[clang] [OpenACC][CIR] Implement 'reduction' combiner lowering for 5 ops (PR #162906)

[Andy Kaylor via cfe-commits]

================
@@ -527,16 +527,140 @@ void OpenACCRecipeBuilderBase::createFirstprivateRecipeCopy(
 // doesn't restore it aftewards.
 void OpenACCRecipeBuilderBase::createReductionRecipeCombiner(
     mlir::Location loc, mlir::Location locEnd, mlir::Value mainOp,
-    mlir::acc::ReductionRecipeOp recipe, size_t numBounds) {
+    mlir::acc::ReductionRecipeOp recipe, size_t numBounds, QualType origType,
+    llvm::ArrayRef<OpenACCReductionRecipe::CombinerRecipe> combinerRecipes) {
   mlir::Block *block =
       createRecipeBlock(recipe.getCombinerRegion(), mainOp.getType(), loc,
                         numBounds, /*isInit=*/false);
   builder.setInsertionPointToEnd(&recipe.getCombinerRegion().back());
   CIRGenFunction::LexicalScope ls(cgf, loc, block);
 
-  mlir::BlockArgument lhsArg = block->getArgument(0);
+  mlir::Value lhsArg = block->getArgument(0);
+  mlir::Value rhsArg = block->getArgument(1);
+  llvm::MutableArrayRef<mlir::BlockArgument> boundsRange =
+      block->getArguments().drop_front(2);
+
+  if (llvm::any_of(combinerRecipes, [](auto &r) { return r.Op == nullptr; })) {
+    cgf.cgm.errorNYI(loc, "OpenACC Reduction combiner not generated");
+    mlir::acc::YieldOp::create(builder, locEnd, block->getArgument(0));
+    return;
+  }
+
+  // apply the bounds so that we can get our bounds emitted correctly.
+  for (mlir::BlockArgument boundArg : llvm::reverse(boundsRange))
+    std::tie(lhsArg, rhsArg) =
+        createBoundsLoop(lhsArg, rhsArg, boundArg, loc, /*inverse=*/false);
+
+  // Emitter for when we know this isn't a struct or array we have to loop
+  // through. This should work for the 'field' once the get-element call has
+  // been made.
+  auto emitSingleCombiner =
+      [&](mlir::Value lhsArg, mlir::Value rhsArg,
+          const OpenACCReductionRecipe::CombinerRecipe &combiner) {
+        mlir::Type elementTy =
+            mlir::cast<cir::PointerType>(lhsArg.getType()).getPointee();
+        CIRGenFunction::DeclMapRevertingRAII declMapRAIILhs{cgf, combiner.LHS};
+        cgf.setAddrOfLocalVar(
+            combiner.LHS, Address{lhsArg, elementTy,
+                                  cgf.getContext().getDeclAlign(combiner.LHS)});
+        CIRGenFunction::DeclMapRevertingRAII declMapRAIIRhs{cgf, combiner.RHS};
+        cgf.setAddrOfLocalVar(
+            combiner.RHS, Address{rhsArg, elementTy,
+                                  cgf.getContext().getDeclAlign(combiner.RHS)});
+
+        [[maybe_unused]] mlir::LogicalResult stmtRes =
+            cgf.emitStmt(combiner.Op, /*useCurrentScope=*/true);
+      };
+
+  // Emitter for when we know this is either a non-array or element of an array
+  // (which also shouldn't be an array type?). This function should generate the
+  // loop to do this on each individual array or struct element (if necessary).
+  auto emitCombiner = [&](mlir::Value lhsArg, mlir::Value rhsArg, QualType Ty) {
+    if (const auto *RD = Ty->getAsRecordDecl()) {
+      if (combinerRecipes.size() == 1 &&
+          cgf.getContext().hasSameType(Ty, combinerRecipes[0].LHS->getType())) {
+        // If this is a 'top level' operator on the type we can just emit this
+        // as a simple one.
+        emitSingleCombiner(lhsArg, rhsArg, combinerRecipes[0]);
+      } else {
+        // else we have to handle each individual field after after a
+        // get-element.
+        for (const auto &[field, combiner] :
+             llvm::zip_equal(RD->fields(), combinerRecipes)) {
+          mlir::Type fieldType = cgf.convertType(field->getType());
+          auto fieldPtr = cir::PointerType::get(fieldType);
+
+          mlir::Value lhsField = builder.createGetMember(
+              loc, fieldPtr, lhsArg, field->getName(), field->getFieldIndex());
+          mlir::Value rhsField = builder.createGetMember(
+              loc, fieldPtr, rhsArg, field->getName(), field->getFieldIndex());
+
+          emitSingleCombiner(lhsField, rhsField, combiner);
+        }
+      }
+
+    } else {
+      // if this is a single-thing (because we should know this isn't an array,
+      // as Sema wouldn't let us get here), we can just do a normal emit call.
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andykaylor wrote:

Maybe assert that it's not an array?

https://github.com/llvm/llvm-project/pull/162906