Mercurial > hg > truffle
annotate src/share/vm/code/compressedStream.cpp @ 10408:836a62f43af9
Merge with http://hg.openjdk.java.net/hsx/hsx25/hotspot/
| author | Doug Simon <doug.simon@oracle.com> |
|---|---|
| date | Wed, 19 Jun 2013 10:45:56 +0200 |
| parents | 47bc9800972c |
| children | de6a9e811145 |
| rev | line source |
|---|---|
| 0 | 1 /* |
| 1972 | 2 * Copyright (c) 1997, 2010, Oracle and/or its affiliates. All rights reserved. |
| 0 | 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| 4 * | |
| 5 * This code is free software; you can redistribute it and/or modify it | |
| 6 * under the terms of the GNU General Public License version 2 only, as | |
| 7 * published by the Free Software Foundation. | |
| 8 * | |
| 9 * This code is distributed in the hope that it will be useful, but WITHOUT | |
| 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
| 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
| 12 * version 2 for more details (a copy is included in the LICENSE file that | |
| 13 * accompanied this code). | |
| 14 * | |
| 15 * You should have received a copy of the GNU General Public License version | |
| 16 * 2 along with this work; if not, write to the Free Software Foundation, | |
| 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | |
| 18 * | |
|
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
| 0 | 22 * |
| 23 */ | |
| 24 | |
| 1972 | 25 #include "precompiled.hpp" |
| 26 #include "code/compressedStream.hpp" | |
| 27 #include "utilities/ostream.hpp" | |
| 0 | 28 |
| 29 // 32-bit one-to-one sign encoding taken from Pack200 | |
| 30 // converts leading sign bits into leading zeroes with trailing sign bit | |
| 31 inline juint CompressedStream::encode_sign(jint value) { | |
| 32 return (value << 1) ^ (value >> 31); | |
| 33 } | |
| 34 inline jint CompressedStream::decode_sign(juint value) { | |
| 35 return (value >> 1) ^ -(jint)(value & 1); | |
| 36 } | |
| 37 | |
| 38 // 32-bit self-inverse encoding of float bits | |
| 39 // converts trailing zeroes (common in floats) to leading zeroes | |
| 40 inline juint CompressedStream::reverse_int(juint i) { | |
| 41 // Hacker's Delight, Figure 7-1 | |
| 42 i = (i & 0x55555555) << 1 | (i >> 1) & 0x55555555; | |
| 43 i = (i & 0x33333333) << 2 | (i >> 2) & 0x33333333; | |
| 44 i = (i & 0x0f0f0f0f) << 4 | (i >> 4) & 0x0f0f0f0f; | |
| 45 i = (i << 24) | ((i & 0xff00) << 8) | ((i >> 8) & 0xff00) | (i >> 24); | |
| 46 return i; | |
| 47 } | |
| 48 | |
| 49 | |
| 50 jint CompressedReadStream::read_signed_int() { | |
| 51 return decode_sign(read_int()); | |
| 52 } | |
| 53 | |
| 54 // Compressing floats is simple, because the only common pattern | |
| 55 // is trailing zeroes. (Compare leading sign bits on ints.) | |
| 56 // Since floats are left-justified, as opposed to right-justified | |
| 57 // ints, we can bit-reverse them in order to take advantage of int | |
| 58 // compression. | |
| 59 | |
| 60 jfloat CompressedReadStream::read_float() { | |
| 61 int rf = read_int(); | |
| 62 int f = reverse_int(rf); | |
| 63 return jfloat_cast(f); | |
| 64 } | |
| 65 | |
| 66 jdouble CompressedReadStream::read_double() { | |
| 67 jint rh = read_int(); | |
| 68 jint rl = read_int(); | |
| 69 jint h = reverse_int(rh); | |
| 70 jint l = reverse_int(rl); | |
| 71 return jdouble_cast(jlong_from(h, l)); | |
| 72 } | |
| 73 | |
| 74 jlong CompressedReadStream::read_long() { | |
| 75 jint low = read_signed_int(); | |
| 76 jint high = read_signed_int(); | |
| 77 return jlong_from(high, low); | |
| 78 } | |
| 79 | |
| 80 CompressedWriteStream::CompressedWriteStream(int initial_size) : CompressedStream(NULL, 0) { | |
| 81 _buffer = NEW_RESOURCE_ARRAY(u_char, initial_size); | |
| 82 _size = initial_size; | |
| 83 _position = 0; | |
| 84 } | |
| 85 | |
| 86 void CompressedWriteStream::grow() { | |
| 87 u_char* _new_buffer = NEW_RESOURCE_ARRAY(u_char, _size * 2); | |
| 88 memcpy(_new_buffer, _buffer, _position); | |
| 89 _buffer = _new_buffer; | |
| 90 _size = _size * 2; | |
| 91 } | |
| 92 | |
| 93 void CompressedWriteStream::write_signed_int(jint value) { | |
| 94 // this encoding, called SIGNED5, is taken from Pack200 | |
| 95 write_int(encode_sign(value)); | |
| 96 } | |
| 97 | |
| 98 void CompressedWriteStream::write_float(jfloat value) { | |
| 99 juint f = jint_cast(value); | |
| 100 juint rf = reverse_int(f); | |
| 101 assert(f == reverse_int(rf), "can re-read same bits"); | |
| 102 write_int(rf); | |
| 103 } | |
| 104 | |
| 105 void CompressedWriteStream::write_double(jdouble value) { | |
| 106 juint h = high(jlong_cast(value)); | |
| 107 juint l = low( jlong_cast(value)); | |
| 108 juint rh = reverse_int(h); | |
| 109 juint rl = reverse_int(l); | |
| 110 assert(h == reverse_int(rh), "can re-read same bits"); | |
| 111 assert(l == reverse_int(rl), "can re-read same bits"); | |
| 112 write_int(rh); | |
| 113 write_int(rl); | |
| 114 } | |
| 115 | |
| 116 void CompressedWriteStream::write_long(jlong value) { | |
| 117 write_signed_int(low(value)); | |
| 118 write_signed_int(high(value)); | |
| 119 } | |
| 120 | |
| 121 | |
| 122 /// The remaining details | |
| 123 | |
| 124 #ifndef PRODUCT | |
| 125 // set this to trigger unit test | |
| 126 void test_compressed_stream(int trace); | |
| 127 bool test_compressed_stream_enabled = false; | |
| 128 #endif | |
| 129 | |
| 130 // This encoding, called UNSIGNED5, is taken from J2SE Pack200. | |
| 131 // It assumes that most values have lots of leading zeroes. | |
| 132 // Very small values, in the range [0..191], code in one byte. | |
| 133 // Any 32-bit value (including negatives) can be coded, in | |
| 134 // up to five bytes. The grammar is: | |
| 135 // low_byte = [0..191] | |
| 136 // high_byte = [192..255] | |
| 137 // any_byte = low_byte | high_byte | |
| 138 // coding = low_byte | |
| 139 // | high_byte low_byte | |
| 140 // | high_byte high_byte low_byte | |
| 141 // | high_byte high_byte high_byte low_byte | |
| 142 // | high_byte high_byte high_byte high_byte any_byte | |
| 143 // Each high_byte contributes six bits of payload. | |
| 144 // The encoding is one-to-one (except for integer overflow) | |
| 145 // and easy to parse and unparse. | |
| 146 | |
| 147 jint CompressedReadStream::read_int_mb(jint b0) { | |
| 148 int pos = position() - 1; | |
| 149 u_char* buf = buffer() + pos; | |
| 150 assert(buf[0] == b0 && b0 >= L, "correctly called"); | |
| 151 jint sum = b0; | |
| 152 // must collect more bytes: b[1]...b[4] | |
| 153 int lg_H_i = lg_H; | |
| 154 for (int i = 0; ; ) { | |
| 155 jint b_i = buf[++i]; // b_i = read(); ++i; | |
| 156 sum += b_i << lg_H_i; // sum += b[i]*(64**i) | |
| 157 if (b_i < L || i == MAX_i) { | |
| 158 set_position(pos+i+1); | |
| 159 return sum; | |
| 160 } | |
| 161 lg_H_i += lg_H; | |
| 162 } | |
| 163 } | |
| 164 | |
| 165 void CompressedWriteStream::write_int_mb(jint value) { | |
| 166 debug_only(int pos1 = position()); | |
| 167 juint sum = value; | |
| 168 for (int i = 0; ; ) { | |
| 169 if (sum < L || i == MAX_i) { | |
| 170 // remainder is either a "low code" or the 5th byte | |
| 171 assert(sum == (u_char)sum, "valid byte"); | |
| 172 write((u_char)sum); | |
| 173 break; | |
| 174 } | |
| 175 sum -= L; | |
| 176 int b_i = L + (sum % H); // this is a "high code" | |
| 177 sum >>= lg_H; // extracted 6 bits | |
| 178 write(b_i); ++i; | |
| 179 } | |
| 180 | |
| 181 #ifndef PRODUCT | |
| 182 if (test_compressed_stream_enabled) { // hack to enable this stress test | |
| 183 test_compressed_stream_enabled = false; | |
| 184 test_compressed_stream(0); | |
| 185 } | |
| 186 #endif | |
| 187 } | |
| 188 | |
| 189 | |
| 190 #ifndef PRODUCT | |
| 191 /// a unit test (can be run by hand from a debugger) | |
| 192 | |
| 193 // Avoid a VS2005 compiler stack overflow w/ fastdebug build. | |
| 194 // The following pragma optimize turns off optimization ONLY | |
| 195 // for this block (a matching directive turns it back on later). | |
| 196 // These directives can be removed once the MS VS.NET 2005 | |
| 197 // compiler stack overflow is fixed. | |
| 8721 | 198 #if defined(_MSC_VER) && _MSC_VER >=1400 && !defined(_WIN64) |
| 0 | 199 #pragma optimize("", off) |
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200 #pragma warning(disable: 4748) |
| 0 | 201 #endif |
| 202 | |
| 203 // generator for an "interesting" set of critical values | |
| 204 enum { stretch_limit = (1<<16) * (64-16+1) }; | |
| 205 static jlong stretch(jint x, int bits) { | |
| 206 // put x[high 4] into place | |
| 207 jlong h = (jlong)((x >> (16-4))) << (bits - 4); | |
| 208 // put x[low 12] into place, sign extended | |
| 209 jlong l = ((jlong)x << (64-12)) >> (64-12); | |
| 210 // move l upwards, maybe | |
| 211 l <<= (x >> 16); | |
| 212 return h ^ l; | |
| 213 } | |
| 214 | |
| 215 void test_compressed_stream(int trace) { | |
| 216 CompressedWriteStream bytes(stretch_limit * 100); | |
| 217 jint n; | |
| 218 int step = 0, fails = 0; | |
| 219 #define CHECKXY(x, y, fmt) { \ | |
| 220 ++step; \ | |
| 221 int xlen = (pos = decode.position()) - lastpos; lastpos = pos; \ | |
| 222 if (trace > 0 && (step % trace) == 0) { \ | |
| 223 tty->print_cr("step %d, n=%08x: value=" fmt " (len=%d)", \ | |
| 224 step, n, x, xlen); } \ | |
| 225 if (x != y) { \ | |
| 226 tty->print_cr("step %d, n=%d: " fmt " != " fmt, step, n, x, y); \ | |
| 227 fails++; \ | |
| 228 } } | |
| 229 for (n = 0; n < (1<<8); n++) { | |
| 230 jbyte x = (jbyte)n; | |
| 231 bytes.write_byte(x); ++step; | |
| 232 } | |
| 233 for (n = 0; n < stretch_limit; n++) { | |
| 234 jint x = (jint)stretch(n, 32); | |
| 235 bytes.write_int(x); ++step; | |
| 236 bytes.write_signed_int(x); ++step; | |
| 237 bytes.write_float(jfloat_cast(x)); ++step; | |
| 238 } | |
| 239 for (n = 0; n < stretch_limit; n++) { | |
| 240 jlong x = stretch(n, 64); | |
| 241 bytes.write_long(x); ++step; | |
| 242 bytes.write_double(jdouble_cast(x)); ++step; | |
| 243 } | |
| 244 int length = bytes.position(); | |
| 245 if (trace != 0) | |
| 246 tty->print_cr("set up test of %d stream values, size %d", step, length); | |
| 247 step = 0; | |
| 248 // now decode it all | |
| 249 CompressedReadStream decode(bytes.buffer()); | |
| 250 int pos, lastpos = decode.position(); | |
| 251 for (n = 0; n < (1<<8); n++) { | |
| 252 jbyte x = (jbyte)n; | |
| 253 jbyte y = decode.read_byte(); | |
| 254 CHECKXY(x, y, "%db"); | |
| 255 } | |
| 256 for (n = 0; n < stretch_limit; n++) { | |
| 257 jint x = (jint)stretch(n, 32); | |
| 258 jint y1 = decode.read_int(); | |
| 259 CHECKXY(x, y1, "%du"); | |
| 260 jint y2 = decode.read_signed_int(); | |
| 261 CHECKXY(x, y2, "%di"); | |
| 262 jint y3 = jint_cast(decode.read_float()); | |
| 263 CHECKXY(x, y3, "%df"); | |
| 264 } | |
| 265 for (n = 0; n < stretch_limit; n++) { | |
| 266 jlong x = stretch(n, 64); | |
| 267 jlong y1 = decode.read_long(); | |
| 268 CHECKXY(x, y1, INT64_FORMAT "l"); | |
| 269 jlong y2 = jlong_cast(decode.read_double()); | |
| 270 CHECKXY(x, y2, INT64_FORMAT "d"); | |
| 271 } | |
| 272 int length2 = decode.position(); | |
| 273 if (trace != 0) | |
| 274 tty->print_cr("finished test of %d stream values, size %d", step, length2); | |
| 275 guarantee(length == length2, "bad length"); | |
| 276 guarantee(fails == 0, "test failures"); | |
| 277 } | |
| 278 | |
| 8721 | 279 #if defined(_MSC_VER) &&_MSC_VER >=1400 && !defined(_WIN64) |
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280 #pragma warning(default: 4748) |
| 0 | 281 #pragma optimize("", on) |
| 282 #endif | |
| 283 | |
| 284 #endif // PRODUCT |