Subzero: Support multiple fixups in one instruction.

src/assembler.cpp

 //===- subzero/src/assembler.cpp - Assembler base class -------------------===//
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 //
 // Modified by the Subzero authors.
 //
 //===----------------------------------------------------------------------===//
 //
 //                        The Subzero Code Generator
@@ skipping 56 matching lines @@
   fixups_processed_ = false;
 #endif // !NDEBUG
 
   // Verify internal state.
   assert(Capacity() == kInitialBufferCapacity);
   assert(Size() == 0);
 }
 
 AssemblerBuffer::~AssemblerBuffer() {}
 
-AssemblerFixup *AssemblerBuffer::GetLatestFixup() const {
-  if (fixups_.empty())
-    return NULL;
-  return fixups_.back();
+// Returns the latest fixup at or after the given position, or NULL if
+// there is none.  Assumes fixups were added in increasing order.
+AssemblerFixup *AssemblerBuffer::GetLatestFixup(intptr_t position) const {
+  AssemblerFixup *latest_fixup = NULL;
+  for (auto I = fixups_.rbegin(), E = fixups_.rend(); I != E; ++I) {
+    if ((*I)->position() < position)
+      return latest_fixup;
+    latest_fixup = *I;
+  }
+  return latest_fixup;
 }
 
 void AssemblerBuffer::ProcessFixups(const MemoryRegion &region) {
   for (SizeT I = 0; I < fixups_.size(); ++I) {
     AssemblerFixup *fixup = fixups_[I];
     fixup->Process(region, fixup->position());
   }
 }
 
 void AssemblerBuffer::FinalizeInstructions(const MemoryRegion &instructions) {
@@ skipping 30 matching lines @@
   // Update the cursor and recompute the limit.
   cursor_ += delta;
   limit_ = ComputeLimit(new_contents, new_capacity);
 
   // Verify internal state.
   assert(Capacity() == new_capacity);
   assert(Size() == old_size);
 }
 
 } // end of namespace Ice