fix(hermes-base): harden switch jump-table normalization

src/utils/hermes-base.ts

@@ -650,9 +650,9 @@ export function normalizeDisassemblyLine(
   //   UIntSwitchImm   rX, <jtOffset>, <defaultLabel>, <min>, <max>
   // Folding only the first shape let a shifted UIntSwitchImm offset read as a
   // real difference and drop an otherwise good delta build.
-  m = /^(\s*(?:String|UInt)?SwitchImm r\d+, \d+, )\d+(, .*)$/.exec(line);
+  m = /^(\s*StringSwitchImm r\d+, \d+, )\d+(, L\d+, \d+)$/.exec(line);
   if (m) line = `${m[1]}<jt>${m[2]}`;
-  m = /^(\s*(?:String|UInt)?SwitchImm r\d+, )\d+(, L\d+, .*)$/.exec(line);
+  m = /^(\s*UIntSwitchImm r\d+, )\d+(, L\d+, \d+, \d+)$/.exec(line);
   if (m) line = `${m[1]}<jt>${m[2]}`;
   if (/^\s*offset \d+$/.test(line)) line = line.replace(/\d+$/, '<jt>');
   return line;

tests/hermes-switch-normalization.test.ts

@@ -0,0 +1,48 @@
+import { describe, expect, test } from 'bun:test';
+import { normalizeDisassemblyLine } from '../src/utils/hermes-base';
+
+const normalize = (line: string) =>
+  normalizeDisassemblyLine(line, new Map<number, string>());
+
+describe('Hermes switch jump-table normalization', () => {
+  test('normalizes only the StringSwitchImm jump-table offset', () => {
+    const baseline = normalize('    StringSwitchImm r13, 2, 4024, L146, 150');
+    expect(baseline).toBe('    StringSwitchImm r13, 2, <jt>, L146, 150');
+    expect(normalize('    StringSwitchImm r13, 2, 4025, L146, 150')).toBe(
+      baseline,
+    );
+    expect(normalize('    StringSwitchImm r13, 3, 4024, L146, 150')).not.toBe(
+      baseline,
+    );
+    expect(normalize('    StringSwitchImm r13, 2, 4024, L147, 150')).not.toBe(
+      baseline,
+    );
+    expect(normalize('    StringSwitchImm r13, 2, 4024, L146, 151')).not.toBe(
+      baseline,
+    );
+  });
+
+  test('normalizes only the UIntSwitchImm jump-table offset', () => {
+    const baseline = normalize('    UIntSwitchImm r40, 5937, L3, 0, 31');
+    expect(baseline).toBe('    UIntSwitchImm r40, <jt>, L3, 0, 31');
+    expect(normalize('    UIntSwitchImm r40, 5938, L3, 0, 31')).toBe(baseline);
+    expect(normalize('    UIntSwitchImm r40, 5937, L4, 0, 31')).not.toBe(
+      baseline,
+    );
+    expect(normalize('    UIntSwitchImm r40, 5937, L3, 1, 31')).not.toBe(
+      baseline,
+    );
+    expect(normalize('    UIntSwitchImm r40, 5937, L3, 0, 32')).not.toBe(
+      baseline,
+    );
+  });
+
+  test('does not fold unsupported or malformed switch shapes', () => {
+    expect(normalize('    SwitchImm r1, 2, 3, L4, 5')).toBe(
+      '    SwitchImm r1, 2, 3, L4, 5',
+    );
+    expect(normalize('    UIntSwitchImm r40, 5937, 3, 0, 31')).toBe(
+      '    UIntSwitchImm r40, 5937, 3, 0, 31',
+    );
+  });
+});