Fix #276

Author: GarboMuffin

src/compiler/iroptimizer.js

@@ -550,7 +550,6 @@ class IROptimizer {
         case StackOpcode.CONTROL_WHILE:
         case StackOpcode.CONTROL_FOR:
         case StackOpcode.CONTROL_REPEAT:
-            modified = this.analyzeInputs(inputs, state) || modified;
             modified = this.analyzeLoopedStack(inputs.do, state, stackBlock) || modified;
             break;
         case StackOpcode.CONTROL_IF_ELSE: {
@@ -642,8 +641,8 @@ class IROptimizer {
             return this.analyzeStack(stack, state) || modified;
         }
 
+        let modified = this.analyzeInputs(block.inputs, state);
         let iterations = 0;
-        let modified = false;
         let keepLooping;
         do {
             // If we are stuck in an apparent infinite loop, give up and assume the worst.
@@ -657,11 +656,20 @@ class IROptimizer {
             }
             iterations++;
 
-            const newState = state.clone();
-            modified = this.analyzeStack(stack, newState) || modified;
-            modified = this.analyzeInputs(block.inputs, newState) || modified;
-            modified = (keepLooping = state.or(newState)) || modified;
+            // Used to detect change to overarching state
+            const originalStateClone = state.clone();
+
+            const afterBody = state.clone();
+            modified = this.analyzeStack(stack, afterBody) || modified;
+
+            // Inputs are also evaluated before the loop body ever runs at all. Can't lose that state
+            // or we will make unfounded assumptions.
+            modified = state.or(afterBody) || modified;
+            modified = this.analyzeInputs(block.inputs, state) || modified;
+
+            modified = (keepLooping = originalStateClone.or(state)) || modified;
         } while (keepLooping);
+
         block.entryState = state.clone();
         return modified;
     }

test/fixtures/execute/tw-loop-condition-optimization-gh-276.sb3

@@ -67,10 +67,10 @@ b0.value = (b1.value[(((((+p1 || 0) + (+p0 || 0)) || 0) / 2) | 0) - 1] ?? "");
 b2.value = p0;
 b3.value = p1;
 while (true) {
-while (compareLessThan((b1.value[(b2.value | 0) - 1] ?? ""), b0.value)) {
+while (compareLessThan(listGet(b1.value, b2.value), b0.value)) {
 b2.value = ((+b2.value || 0) + 1);
 }
-while (compareGreaterThan((b1.value[(b3.value | 0) - 1] ?? ""), b0.value)) {
+while (compareGreaterThan(listGet(b1.value, b3.value), b0.value)) {
 b3.value = ((+b3.value || 0) + -1);
 }
 if (compareGreaterThan(b2.value, b3.value)) {

test/snapshot/__snapshots__/tw-gh-249-quicksort.sb3.tw-snapshot

@@ -0,0 +1,28 @@
+// TW Snapshot
+// Input SHA-256: 3c81a01417b9a927457132a5f89b63e54b2499714376246739535b51dbce2d45
+
+// Sprite1 script
+(function factoryXYZ(thread) { const target = thread.target; const runtime = target.runtime; const stage = runtime.getTargetForStage();
+const b0 = runtime.getOpcodeFunction("looks_say");
+const b1 = stage.variables["`jEk@4|i[#Fk?(8x)AV.-my variable"];
+return function* genXYZ () {
+yield* executeInCompatibilityLayer({"MESSAGE":"plan 1",}, b0, false, false, "g", null);
+thread.procedures["Wtest %s"]("random");
+if ((("" + b1.value).toLowerCase() === "random".toLowerCase())) {
+yield* executeInCompatibilityLayer({"MESSAGE":"pass",}, b0, false, false, "p", null);
+}
+yield* executeInCompatibilityLayer({"MESSAGE":"end",}, b0, false, false, "n", null);
+retire(); return;
+}; })
+
+// Sprite1 Wtest %s
+(function factoryXYZ(thread) { const target = thread.target; const runtime = target.runtime; const stage = runtime.getTargetForStage();
+const b0 = stage.variables["`jEk@4|i[#Fk?(8x)AV.-my variable"];
+const b1 = stage.variables["t)]?yi[*8XU73qhMqOa8"];
+return function funXYZ_test_ (p0) {
+b0.value = p0;
+while (!(("" + listGet(b1.value, b0.value)).toLowerCase() === "something".toLowerCase())) {
+b0.value = ((+b0.value || 0) + 1);
+}
+return "";
+}; })

test/snapshot/__snapshots__/tw-loop-condition-optimization-gh-276.sb3.tw-snapshot

@@ -0,0 +1,29 @@
+// TW Snapshot
+// Input SHA-256: 3c81a01417b9a927457132a5f89b63e54b2499714376246739535b51dbce2d45
+
+// Sprite1 script
+(function factoryXYZ(thread) { const target = thread.target; const runtime = target.runtime; const stage = runtime.getTargetForStage();
+const b0 = runtime.getOpcodeFunction("looks_say");
+const b1 = stage.variables["`jEk@4|i[#Fk?(8x)AV.-my variable"];
+return function* genXYZ () {
+yield* executeInCompatibilityLayer({"MESSAGE":"plan 1",}, b0, false, false, "g", null);
+yield* thread.procedures["Wtest %s"]("random");
+if ((("" + b1.value).toLowerCase() === "random".toLowerCase())) {
+yield* executeInCompatibilityLayer({"MESSAGE":"pass",}, b0, false, false, "p", null);
+}
+yield* executeInCompatibilityLayer({"MESSAGE":"end",}, b0, false, false, "n", null);
+retire(); return;
+}; })
+
+// Sprite1 Wtest %s
+(function factoryXYZ(thread) { const target = thread.target; const runtime = target.runtime; const stage = runtime.getTargetForStage();
+const b0 = stage.variables["`jEk@4|i[#Fk?(8x)AV.-my variable"];
+const b1 = stage.variables["t)]?yi[*8XU73qhMqOa8"];
+return function* genXYZ_test_ (p0) {
+b0.value = p0;
+while (!(("" + listGet(b1.value, b0.value)).toLowerCase() === "something".toLowerCase())) {
+b0.value = ((+b0.value || 0) + 1);
+if (isStuck()) yield;
+}
+return "";
+}; })