Fixed register allocation corner case.

src/lithium-allocator.cc

Index: src/lithium-allocator.cc
diff --git a/src/lithium-allocator.cc b/src/lithium-allocator.cc
index dcfbeadd803d55557b5a23e2906eb37b63b86d24..66397176b6c91421562ffe9abab0ee0da639e10c 100644
--- a/src/lithium-allocator.cc
+++ b/src/lithium-allocator.cc
@@ -206,9 +206,6 @@ UsePosition* LiveRange::NextRegisterPosition(LifetimePosition start) {
 
 
 bool LiveRange::CanBeSpilled(LifetimePosition pos) {
-  // TODO(kmillikin): Comment. Now.
-  if (pos.Value() <= Start().Value() && HasRegisterAssigned()) return false;
-
   // We cannot spill a live range that has a use requiring a register
   // at the current or the immediate next position.
   UsePosition* use_pos = NextRegisterPosition(pos);
@@ -1917,12 +1914,6 @@ void LAllocator::AllocateBlockedReg(LiveRange* current) {
   if (pos.Value() < register_use->pos().Value()) {
     // All registers are blocked before the first use that requires a register.
     // Spill starting part of live range up to that use.
-    //
-    // Corner case: the first use position is equal to the start of the range.
-    // In this case we have nothing to spill and SpillBetween will just return
-    // this range to the list of unhandled ones. This will lead to the infinite
-    // loop.
-    ASSERT(current->Start().Value() < register_use->pos().Value());

[Vyacheslav Egorov (Chromium), 2013/03/11 08:43:15]

I wonder if we should turn ASSERT in the callee into the CHECK to prevent hangs
and get crashes instead.

[Sven Panne, 2013/03/11 09:48:03]

Sounds like a good idea, the check is extremely cheap. I'll change SpillBetween
accordingly.

     SpillBetween(current, current->Start(), register_use->pos());
     return;
   }