ARM64: Avoid iterating through unresolved branches information when unnecessary.

src/arm64/assembler-arm64.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
@@ skipping 438 matching lines @@
 
 
 void Assembler::bind(Label* label) {
   // Bind label to the address at pc_. All instructions (most likely branches)
   // that are linked to this label will be updated to point to the newly-bound
   // label.
 
   ASSERT(!label->is_near_linked());
   ASSERT(!label->is_bound());
 
+  DeleteUnresolvedBranchInfoForLabel(label);
+
   // If the label is linked, the link chain looks something like this:
   //
   // |--I----I-------I-------L
   // |---------------------->| pc_offset
   // |-------------->|         linkoffset = label->pos()
   //         |<------|         link->ImmPCOffset()
   // |------>|                 prevlinkoffset = linkoffset + link->ImmPCOffset()
   //
   // On each iteration, the last link is updated and then removed from the
   // chain until only one remains. At that point, the label is bound.
@@ skipping 21 matching lines @@
       label->Unuse();
     } else {
       // Update the label for the next iteration.
       label->link_to(prevlinkoffset);
     }
   }
   label->bind_to(pc_offset());
 
   ASSERT(label->is_bound());
   ASSERT(!label->is_linked());
-
-  DeleteUnresolvedBranchInfoForLabel(label);
 }
 
 
 int Assembler::LinkAndGetByteOffsetTo(Label* label) {
   ASSERT(sizeof(*pc_) == 1);
   CheckLabelLinkChain(label);
 
   int offset;
   if (label->is_bound()) {
     // The label is bound, so it does not need to be updated. Referring
@@ skipping 32 matching lines @@
   return offset;
 }
 
 
 void Assembler::DeleteUnresolvedBranchInfoForLabel(Label* label) {
   if (unresolved_branches_.empty()) {
     ASSERT(next_veneer_pool_check_ == kMaxInt);
     return;
   }
 
-  // Branches to this label will be resolved when the label is bound below.
-  std::multimap<int, FarBranchInfo>::iterator it_tmp, it;
-  it = unresolved_branches_.begin();
-  while (it != unresolved_branches_.end()) {
-    it_tmp = it++;
-    if (it_tmp->second.label_ == label) {
-      CHECK(it_tmp->first >= pc_offset());
-      unresolved_branches_.erase(it_tmp);
+  if (label->is_linked()) {
+    // Branches to this label will be resolved when the label is bound below.
+    std::multimap<int, FarBranchInfo>::iterator it_tmp, it;
+    it = unresolved_branches_.begin();
+    while (it != unresolved_branches_.end()) {
+      it_tmp = it++;
+      if (it_tmp->second.label_ == label) {
+        CHECK(it_tmp->first >= pc_offset());
+        unresolved_branches_.erase(it_tmp);
+      }
     }
   }
   if (unresolved_branches_.empty()) {
     next_veneer_pool_check_ = kMaxInt;
   } else {
     next_veneer_pool_check_ =
       unresolved_branches_first_limit() - kVeneerDistanceCheckMargin;
   }
 }
 
@@ skipping 2232 matching lines @@
 
 void Assembler::PopulateConstantPool(ConstantPoolArray* constant_pool) {
   // No out-of-line constant pool support.
   UNREACHABLE();
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM64