Rewrite BufferMemrefToFuncArgs as pattern and fold greedily (#853)

Xilinx · Jan 10, 2025 · ad90c73 · ad90c73
1 parent c78cf3f
commit ad90c73
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Showing 3 changed files with 61 additions and 55 deletions.
diff --git a/mlir/include/air/Util/Util.h b/mlir/include/air/Util/Util.h
@@ -252,6 +252,10 @@ SmallVector<Operation *> cloneDefiningOpsInRegion(OpBuilder builder,
                                                   SmallVectorImpl<Value> &opers,
                                                   IRMapping &remap);
 
+// Buffer all allocations of memref directly within the func op's body into the
+// func op's arguments.
+void populateBufferMemrefToFuncArgsPattern(RewritePatternSet &patterns);
+
 } // namespace air
 } // namespace xilinx
 

diff --git a/mlir/lib/Conversion/AIRRtToNpuPass.cpp b/mlir/lib/Conversion/AIRRtToNpuPass.cpp
@@ -1025,11 +1025,10 @@ struct AIRRtToNpuPass : public impl::AIRRtToNpuBase<AIRRtToNpuPass> {
     // Unroll any affine for loops
     unrollAffineFors(module);
 
-    // Buffer npu.dma_memcpy_nd memref to function's argument list.
-    BufferMemrefToFuncArgs(module);
-
-    // Cast buffers to i32 types
+    // Cast buffers to i32 types; buffer npu.dma_memcpy_nd memref to function's
+    // argument list.
     RewritePatternSet castPattern(ctx);
+    air::populateBufferMemrefToFuncArgsPattern(castPattern);
     castPattern.add(CastFunctionArgs);
     (void)applyPatternsAndFoldGreedily(module, std::move(castPattern));
 
@@ -1631,57 +1630,6 @@ struct AIRRtToNpuPass : public impl::AIRRtToNpuBase<AIRRtToNpuPass> {
                              chanToIdMap[col]++));
     });
   }
-
-  // Buffers npu.dma_memcpy_op memref as function argument
-  void BufferMemrefToFuncArgs(ModuleOp module) {
-    module.walk([&](mlir::func::FuncOp f) { BufferMemrefToFuncArgs(f); });
-  }
-  void BufferMemrefToFuncArgs(func::FuncOp funcOp) {
-    if (!funcOp)
-      return;
-
-    // Collect illegal dma ops whose memrefs are not in function's arguments.
-    SmallVector<Type, 6> memrefTypes;
-    SmallVector<Value, 6> memrefs;
-    funcOp.walk([&](AIEX::NpuDmaMemcpyNdOp dma) {
-      Value memref = dma.getMemref();
-      auto args = funcOp.getArguments();
-      // if the memref is an arg, return
-      if (std::find(args.begin(), args.end(), memref) != args.end())
-        return;
-      // if the memref is the result of a cast of an arg, return
-      if (auto cast = dyn_cast_or_null<UnrealizedConversionCastOp>(
-              memref.getDefiningOp())) {
-        if (std::find(args.begin(), args.end(), cast.getOperand(0)) !=
-            args.end())
-          return;
-        else
-          memref = cast.getOperand(0);
-      }
-      // push back if unique
-      if (std::find(memrefs.begin(), memrefs.end(), memref) == memrefs.end()) {
-        memrefs.push_back(memref);
-        memrefTypes.push_back(memref.getType());
-      }
-    });
-
-    // Append memref to function's arguments.
-    auto functionType = funcOp.getFunctionType();
-    auto newArgTypes = llvm::to_vector<6>(
-        llvm::concat<const Type>(functionType.getInputs(), memrefTypes));
-    auto newFunctionType = FunctionType::get(funcOp.getContext(), newArgTypes,
-                                             functionType.getResults());
-    funcOp.setType(newFunctionType);
-
-    // Add the new arguments to the entry block if the function is not external.
-    if (!funcOp.isExternal()) {
-      Location loc = funcOp.getLoc();
-      for (Value v : memrefs) {
-        auto newArg = funcOp.front().addArgument(v.getType(), loc);
-        v.replaceAllUsesWith(newArg);
-      }
-    }
-  }
 };
 
 } // namespace

diff --git a/mlir/lib/Util/Util.cpp b/mlir/lib/Util/Util.cpp
@@ -1693,3 +1693,57 @@ air::cloneDefiningOpsInRegion(OpBuilder builder, Region *region,
     clonedOps.push_back(builder.clone(*op, remap));
   return clonedOps;
 }
+
+// Buffer all allocations of L3 memref directly within the func op's body into
+// the func op's arguments.
+struct BufferMemrefToFuncArgsPattern : public OpRewritePattern<func::FuncOp> {
+  using OpRewritePattern<func::FuncOp>::OpRewritePattern;
+
+  LogicalResult matchAndRewrite(func::FuncOp funcOp,
+                                PatternRewriter &rewriter) const override {
+
+    if (funcOp.isExternal())
+      return failure();
+
+    SmallVector<Type, 6> memrefTypes;
+    llvm::SetVector<Value> memrefs;
+    for (auto &op : funcOp.getFunctionBody().getOps()) {
+      if (isa<CastOpInterface>(op))
+        continue;
+      for (auto res : op.getResults()) {
+        MemRefType resType = dyn_cast<MemRefType>(res.getType());
+        if (!resType)
+          continue;
+        if (resType.getMemorySpaceAsInt() == (int)air::MemorySpace::L3)
+          memrefs.insert(res);
+      }
+    }
+    for (auto memref : memrefs)
+      memrefTypes.push_back(memref.getType());
+    if (memrefs.empty())
+      return failure();
+
+    // Append memref to function's arguments.
+    auto functionType = funcOp.getFunctionType();
+    auto newArgTypes = llvm::to_vector<6>(
+        llvm::concat<const Type>(functionType.getInputs(), memrefTypes));
+    auto newFunctionType = FunctionType::get(funcOp.getContext(), newArgTypes,
+                                             functionType.getResults());
+    funcOp.setType(newFunctionType);
+
+    // Add the new arguments to the entry block if the function is not external.
+    Location loc = funcOp.getLoc();
+    for (Value v : memrefs) {
+      auto newArg = funcOp.front().addArgument(v.getType(), loc);
+      v.replaceAllUsesWith(newArg);
+    }
+    return success();
+  }
+
+private:
+};
+
+void air::populateBufferMemrefToFuncArgsPattern(RewritePatternSet &patterns) {
+  MLIRContext *ctx = patterns.getContext();
+  patterns.insert<BufferMemrefToFuncArgsPattern>(ctx);
+}