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      1 //===-- xray_utils.h --------------------------------------------*- C++ -*-===//
      2 //
      3 //                     The LLVM Compiler Infrastructure
      4 //
      5 // This file is distributed under the University of Illinois Open Source
      6 // License. See LICENSE.TXT for details.
      7 //
      8 //===----------------------------------------------------------------------===//
      9 //
     10 // This file is a part of XRay, a dynamic runtime instrumentation system.
     11 //
     12 // Some shared utilities for the XRay runtime implementation.
     13 //
     14 //===----------------------------------------------------------------------===//
     15 #ifndef XRAY_UTILS_H
     16 #define XRAY_UTILS_H
     17 
     18 #include <cstddef>
     19 #include <cstdint>
     20 #include <sys/types.h>
     21 #include <utility>
     22 
     23 #include "sanitizer_common/sanitizer_common.h"
     24 #if SANITIZER_FUCHSIA
     25 #include <zircon/types.h>
     26 #endif
     27 
     28 namespace __xray {
     29 
     30 class LogWriter {
     31 public:
     32 #if SANITIZER_FUCHSIA
     33  LogWriter(zx_handle_t Vmo) : Vmo(Vmo) {}
     34 #else
     35   explicit LogWriter(int Fd) : Fd(Fd) {}
     36 #endif
     37  ~LogWriter();
     38 
     39  // Write a character range into a log.
     40  void WriteAll(const char *Begin, const char *End);
     41 
     42  void Flush();
     43 
     44  // Returns a new log instance initialized using the flag-provided values.
     45  static LogWriter *Open();
     46  // Closes and deallocates the log instance.
     47  static void Close(LogWriter *LogWriter);
     48 
     49 private:
     50 #if SANITIZER_FUCHSIA
     51  zx_handle_t Vmo = ZX_HANDLE_INVALID;
     52  uint64_t Offset = 0;
     53 #else
     54  int Fd = -1;
     55 #endif
     56 };
     57 
     58 constexpr size_t gcd(size_t a, size_t b) {
     59   return (b == 0) ? a : gcd(b, a % b);
     60 }
     61 
     62 constexpr size_t lcm(size_t a, size_t b) { return a * b / gcd(a, b); }
     63 
     64 constexpr size_t nearest_boundary(size_t number, size_t multiple) {
     65   return multiple * ((number / multiple) + (number % multiple ? 1 : 0));
     66 }
     67 
     68 constexpr size_t next_pow2_helper(size_t num, size_t acc) {
     69   return (1u << acc) >= num ? (1u << acc) : next_pow2_helper(num, acc + 1);
     70 }
     71 
     72 constexpr size_t next_pow2(size_t number) {
     73   return next_pow2_helper(number, 1);
     74 }
     75 
     76 template <class T> constexpr T &max(T &A, T &B) { return A > B ? A : B; }
     77 
     78 template <class T> constexpr T &min(T &A, T &B) { return A <= B ? A : B; }
     79 
     80 constexpr ptrdiff_t diff(uintptr_t A, uintptr_t B) {
     81   return max(A, B) - min(A, B);
     82 }
     83 
     84 } // namespace __xray
     85 
     86 #endif // XRAY_UTILS_H
     87