Remove pad word from arrays

This change removes the 4 byte pad from all arrays except longs and
doubles. It saves 76kb from the boot image, and will also reduce the
size of arrays in the heap (and thereby reduce garbage collection).

Change-Id: I3ff277d5bf14c57c0f7552215818e588ec6cc275

1 files changed, 7 insertions, 4 deletions

diff --git a/src/java_lang_System.cc b/src/java_lang_System.cc
index 78100cf688..b48cee9941 100644
--- a/src/java_lang_System.cc
+++ b/src/java_lang_System.cc
@@ -148,9 +148,6 @@ void System_arraycopy(JNIEnv* env, jclass, jobject javaSrc, jint srcPos, jobject
     return;
   }
 
-  uint8_t* dstBytes = reinterpret_cast<uint8_t*>(dstArray->GetRawData());
-  const uint8_t* srcBytes = reinterpret_cast<const uint8_t*>(srcArray->GetRawData());
-
   // Handle primitive arrays.
   if (srcComponentType->IsPrimitive() || dstComponentType->IsPrimitive()) {
     // If one of the arrays holds a primitive type the other array must hold the exact same type.
@@ -162,7 +159,11 @@ void System_arraycopy(JNIEnv* env, jclass, jobject javaSrc, jint srcPos, jobject
       return;
     }
 
-    switch (srcArray->GetClass()->GetComponentSize()) {
+    size_t width = srcArray->GetClass()->GetComponentSize();
+    uint8_t* dstBytes = reinterpret_cast<uint8_t*>(dstArray->GetRawData(width));
+    const uint8_t* srcBytes = reinterpret_cast<const uint8_t*>(srcArray->GetRawData(width));
+
+    switch (width) {
     case 1:
       memmove(dstBytes + dstPos, srcBytes + srcPos, length);
       break;
@@ -185,6 +186,8 @@ void System_arraycopy(JNIEnv* env, jclass, jobject javaSrc, jint srcPos, jobject
 
   // Neither class is primitive. Are the types trivially compatible?
   const size_t width = sizeof(Object*);
+  uint8_t* dstBytes = reinterpret_cast<uint8_t*>(dstArray->GetRawData(width));
+  const uint8_t* srcBytes = reinterpret_cast<const uint8_t*>(srcArray->GetRawData(width));
   if (dstArray == srcArray || dstComponentType->IsAssignableFrom(srcComponentType)) {
     // Yes. Bulk copy.
     COMPILE_ASSERT(sizeof(width) == sizeof(uint32_t), move32_assumes_Object_references_are_32_bit);