Value block final value has an InstrId

compiler/forget/src/HIR/Codegen.ts

@@ -141,12 +141,12 @@ class CodegenVisitor
   }
   leaveValueBlock(
     block: t.Statement[],
-    place: t.Expression | null
+    place: { value: t.Expression; id: InstructionId } | null
   ): t.Expression {
     this.depth--;
     if (block.length === 0) {
       invariant(place !== null, "Unexpected empty value block");
-      return place;
+      return place.value;
     }
     const expressions = block.map((stmt) => {
       switch (stmt.type) {
@@ -160,7 +160,7 @@ class CodegenVisitor
       }
     });
     if (place !== null) {
-      expressions.push(place);
+      expressions.push(place.value);
     }
     return t.sequenceExpression(expressions);
   }

compiler/forget/src/HIR/HIR.ts

@@ -61,7 +61,10 @@ export type ReactiveBlock = Array<ReactiveStatement>;
 export type ReactiveValueBlock = {
   kind: "value-block";
   instructions: ReactiveBlock;
-  value: InstructionValue | null;
+  last: {
+    value: InstructionValue;
+    id: InstructionId;
+  } | null;
 };
 
 export type ReactiveStatement =

compiler/forget/src/HIR/HIRTreeVisitor.ts

@@ -519,7 +519,10 @@ class Driver<
     }
     const value =
       lastValue !== null
-        ? this.visitor.visitValue(lastValue.value, lastValue.id)
+        ? {
+            value: this.visitor.visitValue(lastValue.value, lastValue.id),
+            id: lastValue.id,
+          }
         : null;
     return this.visitor.leaveValueBlock(valueBlock, value);
   }
@@ -873,7 +876,10 @@ export interface Visitor<
    * Converts the visitor's value block (and final value) to the visitor's
    * value representation.
    */
-  leaveValueBlock(block: TValueBlock, value: TValue | null): TValue;
+  leaveValueBlock(
+    block: TValueBlock,
+    value: { value: TValue; id: InstructionId } | null
+  ): TValue;
 
   enterInitBlock(block: TBlockBuilder): TValueBlock;
 

compiler/forget/src/ReactiveScopes/BuildReactiveFunction.ts

@@ -152,7 +152,7 @@ class ReactiveFunctionBuilder
     return {
       kind: "value-block",
       instructions: [],
-      value: null,
+      last: null,
     };
   }
   appendValueBlock(block: ReactiveValueBlock, item: ReactiveStatement): void {
@@ -160,14 +160,18 @@ class ReactiveFunctionBuilder
   }
   leaveValueBlock(
     block: ReactiveValueBlock,
-    value: InstructionValue | ReactiveValueBlock | null
+    last: {
+      value: InstructionValue | ReactiveValueBlock;
+      id: InstructionId;
+    } | null
   ): InstructionValue | ReactiveValueBlock {
-    if (value !== null) {
+    if (last !== null) {
+      const { id, value } = last;
       invariant(
         value.kind !== "value-block",
         "Expected value block to end in a value"
       );
-      block.value = value;
+      block.last = { id, value };
     }
     return block;
   }

compiler/forget/src/ReactiveScopes/BuildReactiveFunctionWithoutScopes.ts

@@ -19,11 +19,7 @@ import {
   ReactiveTerminal,
   ReactiveValueBlock,
 } from "../HIR/HIR";
-import {
-  BlockTerminal,
-  Visitor,
-  visitTreeForReactiveFunction as visitTree,
-} from "../HIR/ReactiveFunctionVisitor";
+import { BlockTerminal, Visitor, visitTree } from "../HIR/HIRTreeVisitor";
 import { assertExhaustive } from "../Utils/utils";
 
 export function buildReactiveFunction(fn: HIRFunction): ReactiveFunction {
@@ -86,7 +82,7 @@ class ReactiveFunctionBuilder
     return {
       kind: "value-block",
       instructions: [],
-      value: null,
+      last: null,
     };
   }
   appendValueBlock(block: ReactiveValueBlock, item: ReactiveStatement): void {
@@ -94,14 +90,18 @@ class ReactiveFunctionBuilder
   }
   leaveValueBlock(
     block: ReactiveValueBlock,
-    value: InstructionValue | ReactiveValueBlock | null
+    last: {
+      value: InstructionValue | ReactiveValueBlock;
+      id: InstructionId;
+    } | null
   ): InstructionValue | ReactiveValueBlock {
-    if (value !== null) {
+    if (last !== null) {
+      const { id, value } = last;
       invariant(
         value.kind !== "value-block",
         "Expected value block to end in a value"
       );
-      block.value = value;
+      block.last = { id, value };
     }
     return block;
   }

compiler/forget/src/ReactiveScopes/CodegenReactiveFunction.ts

@@ -331,12 +331,12 @@ function codegenForInit(
   init: ReactiveValueBlock
 ): t.Expression | t.VariableDeclaration | null {
   const body = codegenBlock(cx, init.instructions).body;
-  if (init.value !== null) {
+  if (init.last !== null) {
     invariant(
       body.length === 0,
       "Expected for init block to produce only temporaries"
     );
-    return codegenInstructionValue(cx.temp, init.value);
+    return codegenInstructionValue(cx.temp, init.last.value);
   } else {
     invariant(
       body.length === 1,
@@ -363,8 +363,8 @@ function codegenValueBlock(
       todoInvariant(false, `Handle conversion of ${stmt.type} to expression`);
     }
   });
-  if (block.value !== null) {
-    const value = codegenInstructionValue(cx.temp, block.value);
+  if (block.last !== null) {
+    const value = codegenInstructionValue(cx.temp, block.last.value);
     expressions.push(value);
   }
   invariant(

compiler/forget/src/ReactiveScopes/InferReactiveScopes.ts

@@ -268,7 +268,10 @@ class MergeOverlappingReactiveScopesVisitor
   leaveInitBlock(block: void): void {
     this.leaveBlock();
   }
-  leaveValueBlock(block: void, value: void): void {
+  leaveValueBlock(
+    block: void,
+    value: { value: void; id: InstructionId } | null
+  ): void {
     this.leaveBlock();
   }
   visitValue(value: InstructionValue, id: InstructionId): void {
@@ -389,7 +392,10 @@ class AlignReactiveScopesToBlockScopeRangeVisitor
     this.blockScopes.push({ kind: "value", scopes: [] });
   }
   appendValueBlock(block: void, item: void): void {}
-  leaveValueBlock(block: void, value: void): void {
+  leaveValueBlock(
+    block: void,
+    value: { value: void; id: InstructionId } | null
+  ): void {
     const lastScope = this.blockScopes.pop();
     invariant(
       lastScope !== undefined && lastScope.kind === "value",
@@ -409,7 +415,7 @@ class AlignReactiveScopesToBlockScopeRangeVisitor
   }
   appendInitBlock(block: void, item: void): void {}
   leaveInitBlock(block: void): void {
-    this.leaveValueBlock(block);
+    this.leaveValueBlock(block, null);
   }
 
   visitInstruction(instruction: Instruction, value: void): void {

compiler/forget/src/ReactiveScopes/PrintReactiveFunction.ts

@@ -104,8 +104,8 @@ function printValueBlock(writer: Writer, block: ReactiveValueBlock): void {
     for (const instr of block.instructions) {
       printReactiveInstruction(writer, instr);
     }
-    if (block.value !== null) {
-      writer.writeLine(printInstructionValue(block.value));
+    if (block.last !== null) {
+      writer.writeLine(printInstructionValue(block.last.value));
     }
   });
 }

compiler/forget/src/ReactiveScopes/PropagateScopeDependencies.ts

@@ -260,8 +260,8 @@ function visitValueBlock(context: Context, block: ReactiveValueBlock): void {
       visitInstruction(context, initItem.instruction);
     }
   }
-  if (block.value !== null) {
-    visitInstructionValue(context, block.value, null);
+  if (block.last !== null) {
+    visitInstructionValue(context, block.last.value, null);
   }
 }
 

compiler/forget/src/ReactiveScopes/RenameVariables.ts

@@ -83,8 +83,8 @@ function visitValueBlock(scopes: Scopes, block: ReactiveValueBlock): void {
       scopes.visit(stmt.instruction.lvalue.place.identifier);
     }
   }
-  if (block.value !== null) {
-    for (const operand of eachInstructionValueOperand(block.value)) {
+  if (block.last !== null) {
+    for (const operand of eachInstructionValueOperand(block.last.value)) {
       scopes.visit(operand.identifier);
     }
   }

compiler/forget/src/ReactiveScopes/visitors.ts

@@ -74,8 +74,8 @@ export function visitFunction(
   }
   function visitValueBlock(block: ReactiveValueBlock): void {
     visitBlock(block.instructions);
-    if (block.value !== null && visitValue) {
-      visitValue(block.value);
+    if (block.last !== null && visitValue) {
+      visitValue(block.last.value);
     }
   }
   visitBlock(fn.body);