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//===-- lib/MC/Disassembler.cpp - Disassembler Public C Interface ---------===//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
#include "Disassembler.h"
#include "llvm-c/Disassembler.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Triple.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCDisassembler/MCDisassembler.h"
#include "llvm/MC/MCDisassembler/MCRelocationInfo.h"
#include "llvm/MC/MCDisassembler/MCSymbolizer.h"
#include "llvm/MC/MCInst.h"
#include "llvm/MC/MCInstPrinter.h"
#include "llvm/MC/MCInstrDesc.h"
#include "llvm/MC/MCInstrInfo.h"
#include "llvm/MC/MCInstrItineraries.h"
#include "llvm/MC/MCRegisterInfo.h"
#include "llvm/MC/MCSchedule.h"
#include "llvm/MC/MCSubtargetInfo.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/FormattedStream.h"
#include "llvm/Support/TargetRegistry.h"
#include "llvm/Support/raw_ostream.h"
#include <cassert>
#include <cstddef>
#include <cstring>
using namespace llvm;
// LLVMCreateDisasm() creates a disassembler for the TripleName. Symbolic
// disassembly is supported by passing a block of information in the DisInfo
// parameter and specifying the TagType and callback functions as described in
// the header llvm-c/Disassembler.h . The pointer to the block and the
// functions can all be passed as NULL. If successful, this returns a
// disassembler context. If not, it returns NULL.
LLVMCreateDisasmCPUFeatures(const char *TT, const char *CPU,
const char *Features, void *DisInfo, int TagType,
LLVMOpInfoCallback GetOpInfo,
LLVMSymbolLookupCallback SymbolLookUp) {
// Get the target.
std::string Error;
const Target *TheTarget = TargetRegistry::lookupTarget(TT, Error);
if (!TheTarget)
return nullptr;
const MCRegisterInfo *MRI = TheTarget->createMCRegInfo(TT);
if (!MRI)
return nullptr;
// Get the assembler info needed to setup the MCContext.
const MCAsmInfo *MAI = TheTarget->createMCAsmInfo(*MRI, TT);
if (!MAI)
return nullptr;
const MCInstrInfo *MII = TheTarget->createMCInstrInfo();
if (!MII)
return nullptr;
const MCSubtargetInfo *STI =
TheTarget->createMCSubtargetInfo(TT, CPU, Features);
if (!STI)
return nullptr;
// Set up the MCContext for creating symbols and MCExpr's.
MCContext *Ctx = new MCContext(MAI, MRI, nullptr);
if (!Ctx)
return nullptr;
// Set up disassembler.
MCDisassembler *DisAsm = TheTarget->createMCDisassembler(*STI, *Ctx);
if (!DisAsm)
return nullptr;
std::unique_ptr<MCRelocationInfo> RelInfo(
TheTarget->createMCRelocationInfo(TT, *Ctx));
if (!RelInfo)
return nullptr;
std::unique_ptr<MCSymbolizer> Symbolizer(TheTarget->createMCSymbolizer(
TT, GetOpInfo, SymbolLookUp, DisInfo, Ctx, std::move(RelInfo)));
// Set up the instruction printer.
int AsmPrinterVariant = MAI->getAssemblerDialect();
MCInstPrinter *IP = TheTarget->createMCInstPrinter(
Triple(TT), AsmPrinterVariant, *MAI, *MII, *MRI);
if (!IP)
return nullptr;
LLVMDisasmContext *DC =
new LLVMDisasmContext(TT, DisInfo, TagType, GetOpInfo, SymbolLookUp,
TheTarget, MAI, MRI, STI, MII, Ctx, DisAsm, IP);
if (!DC)
return nullptr;
return DC;
LLVMCreateDisasmCPU(const char *TT, const char *CPU, void *DisInfo, int TagType,
LLVMOpInfoCallback GetOpInfo,
LLVMSymbolLookupCallback SymbolLookUp) {
return LLVMCreateDisasmCPUFeatures(TT, CPU, "", DisInfo, TagType, GetOpInfo,
LLVMDisasmContextRef LLVMCreateDisasm(const char *TT, void *DisInfo,
int TagType, LLVMOpInfoCallback GetOpInfo,
LLVMSymbolLookupCallback SymbolLookUp) {
return LLVMCreateDisasmCPUFeatures(TT, "", "", DisInfo, TagType, GetOpInfo,
// LLVMDisasmDispose() disposes of the disassembler specified by the context.
void LLVMDisasmDispose(LLVMDisasmContextRef DCR){
LLVMDisasmContext *DC = static_cast<LLVMDisasmContext *>(DCR);
delete DC;
/// Emits the comments that are stored in \p DC comment stream.
/// Each comment in the comment stream must end with a newline.
static void emitComments(LLVMDisasmContext *DC,
formatted_raw_ostream &FormattedOS) {
// Flush the stream before taking its content.
StringRef Comments = DC->CommentsToEmit.str();
// Get the default information for printing a comment.
const MCAsmInfo *MAI = DC->getAsmInfo();
StringRef CommentBegin = MAI->getCommentString();
unsigned CommentColumn = MAI->getCommentColumn();
bool IsFirst = true;
while (!Comments.empty()) {
if (!IsFirst)
FormattedOS << '\n';
// Emit a line of comments.
size_t Position = Comments.find('\n');
FormattedOS << CommentBegin << ' ' << Comments.substr(0, Position);
// Move after the newline character.
Comments = Comments.substr(Position+1);
IsFirst = false;
// Tell the comment stream that the vector changed underneath it.
/// Gets latency information for \p Inst from the itinerary
/// scheduling model, based on \p DC information.
/// \return The maximum expected latency over all the operands or -1
/// if no information is available.
static int getItineraryLatency(LLVMDisasmContext *DC, const MCInst &Inst) {
const int NoInformationAvailable = -1;
// Check if we have a CPU to get the itinerary information.
if (DC->getCPU().empty())
return NoInformationAvailable;
// Get itinerary information.
const MCSubtargetInfo *STI = DC->getSubtargetInfo();
InstrItineraryData IID = STI->getInstrItineraryForCPU(DC->getCPU());
// Get the scheduling class of the requested instruction.
const MCInstrDesc& Desc = DC->getInstrInfo()->get(Inst.getOpcode());
unsigned SCClass = Desc.getSchedClass();
int Latency = 0;
for (unsigned OpIdx = 0, OpIdxEnd = Inst.getNumOperands(); OpIdx != OpIdxEnd;
Latency = std::max(Latency, IID.getOperandCycle(SCClass, OpIdx));
return Latency;
/// Gets latency information for \p Inst, based on \p DC information.
/// \return The maximum expected latency over all the definitions or -1
/// if no information is available.
static int getLatency(LLVMDisasmContext *DC, const MCInst &Inst) {
// Try to compute scheduling information.
const MCSubtargetInfo *STI = DC->getSubtargetInfo();
const MCSchedModel SCModel = STI->getSchedModel();
const int NoInformationAvailable = -1;
// Check if we have a scheduling model for instructions.
if (!SCModel.hasInstrSchedModel())
// Try to fall back to the itinerary model if the scheduling model doesn't
// have a scheduling table. Note the default does not have a table.
return getItineraryLatency(DC, Inst);
// Get the scheduling class of the requested instruction.
const MCInstrDesc& Desc = DC->getInstrInfo()->get(Inst.getOpcode());
unsigned SCClass = Desc.getSchedClass();
const MCSchedClassDesc *SCDesc = SCModel.getSchedClassDesc(SCClass);
// Resolving the variant SchedClass requires an MI to pass to
// SubTargetInfo::resolveSchedClass.
if (!SCDesc || !SCDesc->isValid() || SCDesc->isVariant())
return NoInformationAvailable;
// Compute output latency.
int16_t Latency = 0;
for (unsigned DefIdx = 0, DefEnd = SCDesc->NumWriteLatencyEntries;
DefIdx != DefEnd; ++DefIdx) {
// Lookup the definition's write latency in SubtargetInfo.
const MCWriteLatencyEntry *WLEntry = STI->getWriteLatencyEntry(SCDesc,
Latency = std::max(Latency, WLEntry->Cycles);
return Latency;
/// Emits latency information in DC->CommentStream for \p Inst, based
/// on the information available in \p DC.
static void emitLatency(LLVMDisasmContext *DC, const MCInst &Inst) {
int Latency = getLatency(DC, Inst);
// Report only interesting latencies.
if (Latency < 2)
DC->CommentStream << "Latency: " << Latency << '\n';
// LLVMDisasmInstruction() disassembles a single instruction using the
// disassembler context specified in the parameter DC. The bytes of the
// instruction are specified in the parameter Bytes, and contains at least
// BytesSize number of bytes. The instruction is at the address specified by
// the PC parameter. If a valid instruction can be disassembled its string is
// returned indirectly in OutString which whos size is specified in the
// parameter OutStringSize. This function returns the number of bytes in the
// instruction or zero if there was no valid instruction. If this function
// returns zero the caller will have to pick how many bytes they want to step
// over by printing a .byte, .long etc. to continue.
size_t LLVMDisasmInstruction(LLVMDisasmContextRef DCR, uint8_t *Bytes,
uint64_t BytesSize, uint64_t PC, char *OutString,
size_t OutStringSize){
LLVMDisasmContext *DC = static_cast<LLVMDisasmContext *>(DCR);
// Wrap the pointer to the Bytes, BytesSize and PC in a MemoryObject.
ArrayRef<uint8_t> Data(Bytes, BytesSize);
uint64_t Size;
MCInst Inst;
const MCDisassembler *DisAsm = DC->getDisAsm();
MCInstPrinter *IP = DC->getIP();
MCDisassembler::DecodeStatus S;
SmallVector<char, 64> InsnStr;
raw_svector_ostream Annotations(InsnStr);
S = DisAsm->getInstruction(Inst, Size, Data, PC,
/*REMOVE*/ nulls(), Annotations);
switch (S) {
case MCDisassembler::Fail:
case MCDisassembler::SoftFail:
// FIXME: Do something different for soft failure modes?
return 0;
case MCDisassembler::Success: {
StringRef AnnotationsStr = Annotations.str();
SmallVector<char, 64> InsnStr;
raw_svector_ostream OS(InsnStr);
formatted_raw_ostream FormattedOS(OS);
IP->printInst(&Inst, FormattedOS, AnnotationsStr, *DC->getSubtargetInfo());
if (DC->getOptions() & LLVMDisassembler_Option_PrintLatency)
emitLatency(DC, Inst);
emitComments(DC, FormattedOS);
assert(OutStringSize != 0 && "Output buffer cannot be zero size");
size_t OutputSize = std::min(OutStringSize-1, InsnStr.size());
std::memcpy(OutString,, OutputSize);
OutString[OutputSize] = '\0'; // Terminate string.
return Size;
llvm_unreachable("Invalid DecodeStatus!");
// LLVMSetDisasmOptions() sets the disassembler's options. It returns 1 if it
// can set all the Options and 0 otherwise.
int LLVMSetDisasmOptions(LLVMDisasmContextRef DCR, uint64_t Options){
if (Options & LLVMDisassembler_Option_UseMarkup){
LLVMDisasmContext *DC = static_cast<LLVMDisasmContext *>(DCR);
MCInstPrinter *IP = DC->getIP();
Options &= ~LLVMDisassembler_Option_UseMarkup;
if (Options & LLVMDisassembler_Option_PrintImmHex){
LLVMDisasmContext *DC = static_cast<LLVMDisasmContext *>(DCR);
MCInstPrinter *IP = DC->getIP();
Options &= ~LLVMDisassembler_Option_PrintImmHex;
if (Options & LLVMDisassembler_Option_AsmPrinterVariant){
LLVMDisasmContext *DC = static_cast<LLVMDisasmContext *>(DCR);
// Try to set up the new instruction printer.
const MCAsmInfo *MAI = DC->getAsmInfo();
const MCInstrInfo *MII = DC->getInstrInfo();
const MCRegisterInfo *MRI = DC->getRegisterInfo();
int AsmPrinterVariant = MAI->getAssemblerDialect();
AsmPrinterVariant = AsmPrinterVariant == 0 ? 1 : 0;
MCInstPrinter *IP = DC->getTarget()->createMCInstPrinter(
Triple(DC->getTripleName()), AsmPrinterVariant, *MAI, *MII, *MRI);
if (IP) {
Options &= ~LLVMDisassembler_Option_AsmPrinterVariant;
if (Options & LLVMDisassembler_Option_SetInstrComments) {
LLVMDisasmContext *DC = static_cast<LLVMDisasmContext *>(DCR);
MCInstPrinter *IP = DC->getIP();
Options &= ~LLVMDisassembler_Option_SetInstrComments;
if (Options & LLVMDisassembler_Option_PrintLatency) {
LLVMDisasmContext *DC = static_cast<LLVMDisasmContext *>(DCR);
Options &= ~LLVMDisassembler_Option_PrintLatency;
return (Options == 0);