[flang-commits] [flang] [flang][fir]: Add conversion of `fir.iterate_while` to `scf.while`. (PR #152439)

[Ming Yan via flang-commits]

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@@ -88,6 +89,85 @@ struct DoLoopConversion : public OpRewritePattern<fir::DoLoopOp> {
   }
 };
 
+struct IterWhileConversion : public OpRewritePattern<fir::IterWhileOp> {
+  using OpRewritePattern<fir::IterWhileOp>::OpRewritePattern;
+
+  LogicalResult matchAndRewrite(fir::IterWhileOp iterWhileOp,
+                                PatternRewriter &rewriter) const override {
+
+    Location loc = iterWhileOp.getLoc();
+    Value lowerBound = iterWhileOp.getLowerBound();
+    Value upperBound = iterWhileOp.getUpperBound();
+    Value step = iterWhileOp.getStep();
+
+    Value okInit = iterWhileOp.getIterateIn();
+    ValueRange iterArgs = iterWhileOp.getInitArgs();
+
+    SmallVector<Value> initVals;
+    initVals.push_back(lowerBound);
+    initVals.push_back(okInit);
+    initVals.append(iterArgs.begin(), iterArgs.end());
+
+    SmallVector<Type> loopTypes;
+    loopTypes.push_back(lowerBound.getType());
+    loopTypes.push_back(okInit.getType());
+    for (auto val : iterArgs)
+      loopTypes.push_back(val.getType());
+
+    auto scfWhileOp = scf::WhileOp::create(rewriter, loc, loopTypes, initVals);
+
+    auto &beforeBlock = *rewriter.createBlock(
+        &scfWhileOp.getBefore(), scfWhileOp.getBefore().end(), loopTypes,
+        SmallVector<Location>(loopTypes.size(), loc));
+
+    auto &afterBlock = *rewriter.createBlock(
+        &scfWhileOp.getAfter(), scfWhileOp.getAfter().end(), loopTypes,
+        SmallVector<Location>(loopTypes.size(), loc));
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NexMing wrote:

If the original block meets the relevant requirements, I think we can use `scfWhileOp.getAfter().takeBody` instead of creating a new block.

https://github.com/llvm/llvm-project/pull/152439