[Mlir-commits] [mlir] [mlir][emitc] Add 'emitc.while' and 'emitc.do' ops to the dialect (PR #143008)

[Gil Rapaport]

================
@@ -336,11 +336,190 @@ LogicalResult IndexSwitchOpLowering::matchAndRewrite(
   return success();
 }
 
+// Lower scf::while to emitc::do using mutable variables to maintain loop state
+// across iterations. The do-while structure ensures the condition is evaluated
+// after each iteration, matching SCF while semantics.
+struct WhileLowering : public OpConversionPattern<WhileOp> {
+  using OpConversionPattern::OpConversionPattern;
+
+  LogicalResult
+  matchAndRewrite(WhileOp whileOp, OpAdaptor adaptor,
+                  ConversionPatternRewriter &rewriter) const override {
+    Location loc = whileOp.getLoc();
+    MLIRContext *context = loc.getContext();
+
+    // Create variable storage for loop-carried values to enable imperative
+    // updates while maintaining SSA semantics at conversion boundaries.
+    SmallVector<Value> variables;
+    if (failed(createInitVariables(whileOp, rewriter, variables, loc, context)))
+      return failure();
+
+    if (failed(lowerDoWhile(whileOp, variables, context, rewriter, loc)))
+      return failure();
+
+    // Create an emitc::variable op for each result. These variables will be
+    // assigned to by emitc::assign ops within the loop body.
+    SmallVector<Value> resultVariables;
+    if (failed(createVariablesForResults(whileOp, getTypeConverter(), rewriter,
+                                         resultVariables))) {
+      return rewriter.notifyMatchFailure(whileOp,
+                                         "Failed to create result variables");
+    }
+
+    rewriter.setInsertionPointAfter(whileOp);
+
+    // Transfer final loop state to result variables and get final SSA results.
+    SmallVector<Value> finalResults =
+        finalizeLoopResults(resultVariables, variables, rewriter, loc);
+
+    rewriter.replaceOp(whileOp, finalResults);
+    return success();
+  }
+
+private:
+  // Initialize variables for loop-carried values to enable state updates
+  // across iterations without SSA argument passing.
+  static LogicalResult createInitVariables(WhileOp whileOp,
+                                           ConversionPatternRewriter &rewriter,
+                                           SmallVectorImpl<Value> &outVars,
+                                           Location loc, MLIRContext *context) {
+    emitc::OpaqueAttr noInit = emitc::OpaqueAttr::get(context, "");
+
+    for (Value init : whileOp.getInits()) {
+      emitc::VariableOp var = rewriter.create<emitc::VariableOp>(
+          loc, emitc::LValueType::get(init.getType()), noInit);
----------------
aniragil wrote:

Seems to require the same change @mgehre-amd did in `createVariablesForResults`, i.e. passing types through `typeConverter->convertType()`

https://github.com/llvm/llvm-project/pull/143008