Fix a bug in simplifyDecRefStack

My bad.  If you're going to gen something with no dest in
simplifier, you need to nop out the old one.  This was leading to
over-decrefs in some cases.

hphp/runtime/vm/translator/hopt/simplifier.cpp

@@ -1688,6 +1688,7 @@ SSATmp* Simplifier::simplifyDecRefStack(IRInstruction* inst) {
   auto const info = getStackValue(inst->getSrc(0),
                                   inst->getExtra<StackOffset>()->offset);
   if (info.value && !info.spansCall) {
+    inst->convertToNop();
     return gen(DecRef, info.knownType, info.value);
   }
   if (!info.knownType.equals(Type::None)) {

hphp/runtime/vm/translator/hopt/tracebuilder.cpp

@@ -915,6 +915,9 @@ void CSEHash::filter(Block* block, IdomVector& idoms) {
  *     fall-through edge to the next block.
  */
 void TraceBuilder::reoptimize() {
+  FTRACE(5, "ReOptimize:vvvvvvvvvvvvvvvvvvvv\n");
+  SCOPE_EXIT { FTRACE(5, "ReOptimize:^^^^^^^^^^^^^^^^^^^^\n"); };
+
   m_enableCse = RuntimeOption::EvalHHIRCse;
   m_enableSimplification = RuntimeOption::EvalHHIRSimplification;
   if (!m_enableCse && !m_enableSimplification) return;
@@ -924,25 +927,31 @@ void TraceBuilder::reoptimize() {
     // t2135219 should address that
     return;
   }
+
   BlockList sortedBlocks = sortCfg(m_trace.get(), m_irFactory);
   IdomVector idoms = findDominators(sortedBlocks);
   clearTrackedState();
+
   auto blocks = std::move(m_trace->getBlocks());
   assert(m_trace->getBlocks().empty());
   while (!blocks.empty()) {
     Block* block = blocks.front();
     blocks.pop_front();
     assert(block->getTrace() == m_trace.get());
+    FTRACE(5, "Block: {}\n", block->postId());
+
     m_trace->push_back(block);
     if (m_snapshots[block]) {
       useState(block);
       m_cseHash.filter(block, idoms);
     }
+
     auto instructions = std::move(block->getInstrs());
     assert(block->empty());
     while (!instructions.empty()) {
       auto *inst = &instructions.front();
       instructions.pop_front();
+
       SSATmp* tmp = optimizeWork(inst); // Can generate new instrs!
       if (!tmp) {
         // Could not optimize; keep the old instruction

hphp/test/slow/ir_inlining/1.php.opts

@@ -0,0 +1 @@
+inlining.opts

hphp/test/slow/ir_inlining/2.php.opts

@@ -0,0 +1 @@
+inlining.opts

hphp/test/slow/ir_inlining/cgetm.php.opts

@@ -0,0 +1 @@
+inlining.opts

hphp/test/slow/ir_inlining/cgetm_complex.php.opts

@@ -0,0 +1 @@
+inlining.opts

hphp/test/slow/ir_inlining/cgetm_dynamic.php.opts

@@ -0,0 +1 @@
+inlining.opts

hphp/test/slow/ir_inlining/collection_literal.php.opts

@@ -0,0 +1 @@
+inlining.opts

hphp/test/slow/ir_inlining/constants.php.opts

@@ -0,0 +1 @@
+inlining.opts

hphp/test/slow/ir_inlining/failing_param.php.opts

@@ -1 +1 @@
-../hiphop.opts
+inlining.opts

hphp/test/slow/ir_inlining/fluent.php.opts

@@ -0,0 +1 @@
+inlining.opts

hphp/test/slow/ir_inlining/generator_body.php.opts

@@ -0,0 +1 @@
+inlining.opts

hphp/test/slow/ir_inlining/generator_nested_fcalls.php.opts

@@ -0,0 +1 @@
+inlining.opts

hphp/test/slow/ir_inlining/getter_internal.php.opts

@@ -0,0 +1 @@
+inlining.opts

hphp/test/slow/ir_inlining/headers.php.opts

@@ -1 +1 @@
-../hiphop.opts
+inlining.opts

hphp/test/slow/ir_inlining/inlining.opts

@@ -0,0 +1 @@
+-vEval.JitEnableRenameFunction=0 -vEval.EnableHipHopSyntax=1

hphp/test/slow/ir_inlining/issetm.php.opts

@@ -0,0 +1 @@
+inlining.opts

hphp/test/slow/ir_inlining/refcount_ctor.php

@@ -0,0 +1,15 @@
+<?php
+
+class Obj {
+  public function __construct() {
+    $this->uniqueVar = "a string";
+  }
+  private $uniqueVar;
+}
+
+function test() {
+  new Obj();
+  echo "done\n";
+}
+
+test();

hphp/test/slow/ir_inlining/refcount_ctor.php.expect

@@ -0,0 +1 @@
+done

hphp/test/slow/ir_inlining/refcount_ctor.php.opts

@@ -0,0 +1 @@
+inlining.opts

hphp/test/slow/ir_inlining/setm.php.opts

@@ -0,0 +1 @@
+inlining.opts

hphp/test/slow/ir_inlining/setter.php.opts

@@ -1 +1 @@
-../hiphop.opts
+inlining.opts

hphp/test/slow/ir_inlining/unset.php.opts

@@ -0,0 +1 @@
+inlining.opts

hphp/test/slow/ir_inlining/weird_getter.php.opts

@@ -0,0 +1 @@
+inlining.opts