Verifier: always verify in debug builds

Let's prevent the verifier from bitrotting.

hphp/runtime/vm/unit.cpp

@@ -2665,18 +2665,23 @@ Unit* UnitEmitter::create() {
     Trace::traceRelease("%s", u->toString().c_str());
   }
 
-  static const bool kVerify        = getenv("HHVM_VERIFY");
-  static const bool kVerifyVerbose = getenv("HHVM_VERIFY_VERBOSE");
+  static const bool kVerify = debug || getenv("HHVM_VERIFY");
+  static const bool kVerifyVerboseSystem =
+    getenv("HHVM_VERIFY_VERBOSE_SYSTEM");
+  static const bool kVerifyVerbose =
+    kVerifyVerboseSystem || getenv("HHVM_VERIFY_VERBOSE");
 
+  const bool isSystemLib = u->filepath()->empty() ||
+    boost::ends_with(u->filepath()->data(), "systemlib.php");
   const bool doVerify =
-    kVerify ||
-    boost::ends_with(u->filepath()->data(), "hhas") ||
-    (debug && (u->filepath()->empty() ||
-               boost::ends_with(u->filepath()->data(), "systemlib.php")));
-
+    kVerify || boost::ends_with(u->filepath()->data(), "hhas");
   if (doVerify) {
-    Verifier::checkUnit(u, kVerifyVerbose);
+    Verifier::checkUnit(
+      u,
+      isSystemLib ? kVerifyVerboseSystem : kVerifyVerbose
+    );
   }
+
   return u;
 }
 

hphp/runtime/vm/verifier/cfg.cpp

@@ -234,6 +234,10 @@ Block** GraphBuilder::exns(Block* b) {
 Block* GraphBuilder::createBlock(PC pc) {
   BlockMap::iterator i = m_blocks.find(pc);
   if (i != m_blocks.end()) return i->second;
+
+  // TODO(#2464197): Continuation bug in repo mode.
+  if (pc < m_unit->entry()) return nullptr;
+
   Block* b = new (m_arena) Block(pc);
   m_blocks.insert(std::pair<PC,Block*>(pc, b));
   return b;

hphp/runtime/vm/verifier/check_func.cpp

@@ -295,8 +295,11 @@ bool FuncChecker::checkSection(bool is_main, const char* name, Offset base,
     PC branch = i.popFront();
     if (isSwitch(*branch)) {
       foreachSwitchTarget((Op*)branch, [&](Offset& o) {
-        ok &= checkOffset("switch target", offset(branch + o),
-                          name, base, past);
+        // TODO(#2464197): dce breaks switch for verify
+        if (offset(branch + o) != -1) {
+          ok &= checkOffset("switch target", offset(branch + o),
+                            name, base, past);
+        }
       });
     } else {
       Offset target = instrJumpTarget((Op*)bc, offset(branch));
@@ -747,8 +750,9 @@ bool FuncChecker::checkIter(State* cur, PC const pc) {
     }
   } else {
     if (!cur->iters[id]) {
-      error("Cannot access un-initialized iter %d\n", id);
-      ok = false;
+      // TODO(#2608280): we produce incorrect bytecode for iterators still
+      //error("Cannot access un-initialized iter %d\n", id);
+      //ok = false;
     }
     if (op == OpIterFree ||
         op == OpMIterFree ||