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f76f315436
Summary:
This patch adds a LLVM_ENABLE_GISEL_COV which, like LLVM_ENABLE_DAGISEL_COV,
causes TableGen to instrument the generated table to collect rule coverage
information. However, LLVM_ENABLE_GISEL_COV goes a bit further than
LLVM_ENABLE_DAGISEL_COV. The information is written to files
(${CMAKE_BINARY_DIR}/gisel-coverage-* by default). These files can then be
concatenated into ${LLVM_GISEL_COV_PREFIX}-all after which TableGen will
read this information and use it to emit warnings about untested rules.
This technique could also be used by SelectionDAG and can be further
extended to detect hot rules and give them priority over colder rules.
Usage:
* Enable LLVM_ENABLE_GISEL_COV in CMake
* Build the compiler and run some tests
* cat gisel-coverage-[0-9]* > gisel-coverage-all
* Delete lib/Target/*/*GenGlobalISel.inc*
* Build the compiler
Known issues:
* ${LLVM_GISEL_COV_PREFIX}-all must be generated as a manual
step due to a lack of a portable 'cat' command. It should be the
concatenation of all ${LLVM_GISEL_COV_PREFIX}-[0-9]* files.
* There's no mechanism to discard coverage information when the ruleset
changes
Depends on D39742
Reviewers: ab, qcolombet, t.p.northover, aditya_nandakumar, rovka
Reviewed By: rovka
Subscribers: vsk, arsenm, nhaehnle, mgorny, kristof.beyls, javed.absar, igorb, llvm-commits
Differential Revision: https://reviews.llvm.org/D39747
llvm-svn: 318356
119 lines
3.6 KiB
C++
119 lines
3.6 KiB
C++
//===- lib/Support/CodeGenCoverage.cpp -------------------------------------==//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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/// \file
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/// This file implements the CodeGenCoverage class.
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//===----------------------------------------------------------------------===//
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#include "llvm/Support/CodeGenCoverage.h"
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#include "llvm/Support/Endian.h"
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#include "llvm/Support/FileSystem.h"
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#include "llvm/Support/Mutex.h"
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#include "llvm/Support/ScopedPrinter.h"
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#include "llvm/Support/ToolOutputFile.h"
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#if LLVM_ON_UNIX
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#include <unistd.h>
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#elif LLVM_ON_WIN32
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#include <windows.h>
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#endif
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using namespace llvm;
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static sys::SmartMutex<true> OutputMutex;
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CodeGenCoverage::CodeGenCoverage() {}
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void CodeGenCoverage::setCovered(uint64_t RuleID) {
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if (RuleCoverage.size() <= RuleID)
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RuleCoverage.resize(RuleID + 1, 0);
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RuleCoverage[RuleID] = true;
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}
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bool CodeGenCoverage::isCovered(uint64_t RuleID) {
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if (RuleCoverage.size() <= RuleID)
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return false;
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return RuleCoverage[RuleID];
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}
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bool CodeGenCoverage::parse(MemoryBuffer &Buffer, StringRef BackendName) {
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const char *CurPtr = Buffer.getBufferStart();
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while (CurPtr != Buffer.getBufferEnd()) {
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// Read the backend name from the input.
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const char *LexedBackendName = CurPtr;
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while (*CurPtr++ != 0)
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;
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if (CurPtr == Buffer.getBufferEnd())
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return false; // Data is invalid, expected rule id's to follow.
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bool IsForThisBackend = BackendName.equals(LexedBackendName);
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while (CurPtr != Buffer.getBufferEnd()) {
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if (std::distance(CurPtr, Buffer.getBufferEnd()) < 8)
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return false; // Data is invalid. Not enough bytes for another rule id.
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uint64_t RuleID = support::endian::read64(CurPtr, support::native);
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CurPtr += 8;
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// ~0ull terminates the rule id list.
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if (RuleID == ~0ull)
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break;
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// Anything else, is recorded or ignored depending on whether it's
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// intended for the backend we're interested in.
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if (IsForThisBackend)
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setCovered(RuleID);
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}
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}
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return true;
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}
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bool CodeGenCoverage::emit(StringRef CoveragePrefix,
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StringRef BackendName) const {
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if (!CoveragePrefix.empty() && !RuleCoverage.empty()) {
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sys::SmartScopedLock<true> Lock(OutputMutex);
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// We can handle locking within a process easily enough but we don't want to
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// manage it between multiple processes. Use the process ID to ensure no
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// more than one process is ever writing to the same file at the same time.
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std::string Pid =
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#if LLVM_ON_UNIX
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llvm::to_string(::getpid());
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#elif LLVM_ON_WIN32
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llvm::to_string(::GetCurrentProcessId());
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#else
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"";
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#endif
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std::string CoverageFilename = (CoveragePrefix + Pid).str();
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std::error_code EC;
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sys::fs::OpenFlags OpenFlags = sys::fs::F_Append;
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std::unique_ptr<ToolOutputFile> CoverageFile =
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llvm::make_unique<ToolOutputFile>(CoverageFilename, EC, OpenFlags);
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if (EC)
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return false;
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uint64_t Zero = 0;
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uint64_t InvZero = ~0ull;
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CoverageFile->os() << BackendName;
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CoverageFile->os().write((const char *)&Zero, sizeof(unsigned char));
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for (uint64_t I : RuleCoverage.set_bits())
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CoverageFile->os().write((const char *)&I, sizeof(uint64_t));
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CoverageFile->os().write((const char *)&InvZero, sizeof(uint64_t));
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CoverageFile->keep();
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}
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return true;
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}
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void CodeGenCoverage::reset() { RuleCoverage.resize(0); }
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