llvm/lib/Support/CodeGenCoverage.cpp

   1 //===- lib/Support/CodeGenCoverage.cpp -------------------------------------==//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 /// \file
   9 /// This file implements the CodeGenCoverage class.
  10 //===----------------------------------------------------------------------===//
  11
  12 #include "llvm/Support/CodeGenCoverage.h"
  13
  14 #include "llvm/Support/Endian.h"
  15 #include "llvm/Support/FileSystem.h"
  16 #include "llvm/Support/MemoryBuffer.h"
  17 #include "llvm/Support/Mutex.h"
  18 #include "llvm/Support/Process.h"
  19 #include "llvm/Support/ScopedPrinter.h"
  20 #include "llvm/Support/ToolOutputFile.h"
  21
  22 using namespace llvm;
  23
  24 CodeGenCoverage::CodeGenCoverage() = default;
  25
  26 void CodeGenCoverage::setCovered(uint64_t RuleID) {
  27   if (RuleCoverage.size() <= RuleID)
  28     RuleCoverage.resize(RuleID + 1, false);
  29   RuleCoverage[RuleID] = true;
  30 }
  31
  32 bool CodeGenCoverage::isCovered(uint64_t RuleID) const {
  33   if (RuleCoverage.size() <= RuleID)
  34     return false;
  35   return RuleCoverage[RuleID];
  36 }
  37
  38 iterator_range<CodeGenCoverage::const_covered_iterator>
  39 CodeGenCoverage::covered() const {
  40   return RuleCoverage.set_bits();
  41 }
  42
  43 bool CodeGenCoverage::parse(MemoryBuffer &Buffer, StringRef BackendName) {
  44   const char *CurPtr = Buffer.getBufferStart();
  45
  46   while (CurPtr != Buffer.getBufferEnd()) {
  47     // Read the backend name from the input.
  48     const char *LexedBackendName = CurPtr;
  49     while (*CurPtr++ != 0)
  50       ;
  51     if (CurPtr == Buffer.getBufferEnd())
  52       return false; // Data is invalid, expected rule id's to follow.
  53
  54     bool IsForThisBackend = BackendName == LexedBackendName;
  55     while (CurPtr != Buffer.getBufferEnd()) {
  56       if (std::distance(CurPtr, Buffer.getBufferEnd()) < 8)
  57         return false; // Data is invalid. Not enough bytes for another rule id.
  58
  59       uint64_t RuleID =
  60           support::endian::read64(CurPtr, llvm::endianness::native);
  61       CurPtr += 8;
  62
  63       // ~0ull terminates the rule id list.
  64       if (RuleID == ~0ull)
  65         break;
  66
  67       // Anything else, is recorded or ignored depending on whether it's
  68       // intended for the backend we're interested in.
  69       if (IsForThisBackend)
  70         setCovered(RuleID);
  71     }
  72   }
  73
  74   return true;
  75 }
  76
  77 bool CodeGenCoverage::emit(StringRef CoveragePrefix,
  78                            StringRef BackendName) const {
  79   if (!CoveragePrefix.empty() && !RuleCoverage.empty()) {
  80     static sys::SmartMutex<true> OutputMutex;
  81     sys::SmartScopedLock<true> Lock(OutputMutex);
  82
  83     // We can handle locking within a process easily enough but we don't want to
  84     // manage it between multiple processes. Use the process ID to ensure no
  85     // more than one process is ever writing to the same file at the same time.
  86     std::string Pid = llvm::to_string(sys::Process::getProcessId());
  87
  88     std::string CoverageFilename = (CoveragePrefix + Pid).str();
  89
  90     std::error_code EC;
  91     sys::fs::OpenFlags OpenFlags = sys::fs::OF_Append;
  92     std::unique_ptr<ToolOutputFile> CoverageFile =
  93         std::make_unique<ToolOutputFile>(CoverageFilename, EC, OpenFlags);
  94     if (EC)
  95       return false;
  96
  97     uint64_t Zero = 0;
  98     uint64_t InvZero = ~0ull;
  99     CoverageFile->os() << BackendName;
 100     CoverageFile->os().write((const char *)&Zero, sizeof(unsigned char));
 101     for (uint64_t I : RuleCoverage.set_bits())
 102       CoverageFile->os().write((const char *)&I, sizeof(uint64_t));
 103     CoverageFile->os().write((const char *)&InvZero, sizeof(uint64_t));
 104
 105     CoverageFile->keep();
 106   }
 107
 108   return true;
 109 }
 110
 111 void CodeGenCoverage::reset() { RuleCoverage.resize(0); }