[valueblocks] Scaffolding for ternary terminals

Core representation for terminals, without the lowering and conversion logic.

compiler/forget/src/HIR/HIR.ts

@@ -238,7 +238,8 @@ export type Terminal =
   | SwitchTerminal
   | ForTerminal
   | WhileTerminal
-  | LogicalTerminal;
+  | LogicalTerminal
+  | TernaryTerminal;
 
 /**
  * Terminal nodes allowed for a value block
@@ -321,6 +322,14 @@ export type LogicalTerminal = {
   loc: SourceLocation;
 };
 
+export type TernaryTerminal = {
+  kind: "ternary";
+  test: BlockId;
+  fallthrough: BlockId;
+  id: InstructionId;
+  loc: SourceLocation;
+};
+
 /**
  * Instructions generally represent expressions but with all nesting flattened away,
  * such that all operands to each instruction are either primitive values OR are

compiler/forget/src/HIR/HIRBuilder.ts

@@ -562,6 +562,7 @@ export function reversePostorderBlocks(func: HIR): void {
         }
         break;
       }
+      case "ternary":
       case "logical": {
         visit(terminal.test);
         break;

compiler/forget/src/HIR/PrintHIR.ts

@@ -79,6 +79,7 @@ export function printMixedHIR(
     case "branch":
     case "if":
     case "logical":
+    case "ternary":
     case "return":
     case "switch":
     case "throw":
@@ -146,6 +147,10 @@ export function printTerminal(terminal: Terminal): Array<string> | string {
       value = `[${terminal.id}] Logical ${terminal.operator} test:bb${terminal.test} fallthrough=bb${terminal.fallthrough}`;
       break;
     }
+    case "ternary": {
+      value = `[${terminal.id}] Ternary test:bb${terminal.test} fallthrough=bb${terminal.fallthrough}`;
+      break;
+    }
     case "throw": {
       value = `[${terminal.id}] Throw ${printPlace(terminal.value)}`;
       break;

compiler/forget/src/HIR/visitors.ts

@@ -294,6 +294,17 @@ export function mapTerminalSuccessors(
         loc: terminal.loc,
       };
     }
+    case "ternary": {
+      const test = fn(terminal.test);
+      const fallthrough = fn(terminal.fallthrough);
+      return {
+        kind: "ternary",
+        test,
+        fallthrough,
+        id: makeInstructionId(0),
+        loc: terminal.loc,
+      };
+    }
     case "return": {
       return {
         kind: "return",
@@ -373,6 +384,7 @@ export function* eachTerminalSuccessor(terminal: Terminal): Iterable<BlockId> {
       }
       break;
     }
+    case "ternary":
     case "logical": {
       yield terminal.test;
       break;
@@ -432,6 +444,7 @@ export function mapTerminalOperands(
       }
       break;
     }
+    case "ternary":
     case "logical":
     case "while":
     case "for":
@@ -476,6 +489,7 @@ export function* eachTerminalOperand(terminal: Terminal): Iterable<Place> {
       }
       break;
     }
+    case "ternary":
     case "logical":
     case "while":
     case "for":

compiler/forget/src/ReactiveScopes/BuildReactiveFunction.ts

@@ -406,6 +406,7 @@ class Driver {
 
         break;
       }
+      case "ternary":
       case "logical": {
         const fallthroughId = terminal.fallthrough;
         invariant(

compiler/forget/src/Utils/VisualizeHIRMermaid.ts

@@ -103,6 +103,10 @@ function printTerminalLabel(terminal: Terminal): string {
       buffer.push(`Logical ${terminal.operator}`);
       break;
     }
+    case "ternary": {
+      buffer.push("Ternary");
+      break;
+    }
     case "while":
       buffer.push("While");
       break;
@@ -144,6 +148,11 @@ function printTerminalArrows(blockId: BlockId, terminal: Terminal): string {
       buffer.push(printJumpArrow(blockId, terminal.fallthrough, "fallthrough"));
       break;
     }
+    case "ternary": {
+      buffer.push(printJumpArrow(blockId, terminal.test, "test"));
+      buffer.push(printJumpArrow(blockId, terminal.fallthrough, "fallthrough"));
+      break;
+    }
     case "goto": {
       buffer.push(printJumpArrow(blockId, terminal.block, null));
       break;