diff --git a/compiler/forget/src/HIR/BuildHIR.ts b/compiler/forget/src/HIR/BuildHIR.ts
index 5bee25f325..ff633bc2fa 100644
--- a/compiler/forget/src/HIR/BuildHIR.ts
+++ b/compiler/forget/src/HIR/BuildHIR.ts
@@ -122,7 +122,7 @@ function lowerStatement(
         value,
         id: makeInstructionId(0),
       };
-      builder.terminate(terminal);
+      builder.terminate("block", terminal);
       return;
     }
     case "ReturnStatement": {
@@ -138,7 +138,7 @@ function lowerStatement(
         value,
         id: makeInstructionId(0),
       };
-      builder.terminateWithContinuation(terminal, fallthrough);
+      builder.terminateWithContinuation("block", terminal, fallthrough);
       return;
     }
     case "IfStatement": {
@@ -146,7 +146,7 @@ function lowerStatement(
       //  Block for code following the if
       const continuationBlock = builder.reserve();
       //  Block for the consequent (if the test is truthy)
-      const consequentBlock = builder.enter((blockId) => {
+      const consequentBlock = builder.enter("block", (blockId) => {
         lowerStatement(builder, stmt.get("consequent"));
         return {
           kind: "goto",
@@ -159,7 +159,7 @@ function lowerStatement(
       let alternateBlock = null;
       const alternate = stmt.get("alternate");
       if (alternate.hasNode()) {
-        alternateBlock = builder.enter((blockId) => {
+        alternateBlock = builder.enter("block", (blockId) => {
           lowerStatement(builder, alternate);
           return {
             kind: "goto",
@@ -181,7 +181,7 @@ function lowerStatement(
         fallthrough: continuationBlock.id,
         id: makeInstructionId(0),
       };
-      builder.terminateWithContinuation(terminal, continuationBlock);
+      builder.terminateWithContinuation("block", terminal, continuationBlock);
       return;
     }
     case "BlockStatement": {
@@ -192,7 +192,7 @@ function lowerStatement(
     case "BreakStatement": {
       const stmt = stmtPath as NodePath<t.BreakStatement>;
       const block = builder.lookupBreak(stmt.node.label?.name ?? null);
-      builder.terminate({
+      builder.terminate("block", {
         kind: "goto",
         block,
         variant: GotoVariant.Break,
@@ -203,7 +203,7 @@ function lowerStatement(
     case "ContinueStatement": {
       const stmt = stmtPath as NodePath<t.ContinueStatement>;
       const block = builder.lookupContinue(stmt.node.label?.name ?? null);
-      builder.terminate({
+      builder.terminate("block", {
         kind: "goto",
         block,
         variant: GotoVariant.Continue,
@@ -217,7 +217,7 @@ function lowerStatement(
       const conditionalBlock = builder.reserve();
       //  Block for code following the loop
       const continuationBlock = builder.reserve();
-      const loopBlock = builder.enter((blockId) => {
+      const loopBlock = builder.enter("block", (blockId) => {
         return builder.loop(
           label,
           conditionalBlock.id,
@@ -235,6 +235,7 @@ function lowerStatement(
       });
       //  End the block leading up to the loop and jump to the conditional block
       builder.terminateWithContinuation(
+        "block",
         {
           kind: "goto",
           block: conditionalBlock.id,
@@ -257,7 +258,7 @@ function lowerStatement(
         fallthrough: continuationBlock.id,
         id: makeInstructionId(0),
       };
-      builder.terminateWithContinuation(terminal, continuationBlock);
+      builder.terminateWithContinuation("block", terminal, continuationBlock);
       return;
     }
     case "ForOfStatement": {
@@ -270,7 +271,7 @@ function lowerStatement(
        * Build the loop body, each iteration loops back to the conditional block
        * to check whether to continue or exit
        */
-      const loopBlock = builder.enter((blockId) => {
+      const loopBlock = builder.enter("block", (blockId) => {
         return builder.loop(
           label,
           conditionalBlock.id,
@@ -288,6 +289,7 @@ function lowerStatement(
       });
       //  End the block leading up to the loop and jump to the conditional block
       builder.terminateWithContinuation(
+        "block",
         {
           kind: "goto",
           block: conditionalBlock.id,
@@ -310,7 +312,7 @@ function lowerStatement(
         fallthrough: continuationBlock.id,
         id: makeInstructionId(0),
       };
-      builder.terminateWithContinuation(terminal, continuationBlock);
+      builder.terminateWithContinuation("block", terminal, continuationBlock);
       return;
     }
     case "ForStatement": {
@@ -320,7 +322,7 @@ function lowerStatement(
       //  Block for code following the loop
       const continuationBlock = builder.reserve();
 
-      const initBlock = builder.enter((blockId) => {
+      const initBlock = builder.enter("value", (blockId) => {
         const init = stmt.get("init") as NodePath<t.VariableDeclaration>;
         todoInvariant(
           t.isVariableDeclaration(init.node),
@@ -335,7 +337,7 @@ function lowerStatement(
         };
       });
 
-      const updateBlock = builder.enter((blockId) => {
+      const updateBlock = builder.enter("value", (blockId) => {
         const update = stmt.get("update");
         todoInvariant(update.hasNode(), "Handle empty for updater");
         if (update.hasNode()) {
@@ -349,7 +351,7 @@ function lowerStatement(
         };
       });
 
-      const bodyBlock = builder.enter((blockId) => {
+      const bodyBlock = builder.enter("block", (blockId) => {
         return builder.loop(label, updateBlock, continuationBlock.id, () => {
           lowerStatement(builder, stmt.get("body"));
           return {
@@ -362,6 +364,7 @@ function lowerStatement(
       });
 
       builder.terminateWithContinuation(
+        "block",
         {
           kind: "for",
           init: initBlock,
@@ -377,6 +380,7 @@ function lowerStatement(
       const test = stmt.get("test");
       todoInvariant(test.hasNode(), "ForStatement without test");
       builder.terminateWithContinuation(
+        "value",
         {
           kind: "if",
           test: lowerExpressionToPlace(builder, test),
@@ -394,7 +398,7 @@ function lowerStatement(
       //  Block for code following the loop
       const continuationBlock = builder.reserve();
       //  Loop body
-      const loopBlock = builder.enter((loopBlock) => {
+      const loopBlock = builder.enter("block", (loopBlock) => {
         return builder.loop(label, loopBlock, continuationBlock.id, () => {
           lowerStatement(builder, stmt.get("body"));
           /**
@@ -415,6 +419,7 @@ function lowerStatement(
       });
       //  do-while unconditionally enters the loop
       builder.terminateWithContinuation(
+        "block",
         {
           kind: "goto",
           block: loopBlock,
@@ -432,7 +437,7 @@ function lowerStatement(
       //  Block for code following the loop
       const continuationBlock = builder.reserve();
       //  Loop body
-      const loopBlock = builder.enter((blockId) => {
+      const loopBlock = builder.enter("block", (blockId) => {
         return builder.loop(
           label,
           conditionalBlock.id,
@@ -455,6 +460,7 @@ function lowerStatement(
       const loc = stmt.node.loc;
       invariant(loc, "while statement must have a location");
       builder.terminateWithContinuation(
+        "block",
         {
           kind: "while",
           loc,
@@ -479,7 +485,7 @@ function lowerStatement(
         id: makeInstructionId(0),
       };
       //  Complete the conditional and continue with code after the loop
-      builder.terminateWithContinuation(terminal, continuationBlock);
+      builder.terminateWithContinuation("value", terminal, continuationBlock);
       return;
     }
     case "LabeledStatement": {
@@ -505,6 +511,7 @@ function lowerStatement(
             lowerStatement(builder, stmt.get("body"));
           });
           builder.terminateWithContinuation(
+            "block",
             {
               kind: "goto",
               block: continuationBlock.id,
@@ -543,7 +550,7 @@ function lowerStatement(
           );
           hasDefault = true;
         }
-        const block = builder.enter((_blockId) => {
+        const block = builder.enter("block", (_blockId) => {
           return builder.switch(label, continuationBlock.id, () => {
             case_
               .get("consequent")
@@ -581,6 +588,7 @@ function lowerStatement(
 
       const test = lowerExpressionToPlace(builder, stmt.get("discriminant"));
       builder.terminateWithContinuation(
+        "block",
         {
           kind: "switch",
           test,
@@ -1192,7 +1200,7 @@ function lowerConditional(
   //  Block for code following the if
   const continuationBlock = builder.reserve();
   //  Block for the consequent (if the test is truthy)
-  const consequentBlock = builder.enter((blockId) => {
+  const consequentBlock = builder.enter("value", (blockId) => {
     let value = consequent();
     builder.push({
       id: makeInstructionId(0),
@@ -1208,7 +1216,7 @@ function lowerConditional(
     };
   });
   //  Block for the alternate (if the test is not truthy)
-  const alternateBlock = builder.enter((blockId) => {
+  const alternateBlock = builder.enter("value", (blockId) => {
     let value = alternate();
     builder.push({
       id: makeInstructionId(0),
@@ -1231,7 +1239,7 @@ function lowerConditional(
     fallthrough: continuationBlock.id,
     id: makeInstructionId(0),
   };
-  builder.terminateWithContinuation(terminal, continuationBlock);
+  builder.terminateWithContinuation("value", terminal, continuationBlock);
   return place;
 }
 
diff --git a/compiler/forget/src/HIR/HIR.ts b/compiler/forget/src/HIR/HIR.ts
index 075669a31e..2fc713b755 100644
--- a/compiler/forget/src/HIR/HIR.ts
+++ b/compiler/forget/src/HIR/HIR.ts
@@ -141,7 +141,9 @@ export type HIR = {
  * an exception occurs, therefore the block model only represents explicit throw
  * statements and not implicit exceptions which may occur.
  */
+export type BlockKind = "block" | "value";
 export type BasicBlock = {
+  kind: BlockKind;
   id: BlockId;
   instructions: Array<Instruction>;
   terminal: Terminal;
@@ -162,6 +164,11 @@ export type Terminal =
   | ForTerminal
   | WhileTerminal;
 
+/**
+ * Terminal nodes allowed for a value block
+ */
+export type ValueTerminal = IfTerminal | GotoTerminal;
+
 export type ThrowTerminal = { kind: "throw"; value: Place; id: InstructionId };
 
 export type ReturnTerminal = {
diff --git a/compiler/forget/src/HIR/HIRBuilder.ts b/compiler/forget/src/HIR/HIRBuilder.ts
index d82bfcca7e..5ed4b9e588 100644
--- a/compiler/forget/src/HIR/HIRBuilder.ts
+++ b/compiler/forget/src/HIR/HIRBuilder.ts
@@ -12,6 +12,7 @@ import { assertExhaustive } from "../Utils/utils";
 import {
   BasicBlock,
   BlockId,
+  BlockKind,
   GeneratedSource,
   GotoVariant,
   HIR,
@@ -146,6 +147,7 @@ export default class HIRBuilder {
   build(): HIR {
     const { id: blockId, instructions } = this.#current;
     this.#completed.set(blockId, {
+      kind: "block",
       id: blockId,
       instructions,
       terminal: {
@@ -177,9 +179,10 @@ export default class HIRBuilder {
   /**
    * Terminate the current block w the given terminal, and start a new block
    */
-  terminate(terminal: Terminal) {
+  terminate(kind: BlockKind, terminal: Terminal) {
     const { id: blockId, instructions } = this.#current;
     this.#completed.set(blockId, {
+      kind,
       id: blockId,
       instructions,
       terminal,
@@ -194,12 +197,17 @@ export default class HIRBuilder {
    * Terminate the current block w the given terminal, and set the previously
    * reserved block as the new current block
    */
-  terminateWithContinuation(terminal: Terminal, continuation: WipBlock) {
+  terminateWithContinuation(
+    kind: BlockKind,
+    terminal: Terminal,
+    continuation: WipBlock
+  ) {
     const { id: blockId, instructions } = this.#current;
     this.#completed.set(blockId, {
+      kind: kind,
       id: blockId,
       instructions,
-      terminal,
+      terminal: terminal,
       preds: new Set(),
       phis: new Set(),
     });
@@ -218,9 +226,10 @@ export default class HIRBuilder {
   /**
    * Save a previously reserved block as completed
    */
-  complete(block: WipBlock, terminal: Terminal) {
+  complete(kind: BlockKind, block: WipBlock, terminal: Terminal) {
     const { id: blockId, instructions } = block;
     this.#completed.set(blockId, {
+      kind,
       id: blockId,
       instructions,
       terminal,
@@ -235,13 +244,14 @@ export default class HIRBuilder {
    * The lambda must return a terminal node, which is used to terminate the
    * newly constructed block.
    */
-  enter(fn: (blockId: BlockId) => Terminal): BlockId {
+  enter(kind: BlockKind, fn: (blockId: BlockId) => Terminal): BlockId {
     const current = this.#current;
     const nextId = makeBlockId(this.#nextId++);
     this.#current = newBlock(nextId);
     const terminal = fn(nextId);
     const { id: blockId, instructions } = this.#current;
     this.#completed.set(blockId, {
+      kind,
       id: blockId,
       instructions,
       terminal,
diff --git a/compiler/forget/src/HIR/MergeConsecutiveBlocks.ts b/compiler/forget/src/HIR/MergeConsecutiveBlocks.ts
index fc84ccc776..5f83abd1ae 100644
--- a/compiler/forget/src/HIR/MergeConsecutiveBlocks.ts
+++ b/compiler/forget/src/HIR/MergeConsecutiveBlocks.ts
@@ -6,7 +6,6 @@
  */
 
 import { invariant } from "../Utils/CompilerError";
-import { assertExhaustive } from "../Utils/utils";
 import {
   BlockId,
   Effect,
@@ -30,40 +29,10 @@ import {
  */
 export function mergeConsecutiveBlocks(fn: HIRFunction): void {
   const merged = new MergedBlocks();
-  const valueBlocks = new Set<BlockId>();
   for (const [, block] of fn.body.blocks) {
-    // Before evaluating the block itself, determine which other blocks
-    // are value blocks. See above TODO which would allow us to bypass this.
-    const terminal = block.terminal;
-    switch (terminal.kind) {
-      case "while": {
-        valueBlocks.add(terminal.test);
-        break;
-      }
-      case "for": {
-        valueBlocks.add(terminal.init);
-        valueBlocks.add(terminal.test);
-        valueBlocks.add(terminal.update);
-        break;
-      }
-      case "if":
-      case "goto":
-      case "return":
-      case "throw":
-      case "switch": {
-        break;
-      }
-      default: {
-        assertExhaustive(
-          terminal,
-          `Unexpected terminal kind '${(terminal as any).kind}'`
-        );
-      }
-    }
-
     // Can only merge blocks with a single predecessor, can't merge
     // value blocks
-    if (block.preds.size !== 1 || valueBlocks.has(block.id)) {
+    if (block.kind === "value" || block.preds.size !== 1) {
       continue;
     }
     const originalPredecessorId = Array.from(block.preds)[0]!;
diff --git a/compiler/forget/src/HIR/PrintHIR.ts b/compiler/forget/src/HIR/PrintHIR.ts
index 43115aa036..88becee2c7 100644
--- a/compiler/forget/src/HIR/PrintHIR.ts
+++ b/compiler/forget/src/HIR/PrintHIR.ts
@@ -47,7 +47,7 @@ export default function printHIR(
     output.push(`${indent}${text}`);
   };
   for (const [blockId, block] of ir.blocks) {
-    output.push(`bb${blockId}:`);
+    output.push(`bb${blockId} (${block.kind}):`);
     if (block.preds.size > 0) {
       const preds = ["predecessor blocks:"];
       for (const pred of block.preds) {
diff --git a/compiler/forget/src/Optimization/ConstantPropagation.ts b/compiler/forget/src/Optimization/ConstantPropagation.ts
index 76316782ec..920421f1ba 100644
--- a/compiler/forget/src/Optimization/ConstantPropagation.ts
+++ b/compiler/forget/src/Optimization/ConstantPropagation.ts
@@ -6,7 +6,6 @@
  */
 
 import {
-  BlockId,
   GotoVariant,
   HIRFunction,
   IdentifierId,
@@ -72,9 +71,6 @@ export function constantPropagation(fn: HIRFunction): void {
 function applyConstantPropagation(fn: HIRFunction): boolean {
   let hasChanges = false;
 
-  // A set of blocks whose terminals can't (yet) be safely rewritten
-  const valueBlocks = new Set<BlockId>();
-
   const constants: Constants = new Map();
   for (const [, block] of fn.body.blocks) {
     // Initialize phi values if all operands have the same known constant value.
@@ -108,7 +104,7 @@ function applyConstantPropagation(fn: HIRFunction): boolean {
       }
     }
 
-    if (valueBlocks.has(block.id)) {
+    if (block.kind === "value") {
       // can't rewrite terminals in value blocks yet
       continue;
     }
@@ -130,16 +126,6 @@ function applyConstantPropagation(fn: HIRFunction): boolean {
         }
         break;
       }
-      case "while": {
-        valueBlocks.add(terminal.test);
-        break;
-      }
-      case "for": {
-        valueBlocks.add(terminal.init);
-        valueBlocks.add(terminal.test);
-        valueBlocks.add(terminal.update);
-        break;
-      }
       default: {
         // no-op
       }
diff --git a/compiler/forget/yarn.lock b/compiler/forget/yarn.lock
index 84bcf2e1ec..13080a3355 100644
--- a/compiler/forget/yarn.lock
+++ b/compiler/forget/yarn.lock
@@ -83,12 +83,12 @@
     "@jridgewell/gen-mapping" "^0.3.2"
     jsesc "^2.5.1"
 
-"@babel/generator@^7.20.5":
-  version "7.20.5"
-  resolved "https://registry.yarnpkg.com/@babel/generator/-/generator-7.20.5.tgz#cb25abee3178adf58d6814b68517c62bdbfdda95"
-  integrity sha512-jl7JY2Ykn9S0yj4DQP82sYvPU+T3g0HFcWTqDLqiuA9tGRNIj9VfbtXGAYTTkyNEnQk1jkMGOdYka8aG/lulCA==
+"@babel/generator@^7.20.7":
+  version "7.20.7"
+  resolved "https://registry.yarnpkg.com/@babel/generator/-/generator-7.20.7.tgz#f8ef57c8242665c5929fe2e8d82ba75460187b4a"
+  integrity sha512-7wqMOJq8doJMZmP4ApXTzLxSr7+oO2jroJURrVEp6XShrQUObV8Tq/D0NCcoYg2uHqUrjzO0zwBjoYzelxK+sw==
   dependencies:
-    "@babel/types" "^7.20.5"
+    "@babel/types" "^7.20.7"
     "@jridgewell/gen-mapping" "^0.3.2"
     jsesc "^2.5.1"
 
@@ -260,10 +260,10 @@
   resolved "https://registry.yarnpkg.com/@babel/parser/-/parser-7.19.3.tgz#8dd36d17c53ff347f9e55c328710321b49479a9a"
   integrity sha512-pJ9xOlNWHiy9+FuFP09DEAFbAn4JskgRsVcc169w2xRBC3FRGuQEwjeIMMND9L2zc0iEhO/tGv4Zq+km+hxNpQ==
 
-"@babel/parser@^7.20.5":
-  version "7.20.5"
-  resolved "https://registry.yarnpkg.com/@babel/parser/-/parser-7.20.5.tgz#7f3c7335fe417665d929f34ae5dceae4c04015e8"
-  integrity sha512-r27t/cy/m9uKLXQNWWebeCUHgnAZq0CpG1OwKRxzJMP1vpSU4bSIK2hq+/cp0bQxetkXx38n09rNu8jVkcK/zA==
+"@babel/parser@^7.20.7":
+  version "7.20.7"
+  resolved "https://registry.yarnpkg.com/@babel/parser/-/parser-7.20.7.tgz#66fe23b3c8569220817d5feb8b9dcdc95bb4f71b"
+  integrity sha512-T3Z9oHybU+0vZlY9CiDSJQTD5ZapcW18ZctFMi0MOAl/4BjFF4ul7NVSARLdbGO5vDqy9eQiGTV0LtKfvCYvcg==
 
 "@babel/plugin-syntax-async-generators@^7.8.4":
   version "7.8.4"
@@ -484,18 +484,18 @@
     lodash "^4.17.10"
 
 "@babel/traverse@^7.19.1":
-  version "7.20.5"
-  resolved "https://registry.yarnpkg.com/@babel/traverse/-/traverse-7.20.5.tgz#78eb244bea8270fdda1ef9af22a5d5e5b7e57133"
-  integrity sha512-WM5ZNN3JITQIq9tFZaw1ojLU3WgWdtkxnhM1AegMS+PvHjkM5IXjmYEGY7yukz5XS4sJyEf2VzWjI8uAavhxBQ==
+  version "7.20.12"
+  resolved "https://registry.yarnpkg.com/@babel/traverse/-/traverse-7.20.12.tgz#7f0f787b3a67ca4475adef1f56cb94f6abd4a4b5"
+  integrity sha512-MsIbFN0u+raeja38qboyF8TIT7K0BFzz/Yd/77ta4MsUsmP2RAnidIlwq7d5HFQrH/OZJecGV6B71C4zAgpoSQ==
   dependencies:
     "@babel/code-frame" "^7.18.6"
-    "@babel/generator" "^7.20.5"
+    "@babel/generator" "^7.20.7"
     "@babel/helper-environment-visitor" "^7.18.9"
     "@babel/helper-function-name" "^7.19.0"
     "@babel/helper-hoist-variables" "^7.18.6"
     "@babel/helper-split-export-declaration" "^7.18.6"
-    "@babel/parser" "^7.20.5"
-    "@babel/types" "^7.20.5"
+    "@babel/parser" "^7.20.7"
+    "@babel/types" "^7.20.7"
     debug "^4.1.0"
     globals "^11.1.0"
 
@@ -534,10 +534,10 @@
     "@babel/helper-validator-identifier" "^7.19.1"
     to-fast-properties "^2.0.0"
 
-"@babel/types@^7.20.5":
-  version "7.20.5"
-  resolved "https://registry.yarnpkg.com/@babel/types/-/types-7.20.5.tgz#e206ae370b5393d94dfd1d04cd687cace53efa84"
-  integrity sha512-c9fst/h2/dcF7H+MJKZ2T0KjEQ8hY/BNnDk/H3XY8C4Aw/eWQXWn/lWntHF9ooUBnGmEvbfGrTgLWc+um0YDUg==
+"@babel/types@^7.20.7":
+  version "7.20.7"
+  resolved "https://registry.yarnpkg.com/@babel/types/-/types-7.20.7.tgz#54ec75e252318423fc07fb644dc6a58a64c09b7f"
+  integrity sha512-69OnhBxSSgK0OzTJai4kyPDiKTIe3j+ctaHdIGVbRahTLAT7L3R9oeXHC2aVSuGYt3cVnoAMDmOCgJ2yaiLMvg==
   dependencies:
     "@babel/helper-string-parser" "^7.19.4"
     "@babel/helper-validator-identifier" "^7.19.1"