Examples with ValueLayout jdk.incubator.foreign.ValueLayout used on opensource projects

Example 1 with ValueLayout

use of jdk.incubator.foreign.ValueLayout in project openj9 by eclipse.

the class LayoutStrPreprocessor method preprocessLayout.

/* Preprocess the layout to generate a concise layout string with all kind symbols
	 * extracted from the layout to simplify parsing the layout string in native.
	 * e.g. a struct layout string with nested struct is as follows: (Only for Java <= 17)
	 * [
	 *   [
	 *    b32(elem1)[abi/kind=INT,layout/name=elem1]
	 *    b32(elem2)[abi/kind=INT,layout/name=elem2]
	 *   ](Struct1_II)[layout/name=Struct1_II]
	 *   [
	 *    b32(elem1)[abi/kind=INT,layout/name=elem1]
	 *    b32(elem2)[abi/kind=INT,layout/name=elem2]
	 *   ](Struct2_II)[layout/name=Struct2_II]
	 * ](nested_struct)[layout/name=nested_struct]
	 *
	 * which ends up with "16#2[#2[II]#2[II]]" by conversion as follows:
	 *
	 *   16#2[  (16 is the byte size of the layout and 2 is the count of the struct elements
	 *        #2[ 2 is the count of the int elements
	 *           I  (INT)
	 *           I  (INT)
	 *          ]
	 *        #2[ 2 is the count of the int elements
	 *           I  (INT)
	 *           I  (INT)
	 *          ]
	 *        ]
	 *  where "#" denotes the start of struct.
	 *
	 *  Note:
	 *  1) the prefix "ByteSize#CountOfElmemnt" and "#CountOfElmemnt" are not required in
	 *  the upcall given the converted layout stirngs are further parsed for the generated
	 *  thunk in native, which is logically different from downcall.
	 *  2) the parsing of primitives in layouts in Java 18 is based on the MemoryLayout.carrier()
	 *  rather than the CLinker.TypeKind which is entirely removed in OpenJDK.
	 */
private static StringBuilder preprocessLayout(MemoryLayout targetLayout, boolean isDownCall) {
    // $NON-NLS-1$
    StringBuilder targetLayoutString = new StringBuilder("");
    /* Directly obtain the kind symbol of the primitive layout */
    if (targetLayout instanceof ValueLayout) {
        targetLayoutString.append(getPrimitiveTypeSymbol((ValueLayout) targetLayout));
    } else if (targetLayout instanceof SequenceLayout) {
        // Intended for nested arrays
        SequenceLayout arrayLayout = (SequenceLayout) targetLayout;
        MemoryLayout elementLayout = arrayLayout.elementLayout();
        long elementCount = arrayLayout.elementCount().getAsLong();
        targetLayoutString.append(elementCount).append(':').append(preprocessLayout(elementLayout, isDownCall));
    } else if (targetLayout instanceof GroupLayout) {
        // Intended for the nested structs
        GroupLayout structLayout = (GroupLayout) targetLayout;
        List<MemoryLayout> elementLayoutList = structLayout.memberLayouts();
        int structElementCount = elementLayoutList.size();
        // $NON-NLS-1$
        StringBuilder elementLayoutStrs = new StringBuilder("");
        int paddingElements = 0;
        for (int elemIndex = 0; elemIndex < structElementCount; elemIndex++) {
            MemoryLayout structElement = elementLayoutList.get(elemIndex);
            /* Ignore any padding element in the struct as it is handled by ffi_call by default */
            if (structElement.isPadding()) {
                paddingElements += 1;
                /* The padding bytes is required in native during the upcall */
                if (!isDownCall) {
                    elementLayoutStrs.append('(').append(structElement.byteSize()).append(')');
                }
            } else {
                elementLayoutStrs.append(preprocessLayout(structElement, isDownCall));
            }
        }
        /* Prefix "#" to denote the start of this layout string in the case of downcall */
        if (isDownCall) {
            targetLayoutString.append('#').append(structElementCount - paddingElements);
        }
        targetLayoutString.append('[').append(elementLayoutStrs).append(']');
    }
    return targetLayoutString;
}