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