From 65258db896c8270873f362d95204336d7d1e333d Mon Sep 17 00:00:00 2001
From: Vladimir Marko <vmarko@google.com>
Date: Thu, 31 Mar 2022 12:39:21 +0000
Subject: Faster class descriptor hashing.

Test: m test-art-host-gtest
Test: testrunner.py --host --optimizing
Bug: 181943478
Change-Id: I94612e8229b6d21abd51ade36ed88c1b5db77764
---
 runtime/class_table.cc | 37 +++++++++++++++++++++++++++++--------
 1 file changed, 29 insertions(+), 8 deletions(-)

(limited to 'runtime/class_table.cc')

diff --git a/runtime/class_table.cc b/runtime/class_table.cc
index bd5d38f80d..acfbcb09a3 100644
--- a/runtime/class_table.cc
+++ b/runtime/class_table.cc
@@ -18,10 +18,39 @@
 
 #include "base/stl_util.h"
 #include "mirror/class-inl.h"
+#include "mirror/string-inl.h"
 #include "oat_file.h"
 
 namespace art {
 
+uint32_t ClassTable::TableSlot::UpdateHashForProxyClass(
+    uint32_t hash, ObjPtr<mirror::Class> proxy_class) {
+  // No read barrier needed, the `name` field is constant for proxy classes and
+  // the contents of the String are also constant. See ReadBarrierOption.
+  // Note: The `proxy_class` can be a from-space reference.
+  DCHECK(proxy_class->IsProxyClass());
+  ObjPtr<mirror::String> name = proxy_class->GetName<kVerifyNone, kWithoutReadBarrier>();
+  DCHECK(name != nullptr);
+  // Update hash for characters we would get from `DotToDescriptor(name->ToModifiedUtf8())`.
+  DCHECK_NE(name->GetLength(), 0);
+  DCHECK_NE(name->CharAt(0), '[');
+  hash = UpdateModifiedUtf8Hash(hash, 'L');
+  if (name->IsCompressed()) {
+    std::string_view dot_name(reinterpret_cast<const char*>(name->GetValueCompressed()),
+                              name->GetLength());
+    for (char c : dot_name) {
+      hash = UpdateModifiedUtf8Hash(hash, (c != '.') ? c : '/');
+    }
+  } else {
+    std::string dot_name = name->ToModifiedUtf8();
+    for (char c : dot_name) {
+      hash = UpdateModifiedUtf8Hash(hash, (c != '.') ? c : '/');
+    }
+  }
+  hash = UpdateModifiedUtf8Hash(hash, ';');
+  return hash;
+}
+
 ClassTable::ClassTable() : lock_("Class loader classes", kClassLoaderClassesLock) {
   Runtime* const runtime = Runtime::Current();
   classes_.push_back(ClassSet(runtime->GetHashTableMinLoadFactor(),
@@ -189,12 +218,4 @@ void ClassTable::ClearStrongRoots() {
   strong_roots_.clear();
 }
 
-ClassTable::TableSlot::TableSlot(ObjPtr<mirror::Class> klass)
-    : TableSlot(klass, HashDescriptor(klass)) {}
-
-uint32_t ClassTable::TableSlot::HashDescriptor(ObjPtr<mirror::Class> klass) {
-  std::string temp;
-  return ComputeModifiedUtf8Hash(klass->GetDescriptor(&temp));
-}
-
 }  // namespace art
-- 
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