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Issue 1024203002: Move some flag-like props from GlobalContext and TargetLowering to ClFlags. (Closed) Base URL: https://chromium.googlesource.com/native_client/pnacl-subzero.git@master
Patch Set: review / clean up formatting Created 5 years, 9 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 // This file implements the random number generator. 10 // This file implements the random number generator.
11 // 11 //
12 //===----------------------------------------------------------------------===// 12 //===----------------------------------------------------------------------===//
13 13
14 #include <time.h> 14 #include <time.h>
15 15
16 #include "llvm/Support/CommandLine.h"
17
18 #include "IceRNG.h" 16 #include "IceRNG.h"
19 17
20 namespace Ice { 18 namespace Ice {
21 19
22 namespace { 20 namespace {
23 namespace cl = llvm::cl;
24
25 // TODO(stichnot): See if we can easily use LLVM's -rng-seed option
26 // and implementation. I expect the implementation is different and
27 // therefore the tests would need to be changed.
28 cl::opt<unsigned long long>
29 RandomSeed("sz-seed", cl::desc("Seed the random number generator"),
30 cl::init(time(0)));
31
32 const unsigned MAX = 2147483647; 21 const unsigned MAX = 2147483647;
33
34 } // end of anonymous namespace 22 } // end of anonymous namespace
35 23
36 // TODO(wala,stichnot): Switch to RNG implementation from LLVM or C++11. 24 // TODO(wala,stichnot): Switch to RNG implementation from LLVM or C++11.
37 // 25 //
38 // TODO(wala,stichnot): Make it possible to replay the RNG sequence in a 26 // TODO(wala,stichnot): Make it possible to replay the RNG sequence in a
39 // subsequent run, for reproducing a bug. Print the seed in a comment 27 // subsequent run, for reproducing a bug. Print the seed in a comment
40 // in the asm output. Embed the seed in the binary via metadata that an 28 // in the asm output. Embed the seed in the binary via metadata that an
41 // attacker can't introspect. 29 // attacker can't introspect.
42 RandomNumberGenerator::RandomNumberGenerator(llvm::StringRef) 30 RandomNumberGenerator::RandomNumberGenerator(uint64_t Seed, llvm::StringRef)
43 : State(RandomSeed) {} 31 : State(Seed) {}
44 32
45 uint64_t RandomNumberGenerator::next(uint64_t Max) { 33 uint64_t RandomNumberGenerator::next(uint64_t Max) {
46 // Lewis, Goodman, and Miller (1969) 34 // Lewis, Goodman, and Miller (1969)
47 State = (16807 * State) % MAX; 35 State = (16807 * State) % MAX;
48 return State % Max; 36 return State % Max;
49 } 37 }
50 38
51 bool RandomNumberGeneratorWrapper::getTrueWithProbability(float Probability) { 39 bool RandomNumberGeneratorWrapper::getTrueWithProbability(float Probability) {
52 return RNG.next(MAX) < Probability * MAX; 40 return RNG.next(MAX) < Probability * MAX;
53 } 41 }
54 42
55 } // end of namespace Ice 43 } // end of namespace Ice
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