Replace "dummy" with "placeholder" for MemMaps.

Test: m
Bug: 161336379
Change-Id: I0b9e94bb4fe288668aa578507e141f09ea84ccba
diff --git a/libartbase/base/mem_map.cc b/libartbase/base/mem_map.cc
index bd880da..aa07f1c 100644
--- a/libartbase/base/mem_map.cc
+++ b/libartbase/base/mem_map.cc
@@ -389,7 +389,7 @@
                 reuse);
 }
 
-MemMap MemMap::MapDummy(const char* name, uint8_t* addr, size_t byte_count) {
+MemMap MemMap::MapPlaceholder(const char* name, uint8_t* addr, size_t byte_count) {
   if (byte_count == 0) {
     return Invalid();
   }
diff --git a/libartbase/base/mem_map.h b/libartbase/base/mem_map.h
index 4b6257b..4c41388 100644
--- a/libartbase/base/mem_map.h
+++ b/libartbase/base/mem_map.h
@@ -171,7 +171,7 @@
   // This is useful when we do not have control over the code calling mmap,
   // but when we still want to keep track of it in the list.
   // The region is not considered to be owned and will not be unmmaped.
-  static MemMap MapDummy(const char* name, uint8_t* addr, size_t byte_count);
+  static MemMap MapPlaceholder(const char* name, uint8_t* addr, size_t byte_count);
 
   // Map part of a file, taking care of non-page aligned offsets.  The
   // "start" offset is absolute, not relative.
diff --git a/runtime/oat_file.cc b/runtime/oat_file.cc
index d8fd1ea..d8ef21d 100644
--- a/runtime/oat_file.cc
+++ b/runtime/oat_file.cc
@@ -1025,7 +1025,7 @@
   // Guarded by host_dlopen_handles_lock_;
   static std::unordered_set<void*> host_dlopen_handles_;
 
-  // Reservation and dummy memory map objects corresponding to the regions mapped by dlopen.
+  // Reservation and placeholder memory map objects corresponding to the regions mapped by dlopen.
   // Note: Must be destroyed after dlclose() as it can hold the owning reservation.
   std::vector<MemMap> dlopen_mmaps_;
 
@@ -1232,7 +1232,7 @@
   LOG(FATAL) << "Should not reach here.";
   UNREACHABLE();
 #else
-  struct DummyMapData {
+  struct PlaceholderMapData {
     const char* name;
     uint8_t* vaddr;
     size_t memsz;
@@ -1264,7 +1264,7 @@
           }
         }
       }
-      // Add dummy mmaps for this file.
+      // Add placeholder mmaps for this file.
       if (contains_begin) {
         for (Elf_Half i = 0; i < info->dlpi_phnum; i++) {
           if (info->dlpi_phdr[i].p_type == PT_LOAD) {
@@ -1272,17 +1272,19 @@
                 info->dlpi_phdr[i].p_vaddr);
             size_t memsz = info->dlpi_phdr[i].p_memsz;
             size_t name_size = strlen(info->dlpi_name) + 1u;
-            std::vector<char>* dummy_maps_names = context->dummy_maps_names_;
+            std::vector<char>* placeholder_maps_names = context->placeholder_maps_names_;
             // We must not allocate any memory in the callback, see b/156312036 .
-            if (name_size < dummy_maps_names->capacity() - dummy_maps_names->size() &&
-                context->dummy_maps_data_->size() < context->dummy_maps_data_->capacity()) {
-              dummy_maps_names->insert(
-                  dummy_maps_names->end(), info->dlpi_name, info->dlpi_name + name_size);
-              const char* name = &(*dummy_maps_names)[dummy_maps_names->size() - name_size];
-              context->dummy_maps_data_->push_back({ name, vaddr, memsz });
+            if (name_size < placeholder_maps_names->capacity() - placeholder_maps_names->size() &&
+                context->placeholder_maps_data_->size() <
+                    context->placeholder_maps_data_->capacity()) {
+              placeholder_maps_names->insert(
+                  placeholder_maps_names->end(), info->dlpi_name, info->dlpi_name + name_size);
+              const char* name =
+                  &(*placeholder_maps_names)[placeholder_maps_names->size() - name_size];
+              context->placeholder_maps_data_->push_back({ name, vaddr, memsz });
             }
-            context->num_dummy_maps_ += 1u;
-            context->dummy_maps_names_size_ += name_size;
+            context->num_placeholder_maps_ += 1u;
+            context->placeholder_maps_names_size_ += name_size;
           }
         }
         return 1;  // Stop iteration and return 1 from dl_iterate_phdr.
@@ -1290,27 +1292,27 @@
       return 0;  // Continue iteration and return 0 from dl_iterate_phdr when finished.
     }
     const uint8_t* const begin_;
-    std::vector<DummyMapData>* dummy_maps_data_;
-    size_t num_dummy_maps_;
-    std::vector<char>* dummy_maps_names_;
-    size_t dummy_maps_names_size_;
+    std::vector<PlaceholderMapData>* placeholder_maps_data_;
+    size_t num_placeholder_maps_;
+    std::vector<char>* placeholder_maps_names_;
+    size_t placeholder_maps_names_size_;
     size_t shared_objects_before;
     size_t shared_objects_seen;
   };
 
   // We must not allocate any memory in the callback, see b/156312036 .
-  // Therefore we pre-allocate storage for the data we need for creating the dummy maps.
-  std::vector<DummyMapData> dummy_maps_data;
-  dummy_maps_data.reserve(32);  // 32 should be enough. If not, we'll retry.
-  std::vector<char> dummy_maps_names;
-  dummy_maps_names.reserve(4 * KB);  // 4KiB should be enough. If not, we'll retry.
+  // Therefore we pre-allocate storage for the data we need for creating the placeholder maps.
+  std::vector<PlaceholderMapData> placeholder_maps_data;
+  placeholder_maps_data.reserve(32);  // 32 should be enough. If not, we'll retry.
+  std::vector<char> placeholder_maps_names;
+  placeholder_maps_names.reserve(4 * KB);  // 4KiB should be enough. If not, we'll retry.
 
   dl_iterate_context context = {
       Begin(),
-      &dummy_maps_data,
-      /*num_dummy_maps_*/ 0u,
-      &dummy_maps_names,
-      /*dummy_maps_names_size_*/ 0u,
+      &placeholder_maps_data,
+      /*num_placeholder_maps_*/ 0u,
+      &placeholder_maps_names,
+      /*placeholder_maps_names_size_*/ 0u,
       shared_objects_before_,
       /*shared_objects_seen*/ 0u
   };
@@ -1320,10 +1322,10 @@
     // before giving up. This should be unusual.
     VLOG(oat) << "Need a second run in PreSetup, didn't find with shared_objects_before="
               << shared_objects_before_;
-    DCHECK(dummy_maps_data.empty());
-    DCHECK_EQ(context.num_dummy_maps_, 0u);
-    DCHECK(dummy_maps_names.empty());
-    DCHECK_EQ(context.dummy_maps_names_size_, 0u);
+    DCHECK(placeholder_maps_data.empty());
+    DCHECK_EQ(context.num_placeholder_maps_, 0u);
+    DCHECK(placeholder_maps_names.empty());
+    DCHECK_EQ(context.placeholder_maps_names_size_, 0u);
     context.shared_objects_before = 0u;
     context.shared_objects_seen = 0u;
     if (dl_iterate_phdr(dl_iterate_context::callback, &context) == 0) {
@@ -1333,26 +1335,27 @@
     }
   }
 
-  if (dummy_maps_data.size() < context.num_dummy_maps_) {
+  if (placeholder_maps_data.size() < context.num_placeholder_maps_) {
     // Insufficient capacity. Reserve more space and retry.
-    dummy_maps_data.clear();
-    dummy_maps_data.reserve(context.num_dummy_maps_);
-    context.num_dummy_maps_ = 0u;
-    dummy_maps_names.clear();
-    dummy_maps_names.reserve(context.dummy_maps_names_size_);
-    context.dummy_maps_names_size_ = 0u;
+    placeholder_maps_data.clear();
+    placeholder_maps_data.reserve(context.num_placeholder_maps_);
+    context.num_placeholder_maps_ = 0u;
+    placeholder_maps_names.clear();
+    placeholder_maps_names.reserve(context.placeholder_maps_names_size_);
+    context.placeholder_maps_names_size_ = 0u;
     context.shared_objects_before = 0u;
     context.shared_objects_seen = 0u;
     bool success = (dl_iterate_phdr(dl_iterate_context::callback, &context) != 0);
     CHECK(success);
   }
 
-  CHECK_EQ(dummy_maps_data.size(), context.num_dummy_maps_);
-  CHECK_EQ(dummy_maps_names.size(), context.dummy_maps_names_size_);
-  DCHECK_EQ(static_cast<size_t>(std::count(dummy_maps_names.begin(), dummy_maps_names.end(), '\0')),
-            context.num_dummy_maps_);
-  for (const DummyMapData& data : dummy_maps_data) {
-    MemMap mmap = MemMap::MapDummy(data.name, data.vaddr, data.memsz);
+  CHECK_EQ(placeholder_maps_data.size(), context.num_placeholder_maps_);
+  CHECK_EQ(placeholder_maps_names.size(), context.placeholder_maps_names_size_);
+  DCHECK_EQ(static_cast<size_t>(std::count(placeholder_maps_names.begin(),
+                                           placeholder_maps_names.end(), '\0')),
+            context.num_placeholder_maps_);
+  for (const PlaceholderMapData& data : placeholder_maps_data) {
+    MemMap mmap = MemMap::MapPlaceholder(data.name, data.vaddr, data.memsz);
     dlopen_mmaps_.push_back(std::move(mmap));
   }
 #endif
@@ -1525,7 +1528,7 @@
     // SetVdex will take ownership of the VdexFile.
     SetVdex(vdex_file.release());
 
-    // Create a dummy OatHeader with a key store containing only the compiler
+    // Create a fake OatHeader with a key store containing only the compiler
     // filter (it helps debugging and is required by
     // OatHeader::GetCompilerFilter).
     std::unique_ptr<const InstructionSetFeatures> isa_features =