[linalg][mlir] Replace getSmallestBoundingIndex in promotion (NFC).

[gysit]

Summary

Replace the getSmallestBoundingIndex method used in promotion by getConstantUpperBoundForIndex that uses flat affine constraints to compute a constant upper bound.

Depends On D113546

mlir/lib/Dialect/Linalg/Transforms/Promotion.cpp

FailureOr<PromotionInfo> mlir::linalg::promoteSubviewAsNewBuffer(
   SmallVector<Value, 4> fullSizes;
   SmallVector<OpFoldResult> partialSizes;
   fullSizes.reserve(rank);
   partialSizes.reserve(rank);
   for (auto en : llvm::enumerate(subView.getOrCreateRanges(b, loc))) {
     auto rangeValue = en.value();
     // Try to extract a tight constant.
     LLVM_DEBUG(llvm::dbgs() << "Extract tightest: " << rangeValue.size << "\n");
-    IntegerAttr sizeAttr = getSmallestBoundingIndex(rangeValue.size);
-    Value size = (!sizeAttr) ? rangeValue.size
-                             : b.create<arith::ConstantOp>(loc, sizeAttr);
+    FailureOr<int64_t> upperBound =
+        getConstantUpperBoundForIndex(rangeValue.size);
+    Value size =
+        failed(upperBound)
+            ? rangeValue.size
+            : b.create<arith::ConstantIndexOp>(loc, upperBound.getValue());
     LLVM_DEBUG(llvm::dbgs() << "Extracted tightest: " << size << "\n");
     fullSizes.push_back(size);
     partialSizes.push_back(
         b.createOrFold<memref::DimOp>(loc, subView, en.index()));
   }
   SmallVector<int64_t, 4> dynSizes(fullSizes.size(), -1);
   // If a callback is not specified, then use the default implementation for
   // allocating the promoted buffer.