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llvm-mirror/lib/TableGen/Main.cpp
Chandler Carruth 5b6b9b3232 Revert r330742: Let TableGen write output only if it changed, instead of doing so in cmake.
This change causes us to re-run tablegen for every single target on
every single build. This is much, much worse than the problem being
fixed AFAICT.

On my system, it makes a clean rebuild of `llc` with nothing changed go
from .5s to over 8s. On systems with less parallelism, slower file
systems, or high process startup overhead this will be even more
extreme.

The only way I see this could be a win is in clean builds where we churn
the filesystem. But I think incremental rebuild is more important, and
so if we want to re-instate this, it needs to be done in a way that
doesn't trigger constant re-runs of tablegen.

llvm-svn: 331702
2018-05-07 23:41:48 +00:00

119 lines
3.8 KiB
C++

//===- Main.cpp - Top-Level TableGen implementation -----------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// TableGen is a tool which can be used to build up a description of something,
// then invoke one or more "tablegen backends" to emit information about the
// description in some predefined format. In practice, this is used by the LLVM
// code generators to automate generation of a code generator through a
// high-level description of the target.
//
//===----------------------------------------------------------------------===//
#include "llvm/TableGen/Main.h"
#include "TGParser.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/ToolOutputFile.h"
#include "llvm/TableGen/Error.h"
#include "llvm/TableGen/Record.h"
#include <algorithm>
#include <cstdio>
#include <system_error>
using namespace llvm;
static cl::opt<std::string>
OutputFilename("o", cl::desc("Output filename"), cl::value_desc("filename"),
cl::init("-"));
static cl::opt<std::string>
DependFilename("d",
cl::desc("Dependency filename"),
cl::value_desc("filename"),
cl::init(""));
static cl::opt<std::string>
InputFilename(cl::Positional, cl::desc("<input file>"), cl::init("-"));
static cl::list<std::string>
IncludeDirs("I", cl::desc("Directory of include files"),
cl::value_desc("directory"), cl::Prefix);
static int reportError(const char *ProgName, Twine Msg) {
errs() << ProgName << ": " << Msg;
errs().flush();
return 1;
}
/// Create a dependency file for `-d` option.
///
/// This functionality is really only for the benefit of the build system.
/// It is similar to GCC's `-M*` family of options.
static int createDependencyFile(const TGParser &Parser, const char *argv0) {
if (OutputFilename == "-")
return reportError(argv0, "the option -d must be used together with -o\n");
std::error_code EC;
ToolOutputFile DepOut(DependFilename, EC, sys::fs::F_Text);
if (EC)
return reportError(argv0, "error opening " + DependFilename + ":" +
EC.message() + "\n");
DepOut.os() << OutputFilename << ":";
for (const auto &Dep : Parser.getDependencies()) {
DepOut.os() << ' ' << Dep.first;
}
DepOut.os() << "\n";
DepOut.keep();
return 0;
}
int llvm::TableGenMain(char *argv0, TableGenMainFn *MainFn) {
RecordKeeper Records;
// Parse the input file.
ErrorOr<std::unique_ptr<MemoryBuffer>> FileOrErr =
MemoryBuffer::getFileOrSTDIN(InputFilename);
if (std::error_code EC = FileOrErr.getError())
return reportError(argv0, "Could not open input file '" + InputFilename +
"': " + EC.message() + "\n");
// Tell SrcMgr about this buffer, which is what TGParser will pick up.
SrcMgr.AddNewSourceBuffer(std::move(*FileOrErr), SMLoc());
// Record the location of the include directory so that the lexer can find
// it later.
SrcMgr.setIncludeDirs(IncludeDirs);
TGParser Parser(SrcMgr, Records);
if (Parser.ParseFile())
return 1;
std::error_code EC;
ToolOutputFile Out(OutputFilename, EC, sys::fs::F_Text);
if (EC)
return reportError(argv0, "error opening " + OutputFilename + ":" +
EC.message() + "\n");
if (!DependFilename.empty()) {
if (int Ret = createDependencyFile(Parser, argv0))
return Ret;
}
if (MainFn(Out.os(), Records))
return 1;
if (ErrorsPrinted > 0)
return reportError(argv0, Twine(ErrorsPrinted) + " errors.\n");
// Declare success.
Out.keep();
return 0;
}