bool
ion::ExtractLinearInequality(MTest *test, BranchDirection direction,
LinearSum *plhs, MDefinition **prhs, bool *plessEqual)
{
if (!test->getOperand(0)->isCompare())
return false;
MCompare *compare = test->getOperand(0)->toCompare();
MDefinition *lhs = compare->getOperand(0);
MDefinition *rhs = compare->getOperand(1);
if (compare->specialization() != MIRType_Int32)
return false;
JS_ASSERT(lhs->type() == MIRType_Int32);
JS_ASSERT(rhs->type() == MIRType_Int32);
JSOp jsop = compare->jsop();
if (direction == FALSE_BRANCH)
jsop = analyze::NegateCompareOp(jsop);
LinearSum lsum = ExtractLinearSum(lhs);
LinearSum rsum = ExtractLinearSum(rhs);
if (!SafeSub(lsum.constant, rsum.constant, &lsum.constant))
return false;
// Normalize operations to use <= or >=.
switch (jsop) {
case JSOP_LE:
*plessEqual = true;
break;
case JSOP_LT:
/* x < y ==> x + 1 <= y */
if (!SafeAdd(lsum.constant, 1, &lsum.constant))
return false;
*plessEqual = true;
break;
case JSOP_GE:
*plessEqual = false;
break;
case JSOP_GT:
/* x > y ==> x - 1 >= y */
if (!SafeSub(lsum.constant, 1, &lsum.constant))
return false;
*plessEqual = false;
break;
default:
return false;
}
*plhs = lsum;
*prhs = rsum.term;
return true;
}
static void
TryEliminateTypeBarrierFromTest(MTypeBarrier *barrier, bool filtersNull, bool filtersUndefined,
MTest *test, BranchDirection direction, bool *eliminated)
{
JS_ASSERT(filtersNull || filtersUndefined);
// Watch for code patterns similar to 'if (x.f) { ... = x.f }'. If x.f
// is either an object or null/undefined, there will be a type barrier on
// the latter read as the null/undefined value is never realized there.
// The type barrier can be eliminated, however, by looking at tests
// performed on the result of the first operation that filter out all
// types that have been seen in the first access but not the second.
// A test 'if (x.f)' filters both null and undefined.
if (test->getOperand(0) == barrier->input() && direction == TRUE_BRANCH) {
*eliminated = true;
barrier->replaceAllUsesWith(barrier->input());
return;
}
if (!test->getOperand(0)->isCompare())
return;
MCompare *compare = test->getOperand(0)->toCompare();
MCompare::CompareType compareType = compare->compareType();
if (compareType != MCompare::Compare_Undefined && compareType != MCompare::Compare_Null)
return;
if (compare->getOperand(0) != barrier->input())
return;
JSOp op = compare->jsop();
JS_ASSERT(op == JSOP_EQ || op == JSOP_STRICTEQ ||
op == JSOP_NE || op == JSOP_STRICTNE);
if ((direction == TRUE_BRANCH) != (op == JSOP_NE || op == JSOP_STRICTNE))
return;
// A test 'if (x.f != null)' or 'if (x.f != undefined)' filters both null
// and undefined. If strict equality is used, only the specified rhs is
// tested for.
if (op == JSOP_STRICTEQ || op == JSOP_STRICTNE) {
if (compareType == MCompare::Compare_Undefined && !filtersUndefined)
return;
if (compareType == MCompare::Compare_Null && !filtersNull)
return;
}
*eliminated = true;
barrier->replaceAllUsesWith(barrier->input());
}
bool
RangeAnalysis::addBetaNobes()
{
IonSpew(IonSpew_Range, "Adding beta nobes");
for (PostorderIterator i(graph_.poBegin()); i != graph_.poEnd(); i++) {
MBasicBlock *block = *i;
IonSpew(IonSpew_Range, "Looking at block %d", block->id());
BranchDirection branch_dir;
MTest *test = block->immediateDominatorBranch(&branch_dir);
if (!test || !test->getOperand(0)->isCompare())
continue;
MCompare *compare = test->getOperand(0)->toCompare();
MDefinition *left = compare->getOperand(0);
MDefinition *right = compare->getOperand(1);
int32 bound;
MDefinition *val = NULL;
JSOp jsop = compare->jsop();
if (branch_dir == FALSE_BRANCH)
jsop = analyze::NegateCompareOp(jsop);
if (left->isConstant() && left->toConstant()->value().isInt32()) {
bound = left->toConstant()->value().toInt32();
val = right;
jsop = analyze::ReverseCompareOp(jsop);
} else if (right->isConstant() && right->toConstant()->value().isInt32()) {
bound = right->toConstant()->value().toInt32();
val = left;
} else {
MDefinition *smaller = NULL;
MDefinition *greater = NULL;
if (jsop == JSOP_LT) {
smaller = left;
greater = right;
} else if (jsop == JSOP_GT) {
smaller = right;
greater = left;
}
if (smaller && greater) {
MBeta *beta;
beta = MBeta::New(smaller, Range(JSVAL_INT_MIN, JSVAL_INT_MAX-1));
block->insertBefore(*block->begin(), beta);
replaceDominatedUsesWith(smaller, beta, block);
beta = MBeta::New(greater, Range(JSVAL_INT_MIN+1, JSVAL_INT_MAX));
block->insertBefore(*block->begin(), beta);
replaceDominatedUsesWith(greater, beta, block);
}
continue;
}
JS_ASSERT(val);
Range comp;
switch (jsop) {
case JSOP_LE:
comp.setUpper(bound);
break;
case JSOP_LT:
if (!SafeSub(bound, 1, &bound))
break;
comp.setUpper(bound);
break;
case JSOP_GE:
comp.setLower(bound);
break;
case JSOP_GT:
if (!SafeAdd(bound, 1, &bound))
break;
comp.setLower(bound);
break;
case JSOP_EQ:
comp.setLower(bound);
comp.setUpper(bound);
default:
break; // well, for neq we could have
// [-\inf, bound-1] U [bound+1, \inf] but we only use contiguous ranges.
}
IonSpew(IonSpew_Range, "Adding beta node for %d", val->id());
MBeta *beta = MBeta::New(val, comp);
block->insertBefore(*block->begin(), beta);
replaceDominatedUsesWith(val, beta, block);
}
return true;
}
