[clang] [OpenACC][CIR] Implement 'num_gangs' lowering (PR #137216)

[Erich Keane via cfe-commits]

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@@ -95,19 +95,41 @@ class OpenACCClauseCIREmitter final
         .CaseLower("radeon", mlir::acc::DeviceType::Radeon);
   }
 
-  // Handle a clause affected by the 'device-type' to the point that they need
-  // to have the attributes added in the correct/corresponding order, such as
-  // 'num_workers' or 'vector_length' on a compute construct. For cases where we
-  // don't have an expression 'argument' that needs to be added to an operand
-  // and only care about the 'device-type' list, we can use this with 'argument'
-  // as 'std::nullopt'.   If 'argument' is NOT 'std::nullopt' (that is, has a
-  // value), argCollection must also be non-null. For cases where we don't have
-  // an argument that needs to be added to an additional one (such as asyncOnly)
-  // we can use this with 'argument' as std::nullopt.
-  mlir::ArrayAttr handleDeviceTypeAffectedClause(
-      mlir::ArrayAttr existingDeviceTypes,
-      std::optional<mlir::Value> argument = std::nullopt,
-      mlir::MutableOperandRange *argCollection = nullptr) {
+  // Overload of this function that only returns the device-types list.
+  mlir::ArrayAttr
+  handleDeviceTypeAffectedClause(mlir::ArrayAttr existingDeviceTypes) {
+    mlir::ValueRange argument;
+    mlir::MutableOperandRange range{operation};
+
+    return handleDeviceTypeAffectedClause(existingDeviceTypes, argument, range);
+  }
+  // Overload of this function for when 'segments' aren't necessary.
+  mlir::ArrayAttr
+  handleDeviceTypeAffectedClause(mlir::ArrayAttr existingDeviceTypes,
+                                 mlir::ValueRange argument,
+                                 mlir::MutableOperandRange argCollection) {
+    llvm::SmallVector<int32_t> segments;
+    assert(argument.size() <= 1 &&
+           "Overload only for cases where segments don't need to be added");
+    return handleDeviceTypeAffectedClause(existingDeviceTypes, argument,
+                                          argCollection, segments);
+  }
+
+  // Handle a clause affected by the 'device_type' to the point that they need
+  // to have attributes added in the correct/corresponding order, such as
+  // 'num_workers' or 'vector_length' on a compute construct. The 'argument' is
+  // a collection of operands that need to be appended to the `argCollection` as
+  // we're adding a 'device_type' entry.  If there is more than 0 elements in
+  // the 'argument', the collection must be non-null, as it is needed to add to
+  // it.
+  // As some clauses, such as 'num_gangs' or 'wait' require a 'segments' list to
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erichkeane wrote:

Hmm.. 'segments' are a little weird, they are a little bit MLIR/OpenACC-Dialect specific perhaps.  I'll try to improve the comment.

As far as zero-arguments between non-zero segments, my understanding is no.

https://github.com/llvm/llvm-project/pull/137216