Introduce number type information in the virtual frame.

src/jump-target.cc

Index: src/jump-target.cc
===================================================================
--- src/jump-target.cc	(revision 3859)
+++ src/jump-target.cc	(working copy)
@@ -101,6 +101,17 @@
         if (element == NULL || !element->is_valid()) break;
 
         element = element->Combine(&reaching_frames_[j]->elements_[i]);
+
+        FrameElement* other = &reaching_frames_[j]->elements_[i];
+        if (element != NULL && !element->is_copy()) {
+          ASSERT(other != NULL);
+          ASSERT(!other->is_copy());
+          // We overwrite the number information of one of the incoming frames.
+          // This is safe because we only use the frame for emitting merge code.
+          // The number information of incoming frames is not used anymore.
+          element->set_number_info(NumberInfo::Combine(element->number_info(),
+                                                       other->number_info()));
+        }
       }
       elements[i] = element;
     }
@@ -117,6 +128,7 @@
     // elements as copied exactly when they have a copy.  Undetermined
     // elements are initially recorded as if in memory.
     if (target != NULL) {
+      ASSERT(!target->is_copy());  // These initial elements are never copies.
       entry_frame_->elements_[index] = *target;
       InitializeEntryElement(index, target);
     }
@@ -125,7 +137,8 @@
   for (; index < length; index++) {
     FrameElement* target = elements[index];
     if (target == NULL) {
-      entry_frame_->elements_.Add(FrameElement::MemoryElement());
+      entry_frame_->elements_.Add(
+          FrameElement::MemoryElement(NumberInfo::kUninitialized));
     } else {
       entry_frame_->elements_.Add(*target);
       InitializeEntryElement(index, target);
@@ -142,9 +155,20 @@
       RegisterFile candidate_registers;
       int best_count = kMinInt;
       int best_reg_num = RegisterAllocator::kInvalidRegister;
+      NumberInfo::Type info = NumberInfo::kUninitialized;
 
       for (int j = 0; j < reaching_frames_.length(); j++) {
         FrameElement element = reaching_frames_[j]->elements_[i];
+        if (direction_ == BIDIRECTIONAL) {
+            info = NumberInfo::kUnknown;
+        } else if (!element.is_copy()) {
+          info = NumberInfo::Combine(info, element.number_info());
+        } else {
+          // New elements will not be copies, so get number information from
+          // backing element in the reaching frame.
+          info = NumberInfo::Combine(info,
+            reaching_frames_[j]->elements_[element.index()].number_info());
+        }
         is_synced = is_synced && element.is_synced();
         if (element.is_register() && !entry_frame_->is_used(element.reg())) {
           // Count the register occurrence and remember it if better
@@ -158,11 +182,17 @@
         }
       }
 
+      // We must have a number type information now (not for copied elements).
+      ASSERT(entry_frame_->elements_[i].is_copy()
+             || info != NumberInfo::kUninitialized);
+
       // If the value is synced on all frames, put it in memory.  This
       // costs nothing at the merge code but will incur a
       // memory-to-register move when the value is needed later.
       if (is_synced) {
         // Already recorded as a memory element.
+        // Set combined number info.
+        entry_frame_->elements_[i].set_number_info(info);
         continue;
       }
 
@@ -183,14 +213,28 @@
         bool is_copied = entry_frame_->elements_[i].is_copied();
         Register reg = RegisterAllocator::ToRegister(best_reg_num);
         entry_frame_->elements_[i] =
-            FrameElement::RegisterElement(reg,
-                                          FrameElement::NOT_SYNCED);
+            FrameElement::RegisterElement(reg, FrameElement::NOT_SYNCED,
+                                          NumberInfo::kUninitialized);
         if (is_copied) entry_frame_->elements_[i].set_copied();
         entry_frame_->set_register_location(reg, i);
       }
+      // Set combined number info.
+      entry_frame_->elements_[i].set_number_info(info);
     }
   }
 
+  // If we have incoming backward edges assert we forget all number information.
+#ifdef DEBUG
+  if (direction_ == BIDIRECTIONAL) {
+    for (int i = 0; i < length; ++i) {
+      if (!entry_frame_->elements_[i].is_copy()) {
+        ASSERT(entry_frame_->elements_[i].number_info() ==
+               NumberInfo::kUnknown);
+      }
+    }
+  }
+#endif
+
   // The stack pointer is at the highest synced element or the base of
   // the expression stack.
   int stack_pointer = length - 1;