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 1997-2007 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.
*
*/
// Inline functions for SPARC frames:
// Constructors
inline frame::frame() {
_pc = NULL;
_sp = NULL;
_younger_sp = NULL;
_cb = NULL;
_deopt_state = unknown;
_sp_adjustment_by_callee = 0;
}
// Accessors:
inline bool frame::equal(frame other) const {
bool ret = sp() == other.sp()
&& fp() == other.fp()
&& pc() == other.pc();
assert(!ret || ret && cb() == other.cb() && _deopt_state == other._deopt_state, "inconsistent construction");
return ret;
}
// Return unique id for this frame. The id must have a value where we can distinguish
// identity and younger/older relationship. NULL represents an invalid (incomparable)
// frame.
inline intptr_t* frame::id(void) const { return unextended_sp(); }
// Relationals on frames based
// Return true if the frame is younger (more recent activation) than the frame represented by id
inline bool frame::is_younger(intptr_t* id) const { assert(this->id() != NULL && id != NULL, "NULL frame id");
return this->id() < id ; }
// Return true if the frame is older (less recent activation) than the frame represented by id
inline bool frame::is_older(intptr_t* id) const { assert(this->id() != NULL && id != NULL, "NULL frame id");
return this->id() > id ; }
inline int frame::frame_size() const { return sender_sp() - sp(); }
inline intptr_t* frame::link() const { return (intptr_t *)(fp()[FP->sp_offset_in_saved_window()] + STACK_BIAS); }
inline void frame::set_link(intptr_t* addr) { assert(link()==addr, "frame nesting is controlled by hardware"); }
inline intptr_t* frame::unextended_sp() const { return sp() + _sp_adjustment_by_callee; }
// return address:
inline address frame::sender_pc() const { return *I7_addr() + pc_return_offset; }
inline address* frame::I7_addr() const { return (address*) &sp()[ I7->sp_offset_in_saved_window()]; }
inline address* frame::I0_addr() const { return (address*) &sp()[ I0->sp_offset_in_saved_window()]; }
inline address* frame::O7_addr() const { return (address*) &younger_sp()[ I7->sp_offset_in_saved_window()]; }
inline address* frame::O0_addr() const { return (address*) &younger_sp()[ I0->sp_offset_in_saved_window()]; }
inline intptr_t* frame::sender_sp() const { return fp(); }
// Used only in frame::oopmapreg_to_location
// This return a value in VMRegImpl::slot_size
inline int frame::pd_oop_map_offset_adjustment() const {
return _sp_adjustment_by_callee * VMRegImpl::slots_per_word;
}
#ifdef CC_INTERP
inline intptr_t** frame::interpreter_frame_locals_addr() const {
interpreterState istate = get_interpreterState();
return (intptr_t**) &istate->_locals;
}
inline intptr_t* frame::interpreter_frame_bcx_addr() const {
interpreterState istate = get_interpreterState();
return (intptr_t*) &istate->_bcp;
}
inline intptr_t* frame::interpreter_frame_mdx_addr() const {
interpreterState istate = get_interpreterState();
return (intptr_t*) &istate->_mdx;
}
inline jint frame::interpreter_frame_expression_stack_direction() { return -1; }
// bottom(base) of the expression stack (highest address)
inline intptr_t* frame::interpreter_frame_expression_stack() const {
return (intptr_t*)interpreter_frame_monitor_end() - 1;
}
// top of expression stack (lowest address)
inline intptr_t* frame::interpreter_frame_tos_address() const {
interpreterState istate = get_interpreterState();
return istate->_stack + 1; // Is this off by one? QQQ
}
// monitor elements
// in keeping with Intel side: end is lower in memory than begin;
// and beginning element is oldest element
// Also begin is one past last monitor.
inline BasicObjectLock* frame::interpreter_frame_monitor_begin() const {
return get_interpreterState()->monitor_base();
}
inline BasicObjectLock* frame::interpreter_frame_monitor_end() const {
return (BasicObjectLock*) get_interpreterState()->stack_base();
}
inline int frame::interpreter_frame_monitor_size() {
return round_to(BasicObjectLock::size(), WordsPerLong);
}
inline methodOop* frame::interpreter_frame_method_addr() const {
interpreterState istate = get_interpreterState();
return &istate->_method;
}
// Constant pool cache
// where LcpoolCache is saved:
inline constantPoolCacheOop* frame::interpreter_frame_cpoolcache_addr() const {
interpreterState istate = get_interpreterState();
return &istate->_constants; // should really use accessor
}
inline constantPoolCacheOop* frame::interpreter_frame_cache_addr() const {
interpreterState istate = get_interpreterState();
return &istate->_constants;
}
#else // !CC_INTERP
inline intptr_t** frame::interpreter_frame_locals_addr() const {
return (intptr_t**) sp_addr_at( Llocals->sp_offset_in_saved_window());
}
inline intptr_t* frame::interpreter_frame_bcx_addr() const {
// %%%%% reinterpreting Lbcp as a bcx
return (intptr_t*) sp_addr_at( Lbcp->sp_offset_in_saved_window());
}
inline intptr_t* frame::interpreter_frame_mdx_addr() const {
// %%%%% reinterpreting ImethodDataPtr as a mdx
return (intptr_t*) sp_addr_at( ImethodDataPtr->sp_offset_in_saved_window());
}
inline jint frame::interpreter_frame_expression_stack_direction() { return -1; }
// bottom(base) of the expression stack (highest address)
inline intptr_t* frame::interpreter_frame_expression_stack() const {
return (intptr_t*)interpreter_frame_monitors() - 1;
}
// top of expression stack (lowest address)
inline intptr_t* frame::interpreter_frame_tos_address() const {
return *interpreter_frame_esp_addr() + 1;
}
inline void frame::interpreter_frame_set_tos_address( intptr_t* x ) {
*interpreter_frame_esp_addr() = x - 1;
}
// monitor elements
// in keeping with Intel side: end is lower in memory than begin;
// and beginning element is oldest element
// Also begin is one past last monitor.
inline BasicObjectLock* frame::interpreter_frame_monitor_begin() const {
int rounded_vm_local_words = round_to(frame::interpreter_frame_vm_local_words, WordsPerLong);
return (BasicObjectLock *)fp_addr_at(-rounded_vm_local_words);
}
inline BasicObjectLock* frame::interpreter_frame_monitor_end() const {
return interpreter_frame_monitors();
}
inline void frame::interpreter_frame_set_monitor_end(BasicObjectLock* value) {
interpreter_frame_set_monitors(value);
}
inline int frame::interpreter_frame_monitor_size() {
return round_to(BasicObjectLock::size(), WordsPerLong);
}
inline methodOop* frame::interpreter_frame_method_addr() const {
return (methodOop*)sp_addr_at( Lmethod->sp_offset_in_saved_window());
}
// Constant pool cache
// where LcpoolCache is saved:
inline constantPoolCacheOop* frame::interpreter_frame_cpoolcache_addr() const {
return (constantPoolCacheOop*)sp_addr_at(LcpoolCache->sp_offset_in_saved_window());
}
inline constantPoolCacheOop* frame::interpreter_frame_cache_addr() const {
return (constantPoolCacheOop*)sp_addr_at( LcpoolCache->sp_offset_in_saved_window());
}
#endif // CC_INTERP
inline JavaCallWrapper* frame::entry_frame_call_wrapper() const {
// note: adjust this code if the link argument in StubGenerator::call_stub() changes!
const Argument link = Argument(0, false);
return (JavaCallWrapper*)sp()[link.as_in().as_register()->sp_offset_in_saved_window()];
}
inline int frame::local_offset_for_compiler(int local_index, int nof_args, int max_nof_locals, int max_nof_monitors) {
// always allocate non-argument locals 0..5 as if they were arguments:
int allocated_above_frame = nof_args;
if (allocated_above_frame < callee_register_argument_save_area_words)
allocated_above_frame = callee_register_argument_save_area_words;
if (allocated_above_frame > max_nof_locals)
allocated_above_frame = max_nof_locals;
// Note: monitors (BasicLock blocks) are never allocated in argument slots
//assert(local_index >= 0 && local_index < max_nof_locals, "bad local index");
if (local_index < allocated_above_frame)
return local_index + callee_register_argument_save_area_sp_offset;
else
return local_index - (max_nof_locals + max_nof_monitors*2) + compiler_frame_vm_locals_fp_offset;
}
inline int frame::monitor_offset_for_compiler(int local_index, int nof_args, int max_nof_locals, int max_nof_monitors) {
assert(local_index >= max_nof_locals && ((local_index - max_nof_locals) & 1) && (local_index - max_nof_locals) < max_nof_monitors*2, "bad monitor index");
// The compiler uses the __higher__ of two indexes allocated to the monitor.
// Increasing local indexes are mapped to increasing memory locations,
// so the start of the BasicLock is associated with the __lower__ index.
int offset = (local_index-1) - (max_nof_locals + max_nof_monitors*2) + compiler_frame_vm_locals_fp_offset;
// We allocate monitors aligned zero mod 8:
assert((offset & 1) == 0, "monitor must be an an even address.");
// This works because all monitors are allocated after
// all locals, and because the highest address corresponding to any
// monitor index is always even.
assert((compiler_frame_vm_locals_fp_offset & 1) == 0, "end of monitors must be even address");
return offset;
}
inline int frame::min_local_offset_for_compiler(int nof_args, int max_nof_locals, int max_nof_monitors) {
// always allocate non-argument locals 0..5 as if they were arguments:
int allocated_above_frame = nof_args;
if (allocated_above_frame < callee_register_argument_save_area_words)
allocated_above_frame = callee_register_argument_save_area_words;
if (allocated_above_frame > max_nof_locals)
allocated_above_frame = max_nof_locals;
int allocated_in_frame = (max_nof_locals + max_nof_monitors*2) - allocated_above_frame;
return compiler_frame_vm_locals_fp_offset - allocated_in_frame;
}
// On SPARC, the %lN and %iN registers are non-volatile.
inline bool frame::volatile_across_calls(Register reg) {
// This predicate is (presently) applied only to temporary registers,
// and so it need not recognize non-volatile globals.
return reg->is_out() || reg->is_global();
}
inline oop frame::saved_oop_result(RegisterMap* map) const {
return *((oop*) map->location(O0->as_VMReg()));
}
inline void frame::set_saved_oop_result(RegisterMap* map, oop obj) {
*((oop*) map->location(O0->as_VMReg())) = obj;
}