fix: canonicalize singleton partition-view axes for GT lowering

lib/PTO/Transforms/PTOToEmitC.cpp

@@ -2864,9 +2864,11 @@ struct SubviewToEmitCPattern : public OpConversionPattern<memref::SubViewOp> {
     // 2. 生成 Shape 模板参数，之后会右对齐有效维度并补齐到 5 维（高维填 1）
     SmallVector<std::string> shapeParamsVec;
     SmallVector<Value> sizeValues; // 每个维度对应的运行时 size（统一为 unsigned）
+    SmallVector<bool> staticSingletonDims; // 可静态证明为 1 的维度
     auto resShape = resTy.getShape();
     auto mixedSizes = op.getMixedSizes();
     sizeValues.reserve(rank);
+    staticSingletonDims.reserve(rank);
     for (int i = 0; i < resTy.getRank(); ++i) {
       if (resShape[i] == ShapedType::kDynamic) {
         shapeParamsVec.push_back("-1");
@@ -2879,6 +2881,13 @@ struct SubviewToEmitCPattern : public OpConversionPattern<memref::SubViewOp> {
       else
         sizeValues.push_back(
             mkU32(resShape[i] == ShapedType::kDynamic ? 1 : resShape[i]));
+
+      std::optional<int64_t> staticDim;
+      if (i < (int)mixedSizes.size())
+        staticDim = extractStaticInt(mixedSizes[i]);
+      if (!staticDim && resShape[i] != ShapedType::kDynamic)
+        staticDim = resShape[i];
+      staticSingletonDims.push_back(staticDim && *staticDim == 1);
     }
 
     // 3. 生成 Stride 模板参数 + 运行时 stride 值（考虑 subview step）
@@ -2917,6 +2926,57 @@ struct SubviewToEmitCPattern : public OpConversionPattern<memref::SubViewOp> {
             rewriter.create<emitc::MulOp>(loc, u32Ty, srcV, stepV));
     }
 
+    // 3.0 对可证明安全的分区视图做 singleton 轴前移：
+    // 仅允许 size==1 的轴跨越其它轴，保证地址集合不变；动态轴视为非 singleton，不重排。
+    if (rank > 2) {
+      int nonSingletonCount = 0;
+      for (bool isSingleton : staticSingletonDims) {
+        if (!isSingleton)
+          ++nonSingletonCount;
+      }
+      if (nonSingletonCount <= 2) {
+        SmallVector<unsigned, 8> permutation;
+        permutation.reserve(rank);
+        for (int i = 0; i < rank; ++i) {
+          if (staticSingletonDims[i])
+            permutation.push_back(i);
+        }
+        for (int i = 0; i < rank; ++i) {
+          if (!staticSingletonDims[i])
+            permutation.push_back(i);
+        }
+
+        bool changed = false;
+        for (int i = 0; i < rank; ++i) {
+          if (permutation[i] != static_cast<unsigned>(i)) {
+            changed = true;
+            break;
+          }
+        }
+
+        if (changed) {
+          SmallVector<std::string> reorderedShape;
+          SmallVector<Value> reorderedSizes;
+          SmallVector<std::string> reorderedStrides;
+          SmallVector<Value> reorderedStrideValues;
+          reorderedShape.reserve(rank);
+          reorderedSizes.reserve(rank);
+          reorderedStrides.reserve(rank);
+          reorderedStrideValues.reserve(rank);
+          for (unsigned idx : permutation) {
+            reorderedShape.push_back(shapeParamsVec[idx]);
+            reorderedSizes.push_back(sizeValues[idx]);
+            reorderedStrides.push_back(dummyStrideVec[idx]);
+            reorderedStrideValues.push_back(strideValues[idx]);
+          }
+          shapeParamsVec = std::move(reorderedShape);
+          sizeValues = std::move(reorderedSizes);
+          dummyStrideVec = std::move(reorderedStrides);
+          strideValues = std::move(reorderedStrideValues);
+        }
+      }
+    }
+
     // 3.1 右对齐到 5 维：shape 补 1；已有维度继承原 stride；
     //      被补出来的高维按“紧密升维”规则连续推导：stride[i] = shape[i+1] * stride[i+1]
     SmallVector<std::string, 5> finalShape(5, "1");

test/basic/issue453_partition_view_singleton_axis_reorder.pto

@@ -0,0 +1,45 @@
+// RUN: ptoas --pto-arch=a5 %s 2>&1 | FileCheck %s --check-prefix=A5
+
+module {
+  // Safe case: only singleton axes are moved. This should canonicalize
+  // [1, 16, 1, 16] -> [1, 1, 16, 16] before 5D right-align, so emitted
+  // GlobalTensor shape becomes <1, 1, 1, 16, 16>.
+  func.func @issue453_singleton_axis_reorder_positive(%src: !pto.ptr<f16>) {
+    %c0 = arith.constant 0 : index
+    %c1 = arith.constant 1 : index
+    %c16 = arith.constant 16 : index
+    %c256 = arith.constant 256 : index
+
+    %tv = pto.make_tensor_view %src, shape = [%c1, %c16, %c1, %c16], strides = [%c256, %c16, %c16, %c1] {layout = #pto.layout<nd>} : !pto.tensor_view<?x?x?x?xf16>
+    %sv = pto.partition_view %tv, offsets = [%c0, %c0, %c0, %c0], sizes = [%c1, %c16, %c1, %c16] : !pto.tensor_view<?x?x?x?xf16> -> !pto.partition_tensor_view<1x16x1x16xf16>
+    %tile = pto.alloc_tile : !pto.tile_buf<loc=mat, dtype=f16, rows=16, cols=16, v_row=16, v_col=16, blayout=col_major, slayout=row_major, fractal=512, pad=0>
+    pto.tload ins(%sv : !pto.partition_tensor_view<1x16x1x16xf16>)
+              outs(%tile : !pto.tile_buf<loc=mat, dtype=f16, rows=16, cols=16, v_row=16, v_col=16, blayout=col_major, slayout=row_major, fractal=512, pad=0>)
+    return
+  }
+
+  // Unsafe case: three non-singleton axes (2,16,16). Reordering is not legal
+  // and must not happen.
+  func.func @issue453_singleton_axis_reorder_negative(%src: !pto.ptr<f16>) {
+    %c0 = arith.constant 0 : index
+    %c1 = arith.constant 1 : index
+    %c2 = arith.constant 2 : index
+    %c16 = arith.constant 16 : index
+    %c256 = arith.constant 256 : index
+
+    %tv = pto.make_tensor_view %src, shape = [%c2, %c16, %c1, %c16], strides = [%c256, %c16, %c16, %c1] {layout = #pto.layout<nd>} : !pto.tensor_view<?x?x?x?xf16>
+    %sv = pto.partition_view %tv, offsets = [%c0, %c0, %c0, %c0], sizes = [%c2, %c16, %c1, %c16] : !pto.tensor_view<?x?x?x?xf16> -> !pto.partition_tensor_view<2x16x1x16xf16>
+    %tile = pto.alloc_tile : !pto.tile_buf<loc=mat, dtype=f16, rows=32, cols=16, v_row=32, v_col=16, blayout=col_major, slayout=row_major, fractal=512, pad=0>
+    pto.tload ins(%sv : !pto.partition_tensor_view<2x16x1x16xf16>)
+              outs(%tile : !pto.tile_buf<loc=mat, dtype=f16, rows=32, cols=16, v_row=32, v_col=16, blayout=col_major, slayout=row_major, fractal=512, pad=0>)
+    return
+  }
+}
+
+// A5-LABEL: AICORE void issue453_singleton_axis_reorder_positive(
+// A5: GlobalTensor<half, pto::Shape<1, 1, 1, 16, 16>
+// A5-NOT: GlobalTensor<half, pto::Shape<1, 1, 16, 1, 16>
+
+// A5-LABEL: AICORE void issue453_singleton_axis_reorder_negative(
+// A5: GlobalTensor<half, pto::Shape<1, 2, 16, 1, 16>
+// A5-NOT: GlobalTensor<half, pto::Shape<1, 1, 2, 16, 16>