fallback memref transformation when alloc / dealloc not in FILO fashion

Author: ZhangYan

lib/gc/Transforms/MemRefToCPURuntime.cpp

@@ -77,6 +77,7 @@ struct ConvertMemRefToCPURuntime
     auto *ctx = &getContext();
     // Create a local set to store operations that should not be transformed.
     llvm::SmallSet<Operation *, 16> noTransformOps;
+    llvm::SmallVector<Operation *, 16> allocStack;
 
     // Walk through the module to find func::FuncOp instances.
     getOperation()->walk([&](func::FuncOp funcOp) {
@@ -96,6 +97,24 @@ struct ConvertMemRefToCPURuntime
               }
             }
           }
+        } else if (isa<memref::AllocOp>(op)) {
+          allocStack.push_back(op);
+        } else if (isa<memref::DeallocOp>(op)) {
+          // fallback alloc / dealloc not in FILO fashion
+          Value deallocMemref = op->getOperands().front();
+          Value topAllocMemref = allocStack.back()->getResults().front();
+          if (deallocMemref == topAllocMemref) {
+            allocStack.pop_back();
+          } else {
+            noTransformOps.insert(op);
+            for (int i = allocStack.size() - 1; i >= 0; --i) {
+              Operation *curAlloc = allocStack[i];
+              if (deallocMemref == curAlloc->getResults().front()) {
+                noTransformOps.insert(curAlloc);
+                allocStack.erase(allocStack.begin() + i);
+              }
+            }
+          }
         }
       });
     });