michael@0: /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
michael@0:  * vim: set ts=8 sts=4 et sw=4 tw=99:
michael@0:  * This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: #include "jit/EffectiveAddressAnalysis.h"
michael@0: #include "jit/MIR.h"
michael@0: #include "jit/MIRGraph.h"
michael@0: 
michael@0: using namespace js;
michael@0: using namespace jit;
michael@0: 
michael@0: static void
michael@0: AnalyzeLsh(TempAllocator &alloc, MLsh *lsh)
michael@0: {
michael@0:     if (lsh->specialization() != MIRType_Int32)
michael@0:         return;
michael@0: 
michael@0:     MDefinition *index = lsh->lhs();
michael@0:     JS_ASSERT(index->type() == MIRType_Int32);
michael@0: 
michael@0:     MDefinition *shift = lsh->rhs();
michael@0:     if (!shift->isConstant())
michael@0:         return;
michael@0: 
michael@0:     Value shiftValue = shift->toConstant()->value();
michael@0:     if (!shiftValue.isInt32() || !IsShiftInScaleRange(shiftValue.toInt32()))
michael@0:         return;
michael@0: 
michael@0:     Scale scale = ShiftToScale(shiftValue.toInt32());
michael@0: 
michael@0:     int32_t displacement = 0;
michael@0:     MInstruction *last = lsh;
michael@0:     MDefinition *base = nullptr;
michael@0:     while (true) {
michael@0:         if (!last->hasOneUse())
michael@0:             break;
michael@0: 
michael@0:         MUseIterator use = last->usesBegin();
michael@0:         if (!use->consumer()->isDefinition() || !use->consumer()->toDefinition()->isAdd())
michael@0:             break;
michael@0: 
michael@0:         MAdd *add = use->consumer()->toDefinition()->toAdd();
michael@0:         if (add->specialization() != MIRType_Int32 || !add->isTruncated())
michael@0:             break;
michael@0: 
michael@0:         MDefinition *other = add->getOperand(1 - use->index());
michael@0: 
michael@0:         if (other->isConstant()) {
michael@0:             displacement += other->toConstant()->value().toInt32();
michael@0:         } else {
michael@0:             if (base)
michael@0:                 break;
michael@0:             base = other;
michael@0:         }
michael@0: 
michael@0:         last = add;
michael@0:     }
michael@0: 
michael@0:     if (!base) {
michael@0:         uint32_t elemSize = 1 << ScaleToShift(scale);
michael@0:         if (displacement % elemSize != 0)
michael@0:             return;
michael@0: 
michael@0:         if (!last->hasOneUse())
michael@0:             return;
michael@0: 
michael@0:         MUseIterator use = last->usesBegin();
michael@0:         if (!use->consumer()->isDefinition() || !use->consumer()->toDefinition()->isBitAnd())
michael@0:             return;
michael@0: 
michael@0:         MBitAnd *bitAnd = use->consumer()->toDefinition()->toBitAnd();
michael@0:         MDefinition *other = bitAnd->getOperand(1 - use->index());
michael@0:         if (!other->isConstant() || !other->toConstant()->value().isInt32())
michael@0:             return;
michael@0: 
michael@0:         uint32_t bitsClearedByShift = elemSize - 1;
michael@0:         uint32_t bitsClearedByMask = ~uint32_t(other->toConstant()->value().toInt32());
michael@0:         if ((bitsClearedByShift & bitsClearedByMask) != bitsClearedByMask)
michael@0:             return;
michael@0: 
michael@0:         bitAnd->replaceAllUsesWith(last);
michael@0:         return;
michael@0:     }
michael@0: 
michael@0:     MEffectiveAddress *eaddr = MEffectiveAddress::New(alloc, base, index, scale, displacement);
michael@0:     last->replaceAllUsesWith(eaddr);
michael@0:     last->block()->insertAfter(last, eaddr);
michael@0: }
michael@0: 
michael@0: // This analysis converts patterns of the form:
michael@0: //   truncate(x + (y << {0,1,2,3}))
michael@0: //   truncate(x + (y << {0,1,2,3}) + imm32)
michael@0: // into a single lea instruction, and patterns of the form:
michael@0: //   asmload(x + imm32)
michael@0: //   asmload(x << {0,1,2,3})
michael@0: //   asmload((x << {0,1,2,3}) + imm32)
michael@0: //   asmload((x << {0,1,2,3}) & mask)            (where mask is redundant with shift)
michael@0: //   asmload(((x << {0,1,2,3}) + imm32) & mask)  (where mask is redundant with shift + imm32)
michael@0: // into a single asmload instruction (and for asmstore too).
michael@0: //
michael@0: // Additionally, we should consider the general forms:
michael@0: //   truncate(x + y + imm32)
michael@0: //   truncate((y << {0,1,2,3}) + imm32)
michael@0: bool
michael@0: EffectiveAddressAnalysis::analyze()
michael@0: {
michael@0:     for (ReversePostorderIterator block(graph_.rpoBegin()); block != graph_.rpoEnd(); block++) {
michael@0:         for (MInstructionIterator i = block->begin(); i != block->end(); i++) {
michael@0:             if (i->isLsh())
michael@0:                 AnalyzeLsh(graph_.alloc(), i->toLsh());
michael@0:         }
michael@0:     }
michael@0:     return true;
michael@0: }