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() {}
27 
28 void CodeGenCoverage::setCovered(uint64_t RuleID) {
29   if (RuleCoverage.size() <= RuleID)
30     RuleCoverage.resize(RuleID + 1, 0);
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 = support::endian::read64(CurPtr, support::native);
62       CurPtr += 8;
63 
64       // ~0ull terminates the rule id list.
65       if (RuleID == ~0ull)
66         break;
67 
68       // Anything else, is recorded or ignored depending on whether it's
69       // intended for the backend we're interested in.
70       if (IsForThisBackend)
71         setCovered(RuleID);
72     }
73   }
74 
75   return true;
76 }
77 
78 bool CodeGenCoverage::emit(StringRef CoveragePrefix,
79                            StringRef BackendName) const {
80   if (!CoveragePrefix.empty() && !RuleCoverage.empty()) {
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); }
112