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 2000-2007 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.
*
*/
// Sets the default values for platform dependent flags used by the server compiler.
// (see c2_globals.hpp). Alpha-sorted.
define_pd_global(bool, BackgroundCompilation, true);
define_pd_global(bool, CICompileOSR, true);
define_pd_global(bool, InlineIntrinsics, false);
define_pd_global(bool, PreferInterpreterNativeStubs, false);
define_pd_global(bool, ProfileTraps, true);
define_pd_global(bool, UseOnStackReplacement, true);
#ifdef CC_INTERP
define_pd_global(bool, ProfileInterpreter, false);
#else
define_pd_global(bool, ProfileInterpreter, true);
#endif // CC_INTERP
define_pd_global(bool, TieredCompilation, false);
#ifdef TIERED
define_pd_global(intx, CompileThreshold, 1000);
define_pd_global(intx, BackEdgeThreshold, 14000);
#else
define_pd_global(intx, CompileThreshold, 10000);
define_pd_global(intx, BackEdgeThreshold, 140000);
#endif // TIERED
define_pd_global(intx, Tier2CompileThreshold, 10000); // unused level
define_pd_global(intx, Tier3CompileThreshold, 10000);
define_pd_global(intx, Tier4CompileThreshold, 40000);
define_pd_global(intx, Tier2BackEdgeThreshold, 100000);
define_pd_global(intx, Tier3BackEdgeThreshold, 100000);
define_pd_global(intx, Tier4BackEdgeThreshold, 100000);
define_pd_global(intx, OnStackReplacePercentage, 140);
define_pd_global(intx, ConditionalMoveLimit, 4);
define_pd_global(intx, FLOATPRESSURE, 52); // C2 on V9 gets to use all the float/double registers
define_pd_global(intx, FreqInlineSize, 175);
define_pd_global(intx, INTPRESSURE, 48); // large register set
define_pd_global(intx, InteriorEntryAlignment, 16); // = CodeEntryAlignment
define_pd_global(intx, NewRatio, 2);
define_pd_global(intx, NewSizeThreadIncrease, ScaleForWordSize(4*K));
// The default setting 16/16 seems to work best.
// (For _228_jack 16/16 is 2% better than 4/4, 16/4, 32/32, 32/16, or 16/32.)
define_pd_global(intx, OptoLoopAlignment, 16); // = 4*wordSize
define_pd_global(intx, RegisterCostAreaRatio, 12000);
define_pd_global(bool, UseTLAB, true);
define_pd_global(bool, ResizeTLAB, true);
define_pd_global(intx, LoopUnrollLimit, 60); // Design center runs on 1.3.1
// Peephole and CISC spilling both break the graph, and so makes the
// scheduler sick.
define_pd_global(bool, OptoPeephole, false);
define_pd_global(bool, UseCISCSpill, false);
define_pd_global(bool, OptoBundling, false);
define_pd_global(bool, OptoScheduling, true);
#ifdef _LP64
// We need to make sure that all generated code is within
// 2 gigs of the libjvm.so runtime routines so we can use
// the faster "call" instruction rather than the expensive
// sequence of instructions to load a 64 bit pointer.
//
// InitialCodeCacheSize derived from specjbb2000 run.
define_pd_global(intx, InitialCodeCacheSize, 2048*K); // Integral multiple of CodeCacheExpansionSize
define_pd_global(intx, ReservedCodeCacheSize, 48*M);
define_pd_global(intx, CodeCacheExpansionSize, 64*K);
// Ergonomics related flags
define_pd_global(uintx, DefaultMaxRAM, 32*G);
#else
// InitialCodeCacheSize derived from specjbb2000 run.
define_pd_global(intx, InitialCodeCacheSize, 1536*K); // Integral multiple of CodeCacheExpansionSize
define_pd_global(intx, ReservedCodeCacheSize, 32*M);
define_pd_global(intx, CodeCacheExpansionSize, 32*K);
// Ergonomics related flags
define_pd_global(uintx, DefaultMaxRAM, 1*G);
#endif
define_pd_global(uintx,CodeCacheMinBlockLength, 4);
// Heap related flags
define_pd_global(uintx, PermSize, ScaleForWordSize(16*M));
define_pd_global(uintx, MaxPermSize, ScaleForWordSize(64*M));
// Ergonomics related flags
define_pd_global(bool, NeverActAsServerClassMachine, false);