[clang] [CIR] Upstream TernaryOp (PR #137184)

[Andy Kaylor via cfe-commits]

================
@@ -1246,6 +1246,59 @@ def SelectOp : CIR_Op<"select", [Pure,
   }];
 }
 
+//===----------------------------------------------------------------------===//
+// TernaryOp
+//===----------------------------------------------------------------------===//
+
+def TernaryOp : CIR_Op<"ternary",
+      [DeclareOpInterfaceMethods<RegionBranchOpInterface>,
+       RecursivelySpeculatable, AutomaticAllocationScope, NoRegionArguments]> {
+  let summary = "The `cond ? a : b` C/C++ ternary operation";
+  let description = [{
+    The `cir.ternary` operation represents C/C++ ternary, much like a `select`
+    operation. The first argument is a `cir.bool` condition to evaluate, followed
+    by two regions to execute (true or false). This is different from `cir.if`
+    since each region is one block sized and the `cir.yield` closing the block
+    scope should have one argument.
+
+    Example:
+
+    ```mlir
+    // x = cond ? a : b;
+
+    %x = cir.ternary (%cond, true_region {
+      ...
+      cir.yield %a : i32
+    }, false_region {
+      ...
+      cir.yield %b : i32
+    }) -> i32
+    ```
+  }];
+  let arguments = (ins CIR_BoolType:$cond);
+  let regions = (region AnyRegion:$trueRegion,
+                        AnyRegion:$falseRegion);
+  let results = (outs Optional<CIR_AnyType>:$result);
----------------
andykaylor wrote:

What does it mean for this to be optional? Can we have a TernaryOp that doesn't return a value?

https://github.com/llvm/llvm-project/pull/137184