[Mlir-commits] [mlir] [mlir][emitc] Add a structured for operation (PR #68206)

[Gil Rapaport]

================
@@ -246,6 +246,65 @@ def EmitC_DivOp : EmitC_BinaryOp<"div", []> {
   let results = (outs FloatIntegerIndexOrOpaqueType);
 }
 
+def EmitC_ForOp : EmitC_Op<"for",
+      [AllTypesMatch<["lowerBound", "upperBound", "step"]>,
+       SingleBlockImplicitTerminator<"emitc::YieldOp">,
+       RecursiveMemoryEffects]> {
+  let summary = "for operation";
+  let description = [{
+    The `emitc.for` operation represents a loop taking 3 SSA values as operands
+    that represent the lower bound, upper bound and step respectively. The
+    operation defines an SSA value for its induction variable. It has one
+    region capturing the loop body. The induction variable is represented as an
+    argument of this region. This SSA value is a signless integer or index.
+    The step is a value of same type but required to be positive. The lower and
+    upper bounds specify a half-open range: the range includes the lower bound
+    but does not include the upper bound. This operation has no result.
+
+    The body region must contain exactly one block that terminates with
+    `emitc.yield`. Calling ForOp::build will create such a region and insert
+    the terminator implicitly if none is defined, so will the parsing even in
+    cases when it is absent from the custom format. For example:
+
+    ```mlir
+    // Index case.
+    emitc.for %iv = %lb to %ub step %step {
+      ... // body
+    }
+    ...
+    // Integer case.
+    emitc.for %iv_32 = %lb_32 to %ub_32 step %step_32 : i32 {
+      ... // body
+    }
+    ```
+  }];
+  let arguments = (ins AnySignlessIntegerOrIndex:$lowerBound,
+                       AnySignlessIntegerOrIndex:$upperBound,
+                       AnySignlessIntegerOrIndex:$step);
----------------
aniragil wrote:

Agree, seems more consistent with other ops.

https://github.com/llvm/llvm-project/pull/68206