[hir] Handle simple aliases when inferring mutable lifetimes (#794)

compiler/forget/src/HIR/InferMutableLifetimes.ts

@@ -7,7 +7,8 @@
 
 import invariant from "invariant";
 import { assertExhaustive } from "../Common/utils";
-import { Effect, HIRFunction, Instruction, Place } from "./HIR";
+import DisjointSet from "./DisjointSet";
+import { Effect, HIRFunction, Identifier, Instruction, Place } from "./HIR";
 import { printInstruction, printPlace } from "./PrintHIR";
 import { eachInstructionOperand } from "./visitors";
 
@@ -76,6 +77,8 @@ function inferPlace(place: Place, instr: Instruction) {
 }
 
 export function inferMutableRanges(func: HIRFunction) {
+  const aliases = new DisjointSet<Identifier>();
+
   for (const [_, block] of func.body.blocks) {
     for (const phi of block.phis) {
       let start = Number.MAX_SAFE_INTEGER;
@@ -100,6 +103,20 @@ export function inferMutableRanges(func: HIRFunction) {
       }
 
       if (instr.lvalue !== null) {
+        if (instr.value.kind === "Identifier") {
+          // TODO(gsn): Handle complex aliasing.
+          if (
+            instr.value.memberPath === null &&
+            instr.lvalue.place.memberPath === null
+          ) {
+            // direct aliasing: `a = b`;
+            aliases.union([
+              instr.lvalue.place.identifier,
+              instr.value.identifier,
+            ]);
+          }
+        }
+
         if (instr.lvalue.place.memberPath === null) {
           const lvalueId = instr.lvalue.place.identifier;
 
@@ -116,4 +133,45 @@ export function inferMutableRanges(func: HIRFunction) {
       }
     }
   }
+
+  const aliasIds: Map<Identifier, number> = new Map();
+  // Store the mutable range and set of identifiers for each scope
+  const aliasIndentifiers: Map<
+    number,
+    { end: number; identifiers: Set<Identifier> }
+  > = new Map();
+
+  aliases.forEach((identifier, groupIdentifier) => {
+    let aliasId = aliasIds.get(groupIdentifier);
+    if (aliasId == null) {
+      aliasId = aliasIds.size;
+      aliasIds.set(groupIdentifier, aliasId);
+    }
+
+    let alias = aliasIndentifiers.get(aliasId);
+    if (alias === undefined) {
+      alias = {
+        end: identifier.mutableRange.end,
+        identifiers: new Set(),
+      };
+      aliasIndentifiers.set(aliasId, alias);
+    } else {
+      alias.end = Math.max(alias.end, identifier.mutableRange.end);
+    }
+    alias.identifiers.add(identifier);
+  });
+
+  for (const [_, alias] of aliasIndentifiers) {
+    // Update mutableRange.end only if the identifiers have actually been
+    // mutated.
+    const haveIdentifiersBeenMutated = [...alias.identifiers].some(
+      (id) => id.mutableRange.end > id.mutableRange.start
+    );
+
+    if (haveIdentifiersBeenMutated) {
+      for (const identifier of alias.identifiers) {
+        identifier.mutableRange.end = alias.end;
+      }
+    }
+  }
 }

compiler/forget/src/__tests__/fixtures/hir/alias-while.expect.md

@@ -0,0 +1,148 @@
+
+## Input
+
+```javascript
+function foo(cond) {
+  let a = {};
+  let b = {};
+  let c = {};
+  while (cond) {
+    let z = a;
+    a = b;
+    b = c;
+    c = z;
+    mutate(a, b);
+  }
+  a;
+  b;
+  c;
+  return a;
+}
+
+function mutate(x, y) {}
+
+```
+
+## HIR
+
+```
+bb0:
+  [1] Let mutate a$2_@0[0:8] = Object {  }
+  [2] Let mutate b$3_@0[0:8] = Object {  }
+  [3] Let mutate c$4_@0[0:8] = Object {  }
+  While test=bb1 loop=bb3 fallthrough=bb2
+bb1:
+  predecessor blocks: bb0 bb3
+  If (read cond$1) then:bb3 else:bb2
+bb3:
+  predecessor blocks: bb1
+  [4] Let mutate z$5_@0[0:8] = read a$2_@0
+  [5] Reassign mutate a$2_@0[0:8] = read b$3_@0
+  [6] Reassign mutate b$3_@0[0:8] = read c$4_@0
+  [7] Reassign mutate c$4_@0[0:8] = read z$5_@0
+  [8] Call mutate mutate$6_@0(mutate a$2_@0, mutate b$3_@0)
+  Goto(Continue) bb1
+bb2:
+  predecessor blocks: bb1
+  [9] read a$2_@0
+  [10] read b$3_@0
+  [11] read c$4_@0
+  Return freeze a$2_@0
+```
+
+### CFG
+
+```mermaid
+flowchart TB
+  %% Basic Blocks
+  subgraph bb0
+    bb0_instrs["
+      [1] Let mutate a$2_@0[0:8] = Object {  }
+      [2] Let mutate b$3_@0[0:8] = Object {  }
+      [3] Let mutate c$4_@0[0:8] = Object {  }
+    "]
+    bb0_instrs --> bb0_terminal(["While"])
+  end
+  subgraph bb1
+    bb1_terminal(["If (read cond$1)"])
+  end
+  subgraph bb3
+    bb3_instrs["
+      [4] Let mutate z$5_@0[0:8] = read a$2_@0
+      [5] Reassign mutate a$2_@0[0:8] = read b$3_@0
+      [6] Reassign mutate b$3_@0[0:8] = read c$4_@0
+      [7] Reassign mutate c$4_@0[0:8] = read z$5_@0
+      [8] Call mutate mutate$6_@0(mutate a$2_@0, mutate b$3_@0)
+    "]
+    bb3_instrs --> bb3_terminal(["Goto"])
+  end
+  subgraph bb2
+    bb2_instrs["
+      [9] read a$2_@0
+      [10] read b$3_@0
+      [11] read c$4_@0
+    "]
+    bb2_instrs --> bb2_terminal(["Return freeze a$2_@0"])
+  end
+
+  %% Jumps
+  bb0_terminal -- "test" --> bb1
+  bb0_terminal -- "loop" --> bb3
+  bb0_terminal -- "fallthrough" --> bb2
+  bb1_terminal -- "then" --> bb3
+  bb1_terminal -- "else" --> bb2
+  bb3_terminal --> bb1
+
+```
+
+## Code
+
+```javascript
+function foo$0(cond$1) {
+  let a$2 = {};
+  let b$3 = {};
+  let c$4 = {};
+  bb2: while (cond$1) {
+    let z$5 = a$2;
+    a$2 = b$3;
+    b$3 = c$4;
+    c$4 = z$5;
+    mutate$6(a$2, b$3);
+  }
+
+  a$2;
+  b$3;
+  c$4;
+  return a$2;
+}
+
+```
+## HIR
+
+```
+bb0:
+  Return
+```
+
+### CFG
+
+```mermaid
+flowchart TB
+  %% Basic Blocks
+  subgraph bb0
+    bb0_terminal(["Return"])
+  end
+
+  %% Jumps
+  %% empty
+```
+
+## Code
+
+```javascript
+function mutate$0(x$1, y$2) {
+  return;
+}
+
+```
+      

compiler/forget/src/__tests__/fixtures/hir/alias-while.js

@@ -0,0 +1,18 @@
+function foo(cond) {
+  let a = {};
+  let b = {};
+  let c = {};
+  while (cond) {
+    let z = a;
+    a = b;
+    b = c;
+    c = z;
+    mutate(a, b);
+  }
+  a;
+  b;
+  c;
+  return a;
+}
+
+function mutate(x, y) {}

compiler/forget/src/__tests__/fixtures/hir/mutable-lifetime-loops.expect.md

@@ -101,20 +101,20 @@ function cond$0(x$1) {
 bb0:
   [1] Let mutate a$2_@0[0:14] = Object {  }
   [2] Let mutate b$3_@0[0:14] = Object {  }
-  [3] Let mutate c$4_@1[0:9] = Object {  }
+  [3] Let mutate c$4_@0[0:14] = Object {  }
   [4] Let mutate d$5_@0[0:14] = Object {  }
   While test=bb1 loop=bb3 fallthrough=bb2
 bb1:
   predecessor blocks: bb0 bb4
-  [5] Const mutate $10_@2 = true
-  If (read $10_@2) then:bb3 else:bb2
+  [5] Const mutate $10_@1 = true
+  If (read $10_@1) then:bb3 else:bb2
 bb3:
   predecessor blocks: bb1
-  [6] Let mutate z$6_@3 = read a$2_@0
+  [6] Let mutate z$6_@0[0:14] = read a$2_@0
   [7] Reassign mutate a$2_@0[0:14] = read b$3_@0
-  [8] Reassign mutate b$3_@0[0:14] = read c$4_@1
-  [9] Reassign mutate c$4_@1[0:9] = read d$5_@0
-  [10] Reassign mutate d$5_@0[0:14] = read z$6_@3
+  [8] Reassign mutate b$3_@0[0:14] = read c$4_@0
+  [9] Reassign mutate c$4_@0[0:14] = read d$5_@0
+  [10] Reassign mutate d$5_@0[0:14] = read z$6_@0
   [11] Call mutate mutate$7_@0(mutate a$2_@0, mutate b$3_@0)
   [12] Const mutate $9_@0[0:14] = Call mutate cond$8_@0(mutate a$2_@0)
   If (read $9_@0) then:bb2 else:bb4
@@ -129,14 +129,14 @@ bb7:
   If (read b$3_@0) then:bb9 else:bb9
 bb9:
   predecessor blocks: bb7
-  If (read c$4_@1) then:bb11 else:bb11
+  If (read c$4_@0) then:bb11 else:bb11
 bb11:
   predecessor blocks: bb9
   If (read d$5_@0) then:bb13 else:bb13
 bb13:
   predecessor blocks: bb11
-  [13] Const mutate $11_@4 = null
-  [14] Call mutate mutate$7_@0(mutate d$5_@0, read $11_@4)
+  [13] Const mutate $11_@2 = null
+  [14] Call mutate mutate$7_@0(mutate d$5_@0, read $11_@2)
   Return
 ```
 
@@ -149,24 +149,24 @@ flowchart TB
     bb0_instrs["
       [1] Let mutate a$2_@0[0:14] = Object {  }
       [2] Let mutate b$3_@0[0:14] = Object {  }
-      [3] Let mutate c$4_@1[0:9] = Object {  }
+      [3] Let mutate c$4_@0[0:14] = Object {  }
       [4] Let mutate d$5_@0[0:14] = Object {  }
     "]
     bb0_instrs --> bb0_terminal(["While"])
   end
   subgraph bb1
     bb1_instrs["
-      [5] Const mutate $10_@2 = true
+      [5] Const mutate $10_@1 = true
     "]
-    bb1_instrs --> bb1_terminal(["If (read $10_@2)"])
+    bb1_instrs --> bb1_terminal(["If (read $10_@1)"])
   end
   subgraph bb3
     bb3_instrs["
-      [6] Let mutate z$6_@3 = read a$2_@0
+      [6] Let mutate z$6_@0[0:14] = read a$2_@0
       [7] Reassign mutate a$2_@0[0:14] = read b$3_@0
-      [8] Reassign mutate b$3_@0[0:14] = read c$4_@1
-      [9] Reassign mutate c$4_@1[0:9] = read d$5_@0
-      [10] Reassign mutate d$5_@0[0:14] = read z$6_@3
+      [8] Reassign mutate b$3_@0[0:14] = read c$4_@0
+      [9] Reassign mutate c$4_@0[0:14] = read d$5_@0
+      [10] Reassign mutate d$5_@0[0:14] = read z$6_@0
       [11] Call mutate mutate$7_@0(mutate a$2_@0, mutate b$3_@0)
       [12] Const mutate $9_@0[0:14] = Call mutate cond$8_@0(mutate a$2_@0)
     "]
@@ -182,15 +182,15 @@ flowchart TB
     bb7_terminal(["If (read b$3_@0)"])
   end
   subgraph bb9
-    bb9_terminal(["If (read c$4_@1)"])
+    bb9_terminal(["If (read c$4_@0)"])
   end
   subgraph bb11
     bb11_terminal(["If (read d$5_@0)"])
   end
   subgraph bb13
     bb13_instrs["
-      [13] Const mutate $11_@4 = null
-      [14] Call mutate mutate$7_@0(mutate d$5_@0, read $11_@4)
+      [13] Const mutate $11_@2 = null
+      [14] Call mutate mutate$7_@0(mutate d$5_@0, read $11_@2)
     "]
     bb13_instrs --> bb13_terminal(["Return"])
   end

compiler/forget/src/__tests__/fixtures/hir/reassignment-conditional.expect.md

@@ -25,7 +25,7 @@ function Component(props) {
 bb0:
   [1] Let mutate x$2_@0[1:4] = Array []
   [2] Call mutate x$2_@0.push(read props$1.p0)
-  [3] Let mutate y$3_@1 = read x$2_@0
+  [3] Let mutate y$3_@0[1:4] = read x$2_@0
   If (read props$1.p1) then:bb2 else:bb1
 bb2:
   predecessor blocks: bb0
@@ -33,10 +33,10 @@ bb2:
   Goto bb1
 bb1:
   predecessor blocks: bb2 bb0
-  [5] Let mutate _$4_@2 = JSX <read Component$0 x={freeze x$2_@0} ></read Component$0>
-  [6] Call read y$3_@1.push(read props$1.p2)
-  [7] Const mutate $5_@3 = JSX <read Component$0 x={read x$2_@0} y={read y$3_@1} ></read Component$0>
-  Return read $5_@3
+  [5] Let mutate _$4_@1 = JSX <read Component$0 x={freeze x$2_@0} ></read Component$0>
+  [6] Call read y$3_@0.push(read props$1.p2)
+  [7] Const mutate $5_@2 = JSX <read Component$0 x={read x$2_@0} y={read y$3_@0} ></read Component$0>
+  Return read $5_@2
 ```
 
 ### CFG
@@ -48,7 +48,7 @@ flowchart TB
     bb0_instrs["
       [1] Let mutate x$2_@0[1:4] = Array []
       [2] Call mutate x$2_@0.push(read props$1.p0)
-      [3] Let mutate y$3_@1 = read x$2_@0
+      [3] Let mutate y$3_@0[1:4] = read x$2_@0
     "]
     bb0_instrs --> bb0_terminal(["If (read props$1.p1)"])
   end
@@ -60,11 +60,11 @@ flowchart TB
   end
   subgraph bb1
     bb1_instrs["
-      [5] Let mutate _$4_@2 = JSX <read Component$0 x={freeze x$2_@0} ></read Component$0>
-      [6] Call read y$3_@1.push(read props$1.p2)
-      [7] Const mutate $5_@3 = JSX <read Component$0 x={read x$2_@0} y={read y$3_@1} ></read Component$0>
+      [5] Let mutate _$4_@1 = JSX <read Component$0 x={freeze x$2_@0} ></read Component$0>
+      [6] Call read y$3_@0.push(read props$1.p2)
+      [7] Const mutate $5_@2 = JSX <read Component$0 x={read x$2_@0} y={read y$3_@0} ></read Component$0>
     "]
-    bb1_instrs --> bb1_terminal(["Return read $5_@3"])
+    bb1_instrs --> bb1_terminal(["Return read $5_@2"])
   end
 
   %% Jumps

compiler/forget/src/__tests__/fixtures/hir/reassignment.expect.md

@@ -21,14 +21,14 @@ function Component(props) {
 
 ```
 bb0:
-  [1] Let mutate x$2_@0[1:2] = Array []
+  [1] Let mutate x$2_@0[1:6] = Array []
   [2] Call mutate x$2_@0.push(read props$1.p0)
-  [3] Let mutate y$3_@1[3:6] = read x$2_@0
-  [4] Reassign mutate x$2_@2 = Array []
-  [5] Let mutate _$4_@3 = JSX <read Component$0 x={freeze x$2_@2} ></read Component$0>
-  [6] Call mutate y$3_@1.push(read props$1.p1)
-  [7] Const mutate $5_@4 = JSX <read Component$0 x={read x$2_@2} y={freeze y$3_@1} ></read Component$0>
-  Return read $5_@4
+  [3] Let mutate y$3_@0[1:6] = read x$2_@0
+  [4] Reassign mutate x$2_@1 = Array []
+  [5] Let mutate _$4_@2 = JSX <read Component$0 x={freeze x$2_@1} ></read Component$0>
+  [6] Call mutate y$3_@0.push(read props$1.p1)
+  [7] Const mutate $5_@3 = JSX <read Component$0 x={read x$2_@1} y={freeze y$3_@0} ></read Component$0>
+  Return read $5_@3
 ```
 
 ### CFG
@@ -38,15 +38,15 @@ flowchart TB
   %% Basic Blocks
   subgraph bb0
     bb0_instrs["
-      [1] Let mutate x$2_@0[1:2] = Array []
+      [1] Let mutate x$2_@0[1:6] = Array []
       [2] Call mutate x$2_@0.push(read props$1.p0)
-      [3] Let mutate y$3_@1[3:6] = read x$2_@0
-      [4] Reassign mutate x$2_@2 = Array []
-      [5] Let mutate _$4_@3 = JSX <read Component$0 x={freeze x$2_@2} ></read Component$0>
-      [6] Call mutate y$3_@1.push(read props$1.p1)
-      [7] Const mutate $5_@4 = JSX <read Component$0 x={read x$2_@2} y={freeze y$3_@1} ></read Component$0>
+      [3] Let mutate y$3_@0[1:6] = read x$2_@0
+      [4] Reassign mutate x$2_@1 = Array []
+      [5] Let mutate _$4_@2 = JSX <read Component$0 x={freeze x$2_@1} ></read Component$0>
+      [6] Call mutate y$3_@0.push(read props$1.p1)
+      [7] Const mutate $5_@3 = JSX <read Component$0 x={read x$2_@1} y={freeze y$3_@0} ></read Component$0>
     "]
-    bb0_instrs --> bb0_terminal(["Return read $5_@4"])
+    bb0_instrs --> bb0_terminal(["Return read $5_@3"])
   end
 
   %% Jumps

compiler/forget/src/__tests__/fixtures/hir/simple-alias.expect.md

@@ -0,0 +1,98 @@
+
+## Input
+
+```javascript
+function mutate() {}
+function foo() {
+  let a = {};
+  let b = {};
+  let c = {};
+  a = b;
+  b = c;
+  c = a;
+  mutate(a, b);
+  return c;
+}
+
+```
+
+## HIR
+
+```
+bb0:
+  Return
+```
+
+### CFG
+
+```mermaid
+flowchart TB
+  %% Basic Blocks
+  subgraph bb0
+    bb0_terminal(["Return"])
+  end
+
+  %% Jumps
+  %% empty
+```
+
+## Code
+
+```javascript
+function mutate$0() {
+  return;
+}
+
+```
+## HIR
+
+```
+bb0:
+  [1] Let mutate a$1_@0 = Object {  }
+  [2] Let mutate b$2_@1[0:7] = Object {  }
+  [3] Let mutate c$3_@1[0:7] = Object {  }
+  [4] Reassign mutate a$1_@1[0:7] = read b$2_@1
+  [5] Reassign mutate b$2_@1[0:7] = read c$3_@1
+  [6] Reassign mutate c$3_@1[0:7] = read a$1_@1
+  [7] Call mutate mutate$4_@1(mutate a$1_@1, mutate b$2_@1)
+  Return freeze c$3_@1
+```
+
+### CFG
+
+```mermaid
+flowchart TB
+  %% Basic Blocks
+  subgraph bb0
+    bb0_instrs["
+      [1] Let mutate a$1_@0 = Object {  }
+      [2] Let mutate b$2_@1[0:7] = Object {  }
+      [3] Let mutate c$3_@1[0:7] = Object {  }
+      [4] Reassign mutate a$1_@1[0:7] = read b$2_@1
+      [5] Reassign mutate b$2_@1[0:7] = read c$3_@1
+      [6] Reassign mutate c$3_@1[0:7] = read a$1_@1
+      [7] Call mutate mutate$4_@1(mutate a$1_@1, mutate b$2_@1)
+    "]
+    bb0_instrs --> bb0_terminal(["Return freeze c$3_@1"])
+  end
+
+  %% Jumps
+  %% empty
+```
+
+## Code
+
+```javascript
+function foo$0() {
+  let a$1 = {};
+  let b$2 = {};
+  let c$3 = {};
+  a$1 = b$2;
+  b$2 = c$3;
+  c$3 = a$1;
+  mutate$4(a$1, b$2);
+  return c$3;
+}
+
+```
+      

compiler/forget/src/__tests__/fixtures/hir/simple-alias.js

@@ -0,0 +1,11 @@
+function mutate() {}
+function foo() {
+  let a = {};
+  let b = {};
+  let c = {};
+  a = b;
+  b = c;
+  c = a;
+  mutate(a, b);
+  return c;
+}

compiler/forget/src/__tests__/fixtures/hir/ssa-complex-multiple-if.expect.md

@@ -21,14 +21,14 @@ function foo() {
 
 ```
 bb0:
-  [1] Let mutate x$1_@0[1:8] = 1
+  [1] Let mutate x$1_@0[1:9] = 1
   [2] Let mutate y$2_@1 = 2
   [3] Const mutate $3_@2 = 2
   [4] Const mutate $4_@3 = Binary read y$2_@1 === read $3_@2
   If (read $4_@3) then:bb2 else:bb1
 bb2:
   predecessor blocks: bb0
-  [5] Reassign mutate x$1_@0[1:8] = 3
+  [5] Reassign mutate x$1_@0[1:9] = 3
   Goto bb1
 bb1:
   predecessor blocks: bb2 bb0
@@ -37,11 +37,11 @@ bb1:
   If (read $6_@5) then:bb4 else:bb3
 bb4:
   predecessor blocks: bb1
-  [8] Reassign mutate x$1_@0[1:8] = 5
+  [8] Reassign mutate x$1_@0[1:9] = 5
   Goto bb3
 bb3:
   predecessor blocks: bb4 bb1
-  [9] Reassign mutate y$2_@6 = read x$1_@0
+  [9] Reassign mutate y$2_@0[1:9] = read x$1_@0
   Return
 ```
 
@@ -52,7 +52,7 @@ flowchart TB
   %% Basic Blocks
   subgraph bb0
     bb0_instrs["
-      [1] Let mutate x$1_@0[1:8] = 1
+      [1] Let mutate x$1_@0[1:9] = 1
       [2] Let mutate y$2_@1 = 2
       [3] Const mutate $3_@2 = 2
       [4] Const mutate $4_@3 = Binary read y$2_@1 === read $3_@2
@@ -61,7 +61,7 @@ flowchart TB
   end
   subgraph bb2
     bb2_instrs["
-      [5] Reassign mutate x$1_@0[1:8] = 3
+      [5] Reassign mutate x$1_@0[1:9] = 3
     "]
     bb2_instrs --> bb2_terminal(["Goto"])
   end
@@ -74,13 +74,13 @@ flowchart TB
   end
   subgraph bb4
     bb4_instrs["
-      [8] Reassign mutate x$1_@0[1:8] = 5
+      [8] Reassign mutate x$1_@0[1:9] = 5
     "]
     bb4_instrs --> bb4_terminal(["Goto"])
   end
   subgraph bb3
     bb3_instrs["
-      [9] Reassign mutate y$2_@6 = read x$1_@0
+      [9] Reassign mutate y$2_@0[1:9] = read x$1_@0
     "]
     bb3_instrs --> bb3_terminal(["Return"])
   end

compiler/forget/src/__tests__/fixtures/hir/ssa-complex-single-if.expect.md

@@ -18,18 +18,18 @@ function foo() {
 
 ```
 bb0:
-  [1] Let mutate x$1_@0[1:5] = 1
+  [1] Let mutate x$1_@0[1:6] = 1
   [2] Let mutate y$2_@1 = 2
   [3] Const mutate $3_@2 = 2
   [4] Const mutate $4_@3 = Binary read y$2_@1 === read $3_@2
   If (read $4_@3) then:bb2 else:bb1
 bb2:
   predecessor blocks: bb0
-  [5] Reassign mutate x$1_@0[1:5] = 3
+  [5] Reassign mutate x$1_@0[1:6] = 3
   Goto bb1
 bb1:
   predecessor blocks: bb2 bb0
-  [6] Reassign mutate y$2_@4 = read x$1_@0
+  [6] Reassign mutate y$2_@0[1:6] = read x$1_@0
   Return
 ```
 
@@ -40,7 +40,7 @@ flowchart TB
   %% Basic Blocks
   subgraph bb0
     bb0_instrs["
-      [1] Let mutate x$1_@0[1:5] = 1
+      [1] Let mutate x$1_@0[1:6] = 1
       [2] Let mutate y$2_@1 = 2
       [3] Const mutate $3_@2 = 2
       [4] Const mutate $4_@3 = Binary read y$2_@1 === read $3_@2
@@ -49,13 +49,13 @@ flowchart TB
   end
   subgraph bb2
     bb2_instrs["
-      [5] Reassign mutate x$1_@0[1:5] = 3
+      [5] Reassign mutate x$1_@0[1:6] = 3
     "]
     bb2_instrs --> bb2_terminal(["Goto"])
   end
   subgraph bb1
     bb1_instrs["
-      [6] Reassign mutate y$2_@4 = read x$1_@0
+      [6] Reassign mutate y$2_@0[1:6] = read x$1_@0
     "]
     bb1_instrs --> bb1_terminal(["Return"])
   end

compiler/forget/src/__tests__/fixtures/hir/ssa-simple-phi.expect.md

@@ -26,15 +26,15 @@ bb0:
   If (read $3_@2) then:bb2 else:bb3
 bb2:
   predecessor blocks: bb0
-  [4] Reassign mutate y$1_@3[4:5] = 1
+  [4] Reassign mutate y$1_@3[4:6] = 1
   Goto bb1
 bb3:
   predecessor blocks: bb0
-  [5] Reassign mutate y$1_@3[4:5] = 2
+  [5] Reassign mutate y$1_@3[4:6] = 2
   Goto bb1
 bb1:
   predecessor blocks: bb2 bb3
-  [6] Let mutate x$4_@4 = read y$1_@3
+  [6] Let mutate x$4_@3[4:6] = read y$1_@3
   Return
 ```
 
@@ -53,19 +53,19 @@ flowchart TB
   end
   subgraph bb2
     bb2_instrs["
-      [4] Reassign mutate y$1_@3[4:5] = 1
+      [4] Reassign mutate y$1_@3[4:6] = 1
     "]
     bb2_instrs --> bb2_terminal(["Goto"])
   end
   subgraph bb3
     bb3_instrs["
-      [5] Reassign mutate y$1_@3[4:5] = 2
+      [5] Reassign mutate y$1_@3[4:6] = 2
     "]
     bb3_instrs --> bb3_terminal(["Goto"])
   end
   subgraph bb1
     bb1_instrs["
-      [6] Let mutate x$4_@4 = read y$1_@3
+      [6] Let mutate x$4_@3[4:6] = read y$1_@3
     "]
     bb1_instrs --> bb1_terminal(["Return"])
   end

compiler/forget/src/__tests__/fixtures/hir/ssa-switch.expect.md

@@ -40,21 +40,21 @@ bb0:
 bb5:
   predecessor blocks: bb0
   [6] Const mutate $6_@5 = 1
-  [7] Reassign mutate x$1_@6[7:11] = Binary read x$1_@0 + read $6_@5
+  [7] Reassign mutate x$1_@6[7:12] = Binary read x$1_@0 + read $6_@5
   Goto bb1
 bb3:
   predecessor blocks: bb0
   [8] Const mutate $3_@7 = 2
-  [9] Reassign mutate x$1_@6[7:11] = Binary read x$1_@0 + read $3_@7
+  [9] Reassign mutate x$1_@6[7:12] = Binary read x$1_@0 + read $3_@7
   Goto bb1
 bb2:
   predecessor blocks: bb0
   [10] Const mutate $2_@8 = 3
-  [11] Reassign mutate x$1_@6[7:11] = Binary read x$1_@0 + read $2_@8
+  [11] Reassign mutate x$1_@6[7:12] = Binary read x$1_@0 + read $2_@8
   Goto bb1
 bb1:
   predecessor blocks: bb5 bb3 bb2
-  [12] Let mutate y$9_@9 = read x$1_@6
+  [12] Let mutate y$9_@6[7:12] = read x$1_@6
   Return
 ```
 
@@ -76,27 +76,27 @@ flowchart TB
   subgraph bb5
     bb5_instrs["
       [6] Const mutate $6_@5 = 1
-      [7] Reassign mutate x$1_@6[7:11] = Binary read x$1_@0 + read $6_@5
+      [7] Reassign mutate x$1_@6[7:12] = Binary read x$1_@0 + read $6_@5
     "]
     bb5_instrs --> bb5_terminal(["Goto"])
   end
   subgraph bb3
     bb3_instrs["
       [8] Const mutate $3_@7 = 2
-      [9] Reassign mutate x$1_@6[7:11] = Binary read x$1_@0 + read $3_@7
+      [9] Reassign mutate x$1_@6[7:12] = Binary read x$1_@0 + read $3_@7
     "]
     bb3_instrs --> bb3_terminal(["Goto"])
   end
   subgraph bb2
     bb2_instrs["
       [10] Const mutate $2_@8 = 3
-      [11] Reassign mutate x$1_@6[7:11] = Binary read x$1_@0 + read $2_@8
+      [11] Reassign mutate x$1_@6[7:12] = Binary read x$1_@0 + read $2_@8
     "]
     bb2_instrs --> bb2_terminal(["Goto"])
   end
   subgraph bb1
     bb1_instrs["
-      [12] Let mutate y$9_@9 = read x$1_@6
+      [12] Let mutate y$9_@6[7:12] = read x$1_@6
     "]
     bb1_instrs --> bb1_terminal(["Return"])
   end

compiler/forget/src/__tests__/fixtures/hir/switch-non-final-default.expect.md

@@ -32,31 +32,31 @@ function Component(props) {
 
 ```
 bb0:
-  [1] Let mutate x$2_@0[1:6] = Array []
-  [2] Let mutate y$3_@1[2:8] = undefined
-  [3] Const mutate $4_@2 = false
-  [4] Const mutate $5_@3 = true
-  [5] Const mutate $6_@4 = 1
+  [1] Let mutate x$2_@0[1:8] = Array []
+  [2] Let mutate y$3_@0[1:8] = undefined
+  [3] Const mutate $4_@1 = false
+  [4] Const mutate $5_@2 = true
+  [5] Const mutate $6_@3 = 1
   Switch (read props$1.p0)
-    Case read $6_@4: bb1
-    Case read $5_@3: bb6
+    Case read $6_@3: bb1
+    Case read $5_@2: bb6
     Default: bb1
-    Case read $4_@2: bb2
+    Case read $4_@1: bb2
 bb6:
   predecessor blocks: bb0
   [6] Call mutate x$2_@0.push(read props$1.p2)
-  [7] Reassign mutate y$3_@1[2:8] = Array []
+  [7] Reassign mutate y$3_@0[1:8] = Array []
   Goto bb1
 bb2:
   predecessor blocks: bb0
-  [8] Reassign mutate y$3_@1[2:8] = read x$2_@0
+  [8] Reassign mutate y$3_@0[1:8] = read x$2_@0
   Goto bb1
 bb1:
   predecessor blocks: bb0 bb6 bb2
-  [9] Const mutate child$7_@5 = JSX <read Component$0 data={freeze x$2_@0} ></read Component$0>
-  [10] Call read y$3_@1.push(read props$1.p4)
-  [11] Const mutate $8_@6 = JSX <read Component$0 data={freeze y$3_@1} >{read child$7_@5}</read Component$0>
-  Return read $8_@6
+  [9] Const mutate child$7_@4 = JSX <read Component$0 data={freeze x$2_@0} ></read Component$0>
+  [10] Call read y$3_@0.push(read props$1.p4)
+  [11] Const mutate $8_@5 = JSX <read Component$0 data={freeze y$3_@0} >{read child$7_@4}</read Component$0>
+  Return read $8_@5
 ```
 
 ### CFG
@@ -66,41 +66,41 @@ flowchart TB
   %% Basic Blocks
   subgraph bb0
     bb0_instrs["
-      [1] Let mutate x$2_@0[1:6] = Array []
-      [2] Let mutate y$3_@1[2:8] = undefined
-      [3] Const mutate $4_@2 = false
-      [4] Const mutate $5_@3 = true
-      [5] Const mutate $6_@4 = 1
+      [1] Let mutate x$2_@0[1:8] = Array []
+      [2] Let mutate y$3_@0[1:8] = undefined
+      [3] Const mutate $4_@1 = false
+      [4] Const mutate $5_@2 = true
+      [5] Const mutate $6_@3 = 1
     "]
     bb0_instrs --> bb0_terminal(["Switch (read props$1.p0)"])
   end
   subgraph bb6
     bb6_instrs["
       [6] Call mutate x$2_@0.push(read props$1.p2)
-      [7] Reassign mutate y$3_@1[2:8] = Array []
+      [7] Reassign mutate y$3_@0[1:8] = Array []
     "]
     bb6_instrs --> bb6_terminal(["Goto"])
   end
   subgraph bb2
     bb2_instrs["
-      [8] Reassign mutate y$3_@1[2:8] = read x$2_@0
+      [8] Reassign mutate y$3_@0[1:8] = read x$2_@0
     "]
     bb2_instrs --> bb2_terminal(["Goto"])
   end
   subgraph bb1
     bb1_instrs["
-      [9] Const mutate child$7_@5 = JSX <read Component$0 data={freeze x$2_@0} ></read Component$0>
-      [10] Call read y$3_@1.push(read props$1.p4)
-      [11] Const mutate $8_@6 = JSX <read Component$0 data={freeze y$3_@1} >{read child$7_@5}</read Component$0>
+      [9] Const mutate child$7_@4 = JSX <read Component$0 data={freeze x$2_@0} ></read Component$0>
+      [10] Call read y$3_@0.push(read props$1.p4)
+      [11] Const mutate $8_@5 = JSX <read Component$0 data={freeze y$3_@0} >{read child$7_@4}</read Component$0>
     "]
-    bb1_instrs --> bb1_terminal(["Return read $8_@6"])
+    bb1_instrs --> bb1_terminal(["Return read $8_@5"])
   end
 
   %% Jumps
-  bb0_terminal -- "read $6_@4" --> bb1
-  bb0_terminal -- "read $5_@3" --> bb6
+  bb0_terminal -- "read $6_@3" --> bb1
+  bb0_terminal -- "read $5_@2" --> bb6
   bb0_terminal -- "default" --> bb1
-  bb0_terminal -- "read $4_@2" --> bb2
+  bb0_terminal -- "read $4_@1" --> bb2
   bb0_terminal -- "fallthrough" --> bb1
   bb6_terminal --> bb1
   bb2_terminal --> bb1

compiler/forget/src/__tests__/fixtures/hir/switch.expect.md

@@ -28,30 +28,30 @@ function Component(props) {
 
 ```
 bb0:
-  [1] Let mutate x$2_@0[1:6] = Array []
-  [2] Let mutate y$3_@1[2:8] = undefined
-  [3] Const mutate $4_@2 = false
-  [4] Const mutate $5_@3 = true
+  [1] Let mutate x$2_@0[1:8] = Array []
+  [2] Let mutate y$3_@0[1:8] = undefined
+  [3] Const mutate $4_@1 = false
+  [4] Const mutate $5_@2 = true
   Switch (read props$1.p0)
-    Case read $5_@3: bb4
-    Case read $4_@2: bb2
+    Case read $5_@2: bb4
+    Case read $4_@1: bb2
     Default: bb1
 bb4:
   predecessor blocks: bb0
   [5] Call mutate x$2_@0.push(read props$1.p2)
   [6] Call mutate x$2_@0.push(read props$1.p3)
-  [7] Reassign mutate y$3_@4 = Array []
+  [7] Reassign mutate y$3_@3 = Array []
   Goto bb2
 bb2:
   predecessor blocks: bb4 bb0
-  [8] Reassign mutate y$3_@1[2:8] = read x$2_@0
+  [8] Reassign mutate y$3_@0[1:8] = read x$2_@0
   Goto bb1
 bb1:
   predecessor blocks: bb2 bb0
-  [9] Const mutate child$6_@5 = JSX <read Component$0 data={freeze x$2_@0} ></read Component$0>
-  [10] Call read y$3_@1.push(read props$1.p4)
-  [11] Const mutate $7_@6 = JSX <read Component$0 data={read y$3_@1} >{read child$6_@5}</read Component$0>
-  Return read $7_@6
+  [9] Const mutate child$6_@4 = JSX <read Component$0 data={freeze x$2_@0} ></read Component$0>
+  [10] Call read y$3_@0.push(read props$1.p4)
+  [11] Const mutate $7_@5 = JSX <read Component$0 data={read y$3_@0} >{read child$6_@4}</read Component$0>
+  Return read $7_@5
 ```
 
 ### CFG
@@ -61,10 +61,10 @@ flowchart TB
   %% Basic Blocks
   subgraph bb0
     bb0_instrs["
-      [1] Let mutate x$2_@0[1:6] = Array []
-      [2] Let mutate y$3_@1[2:8] = undefined
-      [3] Const mutate $4_@2 = false
-      [4] Const mutate $5_@3 = true
+      [1] Let mutate x$2_@0[1:8] = Array []
+      [2] Let mutate y$3_@0[1:8] = undefined
+      [3] Const mutate $4_@1 = false
+      [4] Const mutate $5_@2 = true
     "]
     bb0_instrs --> bb0_terminal(["Switch (read props$1.p0)"])
   end
@@ -72,28 +72,28 @@ flowchart TB
     bb4_instrs["
       [5] Call mutate x$2_@0.push(read props$1.p2)
       [6] Call mutate x$2_@0.push(read props$1.p3)
-      [7] Reassign mutate y$3_@4 = Array []
+      [7] Reassign mutate y$3_@3 = Array []
     "]
     bb4_instrs --> bb4_terminal(["Goto"])
   end
   subgraph bb2
     bb2_instrs["
-      [8] Reassign mutate y$3_@1[2:8] = read x$2_@0
+      [8] Reassign mutate y$3_@0[1:8] = read x$2_@0
     "]
     bb2_instrs --> bb2_terminal(["Goto"])
   end
   subgraph bb1
     bb1_instrs["
-      [9] Const mutate child$6_@5 = JSX <read Component$0 data={freeze x$2_@0} ></read Component$0>
-      [10] Call read y$3_@1.push(read props$1.p4)
-      [11] Const mutate $7_@6 = JSX <read Component$0 data={read y$3_@1} >{read child$6_@5}</read Component$0>
+      [9] Const mutate child$6_@4 = JSX <read Component$0 data={freeze x$2_@0} ></read Component$0>
+      [10] Call read y$3_@0.push(read props$1.p4)
+      [11] Const mutate $7_@5 = JSX <read Component$0 data={read y$3_@0} >{read child$6_@4}</read Component$0>
     "]
-    bb1_instrs --> bb1_terminal(["Return read $7_@6"])
+    bb1_instrs --> bb1_terminal(["Return read $7_@5"])
   end
 
   %% Jumps
-  bb0_terminal -- "read $5_@3" --> bb4
-  bb0_terminal -- "read $4_@2" --> bb2
+  bb0_terminal -- "read $5_@2" --> bb4
+  bb0_terminal -- "read $4_@1" --> bb2
   bb0_terminal -- "default" --> bb1
   bb0_terminal -- "fallthrough" --> bb1
   bb4_terminal --> bb2