6800154: Add comments to long_by_long_mulhi() for better understandability
Summary: This patch adds a comment pointing to the Hacker's Delight version of the algorithm plus a verbatim copy of it. Furthermore it adds inline comments.
Reviewed-by: kvn, jrose
/*
* Copyright 2002-2008 Sun Microsystems, Inc. All Rights Reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
* CA 95054 USA or visit www.sun.com if you need additional information or
* have any questions.
*
*/
// Platform specific for C++ based Interpreter
#define LOTS_OF_REGS /* Lets interpreter use plenty of registers */
private:
// save the bottom of the stack after frame manager setup. For ease of restoration after return
// from recursive interpreter call
intptr_t* _frame_bottom; /* saved bottom of frame manager frame */
intptr_t* _last_Java_pc; /* pc to return to in frame manager */
interpreterState _self_link; /* Previous interpreter state */ /* sometimes points to self??? */
double _native_fresult; /* save result of native calls that might return floats */
intptr_t _native_lresult; /* save result of native calls that might return handle/longs */
public:
static void pd_layout_interpreterState(interpreterState istate, address last_Java_pc, intptr_t* last_Java_fp);
#define SET_LAST_JAVA_FRAME()
#define RESET_LAST_JAVA_FRAME() THREAD->frame_anchor()->set_flags(0);
/*
* Macros for accessing the stack.
*/
#undef STACK_INT
#undef STACK_FLOAT
#undef STACK_ADDR
#undef STACK_OBJECT
#undef STACK_DOUBLE
#undef STACK_LONG
// JavaStack Implementation
#define GET_STACK_SLOT(offset) (*((intptr_t*) &topOfStack[-(offset)]))
#define STACK_SLOT(offset) ((address) &topOfStack[-(offset)])
#define STACK_ADDR(offset) (*((address *) &topOfStack[-(offset)]))
#define STACK_INT(offset) (*((jint*) &topOfStack[-(offset)]))
#define STACK_FLOAT(offset) (*((jfloat *) &topOfStack[-(offset)]))
#define STACK_OBJECT(offset) (*((oop *) &topOfStack [-(offset)]))
#define STACK_DOUBLE(offset) (((VMJavaVal64*) &topOfStack[-(offset)])->d)
#define STACK_LONG(offset) (((VMJavaVal64 *) &topOfStack[-(offset)])->l)
#define SET_STACK_SLOT(value, offset) (*(intptr_t*)&topOfStack[-(offset)] = *(intptr_t*)(value))
#define SET_STACK_ADDR(value, offset) (*((address *)&topOfStack[-(offset)]) = (value))
#define SET_STACK_INT(value, offset) (*((jint *)&topOfStack[-(offset)]) = (value))
#define SET_STACK_FLOAT(value, offset) (*((jfloat *)&topOfStack[-(offset)]) = (value))
#define SET_STACK_OBJECT(value, offset) (*((oop *)&topOfStack[-(offset)]) = (value))
#define SET_STACK_DOUBLE(value, offset) (((VMJavaVal64*)&topOfStack[-(offset)])->d = (value))
#define SET_STACK_DOUBLE_FROM_ADDR(addr, offset) (((VMJavaVal64*)&topOfStack[-(offset)])->d = \
((VMJavaVal64*)(addr))->d)
#define SET_STACK_LONG(value, offset) (((VMJavaVal64*)&topOfStack[-(offset)])->l = (value))
#define SET_STACK_LONG_FROM_ADDR(addr, offset) (((VMJavaVal64*)&topOfStack[-(offset)])->l = \
((VMJavaVal64*)(addr))->l)
#define LOCALS_SLOT(offset) ((intptr_t*)&locals[-(offset)])
#define LOCALS_ADDR(offset) ((address)locals[-(offset)])
#define LOCALS_INT(offset) (*((jint*)&locals[-(offset)]))
#define LOCALS_FLOAT(offset) (*((jfloat*)&locals[-(offset)]))
#define LOCALS_OBJECT(offset) ((oop)locals[-(offset)])
#define LOCALS_DOUBLE(offset) (((VMJavaVal64*)&locals[-((offset) + 1)])->d)
#define LOCALS_LONG(offset) (((VMJavaVal64*)&locals[-((offset) + 1)])->l)
#define LOCALS_LONG_AT(offset) (((address)&locals[-((offset) + 1)]))
#define LOCALS_DOUBLE_AT(offset) (((address)&locals[-((offset) + 1)]))
#define SET_LOCALS_SLOT(value, offset) (*(intptr_t*)&locals[-(offset)] = *(intptr_t *)(value))
#define SET_LOCALS_ADDR(value, offset) (*((address *)&locals[-(offset)]) = (value))
#define SET_LOCALS_INT(value, offset) (*((jint *)&locals[-(offset)]) = (value))
#define SET_LOCALS_FLOAT(value, offset) (*((jfloat *)&locals[-(offset)]) = (value))
#define SET_LOCALS_OBJECT(value, offset) (*((oop *)&locals[-(offset)]) = (value))
#define SET_LOCALS_DOUBLE(value, offset) (((VMJavaVal64*)&locals[-((offset)+1)])->d = (value))
#define SET_LOCALS_LONG(value, offset) (((VMJavaVal64*)&locals[-((offset)+1)])->l = (value))
#define SET_LOCALS_DOUBLE_FROM_ADDR(addr, offset) (((VMJavaVal64*)&locals[-((offset)+1)])->d = \
((VMJavaVal64*)(addr))->d)
#define SET_LOCALS_LONG_FROM_ADDR(addr, offset) (((VMJavaVal64*)&locals[-((offset)+1)])->l = \
((VMJavaVal64*)(addr))->l)