//===----- HexagonMCChecker.cpp - Instruction bundle checking -------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This implements the checking of insns inside a bundle according to the
// packet constraint rules of the Hexagon ISA.
//
//===----------------------------------------------------------------------===//
#include "HexagonMCChecker.h"
#include "HexagonBaseInfo.h"
#include "llvm/MC/MCInstrDesc.h"
#include "llvm/MC/MCInstrInfo.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;
static cl::opt<bool> RelaxNVChecks("relax-nv-checks", cl::init(false),
cl::ZeroOrMore, cl::Hidden, cl::desc("Relax checks of new-value validity"));
const HexagonMCChecker::PredSense
HexagonMCChecker::Unconditional(Hexagon::NoRegister, false);
void HexagonMCChecker::init() {
// Initialize read-only registers set.
ReadOnly.insert(Hexagon::PC);
// Figure out the loop-registers definitions.
if (HexagonMCInstrInfo::isInnerLoop(MCB)) {
Defs[Hexagon::SA0].insert(Unconditional); // FIXME: define or change SA0?
Defs[Hexagon::LC0].insert(Unconditional);
}
if (HexagonMCInstrInfo::isOuterLoop(MCB)) {
Defs[Hexagon::SA1].insert(Unconditional); // FIXME: define or change SA0?
Defs[Hexagon::LC1].insert(Unconditional);
}
if (HexagonMCInstrInfo::isBundle(MCB))
// Unfurl a bundle.
for (auto const&I : HexagonMCInstrInfo::bundleInstructions(MCB)) {
init(*I.getInst());
}
else
init(MCB);
}
void HexagonMCChecker::init(MCInst const& MCI) {
const MCInstrDesc& MCID = HexagonMCInstrInfo::getDesc(MCII, MCI);
unsigned PredReg = Hexagon::NoRegister;
bool isTrue = false;
// Get used registers.
for (unsigned i = MCID.getNumDefs(); i < MCID.getNumOperands(); ++i)
if (MCI.getOperand(i).isReg()) {
unsigned R = MCI.getOperand(i).getReg();
if (HexagonMCInstrInfo::isPredicated(MCII, MCI) && isPredicateRegister(R)) {
// Note an used predicate register.
PredReg = R;
isTrue = HexagonMCInstrInfo::isPredicatedTrue(MCII, MCI);
// Note use of new predicate register.
if (HexagonMCInstrInfo::isPredicatedNew(MCII, MCI))
NewPreds.insert(PredReg);
}
else
// Note register use. Super-registers are not tracked directly,
// but their components.
for(MCRegAliasIterator SRI(R, &RI, !MCSubRegIterator(R, &RI).isValid());
SRI.isValid();
++SRI)
if (!MCSubRegIterator(*SRI, &RI).isValid())
// Skip super-registers used indirectly.
Uses.insert(*SRI);
}
// Get implicit register definitions.
if (const MCPhysReg *ImpDef = MCID.getImplicitDefs())
for (; *ImpDef; ++ImpDef) {
unsigned R = *ImpDef;
if (Hexagon::R31 != R && MCID.isCall())
// Any register other than the LR and the PC are actually volatile ones
// as defined by the ABI, not modified implicitly by the call insn.
continue;
if (Hexagon::PC == R)
// Branches are the only insns that can change the PC,
// otherwise a read-only register.
continue;
if (Hexagon::USR_OVF == R)
// Many insns change the USR implicitly, but only one or another flag.
// The instruction table models the USR.OVF flag, which can be implicitly
// modified more than once, but cannot be modified in the same packet
// with an instruction that modifies is explicitly. Deal with such situ-
// ations individually.
SoftDefs.insert(R);
else if (isPredicateRegister(R) &&
HexagonMCInstrInfo::isPredicateLate(MCII, MCI))
// Include implicit late predicates.
LatePreds.insert(R);
else
Defs[R].insert(PredSense(PredReg, isTrue));
}
// Figure out explicit register definitions.
for (unsigned i = 0; i < MCID.getNumDefs(); ++i) {
unsigned R = MCI.getOperand(i).getReg(),
S = Hexagon::NoRegister;
// USR has subregisters (while C8 does not for technical reasons), so
// reset R to USR, since we know how to handle multiple defs of USR,
// taking into account its subregisters.
if (R == Hexagon::C8)
R = Hexagon::USR;
// Note register definitions, direct ones as well as indirect side-effects.
// Super-registers are not tracked directly, but their components.
for(MCRegAliasIterator SRI(R, &RI, !MCSubRegIterator(R, &RI).isValid());
SRI.isValid();
++SRI) {
if (MCSubRegIterator(*SRI, &RI).isValid())
// Skip super-registers defined indirectly.
continue;
if (R == *SRI) {
if (S == R)
// Avoid scoring the defined register multiple times.
continue;
else
// Note that the defined register has already been scored.
S = R;
}
if (Hexagon::P3_0 != R && Hexagon::P3_0 == *SRI)
// P3:0 is a special case, since multiple predicate register definitions
// in a packet is allowed as the equivalent of their logical "and".
// Only an explicit definition of P3:0 is noted as such; if a
// side-effect, then note as a soft definition.
SoftDefs.insert(*SRI);
else if (HexagonMCInstrInfo::isPredicateLate(MCII, MCI) && isPredicateRegister(*SRI))
// Some insns produce predicates too late to be used in the same packet.
LatePreds.insert(*SRI);
else if (i == 0 && llvm::HexagonMCInstrInfo::getType(MCII, MCI) == HexagonII::TypeCVI_VM_CUR_LD)
// Current loads should be used in the same packet.
// TODO: relies on the impossibility of a current and a temporary loads
// in the same packet.
CurDefs.insert(*SRI), Defs[*SRI].insert(PredSense(PredReg, isTrue));
else if (i == 0 && llvm::HexagonMCInstrInfo::getType(MCII, MCI) == HexagonII::TypeCVI_VM_TMP_LD)
// Temporary loads should be used in the same packet, but don't commit
// results, so it should be disregarded if another insn changes the same
// register.
// TODO: relies on the impossibility of a current and a temporary loads
// in the same packet.
TmpDefs.insert(*SRI);
else if (i <= 1 && llvm::HexagonMCInstrInfo::hasNewValue2(MCII, MCI) )
// vshuff(Vx, Vy, Rx) <- Vx(0) and Vy(1) are both source and
// destination registers with this instruction. same for vdeal(Vx,Vy,Rx)
Uses.insert(*SRI);
else
Defs[*SRI].insert(PredSense(PredReg, isTrue));
}
}
// Figure out register definitions that produce new values.
if (HexagonMCInstrInfo::hasNewValue(MCII, MCI)) {
unsigned R = HexagonMCInstrInfo::getNewValueOperand(MCII, MCI).getReg();
if (HexagonMCInstrInfo::isCompound(MCII, MCI))
compoundRegisterMap(R); // Compound insns have a limited register range.
for(MCRegAliasIterator SRI(R, &RI, !MCSubRegIterator(R, &RI).isValid());
SRI.isValid();
++SRI)
if (!MCSubRegIterator(*SRI, &RI).isValid())
// No super-registers defined indirectly.
NewDefs[*SRI].push_back(NewSense::Def(PredReg, HexagonMCInstrInfo::isPredicatedTrue(MCII, MCI),
HexagonMCInstrInfo::isFloat(MCII, MCI)));
// For fairly unique 2-dot-new producers, example:
// vdeal(V1, V9, R0) V1.new and V9.new can be used by consumers.
if (HexagonMCInstrInfo::hasNewValue2(MCII, MCI)) {
unsigned R2 = HexagonMCInstrInfo::getNewValueOperand2(MCII, MCI).getReg();
for(MCRegAliasIterator SRI(R2, &RI, !MCSubRegIterator(R2, &RI).isValid());
SRI.isValid();
++SRI)
if (!MCSubRegIterator(*SRI, &RI).isValid())
NewDefs[*SRI].push_back(NewSense::Def(PredReg, HexagonMCInstrInfo::isPredicatedTrue(MCII, MCI),
HexagonMCInstrInfo::isFloat(MCII, MCI)));
}
}
// Figure out definitions of new predicate registers.
if (HexagonMCInstrInfo::isPredicatedNew(MCII, MCI))
for (unsigned i = MCID.getNumDefs(); i < MCID.getNumOperands(); ++i)
if (MCI.getOperand(i).isReg()) {
unsigned P = MCI.getOperand(i).getReg();
if (isPredicateRegister(P))
NewPreds.insert(P);
}
// Figure out uses of new values.
if (HexagonMCInstrInfo::isNewValue(MCII, MCI)) {
unsigned N = HexagonMCInstrInfo::getNewValueOperand(MCII, MCI).getReg();
if (!MCSubRegIterator(N, &RI).isValid()) {
// Super-registers cannot use new values.
if (MCID.isBranch())
NewUses[N] = NewSense::Jmp(llvm::HexagonMCInstrInfo::getType(MCII, MCI) == HexagonII::TypeNV);
else
NewUses[N] = NewSense::Use(PredReg, HexagonMCInstrInfo::isPredicatedTrue(MCII, MCI));
}
}
}
HexagonMCChecker::HexagonMCChecker(MCInstrInfo const &MCII, MCSubtargetInfo const &STI, MCInst &mcb, MCInst &mcbdx,
MCRegisterInfo const &ri)
: MCB(mcb), MCBDX(mcbdx), RI(ri), MCII(MCII), STI(STI),
bLoadErrInfo(false) {
init();
}
bool HexagonMCChecker::check() {
bool chkB = checkBranches();
bool chkP = checkPredicates();
bool chkNV = checkNewValues();
bool chkR = checkRegisters();
bool chkS = checkSolo();
bool chkSh = checkShuffle();
bool chkSl = checkSlots();
bool chk = chkB && chkP && chkNV && chkR && chkS && chkSh && chkSl;
return chk;
}
bool HexagonMCChecker::checkSlots()
{
unsigned slotsUsed = 0;
for (auto HMI: HexagonMCInstrInfo::bundleInstructions(MCBDX)) {
MCInst const& MCI = *HMI.getInst();
if (HexagonMCInstrInfo::isImmext(MCI))
continue;
if (HexagonMCInstrInfo::isDuplex(MCII, MCI))
slotsUsed += 2;
else
++slotsUsed;
}
if (slotsUsed > HEXAGON_PACKET_SIZE) {
HexagonMCErrInfo errInfo;
errInfo.setError(HexagonMCErrInfo::CHECK_ERROR_NOSLOTS);
addErrInfo(errInfo);
return false;
}
return true;
}
// Check legal use of branches.
bool HexagonMCChecker::checkBranches() {
HexagonMCErrInfo errInfo;
if (HexagonMCInstrInfo::isBundle(MCB)) {
bool hasConditional = false;
unsigned Branches = 0, Returns = 0, NewIndirectBranches = 0,
NewValueBranches = 0, Conditional = HEXAGON_PRESHUFFLE_PACKET_SIZE,
Unconditional = HEXAGON_PRESHUFFLE_PACKET_SIZE;
for (unsigned i = HexagonMCInstrInfo::bundleInstructionsOffset;
i < MCB.size(); ++i) {
MCInst const &MCI = *MCB.begin()[i].getInst();
if (HexagonMCInstrInfo::isImmext(MCI))
continue;
if (HexagonMCInstrInfo::getDesc(MCII, MCI).isBranch() ||
HexagonMCInstrInfo::getDesc(MCII, MCI).isCall()) {
++Branches;
if (HexagonMCInstrInfo::getDesc(MCII, MCI).isIndirectBranch() &&
HexagonMCInstrInfo::isPredicatedNew(MCII, MCI))
++NewIndirectBranches;
if (HexagonMCInstrInfo::isNewValue(MCII, MCI))
++NewValueBranches;
if (HexagonMCInstrInfo::isPredicated(MCII, MCI) ||
HexagonMCInstrInfo::isPredicatedNew(MCII, MCI)) {
hasConditional = true;
Conditional = i; // Record the position of the conditional branch.
} else {
Unconditional = i; // Record the position of the unconditional branch.
}
}
if (HexagonMCInstrInfo::getDesc(MCII, MCI).isReturn() &&
HexagonMCInstrInfo::getDesc(MCII, MCI).mayLoad())
++Returns;
}
if (Branches) // FIXME: should "Defs.count(Hexagon::PC)" be here too?
if (HexagonMCInstrInfo::isInnerLoop(MCB) ||
HexagonMCInstrInfo::isOuterLoop(MCB)) {
// Error out if there's any branch in a loop-end packet.
errInfo.setError(HexagonMCErrInfo::CHECK_ERROR_ENDLOOP, Hexagon::PC);
addErrInfo(errInfo);
return false;
}
if (Branches > 1)
if (!hasConditional || Conditional > Unconditional) {
// Error out if more than one unconditional branch or
// the conditional branch appears after the unconditional one.
errInfo.setError(HexagonMCErrInfo::CHECK_ERROR_BRANCHES);
addErrInfo(errInfo);
return false;
}
}
return true;
}
// Check legal use of predicate registers.
bool HexagonMCChecker::checkPredicates() {
HexagonMCErrInfo errInfo;
// Check for proper use of new predicate registers.
for (const auto& I : NewPreds) {
unsigned P = I;
if (!Defs.count(P) || LatePreds.count(P)) {
// Error out if the new predicate register is not defined,
// or defined "late"
// (e.g., "{ if (p3.new)... ; p3 = sp1loop0(#r7:2, Rs) }").
errInfo.setError(HexagonMCErrInfo::CHECK_ERROR_NEWP, P);
addErrInfo(errInfo);
return false;
}
}
// Check for proper use of auto-anded of predicate registers.
for (const auto& I : LatePreds) {
unsigned P = I;
if (LatePreds.count(P) > 1 || Defs.count(P)) {
// Error out if predicate register defined "late" multiple times or
// defined late and regularly defined
// (e.g., "{ p3 = sp1loop0(...); p3 = cmp.eq(...) }".
errInfo.setError(HexagonMCErrInfo::CHECK_ERROR_REGISTERS, P);
addErrInfo(errInfo);
return false;
}
}
return true;
}
// Check legal use of new values.
bool HexagonMCChecker::checkNewValues() {
HexagonMCErrInfo errInfo;
memset(&errInfo, 0, sizeof(errInfo));
for (auto& I : NewUses) {
unsigned R = I.first;
NewSense &US = I.second;
if (!hasValidNewValueDef(US, NewDefs[R])) {
errInfo.setError(HexagonMCErrInfo::CHECK_ERROR_NEWV, R);
addErrInfo(errInfo);
return false;
}
}
return true;
}
// Check for legal register uses and definitions.
bool HexagonMCChecker::checkRegisters() {
HexagonMCErrInfo errInfo;
// Check for proper register definitions.
for (const auto& I : Defs) {
unsigned R = I.first;
if (ReadOnly.count(R)) {
// Error out for definitions of read-only registers.
errInfo.setError(HexagonMCErrInfo::CHECK_ERROR_READONLY, R);
addErrInfo(errInfo);
return false;
}
if (isLoopRegister(R) && Defs.count(R) > 1 &&
(HexagonMCInstrInfo::isInnerLoop(MCB) ||
HexagonMCInstrInfo::isOuterLoop(MCB))) {
// Error out for definitions of loop registers at the end of a loop.
errInfo.setError(HexagonMCErrInfo::CHECK_ERROR_LOOP, R);
addErrInfo(errInfo);
return false;
}
if (SoftDefs.count(R)) {
// Error out for explicit changes to registers also weakly defined
// (e.g., "{ usr = r0; r0 = sfadd(...) }").
unsigned UsrR = Hexagon::USR; // Silence warning about mixed types in ?:.
unsigned BadR = RI.isSubRegister(Hexagon::USR, R) ? UsrR : R;
errInfo.setError(HexagonMCErrInfo::CHECK_ERROR_REGISTERS, BadR);
addErrInfo(errInfo);
return false;
}
if (!isPredicateRegister(R) && Defs[R].size() > 1) {
// Check for multiple register definitions.
PredSet &PM = Defs[R];
// Check for multiple unconditional register definitions.
if (PM.count(Unconditional)) {
// Error out on an unconditional change when there are any other
// changes, conditional or not.
unsigned UsrR = Hexagon::USR;
unsigned BadR = RI.isSubRegister(Hexagon::USR, R) ? UsrR : R;
errInfo.setError(HexagonMCErrInfo::CHECK_ERROR_REGISTERS, BadR);
addErrInfo(errInfo);
return false;
}
// Check for multiple conditional register definitions.
for (const auto& J : PM) {
PredSense P = J;
// Check for multiple uses of the same condition.
if (PM.count(P) > 1) {
// Error out on conditional changes based on the same predicate
// (e.g., "{ if (!p0) r0 =...; if (!p0) r0 =... }").
errInfo.setError(HexagonMCErrInfo::CHECK_ERROR_REGISTERS, R);
addErrInfo(errInfo);
return false;
}
// Check for the use of the complementary condition.
P.second = !P.second;
if (PM.count(P) && PM.size() > 2) {
// Error out on conditional changes based on the same predicate
// multiple times
// (e.g., "{ if (p0) r0 =...; if (!p0) r0 =... }; if (!p0) r0 =... }").
errInfo.setError(HexagonMCErrInfo::CHECK_ERROR_REGISTERS, R);
addErrInfo(errInfo);
return false;
}
}
}
}
// Check for use of current definitions.
for (const auto& I : CurDefs) {
unsigned R = I;
if (!Uses.count(R)) {
// Warn on an unused current definition.
errInfo.setWarning(HexagonMCErrInfo::CHECK_WARN_CURRENT, R);
addErrInfo(errInfo);
return true;
}
}
// Check for use of temporary definitions.
for (const auto& I : TmpDefs) {
unsigned R = I;
if (!Uses.count(R)) {
// special case for vhist
bool vHistFound = false;
for (auto const&HMI : HexagonMCInstrInfo::bundleInstructions(MCB)) {
if(llvm::HexagonMCInstrInfo::getType(MCII, *HMI.getInst()) == HexagonII::TypeCVI_HIST) {
vHistFound = true; // vhist() implicitly uses ALL REGxx.tmp
break;
}
}
// Warn on an unused temporary definition.
if (vHistFound == false) {
errInfo.setWarning(HexagonMCErrInfo::CHECK_WARN_TEMPORARY, R);
addErrInfo(errInfo);
return true;
}
}
}
return true;
}
// Check for legal use of solo insns.
bool HexagonMCChecker::checkSolo() {
HexagonMCErrInfo errInfo;
if (HexagonMCInstrInfo::isBundle(MCB) &&
HexagonMCInstrInfo::bundleSize(MCB) > 1) {
for (auto const&I : HexagonMCInstrInfo::bundleInstructions(MCB)) {
if (llvm::HexagonMCInstrInfo::isSolo(MCII, *I.getInst())) {
errInfo.setError(HexagonMCErrInfo::CHECK_ERROR_SOLO);
addErrInfo(errInfo);
return false;
}
}
}
return true;
}
bool HexagonMCChecker::checkShuffle() {
HexagonMCErrInfo errInfo;
// Branch info is lost when duplexing. The unduplexed insns must be
// checked and only branch errors matter for this case.
HexagonMCShuffler MCS(MCII, STI, MCB);
if (!MCS.check()) {
if (MCS.getError() == HexagonShuffler::SHUFFLE_ERROR_BRANCHES) {
errInfo.setError(HexagonMCErrInfo::CHECK_ERROR_SHUFFLE);
errInfo.setShuffleError(MCS.getError());
addErrInfo(errInfo);
return false;
}
}
HexagonMCShuffler MCSDX(MCII, STI, MCBDX);
if (!MCSDX.check()) {
errInfo.setError(HexagonMCErrInfo::CHECK_ERROR_SHUFFLE);
errInfo.setShuffleError(MCSDX.getError());
addErrInfo(errInfo);
return false;
}
return true;
}
void HexagonMCChecker::compoundRegisterMap(unsigned& Register) {
switch (Register) {
default:
break;
case Hexagon::R15:
Register = Hexagon::R23;
break;
case Hexagon::R14:
Register = Hexagon::R22;
break;
case Hexagon::R13:
Register = Hexagon::R21;
break;
case Hexagon::R12:
Register = Hexagon::R20;
break;
case Hexagon::R11:
Register = Hexagon::R19;
break;
case Hexagon::R10:
Register = Hexagon::R18;
break;
case Hexagon::R9:
Register = Hexagon::R17;
break;
case Hexagon::R8:
Register = Hexagon::R16;
break;
}
}
bool HexagonMCChecker::hasValidNewValueDef(const NewSense &Use,
const NewSenseList &Defs) const {
bool Strict = !RelaxNVChecks;
for (unsigned i = 0, n = Defs.size(); i < n; ++i) {
const NewSense &Def = Defs[i];
// NVJ cannot use a new FP value [7.6.1]
if (Use.IsNVJ && (Def.IsFloat || Def.PredReg != 0))
continue;
// If the definition was not predicated, then it does not matter if
// the use is.
if (Def.PredReg == 0)
return true;
// With the strict checks, both the definition and the use must be
// predicated on the same register and condition.
if (Strict) {
if (Def.PredReg == Use.PredReg && Def.Cond == Use.Cond)
return true;
} else {
// With the relaxed checks, if the definition was predicated, the only
// detectable violation is if the use is predicated on the opposing
// condition, otherwise, it's ok.
if (Def.PredReg != Use.PredReg || Def.Cond == Use.Cond)
return true;
}
}
return false;
}