim == 1) ||
-             (lowerRankDim == higherRankDim))
-      reshapeOutputShape[i] = lowerRankDim;
-    else if (higherRankDim != lowerRankDim)
+    if (lowerRankDim != 1 && higherRankDim != 1 &&
+        lowerRankDim != higherRankDim)
       return failure();
+
+    reshapeOutputShape[i + rankDiff] = lowerRankDim == 1 ? 1 : lowerRankDim;
   }
   return success();
 }