jdk8-mips64-public/hotspot: src/share/vm/code/compressedStream.cpp@f90c822e73f8 (annotated)

src/share/vm/code/compressedStream.cpp@f90c822e73f8 (annotated)

src/share/vm/code/compressedStream.cpp

Wed, 27 Apr 2016 01:25:04 +0800

author: aoqi
date: Wed, 27 Apr 2016 01:25:04 +0800
changeset 0: f90c822e73f8
child 6876: 710a3c8b516e
permissions: -rw-r--r--

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http://hg.openjdk.java.net/jdk8u/jdk8u/hotspot/
changeset: 6782:28b50d07f6f8
tag: jdk8u25-b17

 /*
  * Copyright (c) 1997, 2014, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  *
  */
 #include "precompiled.hpp"
 #include "code/compressedStream.hpp"
 #include "utilities/ostream.hpp"
 // 32-bit one-to-one sign encoding taken from Pack200
 // converts leading sign bits into leading zeroes with trailing sign bit
 inline juint CompressedStream::encode_sign(jint  value) {
   return (value << 1) ^ (value >> 31);
 }
 inline jint  CompressedStream::decode_sign(juint value) {
   return (value >> 1) ^ -(jint)(value & 1);
 }
 // 32-bit self-inverse encoding of float bits
 // converts trailing zeroes (common in floats) to leading zeroes
 inline juint CompressedStream::reverse_int(juint i) {
   // Hacker's Delight, Figure 7-1
   i = (i & 0x55555555) << 1 | (i >> 1) & 0x55555555;
   i = (i & 0x33333333) << 2 | (i >> 2) & 0x33333333;
   i = (i & 0x0f0f0f0f) << 4 | (i >> 4) & 0x0f0f0f0f;
   i = (i << 24) | ((i & 0xff00) << 8) | ((i >> 8) & 0xff00) | (i >> 24);
   return i;
 }
 jint CompressedReadStream::read_signed_int() {
   return decode_sign(read_int());
 }
 // Compressing floats is simple, because the only common pattern
 // is trailing zeroes.  (Compare leading sign bits on ints.)
 // Since floats are left-justified, as opposed to right-justified
 // ints, we can bit-reverse them in order to take advantage of int
 // compression.
 jfloat CompressedReadStream::read_float() {
   int rf = read_int();
   int f  = reverse_int(rf);
   return jfloat_cast(f);
 }
 jdouble CompressedReadStream::read_double() {
   jint rh = read_int();
   jint rl = read_int();
   jint h  = reverse_int(rh);
   jint l  = reverse_int(rl);
   return jdouble_cast(jlong_from(h, l));
 }
 jlong CompressedReadStream::read_long() {
   jint low  = read_signed_int();
   jint high = read_signed_int();
   return jlong_from(high, low);
 }
 CompressedWriteStream::CompressedWriteStream(int initial_size) : CompressedStream(NULL, 0) {
   _buffer   = NEW_RESOURCE_ARRAY(u_char, initial_size);
   _size     = initial_size;
   _position = 0;
 }
 void CompressedWriteStream::grow() {
   u_char* _new_buffer = NEW_RESOURCE_ARRAY(u_char, _size * 2);
   memcpy(_new_buffer, _buffer, _position);
   _buffer = _new_buffer;
   _size   = _size * 2;
 }
 void CompressedWriteStream::write_signed_int(jint value) {
   // this encoding, called SIGNED5, is taken from Pack200
   write_int(encode_sign(value));
 }
 void CompressedWriteStream::write_float(jfloat value) {
   juint f = jint_cast(value);
   juint rf = reverse_int(f);
   assert(f == reverse_int(rf), "can re-read same bits");
   write_int(rf);
 }
 void CompressedWriteStream::write_double(jdouble value) {
   juint h  = high(jlong_cast(value));
   juint l  = low( jlong_cast(value));
   juint rh = reverse_int(h);
   juint rl = reverse_int(l);
   assert(h == reverse_int(rh), "can re-read same bits");
   assert(l == reverse_int(rl), "can re-read same bits");
   write_int(rh);
   write_int(rl);
 }
 void CompressedWriteStream::write_long(jlong value) {
   write_signed_int(low(value));
   write_signed_int(high(value));
 }
 /// The remaining details
 #ifndef PRODUCT
 // set this to trigger unit test
 void test_compressed_stream(int trace);
 bool test_compressed_stream_enabled = false;
 #endif
 // This encoding, called UNSIGNED5, is taken from J2SE Pack200.
 // It assumes that most values have lots of leading zeroes.
 // Very small values, in the range [0..191], code in one byte.
 // Any 32-bit value (including negatives) can be coded, in
 // up to five bytes.  The grammar is:
 //    low_byte  = [0..191]
 //    high_byte = [192..255]
 //    any_byte  = low_byte | high_byte
 //    coding = low_byte
 //           | high_byte low_byte
 //           | high_byte high_byte low_byte
 //           | high_byte high_byte high_byte low_byte
 //           | high_byte high_byte high_byte high_byte any_byte
 // Each high_byte contributes six bits of payload.
 // The encoding is one-to-one (except for integer overflow)
 // and easy to parse and unparse.
 jint CompressedReadStream::read_int_mb(jint b0) {
   int     pos = position() - 1;
   u_char* buf = buffer() + pos;
   assert(buf[0] == b0 && b0 >= L, "correctly called");
   jint    sum = b0;
   // must collect more bytes:  b[1]...b[4]
   int lg_H_i = lg_H;
   for (int i = 0; ; ) {
     jint b_i = buf[++i]; // b_i = read(); ++i;
     sum += b_i << lg_H_i;  // sum += b[i]*(64**i)
     if (b_i < L || i == MAX_i) {
       set_position(pos+i+1);
       return sum;
     }
     lg_H_i += lg_H;
   }
 }
 void CompressedWriteStream::write_int_mb(jint value) {
   debug_only(int pos1 = position());
   juint sum = value;
   for (int i = 0; ; ) {
     if (sum < L || i == MAX_i) {
       // remainder is either a "low code" or the 5th byte
       assert(sum == (u_char)sum, "valid byte");
       write((u_char)sum);
       break;
     }
     sum -= L;
     int b_i = L + (sum % H);  // this is a "high code"
     sum >>= lg_H;             // extracted 6 bits
     write(b_i); ++i;
   }
 #ifndef PRODUCT
   if (test_compressed_stream_enabled) {  // hack to enable this stress test
     test_compressed_stream_enabled = false;
     test_compressed_stream(0);
   }
 #endif
 }
 #ifndef PRODUCT
 /// a unit test (can be run by hand from a debugger)
 // Avoid a VS2005 compiler stack overflow w/ fastdebug build.
 // The following pragma optimize turns off optimization ONLY
 // for this block (a matching directive turns it back on later).
 // These directives can be removed once the MS VS.NET 2005
 // compiler stack overflow is fixed.
 #if defined(_MSC_VER) && _MSC_VER >=1400 && !defined(_WIN64)
 #pragma optimize("", off)
 #pragma warning(disable: 4748)
 #endif
 // generator for an "interesting" set of critical values
 enum { stretch_limit = (1<<16) * (64-16+1) };
 static jlong stretch(jint x, int bits) {
   // put x[high 4] into place
   jlong h = (jlong)((x >> (16-4))) << (bits - 4);
   // put x[low 12] into place, sign extended
   jlong l = ((jlong)x << (64-12)) >> (64-12);
   // move l upwards, maybe
   l <<= (x >> 16);
   return h ^ l;
 }
 PRAGMA_DIAG_PUSH
 PRAGMA_FORMAT_IGNORED // Someone needs to deal with this.
 void test_compressed_stream(int trace) {
   CompressedWriteStream bytes(stretch_limit * 100);
   jint n;
   int step = 0, fails = 0;
 #define CHECKXY(x, y, fmt) { \
     ++step; \
     int xlen = (pos = decode.position()) - lastpos; lastpos = pos; \
     if (trace > 0 && (step % trace) == 0) { \
       tty->print_cr("step %d, n=%08x: value=" fmt " (len=%d)", \
                     step, n, x, xlen); } \
     if (x != y) {                                                     \
       tty->print_cr("step %d, n=%d: " fmt " != " fmt, step, n, x, y); \
       fails++; \
     } }
   for (n = 0; n < (1<<8); n++) {
     jbyte x = (jbyte)n;
     bytes.write_byte(x); ++step;
   }
   for (n = 0; n < stretch_limit; n++) {
     jint x = (jint)stretch(n, 32);
     bytes.write_int(x); ++step;
     bytes.write_signed_int(x); ++step;
     bytes.write_float(jfloat_cast(x)); ++step;
   }
   for (n = 0; n < stretch_limit; n++) {
     jlong x = stretch(n, 64);
     bytes.write_long(x); ++step;
     bytes.write_double(jdouble_cast(x)); ++step;
   }
   int length = bytes.position();
   if (trace != 0)
     tty->print_cr("set up test of %d stream values, size %d", step, length);
   step = 0;
   // now decode it all
   CompressedReadStream decode(bytes.buffer());
   int pos, lastpos = decode.position();
   for (n = 0; n < (1<<8); n++) {
     jbyte x = (jbyte)n;
     jbyte y = decode.read_byte();
     CHECKXY(x, y, "%db");
   }
   for (n = 0; n < stretch_limit; n++) {
     jint x = (jint)stretch(n, 32);
     jint y1 = decode.read_int();
     CHECKXY(x, y1, "%du");
     jint y2 = decode.read_signed_int();
     CHECKXY(x, y2, "%di");
     jint y3 = jint_cast(decode.read_float());
     CHECKXY(x, y3, "%df");
   }
   for (n = 0; n < stretch_limit; n++) {
     jlong x = stretch(n, 64);
     jlong y1 = decode.read_long();
     CHECKXY(x, y1, INT64_FORMAT "l");
     jlong y2 = jlong_cast(decode.read_double());
     CHECKXY(x, y2, INT64_FORMAT "d");
   }
   int length2 = decode.position();
   if (trace != 0)
     tty->print_cr("finished test of %d stream values, size %d", step, length2);
   guarantee(length == length2, "bad length");
   guarantee(fails == 0, "test failures");
 }
 PRAGMA_DIAG_POP
 #if defined(_MSC_VER) &&_MSC_VER >=1400 && !defined(_WIN64)
 #pragma warning(default: 4748)
 #pragma optimize("", on)
 #endif
 #endif // PRODUCT

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/code/compressedStream.cpp@f90c822e73f8 (annotated)

src/share/vm/code/compressedStream.cpp