From f72684f07a7ad9d96862e23aec5737dd3d5d9484 Mon Sep 17 00:00:00 2001
From: mwilliams <mwilliams@fb.com>
Date: Mon, 1 Jul 2013 16:47:21 -0700
Subject: [PATCH] Fix spilling bug in linearscan

If we reload a value in an exit trace that was spilled
in the main trace, a comment tells us that we reload it at the
start of the exit trace. In fact the reload was inserted at the
start of the main trace.

Fixed the code to match the comment.
---
 hphp/runtime/vm/jit/linearscan.cpp            |  2 +-
 hphp/test/slow/compilation/exitspill.php      | 28 +++++++++++++++++++
 .../slow/compilation/exitspill.php.expect     | 15 ++++++++++
 3 files changed, 44 insertions(+), 1 deletion(-)
 create mode 100644 hphp/test/slow/compilation/exitspill.php
 create mode 100644 hphp/test/slow/compilation/exitspill.php.expect

diff --git a/hphp/runtime/vm/jit/linearscan.cpp b/hphp/runtime/vm/jit/linearscan.cpp
index 0763eb24d..dc20fc240 100644
--- a/hphp/runtime/vm/jit/linearscan.cpp
+++ b/hphp/runtime/vm/jit/linearscan.cpp
@@ -1191,7 +1191,7 @@ void LinearScan::allocRegsOneTrace(BlockList::iterator& blockIt,
         assert(!spill->block()->trace()->isMain());
         spill = spill->clone(m_irFactory);
       }
-      block->trace()->front()->prepend(spill);
+      trace->front()->prepend(spill);
     } else if (inst->isBlockEnd()) {
       block->next()->prepend(spill);
     } else {
diff --git a/hphp/test/slow/compilation/exitspill.php b/hphp/test/slow/compilation/exitspill.php
new file mode 100644
index 000000000..19e3b567c
--- /dev/null
+++ b/hphp/test/slow/compilation/exitspill.php
@@ -0,0 +1,28 @@
+<?php
+
+define('FIZ', 32);
+
+class X {
+  const FOO = 1;
+  const BAR = FIZ;
+  const BAZ = FIZ;
+  const BOO = FIZ;
+  const BIZ = FIZ;
+  const FIZ = FIZ;
+}
+
+function foo($a, $b) {
+  var_dump($a, $b);
+}
+
+function f() { return FIZ; }
+
+function test() {
+  foo(f(), array(X::FOO, X::BAZ,
+                 X::BAR, X::BAZ,
+                 X::BOO, X::BIZ));
+}
+
+test();
+
+
diff --git a/hphp/test/slow/compilation/exitspill.php.expect b/hphp/test/slow/compilation/exitspill.php.expect
new file mode 100644
index 000000000..ed77cd276
--- /dev/null
+++ b/hphp/test/slow/compilation/exitspill.php.expect
@@ -0,0 +1,15 @@
+int(32)
+array(6) {
+  [0]=>
+  int(1)
+  [1]=>
+  int(32)
+  [2]=>
+  int(32)
+  [3]=>
+  int(32)
+  [4]=>
+  int(32)
+  [5]=>
+  int(32)
+}