Add array shrinking

Author: msimacek

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/modules/ArrayModuleBuiltins.java

@@ -252,7 +252,7 @@ PArray arrayIteratorInitializer(VirtualFrame frame, Object cls, String typeCode,
                     }
                     try {
                         length = PythonUtils.addExact(length, 1);
-                        array.ensureCapacity(length);
+                        array.resizeStorage(length);
                     } catch (OverflowException e) {
                         CompilerDirectives.transferToInterpreterAndInvalidate();
                         throw raise(MemoryError);

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/objects/array/ArrayBuiltins.java

@@ -688,7 +688,7 @@ Object extend(PArray self, PArray value) {
             try {
                 int newLength = PythonUtils.addExact(self.getLength(), value.getLength());
                 int itemsize = self.getFormat().bytesize;
-                self.ensureCapacity(newLength);
+                self.resizeStorage(newLength);
                 PythonUtils.arraycopy(value.getBuffer(), 0, self.getBuffer(), self.getLength() * itemsize, value.getLength() * itemsize);
                 self.setLength(newLength);
                 return PNone.NONE;
@@ -708,7 +708,7 @@ Object extend(VirtualFrame frame, PArray self, PSequence value,
             int storageLength = lenNode.execute(storage);
             boolean capacityEnsured = false;
             try {
-                self.ensureCapacity(PythonUtils.addExact(self.getLength(), storageLength));
+                self.resizeStorage(PythonUtils.addExact(self.getLength(), storageLength));
                 capacityEnsured = true;
             } catch (OverflowException e) {
                 CompilerDirectives.transferToInterpreterAndInvalidate();
@@ -724,7 +724,7 @@ Object extend(VirtualFrame frame, PArray self, PSequence value,
                 } else {
                     try {
                         length = PythonUtils.addExact(length, 1);
-                        self.ensureCapacity(length);
+                        self.resizeStorage(length);
                     } catch (OverflowException e) {
                         CompilerDirectives.transferToInterpreterAndInvalidate();
                         throw raise(MemoryError);
@@ -757,7 +757,7 @@ Object extend(VirtualFrame frame, PArray self, Object value,
                 // in CPython
                 try {
                     length = PythonUtils.addExact(length, 1);
-                    self.ensureCapacity(length);
+                    self.resizeStorage(length);
                 } catch (OverflowException e) {
                     CompilerDirectives.transferToInterpreterAndInvalidate();
                     throw raise(MemoryError);
@@ -936,7 +936,7 @@ Object fromlist(VirtualFrame frame, PArray self, PList list,
                 SequenceStorage storage = getSequenceStorageNode.execute(list);
                 int length = lenNode.execute(storage);
                 int newLength = PythonUtils.addExact(self.getLength(), length);
-                self.ensureCapacity(newLength);
+                self.resizeStorage(newLength);
                 for (int i = 0; i < length; i++) {
                     putValueNode.execute(frame, self, self.getLength() + i, getItemScalarNode.execute(storage, i));
                 }
@@ -988,7 +988,7 @@ Object fromunicode(VirtualFrame frame, PArray self, String str,
             try {
                 int length = PString.codePointCount(str, 0, str.length());
                 int newLength = PythonUtils.addExact(self.getLength(), length);
-                self.ensureCapacity(newLength);
+                self.resizeStorage(newLength);
                 for (int i = 0, index = 0; i < length; index++) {
                     int cpCount = PString.charCount(PString.codePointAt(str, i));
                     String value = PString.substring(str, i, i + cpCount);

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/objects/array/PArray.java

@@ -85,26 +85,33 @@ public void setLength(int length) {
     }
 
     private int computeNewSize(int newLength, int itemsize) throws OverflowException {
-        // Overallocation using the same formula as CPython
-        int newSize = ((newLength >> 4) + (length < 8 ? 3 : 7) + newLength) * itemsize;
+        int newSize = computeNewSizeNoOverflowCheck(newLength, itemsize);
         if (newSize / itemsize < newLength) {
             throw OverflowException.INSTANCE;
         }
         return newSize;
     }
 
-    public void ensureCapacity(int newLength) throws OverflowException {
+    private int computeNewSizeNoOverflowCheck(int newLength, int itemsize) {
+        if (newLength == 0) {
+            return 0;
+        }
+        // Overallocation using the same formula as CPython
+        return ((newLength >> 4) + (length < 8 ? 3 : 7) + newLength) * itemsize;
+    }
+
+    public void resizeStorage(int newLength) throws OverflowException {
         assert newLength >= 0;
         int itemsize = format.bytesize;
-        if (buffer.length / itemsize < newLength) {
+        if (buffer.length / itemsize < newLength || length + 16 >= newLength) {
             byte[] newBuffer = new byte[computeNewSize(newLength, itemsize)];
-            PythonUtils.arraycopy(buffer, 0, newBuffer, 0, buffer.length);
+            PythonUtils.arraycopy(buffer, 0, newBuffer, 0, Math.min(buffer.length, newBuffer.length));
             buffer = newBuffer;
         }
     }
 
     public void resize(int newLength) throws OverflowException {
-        ensureCapacity(newLength);
+        resizeStorage(newLength);
         length = newLength;
     }
 
@@ -129,9 +136,15 @@ public void delSlice(int at, int count) {
         assert at + count <= length;
         int newLength = length - count;
         assert newLength >= 0;
-        // TODO shrink?
         int itemsize = format.bytesize;
-        PythonUtils.arraycopy(buffer, (at + count) * itemsize, buffer, at * itemsize, (length - at - count) * itemsize);
+        if (length + 16 >= newLength) {
+            byte[] newBuffer = new byte[computeNewSizeNoOverflowCheck(newLength, itemsize)];
+            PythonUtils.arraycopy(buffer, 0, newBuffer, 0, at * itemsize);
+            PythonUtils.arraycopy(buffer, (at + count) * itemsize, newBuffer, at * itemsize, (length - at - count) * itemsize);
+            buffer = newBuffer;
+        } else {
+            PythonUtils.arraycopy(buffer, (at + count) * itemsize, buffer, at * itemsize, (length - at - count) * itemsize);
+        }
         length = newLength;
     }