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llvm-mirror/lib/MC/MCInst.cpp
Sameer AbuAsal 9cc166efe6 [RISCV] Tablegen-driven Instruction Compression.
Summary:

    This patch implements a tablegen-driven Instruction Compression
    mechanism for generating RISCV compressed instructions
    (C Extension) from the expanded instruction form.

    This tablegen backend processes CompressPat declarations in a
    td file and generates all the compile-time and runtime checks
    required to validate the declarations, validate the input
    operands and generate correct instructions.

    The checks include validating register operands, immediate
    operands, fixed register operands and fixed immediate operands.

    Example:
      class CompressPat<dag input, dag output> {
        dag Input  = input;
        dag Output    = output;
        list<Predicate> Predicates = [];
      }

      let Predicates = [HasStdExtC] in {
      def : CompressPat<(ADD GPRNoX0:$rs1, GPRNoX0:$rs1, GPRNoX0:$rs2),
                        (C_ADD GPRNoX0:$rs1, GPRNoX0:$rs2)>;
      }

    The result is an auto-generated header file
    'RISCVGenCompressEmitter.inc' which exports two functions for
    compressing/uncompressing MCInst instructions, plus
    some helper functions:

      bool compressInst(MCInst& OutInst, const MCInst &MI,
                        const MCSubtargetInfo &STI,
                        MCContext &Context);

      bool uncompressInst(MCInst& OutInst, const MCInst &MI,
                          const MCRegisterInfo &MRI,
                          const MCSubtargetInfo &STI);

    The clients that include this auto-generated header file and
    invoke these functions can compress an instruction before emitting
    it, in the target-specific ASM or ELF streamer, or can uncompress
    an instruction before printing it, when the expanded instruction
    format aliases is favored.

    The following clients were added to implement compression\uncompression
    for RISCV:

    1) RISCVAsmParser::MatchAndEmitInstruction:
       Inserted a call to compressInst() to compresses instructions
       parsed by llvm-mc coming from an ASM input.
    2) RISCVAsmPrinter::EmitInstruction:
       Inserted a call to compressInst() to compress instructions that
       were lowered from Machine Instructions (MachineInstr).
    3) RVInstPrinter::printInst:
       Inserted a call to uncompressInst() to print the expanded
       version of the instruction instead of the compressed one (e.g,
       add s0, s0, a5 instead of c.add s0, a5) when -riscv-no-aliases
       is not passed.

This patch squashes D45119, D42780 and D41932. It was reviewed in  smaller patches by
asb, efriedma, apazos and mgrang.

Reviewers: asb, efriedma, apazos, llvm-commits, sabuasal

Reviewed By: sabuasal

Subscribers: mgorny, eraman, asb, rbar, johnrusso, simoncook, jordy.potman.lists, apazos, niosHD, kito-cheng, shiva0217, zzheng

Differential Revision: https://reviews.llvm.org/D45385

llvm-svn: 329455
2018-04-06 21:07:05 +00:00

93 lines
2.3 KiB
C++

//===- lib/MC/MCInst.cpp - MCInst implementation --------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "llvm/MC/MCInst.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCInstPrinter.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;
void MCOperand::print(raw_ostream &OS) const {
OS << "<MCOperand ";
if (!isValid())
OS << "INVALID";
else if (isReg())
OS << "Reg:" << getReg();
else if (isImm())
OS << "Imm:" << getImm();
else if (isFPImm())
OS << "FPImm:" << getFPImm();
else if (isExpr()) {
OS << "Expr:(" << *getExpr() << ")";
} else if (isInst()) {
OS << "Inst:(" << *getInst() << ")";
} else
OS << "UNDEFINED";
OS << ">";
}
bool MCOperand::evaluateAsConstantImm(int64_t &Imm) const {
if (isImm()) {
Imm = getImm();
return true;
}
return false;
}
bool MCOperand::isBareSymbolRef() const {
assert(isExpr() &&
"isBareSymbolRef expects only expressions");
const MCExpr *Expr = getExpr();
MCExpr::ExprKind Kind = getExpr()->getKind();
return Kind == MCExpr::SymbolRef &&
cast<MCSymbolRefExpr>(Expr)->getKind() == MCSymbolRefExpr::VK_None;
}
#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
LLVM_DUMP_METHOD void MCOperand::dump() const {
print(dbgs());
dbgs() << "\n";
}
#endif
void MCInst::print(raw_ostream &OS) const {
OS << "<MCInst " << getOpcode();
for (unsigned i = 0, e = getNumOperands(); i != e; ++i) {
OS << " ";
getOperand(i).print(OS);
}
OS << ">";
}
void MCInst::dump_pretty(raw_ostream &OS, const MCInstPrinter *Printer,
StringRef Separator) const {
OS << "<MCInst #" << getOpcode();
// Show the instruction opcode name if we have access to a printer.
if (Printer)
OS << ' ' << Printer->getOpcodeName(getOpcode());
for (unsigned i = 0, e = getNumOperands(); i != e; ++i) {
OS << Separator;
getOperand(i).print(OS);
}
OS << ">";
}
#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
LLVM_DUMP_METHOD void MCInst::dump() const {
print(dbgs());
dbgs() << "\n";
}
#endif