Merge pull request #4328 from gacholio/jvm

Initial implementation of JVM_CopySwapMemory
eclipse-openj9 · Jan 17, 2019 · 92e9b4b · 92e9b4b
2 parents ee2036a + 0362067
commit 92e9b4b
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Showing 3 changed files with 116 additions and 3 deletions.
diff --git a/runtime/j9vm/j8vmi.c b/runtime/j9vm/j8vmi.c
@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2002, 2017 IBM Corp. and others
+ * Copyright (c) 2002, 2019 IBM Corp. and others
  *
  * This program and the accompanying materials are made available under
  * the terms of the Eclipse Public License 2.0 which accompanies this
@@ -99,3 +99,114 @@ JVM_GetTemporaryDirectory(JNIEnv *env)
 	return result;
 }
 
+
+/**
+ * Copies memory from one place to another, endian flipping the data.
+ *
+ * @param [in] env Pointer to JNI environment
+ * @param [in] srcObj Source primitive array (NULL means srcOffset represents native memory)
+ * @param [in] srcOffset Offset in source array / address in native memory
+ * @param [in] dstObj Destination primitive array (NULL means dstOffset represents native memory)
+ * @param [in] dstOffset Offset in destination array / address in native memory
+ * @param [in] size Number of bytes to copy
+ * @param [in] elemSize Size of elements to copy and flip
+ *
+ * elemSize = 1 means a straight byte copy
+ * elemSize = 2 means byte order 1,2 becomes 2,1
+ * elemSize = 4 means byte order 1,2,3,4 becomes 4,3,2,1
+ * elemSize = 8 means byte order 1,2,3,4,5,6,7,8 becomes 8,7,6,5,4,3,2,1
+ */
+void JNICALL
+JVM_CopySwapMemory(JNIEnv *env, jobject srcObj, jlong srcOffset, jobject dstObj, jlong dstOffset, jlong size, jlong elemSize)
+{
+	void *srcBytes = NULL;
+	void *dstBytes = NULL;
+	U_8 *srcAddr = NULL;
+	U_8 *dstAddr = NULL;
+	/* Ensure that size is a non-negative multiple of elemSize */
+	Assert_SC_true(size >= 0);
+	Assert_SC_true(0 == (size % elemSize));
+	if (NULL != srcObj) {
+		/* Disallow negative object offsets */
+		Assert_SC_true(srcOffset >= 0);
+		srcBytes = (*env)->GetPrimitiveArrayCritical(env, srcObj, NULL);
+		srcAddr = srcBytes;
+	}
+	if (NULL != dstObj) {
+		/* Disallow negative object offsets */
+		Assert_SC_true(dstOffset >= 0);
+		dstBytes = (*env)->GetPrimitiveArrayCritical(env, dstObj, NULL);
+		dstAddr = dstBytes;
+	}
+	srcAddr += (UDATA)srcOffset;
+	dstAddr += (UDATA)dstOffset;
+/*
+	Generic code would be:
+
+		jlong elemCount = size / elemSize;
+		for (jlong i = 0; i < elemCount; ++i) {
+			for (UDATA j = 0; j < elemSize; ++j) {
+				dstAddr[j] = srcAddr[elemSize - j - 1];
+			}
+			srcAddr += elemSize;
+			dstAddr += elemSize;
+		}
+		break;
+	}
+ */
+	switch(elemSize) {
+	case 1:
+		memcpy(dstAddr, srcAddr, (size_t)size);
+		break;
+	case 2: {
+		jlong elemCount = size / 2;
+		while (0 != elemCount) {
+			dstAddr[0] = srcAddr[1];
+			dstAddr[1] = srcAddr[0];
+			srcAddr += 2;
+			dstAddr += 2;
+			elemCount -= 1;
+		}
+		break;
+	}
+	case 4: {
+		jlong elemCount = size / 4;
+		while (0 != elemCount) {
+			dstAddr[0] = srcAddr[3];
+			dstAddr[1] = srcAddr[2];
+			dstAddr[2] = srcAddr[1];
+			dstAddr[3] = srcAddr[0];
+			srcAddr += 4;
+			dstAddr += 4;
+			elemCount -= 1;
+		}
+		break;
+	}
+	case 8: {
+		jlong elemCount = size / 8;
+		while (0 != elemCount) {
+			dstAddr[0] = srcAddr[7];
+			dstAddr[1] = srcAddr[6];
+			dstAddr[2] = srcAddr[5];
+			dstAddr[3] = srcAddr[4];
+			dstAddr[4] = srcAddr[3];
+			dstAddr[5] = srcAddr[2];
+			dstAddr[6] = srcAddr[1];
+			dstAddr[7] = srcAddr[0];
+			srcAddr += 8;
+			dstAddr += 8;
+			elemCount -= 1;
+		}
+		break;
+	}
+	default:
+		Assert_SC_unreachable();
+		break;
+	}
+	if (NULL != srcObj) {
+		(*env)->ReleasePrimitiveArrayCritical(env, srcObj, srcBytes, 0);
+	}
+	if (NULL != dstObj) {
+		(*env)->ReleasePrimitiveArrayCritical(env, dstObj, dstBytes, 0);
+	}
+}
diff --git a/runtime/j9vm/j9vmnatives.xml b/runtime/j9vm/j9vmnatives.xml
@@ -1,5 +1,5 @@
 <!--
-Copyright (c) 2007, 2018 IBM Corp. and others
+Copyright (c) 2007, 2019 IBM Corp. and others
 
 This program and the accompanying materials are made available under
 the terms of the Eclipse Public License 2.0 which accompanies this
@@ -287,6 +287,7 @@ SPDX-License-Identifier: EPL-2.0 OR Apache-2.0 OR GPL-2.0 WITH Classpath-excepti
 		<export name="_JVM_GetMethodTypeAnnotations@8"/>
 		<export name="_JVM_IsVMGeneratedMethodIx@12"/>
 		<export name="JVM_GetTemporaryDirectory"/>
+		<export name="_JVM_CopySwapMemory@44"/>
 
 		<!-- Additions for Java 9 (Modularity) -->
 		<export name="JVM_DefineModule"/>

diff --git a/runtime/redirector/forwarders.m4 b/runtime/redirector/forwarders.m4
@@ -1,4 +1,4 @@
-dnl Copyright (c) 2001, 2018 IBM Corp. and others
+dnl Copyright (c) 2001, 2019 IBM Corp. and others
 dnl
 dnl This program and the accompanying materials are made available under
 dnl the terms of the Eclipse Public License 2.0 which accompanies this
@@ -256,6 +256,7 @@ _X(JVM_GetMethodParameters,JNICALL,true,jobjectArray ,JNIEnv *env, jobject metho
 _X(JVM_GetMethodTypeAnnotations,JNICALL,true,jbyteArray ,JNIEnv *env, jobject method)
 _X(JVM_IsVMGeneratedMethodIx,JNICALL,true,jboolean ,JNIEnv *env, jclass cb, jint index)
 _X(JVM_GetTemporaryDirectory,JNICALL,false,jstring ,JNIEnv *env)
+_X(JVM_CopySwapMemory,JNICALL,true,void ,JNIEnv *env, jobject srcObj, jlong srcOffset, jobject dstObj, jlong dstOffset, jlong size, jlong elemSize)
 _X(JVM_GetPrimitiveField,JNICALL,true,jobject ,jint arg0, jint arg1, jint arg2, jint arg3)
 _X(JVM_InitializeCompiler,JNICALL,true,jobject ,jint arg0, jint arg1)
 _X(JVM_IsSilentCompiler,JNICALL,true,jobject ,jint arg0, jint arg1)