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Issue 1341423002: Reflow comments to use the full width. (Closed) Base URL: https://chromium.googlesource.com/native_client/pnacl-subzero.git@master
Patch Set: Fix spelling and rebase Created 5 years, 3 months ago
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1 //===- subzero/src/IceRNG.cpp - PRNG implementation -----------------------===// 1 //===- subzero/src/IceRNG.cpp - PRNG implementation -----------------------===//
2 // 2 //
3 // The Subzero Code Generator 3 // The Subzero Code Generator
4 // 4 //
5 // This file is distributed under the University of Illinois Open Source 5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details. 6 // License. See LICENSE.TXT for details.
7 // 7 //
8 //===----------------------------------------------------------------------===// 8 //===----------------------------------------------------------------------===//
9 /// 9 ///
10 /// \file 10 /// \file
11 /// This file implements the random number generator. 11 /// This file implements the random number generator.
12 /// 12 ///
13 //===----------------------------------------------------------------------===// 13 //===----------------------------------------------------------------------===//
14 14
15 #include "IceRNG.h" 15 #include "IceRNG.h"
16 16
17 #include <ctime> 17 #include <ctime>
18 18
19 namespace Ice { 19 namespace Ice {
20 20
21 namespace { 21 namespace {
22 constexpr unsigned MAX = 2147483647; 22 constexpr unsigned MAX = 2147483647;
23 } // end of anonymous namespace 23 } // end of anonymous namespace
24 24
25 // TODO(wala,stichnot): Switch to RNG implementation from LLVM or C++11. 25 // TODO(wala,stichnot): Switch to RNG implementation from LLVM or C++11.
26 // 26 //
27 // TODO(wala,stichnot): Make it possible to replay the RNG sequence in a 27 // TODO(wala,stichnot): Make it possible to replay the RNG sequence in a
28 // subsequent run, for reproducing a bug. Print the seed in a comment 28 // subsequent run, for reproducing a bug. Print the seed in a comment in the
29 // in the asm output. Embed the seed in the binary via metadata that an 29 // asm output. Embed the seed in the binary via metadata that an attacker can't
30 // attacker can't introspect. 30 // introspect.
31 RandomNumberGenerator::RandomNumberGenerator(uint64_t Seed, llvm::StringRef) 31 RandomNumberGenerator::RandomNumberGenerator(uint64_t Seed, llvm::StringRef)
32 : State(Seed) {} 32 : State(Seed) {}
33 33
34 RandomNumberGenerator::RandomNumberGenerator( 34 RandomNumberGenerator::RandomNumberGenerator(
35 uint64_t Seed, RandomizationPassesEnum RandomizationPassID, uint64_t Salt) { 35 uint64_t Seed, RandomizationPassesEnum RandomizationPassID, uint64_t Salt) {
36 constexpr unsigned NumBitsGlobalSeed = CHAR_BIT * sizeof(State); 36 constexpr unsigned NumBitsGlobalSeed = CHAR_BIT * sizeof(State);
37 constexpr unsigned NumBitsPassID = 4; 37 constexpr unsigned NumBitsPassID = 4;
38 constexpr unsigned NumBitsSalt = 12; 38 constexpr unsigned NumBitsSalt = 12;
39 static_assert(RPE_num < (1 << NumBitsPassID), "NumBitsPassID too small"); 39 static_assert(RPE_num < (1 << NumBitsPassID), "NumBitsPassID too small");
40 State = Seed ^ ((uint64_t)RandomizationPassID 40 State = Seed ^ ((uint64_t)RandomizationPassID
41 << (NumBitsGlobalSeed - NumBitsPassID)) ^ 41 << (NumBitsGlobalSeed - NumBitsPassID)) ^
42 (Salt << (NumBitsGlobalSeed - NumBitsPassID - NumBitsSalt)); 42 (Salt << (NumBitsGlobalSeed - NumBitsPassID - NumBitsSalt));
43 } 43 }
44 uint64_t RandomNumberGenerator::next(uint64_t Max) { 44 uint64_t RandomNumberGenerator::next(uint64_t Max) {
45 // Lewis, Goodman, and Miller (1969) 45 // Lewis, Goodman, and Miller (1969)
46 State = (16807 * State) % MAX; 46 State = (16807 * State) % MAX;
47 return State % Max; 47 return State % Max;
48 } 48 }
49 49
50 bool RandomNumberGeneratorWrapper::getTrueWithProbability(float Probability) { 50 bool RandomNumberGeneratorWrapper::getTrueWithProbability(float Probability) {
51 return RNG.next(MAX) < Probability * MAX; 51 return RNG.next(MAX) < Probability * MAX;
52 } 52 }
53 53
54 } // end of namespace Ice 54 } // end of namespace Ice
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