[flang-commits] [flang] [flang][fir] Add FIR structured control flow ops to SCF dialect pass. (PR #140374)

[Kiran Chandramohan via flang-commits]

================
@@ -0,0 +1,103 @@
+//===-- FIRToSCF.cpp ------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "flang/Optimizer/Dialect/FIRDialect.h"
+#include "flang/Optimizer/Transforms/Passes.h"
+#include "mlir/Dialect/SCF/IR/SCF.h"
+#include "mlir/Transforms/DialectConversion.h"
+
+namespace fir {
+#define GEN_PASS_DEF_FIRTOSCFPASS
+#include "flang/Optimizer/Transforms/Passes.h.inc"
+} // namespace fir
+
+using namespace fir;
+using namespace mlir;
+
+namespace {
+class FIRToSCFPass : public fir::impl::FIRToSCFPassBase<FIRToSCFPass> {
+public:
+  void runOnOperation() override;
+};
+} // namespace
+
+struct DoLoopConversion : public OpRewritePattern<fir::DoLoopOp> {
+  using OpRewritePattern<fir::DoLoopOp>::OpRewritePattern;
+
+  LogicalResult matchAndRewrite(fir::DoLoopOp doLoopOp,
+                                PatternRewriter &rewriter) const override {
+    auto loc = doLoopOp.getLoc();
+    bool hasFinalValue = doLoopOp.getFinalValue().has_value();
+
+    // Get loop values from the DoLoopOp
+    auto low = doLoopOp.getLowerBound();
+    auto high = doLoopOp.getUpperBound();
+    assert(low && high && "must be a Value");
+    auto step = doLoopOp.getStep();
+    llvm::SmallVector<mlir::Value> iterArgs;
+    if (hasFinalValue)
+      iterArgs.push_back(low);
+    iterArgs.append(doLoopOp.getIterOperands().begin(),
+                    doLoopOp.getIterOperands().end());
+
+    // Caculate the trip count.
----------------
kiranchandramohan wrote:

Could you add a brief comment on the semantic difference between `scf.for` and `fir.do_loop`? Particularly, whether the upperbound is included, the step value needing to be positive etc. Generally what are the differences that you should account for while converting.


https://github.com/llvm/llvm-project/pull/140374