[PATCH] MIR Serialization: Serialize machine instruction names.

[Alex L]

2015-06-17 15:25 GMT-07:00 Duncan P. N. Exon Smith <dexonsmith at apple.com>:

>
> > On 2015 Jun 16, at 10:42, Alex Lorenz <arphaman at gmail.com> wrote:
> >
> > Hi dexonsmith, bob.wilson, bogner,
> >
> > This patch is based on a patch that implements initial serialization of
> machine basic blocks (http://reviews.llvm.org/D10465).
> >
> > This patch is the initial patch for machine instruction serialization.
> Only the machine instruction names are serialized by this patch. The
> instructions are represented using a YAML sequence of string literals and
> are a part of machine basic block YAML mapping. An example of such MBB
> mapping is shown below:
> >
> >  name: entry
> >  instructions:
> >    - mov32r0
> >    - retq
> >
> > A machine instruction parser class 'MIParser' is introduced by this
> patch. This class will be used to parse the machine instructions. A
> supporting machine instruction lexing class will be added in the upcoming
> patch.
> >
> > REPOSITORY
> >  rL LLVM
> >
> > http://reviews.llvm.org/D10481
> >
> > Files:
> >  include/llvm/CodeGen/MIRYamlMapping.h
> >  lib/CodeGen/MIRParser/CMakeLists.txt
> >  lib/CodeGen/MIRParser/MIParser.cpp
> >  lib/CodeGen/MIRParser/MIParser.h
> >  lib/CodeGen/MIRParser/MIRParser.cpp
> >  lib/CodeGen/MIRPrinter.cpp
> >  test/CodeGen/MIR/X86/lit.local.cfg
> >  test/CodeGen/MIR/X86/machine-instructions.mir
> >  test/CodeGen/MIR/X86/unknown-instruction.mir
> >
> > EMAIL PREFERENCES
> >  http://reviews.llvm.org/settings/panel/emailpreferences/
> > <D10481.27769.patch>
>
> LGTM with a few minor nitpicks, although I know you're waiting on the
> MBB parsing.
>
> > Index: lib/CodeGen/MIRParser/MIParser.cpp
> > ===================================================================
> > --- /dev/null
> > +++ lib/CodeGen/MIRParser/MIParser.cpp
> > @@ -0,0 +1,105 @@
> > +//===- MIParser.cpp - Machine instructions parser implementation
> ----------===//
> > +//
> > +//                     The LLVM Compiler Infrastructure
> > +//
> > +// This file is distributed under the University of Illinois Open Source
> > +// License. See LICENSE.TXT for details.
> > +//
> >
> +//===----------------------------------------------------------------------===//
> > +//
> > +// This file implements the parsing of machine instructions.
> > +//
> >
> +//===----------------------------------------------------------------------===//
> > +
> > +#include "MIParser.h"
> > +#include "llvm/ADT/StringMap.h"
> > +#include "llvm/CodeGen/MachineBasicBlock.h"
> > +#include "llvm/CodeGen/MachineFunction.h"
> > +#include "llvm/CodeGen/MachineInstr.h"
> > +#include "llvm/Support/raw_ostream.h"
> > +#include "llvm/Support/SourceMgr.h"
> > +#include "llvm/Target/TargetSubtargetInfo.h"
> > +#include "llvm/Target/TargetInstrInfo.h"
> > +
> > +using namespace llvm;
> > +
> > +namespace {
> > +
> > +class MIParser {
> > +  SourceMgr &SM;
> > +  MachineFunction &MF;
> > +  SMDiagnostic &Error;
> > +  StringRef Source;
> > +  /// Maps from instruction names to op codes.
> > +  StringMap<unsigned> Names2InstrOpCodes;
> > +
> > +public:
> > +  MIParser(SourceMgr &SM, MachineFunction &MF, SMDiagnostic &Error,
> > +           StringRef Source);
> > +
> > +  /// Report an error at the current location with the given message.
> > +  ///
> > +  /// This function always return true.
> > +  bool error(const Twine &Msg);
> > +
> > +  MachineInstr *parse();
> > +
> > +private:
> > +  void initNames2InstrOpCodes();
> > +
> > +  /// Try to convert an instruction name to an opcode. Return true if
> the
> > +  /// instruction name is invalid.
> > +  bool parseInstrName(StringRef InstrName, unsigned &OpCode);
> > +};
> > +
> > +} // end anonymous namespace
> > +
> > +MIParser::MIParser(SourceMgr &SM, MachineFunction &MF, SMDiagnostic
> &Error,
> > +                   StringRef Source)
> > +    : SM(SM), MF(MF), Error(Error), Source(Source) {}
> > +
> > +bool MIParser::error(const Twine &Msg) {
> > +  // TODO: Get the proper location in the MIR file, not just a location
> inside
> > +  // the string.
> > +  Error =
> > +      SMDiagnostic(SM, SMLoc(), SM.getMemoryBuffer(SM.getMainFileID())
> > +                                    ->getBufferIdentifier(),
> > +                   1, 0, SourceMgr::DK_Error, Msg.str(), Source, None,
> None);
> > +  return true;
> > +}
> > +
> > +MachineInstr *MIParser::parse() {
> > +  StringRef InstrName = Source;
> > +  unsigned OpCode;
> > +  if (parseInstrName(InstrName, OpCode)) {
> > +    error(Twine("unknown machine instruction name '") + InstrName +
> "'");
> > +    return nullptr;
> > +  }
>
> We need a TODO somewhere (maybe here?) for the rest of the instruction ;).
>
> > +
> > +  const auto &MCID = MF.getSubtarget().getInstrInfo()->get(OpCode);
> > +  auto *MI = MF.CreateMachineInstr(MCID, DebugLoc());
> > +  return MI;
> > +}
> > +
> > +void MIParser::initNames2InstrOpCodes() {
> > +  if (!Names2InstrOpCodes.empty())
> > +    return;
> > +  const auto *TII = MF.getSubtarget().getInstrInfo();
>
> Something like:
>
>     assert(TII && "Expected target instruction info");
>
> might be nice.
>
> > +  for (unsigned I = 0, E = TII->getNumOpcodes(); I < E; ++I)
> > +    Names2InstrOpCodes.insert(
> > +        std::make_pair(StringRef(TII->getName(I)).lower(), I));
> > +}
> > +
> > +bool MIParser::parseInstrName(StringRef InstrName, unsigned &OpCode) {
> > +  initNames2InstrOpCodes();
> > +  auto InstrInfo = Names2InstrOpCodes.find(InstrName);
>
> Should we support other cases, using `InstrName.lower()`, here?  (I'm
> not sure we should; really just a question.  I'm happy to go ahead with
> what you have, since it's easy to loosen later.)
>

I'm not sure really, I just print and parse everything using lowercase
name, like LLVM IR.
I think this can be changed later if other people want case insensitive
format.


>
> > +  if (InstrInfo == Names2InstrOpCodes.end())
> > +    return true;
> > +  OpCode = InstrInfo->getValue();
> > +  return false;
> > +}
> > +
> > +MachineInstr *llvm::parseMachineInstr(SourceMgr &SM, MachineFunction
> &MF,
> > +                                      StringRef Src, SMDiagnostic
> &Error) {
> > +  return MIParser(SM, MF, Error, Src).parse();
> > +}
>
>
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