mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2024-08-23 02:29:18 +00:00
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@128826 91177308-0d34-0410-b5e6-96231b3b80d8
139 lines
6.0 KiB
C++
139 lines
6.0 KiB
C++
//===- DisassemblerEmitter.cpp - Generate a disassembler ------------------===//
|
|
//
|
|
// The LLVM Compiler Infrastructure
|
|
//
|
|
// This file is distributed under the University of Illinois Open Source
|
|
// License. See LICENSE.TXT for details.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#include "DisassemblerEmitter.h"
|
|
#include "CodeGenTarget.h"
|
|
#include "Record.h"
|
|
#include "X86DisassemblerTables.h"
|
|
#include "X86RecognizableInstr.h"
|
|
#include "ARMDecoderEmitter.h"
|
|
#include "FixedLenDecoderEmitter.h"
|
|
|
|
using namespace llvm;
|
|
using namespace llvm::X86Disassembler;
|
|
|
|
/// DisassemblerEmitter - Contains disassembler table emitters for various
|
|
/// architectures.
|
|
|
|
/// X86 Disassembler Emitter
|
|
///
|
|
/// *** IF YOU'RE HERE TO RESOLVE A "Primary decode conflict", LOOK DOWN NEAR
|
|
/// THE END OF THIS COMMENT!
|
|
///
|
|
/// The X86 disassembler emitter is part of the X86 Disassembler, which is
|
|
/// documented in lib/Target/X86/X86Disassembler.h.
|
|
///
|
|
/// The emitter produces the tables that the disassembler uses to translate
|
|
/// instructions. The emitter generates the following tables:
|
|
///
|
|
/// - One table (CONTEXTS_SYM) that contains a mapping of attribute masks to
|
|
/// instruction contexts. Although for each attribute there are cases where
|
|
/// that attribute determines decoding, in the majority of cases decoding is
|
|
/// the same whether or not an attribute is present. For example, a 64-bit
|
|
/// instruction with an OPSIZE prefix and an XS prefix decodes the same way in
|
|
/// all cases as a 64-bit instruction with only OPSIZE set. (The XS prefix
|
|
/// may have effects on its execution, but does not change the instruction
|
|
/// returned.) This allows considerable space savings in other tables.
|
|
/// - Six tables (ONEBYTE_SYM, TWOBYTE_SYM, THREEBYTE38_SYM, THREEBYTE3A_SYM,
|
|
/// THREEBYTEA6_SYM, and THREEBYTEA7_SYM contain the hierarchy that the
|
|
/// decoder traverses while decoding an instruction. At the lowest level of
|
|
/// this hierarchy are instruction UIDs, 16-bit integers that can be used to
|
|
/// uniquely identify the instruction and correspond exactly to its position
|
|
/// in the list of CodeGenInstructions for the target.
|
|
/// - One table (INSTRUCTIONS_SYM) contains information about the operands of
|
|
/// each instruction and how to decode them.
|
|
///
|
|
/// During table generation, there may be conflicts between instructions that
|
|
/// occupy the same space in the decode tables. These conflicts are resolved as
|
|
/// follows in setTableFields() (X86DisassemblerTables.cpp)
|
|
///
|
|
/// - If the current context is the native context for one of the instructions
|
|
/// (that is, the attributes specified for it in the LLVM tables specify
|
|
/// precisely the current context), then it has priority.
|
|
/// - If the current context isn't native for either of the instructions, then
|
|
/// the higher-priority context wins (that is, the one that is more specific).
|
|
/// That hierarchy is determined by outranks() (X86DisassemblerTables.cpp)
|
|
/// - If the current context is native for both instructions, then the table
|
|
/// emitter reports a conflict and dies.
|
|
///
|
|
/// *** RESOLUTION FOR "Primary decode conflict"S
|
|
///
|
|
/// If two instructions collide, typically the solution is (in order of
|
|
/// likelihood):
|
|
///
|
|
/// (1) to filter out one of the instructions by editing filter()
|
|
/// (X86RecognizableInstr.cpp). This is the most common resolution, but
|
|
/// check the Intel manuals first to make sure that (2) and (3) are not the
|
|
/// problem.
|
|
/// (2) to fix the tables (X86.td and its subsidiaries) so the opcodes are
|
|
/// accurate. Sometimes they are not.
|
|
/// (3) to fix the tables to reflect the actual context (for example, required
|
|
/// prefixes), and possibly to add a new context by editing
|
|
/// lib/Target/X86/X86DisassemblerDecoderCommon.h. This is unlikely to be
|
|
/// the cause.
|
|
///
|
|
/// DisassemblerEmitter.cpp contains the implementation for the emitter,
|
|
/// which simply pulls out instructions from the CodeGenTarget and pushes them
|
|
/// into X86DisassemblerTables.
|
|
/// X86DisassemblerTables.h contains the interface for the instruction tables,
|
|
/// which manage and emit the structures discussed above.
|
|
/// X86DisassemblerTables.cpp contains the implementation for the instruction
|
|
/// tables.
|
|
/// X86ModRMFilters.h contains filters that can be used to determine which
|
|
/// ModR/M values are valid for a particular instruction. These are used to
|
|
/// populate ModRMDecisions.
|
|
/// X86RecognizableInstr.h contains the interface for a single instruction,
|
|
/// which knows how to translate itself from a CodeGenInstruction and provide
|
|
/// the information necessary for integration into the tables.
|
|
/// X86RecognizableInstr.cpp contains the implementation for a single
|
|
/// instruction.
|
|
|
|
void DisassemblerEmitter::run(raw_ostream &OS) {
|
|
CodeGenTarget Target(Records);
|
|
|
|
OS << "/*===- TableGen'erated file "
|
|
<< "---------------------------------------*- C -*-===*\n"
|
|
<< " *\n"
|
|
<< " * " << Target.getName() << " Disassembler\n"
|
|
<< " *\n"
|
|
<< " * Automatically generated file, do not edit!\n"
|
|
<< " *\n"
|
|
<< " *===---------------------------------------------------------------"
|
|
<< "-------===*/\n";
|
|
|
|
// X86 uses a custom disassembler.
|
|
if (Target.getName() == "X86") {
|
|
DisassemblerTables Tables;
|
|
|
|
const std::vector<const CodeGenInstruction*> &numberedInstructions =
|
|
Target.getInstructionsByEnumValue();
|
|
|
|
for (unsigned i = 0, e = numberedInstructions.size(); i != e; ++i)
|
|
RecognizableInstr::processInstr(Tables, *numberedInstructions[i], i);
|
|
|
|
// FIXME: As long as we are using exceptions, might as well drop this to the
|
|
// actual conflict site.
|
|
if (Tables.hasConflicts())
|
|
throw TGError(Target.getTargetRecord()->getLoc(),
|
|
"Primary decode conflict");
|
|
|
|
Tables.emit(OS);
|
|
return;
|
|
}
|
|
|
|
// Fixed-instruction-length targets use a common disassembler.
|
|
// ARM use its own implementation for now.
|
|
if (Target.getName() == "ARM") {
|
|
ARMDecoderEmitter(Records).run(OS);
|
|
return;
|
|
}
|
|
|
|
FixedLenDecoderEmitter(Records).run(OS);
|
|
}
|