[MLIR][OpenMP] Unroll Construct operation

[abidmalikwaterloo]

Summary

The patch adds OpenMP unroll operation for the OMP dialect.

[Meinersbur]

I am not familiar with the MLIR tablegen format, but there might two issues:

• The full clause does not have an operand, it is more similar to a flag like nowait.
• The partial clauses operand is optional. $partial_operand is AnyInteger. Is there a sentinal value for $partial_operand if the clauses operand is omitted?

[abidmalikwaterloo]

In D130851#3694338, @Meinersbur wrote:

I am not familiar with the MLIR tablegen format, but there might two issues:

• The full clause does not have an operand, it is more similar to a flag like nowait.

nowait is unitAtt. full can be treated the same way. I am considering it as boolean with 0 as false and 1 as true <

• The partial clauses operand is optional. $partial_operand is AnyInteger. Is there a sentinal value for $partial_operand if the clauses operand is omitted?

Partial Clause has unroll factor which is an integer expression. There is no sentinal value, I think!

[Meinersbur]

In D130851#3695118, @abidmalikwaterloo wrote:

• The full clause does not have an operand, it is more similar to a flag like nowait.

nowait is unitAtt. full can be treated the same way. I am considering it as boolean with 0 as false and 1 as true <

full(0) or full(1) feels clunkier than a flag. $full_operand is also an Optional, does it mean that full() is valid as well? Any reason to not also make it a unitAtt?

Partial Clause has unroll factor which is an integer expression. There is no sentinal value, I think!

I think I oversaw that it is an Optional<>, hence None would be that sentinel.

[abidmalikwaterloo]

In D130851#3696913, @Meinersbur wrote:

In D130851#3695118, @abidmalikwaterloo wrote:

• The full clause does not have an operand, it is more similar to a flag like nowait.

nowait is unitAtt. full can be treated the same way. I am considering it as boolean with 0 as false and 1 as true <

full(0) or full(1) feels clunkier than a flag. $full_operand is also an Optional, does it mean that full() is valid as well? Any reason to not also make it a unitAtt?

I will make it UnitAtt.

Partial Clause has unroll factor which is an integer expression. There is no sentinal value, I think!

I think I oversaw that it is an Optional<>, hence None would be that sentinel.

Ok. Will do and update the patch. accordingly

[kiranchandramohan]

I think we should discuss this operation a bit more before proceeding. If the loop and its control are not part of the unroll OpenMP dialect operation then there is no guarantee that the unroll operation will happen. The loop can be modified or converted by other transformations or conversions.

mlir/include/mlir/Dialect/OpenMP/OpenMPOps.td

let description = [{
     The taskyield construct specifies that the current task can be suspended
     in favor of execution of a different task.
   }];
 
   let assemblyFormat = "attr-dict";
 }
 
 //===----------------------------------------------------------------------===//
+// 2.11.9.2 unroll Construct
+//===----------------------------------------------------------------------===//
+def UnrollOp : OpenMP_Op<"unroll", [AttrSizedOperandSegments]> {
+  let summary = "unroll construct";
+  let description = [{
+    The unroll construct fully or partially unrolls a loop.
+  }];
+
+  let arguments = (ins Optional<I1>:$full_operand,
+                       Optional<AnyInteger>:$partial_operand);
+
+  let regions = (region AnyRegion:$region);
+
+  let assemblyFormat = [{ ( `full` `(` $full_operand^ `:` type($full_operand) `)` )?
+           ( `partial` `(` $partial_operand^ `:`  
+                    type($partial_operand)`)` )?     
+     $region attr-dict
+  }];
+}
+
+//===----------------------------------------------------------------------===//
 // 2.13.7 flush Construct
 //===----------------------------------------------------------------------===//
 def FlushOp : OpenMP_Op<"flush"> {
   let summary = "flush construct";
   let description = [{
     The flush construct executes the OpenMP flush operation. This operation
     makes a thread’s temporary view of memory consistent with memory and
     enforces an order on the memory operations of the variables explicitly