static void registerClobberCheck(AssemblyHelpers& jit, RegisterSet dontClobber)
{
if (!Options::clobberAllRegsInFTLICSlowPath())
return;
RegisterSet clobber = RegisterSet::allRegisters();
clobber.exclude(RegisterSet::reservedHardwareRegisters());
clobber.exclude(RegisterSet::stackRegisters());
clobber.exclude(RegisterSet::calleeSaveRegisters());
clobber.exclude(dontClobber);
GPRReg someGPR;
for (Reg reg = Reg::first(); reg <= Reg::last(); reg = reg.next()) {
if (!clobber.get(reg) || !reg.isGPR())
continue;
jit.move(AssemblyHelpers::TrustedImm32(0x1337beef), reg.gpr());
someGPR = reg.gpr();
}
for (Reg reg = Reg::first(); reg <= Reg::last(); reg = reg.next()) {
if (!clobber.get(reg) || !reg.isFPR())
continue;
jit.move64ToDouble(someGPR, reg.fpr());
}
}
void CallFrameShuffler::emitDisplace(CachedRecovery& cachedRecovery)
{
Reg wantedReg;
if (!(wantedReg = Reg { cachedRecovery.wantedJSValueRegs().gpr() }))
wantedReg = Reg { cachedRecovery.wantedFPR() };
ASSERT(wantedReg);
ASSERT(!m_lockedRegisters.get(wantedReg));
if (CachedRecovery* current = m_registers[wantedReg]) {
if (current == &cachedRecovery) {
if (verbose)
dataLog(" + ", wantedReg, " is OK\n");
return;
}
// We could do a more complex thing by finding cycles
// etc. in that case.
// However, ending up in this situation will be super
// rare, and should actually be outright impossible for
// non-FTL tiers, since:
// (a) All doubles have been converted into JSValues with
// ValueRep nodes, so FPRs are initially free
//
// (b) The only recoveries with wanted registers are the
// callee (which always starts out in a register) and
// the callee-save registers
//
// (c) The callee-save registers are the first things we
// load (after the return PC), and they are loaded as JSValues
//
// (d) We prefer loading JSValues into FPRs if their
// wanted GPR is not available
//
// (e) If we end up spilling some registers with a
// target, we won't load them again before the very
// end of the algorithm
//
// Combined, this means that we will never load a recovery
// with a wanted GPR into any GPR other than its wanted
// GPR. The callee could however have been initially in
// one of the callee-save registers - but since the wanted
// GPR for the callee is always regT0, it will be the
// first one to be displaced, and we won't see it when
// handling any of the callee-save registers.
//
// Thus, the only way we could ever reach this path is in
// the FTL, when there is so much pressure that we
// absolutely need to load the callee-save registers into
// different GPRs initially but not enough pressure to
// then have to spill all of them. And even in that case,
// depending on the order in which B3 saves the
// callee-saves, we will probably still be safe. Anyway,
// the couple extra move instructions compared to an
// efficient cycle-based algorithm are not going to hurt
// us.
if (wantedReg.isFPR()) {
FPRReg tempFPR = getFreeFPR();
if (verbose)
dataLog(" * Moving ", wantedReg, " into ", tempFPR, "\n");
m_jit.moveDouble(wantedReg.fpr(), tempFPR);
updateRecovery(*current,
ValueRecovery::inFPR(tempFPR, current->recovery().dataFormat()));
} else {
GPRReg tempGPR = getFreeGPR();
if (verbose)
dataLog(" * Moving ", wantedReg.gpr(), " into ", tempGPR, "\n");
m_jit.move(wantedReg.gpr(), tempGPR);
updateRecovery(*current,
ValueRecovery::inGPR(tempGPR, current->recovery().dataFormat()));
}
}
ASSERT(!m_registers[wantedReg]);
if (cachedRecovery.recovery().isConstant()) {
// We only care about callee saves for wanted FPRs, and those are never constants
ASSERT(wantedReg.isGPR());
if (verbose)
dataLog(" * Loading ", cachedRecovery.recovery().constant(), " into ", wantedReg, "\n");
m_jit.moveTrustedValue(cachedRecovery.recovery().constant(), JSValueRegs { wantedReg.gpr() });
updateRecovery(
cachedRecovery,
ValueRecovery::inRegister(wantedReg, DataFormatJS));
} else if (cachedRecovery.recovery().isInGPR()) {
if (verbose)
dataLog(" * Moving ", cachedRecovery.recovery(), " into ", wantedReg, "\n");
if (wantedReg.isGPR())
m_jit.move(cachedRecovery.recovery().gpr(), wantedReg.gpr());
else
m_jit.move64ToDouble(cachedRecovery.recovery().gpr(), wantedReg.fpr());
RELEASE_ASSERT(cachedRecovery.recovery().dataFormat() == DataFormatJS);
updateRecovery(cachedRecovery,
ValueRecovery::inRegister(wantedReg, DataFormatJS));
} else {
ASSERT(cachedRecovery.recovery().isInFPR());
if (cachedRecovery.recovery().dataFormat() == DataFormatDouble) {
// We only care about callee saves for wanted FPRs, and those are always DataFormatJS
ASSERT(wantedReg.isGPR());
// This will automatically pick the wanted GPR
emitBox(cachedRecovery);
} else {
if (verbose)
dataLog(" * Moving ", cachedRecovery.recovery().fpr(), " into ", wantedReg, "\n");
if (wantedReg.isGPR())
m_jit.moveDoubleTo64(cachedRecovery.recovery().fpr(), wantedReg.gpr());
else
m_jit.moveDouble(cachedRecovery.recovery().fpr(), wantedReg.fpr());
RELEASE_ASSERT(cachedRecovery.recovery().dataFormat() == DataFormatJS);
updateRecovery(cachedRecovery,
ValueRecovery::inRegister(wantedReg, DataFormatJS));
}
}
ASSERT(m_registers[wantedReg] == &cachedRecovery);
}