/**
* Demand zero mmaps an area of virtual memory.
*
* @param start the address of the start of the area to be mapped
* @param size the size, in bytes, of the area to be mapped
* @return 0 if successful, otherwise the system errno
*/
public final int dzmmap(Address start, int size) {
Address result = org.jikesrvm.runtime.Memory.dzmmap(start, Extent.fromIntZeroExtend(size));
if (result.EQ(start)) return 0;
if (result.GT(Address.fromIntZeroExtend(127))) {
VM.sysWrite("demand zero mmap with MAP_FIXED on ", start);
VM.sysWriteln(" returned some other address", result);
VM.sysFail("mmap with MAP_FIXED has unexpected behavior");
}
return result.toInt();
}
/**
* Allocate space for a new object. This is frequently executed code and the coding is
* deliberaetly sensitive to the optimizing compiler. After changing this, always check the IR/MC
* that is generated.
*
* @param bytes The number of bytes allocated
* @param align The requested alignment
* @param offset The offset from the alignment
* @return The address of the first byte of the allocated region
*/
@Inline
public final Address alloc(int bytes, int align, int offset) {
/* establish how much we need */
Address start = alignAllocationNoFill(cursor, align, offset);
Address end = start.plus(bytes);
/* check whether we've exceeded the limit */
if (end.GT(limit)) {
if (bytes > BYTES_IN_LINE) return overflowAlloc(bytes, align, offset);
else return allocSlowHot(bytes, align, offset);
}
/* sufficient memory is available, so we can finish performing the allocation */
fillAlignmentGap(cursor, start);
cursor = end;
return start;
}
/**
* Allocate space for a new object. This is frequently executed code and the coding is
* deliberaetly sensitive to the optimizing compiler. After changing this, always check the IR/MC
* that is generated.
*
* @param bytes The number of bytes allocated
* @param align The requested alignment
* @param offset The offset from the alignment
* @return The address of the first byte of the allocated region
*/
public final Address overflowAlloc(int bytes, int align, int offset) {
/* establish how much we need */
Address start = alignAllocationNoFill(largeCursor, align, offset);
Address end = start.plus(bytes);
/* check whether we've exceeded the limit */
if (end.GT(largeLimit)) {
requestForLarge = true;
Address rtn = allocSlowInline(bytes, align, offset);
requestForLarge = false;
return rtn;
}
/* sufficient memory is available, so we can finish performing the allocation */
fillAlignmentGap(largeCursor, start);
largeCursor = end;
return start;
}