[mlir] PromoteBuffersToStackPass - Copy attributes of original AllocOp

[mamrami]

Add custom attribute to the lit test

[mamrami]

ping @dfki-jugr @pifon2a @herhut @nicolasvasilache

mlir/lib/Dialect/Bufferization/Transforms/BufferOptimizations.cpp

for (BufferPlacementAllocs::AllocEntry &entry : allocs) {
       Operation *startOperation = BufferPlacementAllocs::getStartOperation(
           alloc, alloc.getParentBlock(), liveness);
       // Build a new alloca that is associated with its parent
       // `AutomaticAllocationScope` determined during the initialization phase.
       OpBuilder builder(startOperation);
       Operation *allocOp = alloc.getDefiningOp();
       Operation *alloca = builder.create<memref::AllocaOp>(
           alloc.getLoc(), alloc.getType().cast<MemRefType>(),
-          allocOp->getOperands());
+          allocOp->getOperands(), allocOp->getAttrs());
 
       // Replace the original alloc by a newly created alloca.
       allocOp->replaceAllUsesWith(alloca);
       allocOp->erase();
     }
   }
 };
 

mlir/test/Transforms/promote-buffers-to-stack.mlir

 // RANK-NEXT: memref.alloca()
 // CHECK-NEXT: return
 
 // -----
 
 // CHECK-LABEL: func @bigIndexElementType
 module attributes { dlti.dl_spec = #dlti.dl_spec<#dlti.dl_entry<index, 256>>} {
   func.func @bigIndexElementType() {
-    %0 = memref.alloc() : memref<4xindex>
+    %0 = memref.alloc() {alignment = 64 : i64, custom_attr} : memref<4xindex>
     return
   }
 }
-// DEFINDEX-NEXT: memref.alloca()
-// LOWLIMIT-NEXT: memref.alloc()
-// RANK-NEXT: memref.alloca()
+// DEFINDEX-NEXT: memref.alloca() {alignment = 64 : i64, custom_attr}
+// LOWLIMIT-NEXT: memref.alloc() {alignment = 64 : i64, custom_attr}
+// RANK-NEXT: memref.alloca() {alignment = 64 : i64, custom_attr}
 // CHECK-NEXT: return