WebKit/Source/JavaScriptCore/b3/air/AirReportUsedRegisters.cpp at main · WebKit/WebKit · GitHub

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* Redistribution and use in source and binary forms, with or without

* modification, are permitted provided that the following conditions

* are met:

* 1. Redistributions of source code must retain the above copyright

* notice, this list of conditions and the following disclaimer.

* 2. Redistributions in binary form must reproduce the above copyright

* notice, this list of conditions and the following disclaimer in the

* documentation and/or other materials provided with the distribution.

* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY

* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR

* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR

* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,

* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,

* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR

* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY

* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE

* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

#include "config.h"

#include "AirReportUsedRegisters.h"

#if ENABLE(B3_JIT)

#include "AirCode.h"

#include "AirInstInlines.h"

#include "AirPadInterference.h"

#include "AirRegLiveness.h"

#include "AirPhaseScope.h"

namespace JSC { namespace B3 { namespace Air {

bool reportUsedRegisters(Code& code)

{

PhaseScope phaseScope(code, "reportUsedRegisters"_s);

static constexpr bool verbose = false;

// The RegLiveness below reasons about interference at instruction boundaries, so it is only

// correct once padding separates a late use or def from a following early def.

padInterference(code);

if (verbose)

dataLog("Doing reportUsedRegisters on:\n", code);

RegLiveness liveness(code);

bool changed = false;

for (BasicBlock* block : code) {

if (verbose)

dataLog("Looking at: ", *block, "\n");

RegLiveness::LocalCalc localCalc(liveness, block);

for (unsigned instIndex = block->size(); instIndex--;) {

Inst& inst = block->at(instIndex);

if (verbose)

dataLog(" Looking at: ", inst, "\n");

// Kill dead assignments to registers. For simplicity we say that a store is killable if

// it has only late defs and those late defs are to registers that are dead right now.

if (!inst.hasNonArgEffects()) {

bool canDelete = true;

inst.forEachArg(

[&] (Arg& arg, Arg::Role role, Bank, Width) {

if (Arg::isEarlyDef(role)) {

if (verbose)

dataLog(" Cannot delete because of ", arg, "\n");

canDelete = false;

return;

}

if (!Arg::isLateDef(role))

return;

if (!arg.isReg()) {

if (verbose)

dataLog(" Cannot delete because arg is not reg: ", arg, "\n");

canDelete = false;

return;

}

if (localCalc.isLive(arg.reg())) {

if (verbose)

dataLog(" Cannot delete because arg is live: ", arg, "\n");

canDelete = false;

return;

}

});

if (canDelete)

inst = Inst();

}

if (inst.kind.opcode == Patch)

inst.reportUsedRegisters(localCalc.live());

localCalc.execute(instIndex);

}

unsigned sizeBefore = block->size();

unsigned removed = block->insts().removeAllMatching(

[&](const Inst& inst) -> bool {

return !inst;

});

if (removed && sizeBefore - removed <= 1)

changed = true;

}

if (verbose)

dataLog("After reportUsedRegisters:\n", code);

return changed;

}

} } } // namespace JSC::B3::Air

#endif // ENABLE(B3_JIT)

WebKit/Source/JavaScriptCore/b3/air/AirReportUsedRegisters.cpp at main · WebKit/WebKit · GitHub

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