[Mlir-commits] [mlir] [mlir][affine] Skip point-wise copy for scalar memref (PR #129183)

[llvmlistbot at llvm.org]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-mlir-affine

Author: Kai Sasaki (Lewuathe)

<details>
<summary>Changes</summary>

Point wise copy does not consider scalar typed memref and it does not generate any affine.for on top. It causes segmentation fault. We can skip the point-wise copy in case of scalar memref.

Fixes https://github.com/llvm/llvm-project/issues/61167

---
Full diff: https://github.com/llvm/llvm-project/pull/129183.diff


2 Files Affected:

- (modified) mlir/lib/Dialect/Affine/Utils/LoopUtils.cpp (+3) 
- (modified) mlir/test/Dialect/Affine/affine-data-copy.mlir (+49) 


``````````diff
diff --git a/mlir/lib/Dialect/Affine/Utils/LoopUtils.cpp b/mlir/lib/Dialect/Affine/Utils/LoopUtils.cpp
index 6833d6583c27a..4b9c872bff1ec 100644
--- a/mlir/lib/Dialect/Affine/Utils/LoopUtils.cpp
+++ b/mlir/lib/Dialect/Affine/Utils/LoopUtils.cpp
@@ -2131,6 +2131,9 @@ static LogicalResult generateCopy(
 
   if (!copyOptions.generateDma) {
     // Point-wise copy generation.
+    // Unable to copy generation for scala memref due to lack of access point.
+    if (rank == 0)
+      return failure();
     auto copyNest =
         generatePointWiseCopy(loc, memref, fastMemRef, lbMaps,
                               /*lbOperands=*/regionSymbols, ubMaps,
diff --git a/mlir/test/Dialect/Affine/affine-data-copy.mlir b/mlir/test/Dialect/Affine/affine-data-copy.mlir
index 5615acae5ecc4..5e97f97f8c251 100644
--- a/mlir/test/Dialect/Affine/affine-data-copy.mlir
+++ b/mlir/test/Dialect/Affine/affine-data-copy.mlir
@@ -354,3 +354,52 @@ func.func @arbitrary_memory_space() {
   }
   return
 }
+
+
+// CHECK-LABEL: func @scalar_memref_copy_without_dma
+func.func @scalar_memref_copy_without_dma() {
+    %false = arith.constant false
+    %4 = memref.alloc() {alignment = 128 : i64} : memref<i1>
+    affine.store %false, %4[] : memref<i1>
+
+    // CHECK: %[[FALSE:.*]] = arith.constant false
+    // CHECK: %[[MEMREF:.*]] = memref.alloc() {alignment = 128 : i64} : memref<i1>
+    // CHECK: affine.store %[[FALSE]], %[[MEMREF]][] : memref<i1>
+    return
+}
+
+// CHECK-LABEL: func @scalar_memref_copy_in_loop
+func.func @scalar_memref_copy_in_loop(%3:memref<480xi1>) {
+  %false = arith.constant false
+  %4 = memref.alloc() {alignment = 128 : i64} : memref<i1>
+  affine.store %false, %4[] : memref<i1>
+  %5 = memref.alloc() {alignment = 128 : i64} : memref<i1>
+  memref.copy %4, %5 : memref<i1> to memref<i1>
+  affine.for %arg0 = 0 to 480 {
+    %11 = affine.load %3[%arg0] : memref<480xi1>
+    %12 = affine.load %5[] : memref<i1>
+    %13 = arith.cmpi slt, %11, %12 : i1
+    %14 = arith.select %13, %11, %12 : i1
+    affine.store %14, %5[] : memref<i1>
+  }
+
+  // CHECK: %[[FALSE:.*]] = arith.constant false
+  // CHECK: %[[MEMREF:.*]] = memref.alloc() {alignment = 128 : i64} : memref<i1>
+  // CHECK: affine.store %[[FALSE]], %[[MEMREF]][] : memref<i1>
+  // CHECK: %[[TARGET:.*]] = memref.alloc() {alignment = 128 : i64} : memref<i1>
+  // CHECK: memref.copy %alloc, %[[TARGET]] : memref<i1> to memref<i1>
+  // CHECK: %[[FAST_MEMREF:.*]] = memref.alloc() : memref<480xi1>
+  // CHECK: affine.for %{{.*}} = 0 to 480 {
+  // CHECK:   %{{.*}} = affine.load %arg0[%{{.*}}] : memref<480xi1>
+  // CHECK:   affine.store %{{.*}}, %[[FAST_MEMREF]][%{{.*}}] : memref<480xi1>
+  // CHECK: }
+  // CHECK: affine.for %arg1 = 0 to 480 {
+  // CHECK:   %[[L0:.*]] = affine.load %[[FAST_MEMREF]][%arg1] : memref<480xi1>
+  // CHECK:   %[[L1:.*]] = affine.load %[[TARGET]][] : memref<i1>
+  // CHECK:   %[[CMPI:.*]] = arith.cmpi slt, %[[L0]], %[[L1]] : i1
+  // CHECK:   %[[SELECT:.*]] = arith.select %[[CMPI]], %[[L0]], %[[L1]] : i1
+  // CHECK:   affine.store %[[SELECT]], %[[TARGET]][] : memref<i1>
+  // CHECK: }
+  // CHECK: memref.dealloc %[[FAST_MEMREF]] : memref<480xi1>
+  return
+}
\ No newline at end of file

``````````

</details>


https://github.com/llvm/llvm-project/pull/129183