void Canonicalizer::do_ShiftOp (ShiftOp* x) {
ValueType* t = x->x()->type();
ValueType* t2 = x->y()->type();
if (t->is_constant()) {
switch (t->tag()) {
case intTag : if (t->as_IntConstant()->value() == 0) { set_constant(0); return; } break;
case longTag : if (t->as_LongConstant()->value() == (jlong)0) { set_constant(jlong_cast(0)); return; } break;
default : ShouldNotReachHere();
}
if (t2->is_constant()) {
if (t->tag() == intTag) {
int value = t->as_IntConstant()->value();
int shift = t2->as_IntConstant()->value() & 31;
jint mask = ~(~0 << (32 - shift));
if (shift == 0) mask = ~0;
switch (x->op()) {
case Bytecodes::_ishl: set_constant(value << shift); return;
case Bytecodes::_ishr: set_constant(value >> shift); return;
case Bytecodes::_iushr: set_constant((value >> shift) & mask); return;
}
} else if (t->tag() == longTag) {
jlong value = t->as_LongConstant()->value();
int shift = t2->as_IntConstant()->value() & 63;
jlong mask = ~(~jlong_cast(0) << (64 - shift));
if (shift == 0) mask = ~jlong_cast(0);
switch (x->op()) {
case Bytecodes::_lshl: set_constant(value << shift); return;
case Bytecodes::_lshr: set_constant(value >> shift); return;
case Bytecodes::_lushr: set_constant((value >> shift) & mask); return;
}
}
void Canonicalizer::do_NegateOp(NegateOp* x) {
ValueType* t = x->x()->type();
if (t->is_constant()) {
switch (t->tag()) {
case intTag : set_constant(-t->as_IntConstant ()->value()); return;
case longTag : set_constant(-t->as_LongConstant ()->value()); return;
case floatTag : set_constant(-t->as_FloatConstant ()->value()); return;
case doubleTag: set_constant(-t->as_DoubleConstant()->value()); return;
default : ShouldNotReachHere();
}
}
}
void Canonicalizer::do_ShiftOp (ShiftOp* x) {
ValueType* t = x->x()->type();
if (t->is_constant()) {
switch (t->tag()) {
case intTag : if (t->as_IntConstant()->value() == 0) set_constant(0); return;
case longTag : if (t->as_LongConstant()->value() == (jlong)0) set_constant(jlong_cast(0)); return;
default : ShouldNotReachHere();
}
}
ValueType* t2 = x->y()->type();
if (t2->is_constant()) {
switch (t2->tag()) {
case intTag : if (t2->as_IntConstant()->value() == 0) set_canonical(x->x()); return;
default : ShouldNotReachHere();
}
}
}
void Canonicalizer::do_If(If* x) {
// move const to right
if (x->x()->type()->is_constant()) x->swap_operands();
// simplify
const Value l = x->x(); ValueType* lt = l->type();
const Value r = x->y(); ValueType* rt = r->type();
if (lt->is_constant() && rt->is_constant()) {
// pattern: If (lc cond rc) => simplify to: Goto
Goto* g = NULL;
switch (lt->tag()) {
case intTag:
g = new Goto(x->sux_for(is_true(lt->as_IntConstant ()->value(), x->cond(), rt->as_IntConstant ()->value())), x->is_safepoint());
break;
case longTag:
g = new Goto(x->sux_for(is_true(lt->as_LongConstant()->value(), x->cond(), rt->as_LongConstant()->value())), x->is_safepoint());
break;
// other cases not implemented (must be extremely careful with floats & doubles!)
}
if (g != NULL) {
// If this If is a safepoint then the debug information should come from the state_before of the If.
g->set_state_before(x->state_before());
set_canonical(g);
}
} else if (rt->as_IntConstant() != NULL) {
// pattern: If (l cond rc) => investigate further
const jint rc = rt->as_IntConstant()->value();
if (l->as_CompareOp() != NULL) {
// pattern: If ((a cmp b) cond rc) => simplify to: If (x cond y) or: Goto
CompareOp* cmp = l->as_CompareOp();
bool unordered_is_less = cmp->op() == Bytecodes::_fcmpl || cmp->op() == Bytecodes::_dcmpl;
BlockBegin* lss_sux = x->sux_for(is_true(-1, x->cond(), rc)); // successor for a < b
BlockBegin* eql_sux = x->sux_for(is_true( 0, x->cond(), rc)); // successor for a = b
BlockBegin* gtr_sux = x->sux_for(is_true(+1, x->cond(), rc)); // successor for a > b
BlockBegin* nan_sux = unordered_is_less ? lss_sux : gtr_sux ; // successor for unordered
// Note: At this point all successors (lss_sux, eql_sux, gtr_sux, nan_sux) are
// equal to x->tsux() or x->fsux(). Furthermore, nan_sux equals either
// lss_sux or gtr_sux.
if (lss_sux == eql_sux && eql_sux == gtr_sux) {
// all successors identical => simplify to: Goto
set_canonical(new Goto(lss_sux, x->is_safepoint()));
} else {
// two successors differ and two successors are the same => simplify to: If (x cmp y)
// determine new condition & successors
If::Condition cond;
BlockBegin* tsux = NULL;
BlockBegin* fsux = NULL;
if (lss_sux == eql_sux) { cond = If::leq; tsux = lss_sux; fsux = gtr_sux; }
else if (lss_sux == gtr_sux) { cond = If::neq; tsux = lss_sux; fsux = eql_sux; }
else if (eql_sux == gtr_sux) { cond = If::geq; tsux = eql_sux; fsux = lss_sux; }
else { ShouldNotReachHere(); }
set_canonical(new If(cmp->x(), cond, nan_sux == tsux, cmp->y(), tsux, fsux, cmp->state_before(), x->is_safepoint()));
set_bci(cmp->bci());
}
} else if (l->as_InstanceOf() != NULL) {
// NOTE: Code permanently disabled for now since it leaves the old InstanceOf
// instruction in the graph (it is pinned). Need to fix this at some point.
return;
// pattern: If ((obj instanceof klass) cond rc) => simplify to: IfInstanceOf or: Goto
InstanceOf* inst = l->as_InstanceOf();
BlockBegin* is_inst_sux = x->sux_for(is_true(1, x->cond(), rc)); // successor for instanceof == 1
BlockBegin* no_inst_sux = x->sux_for(is_true(0, x->cond(), rc)); // successor for instanceof == 0
if (is_inst_sux == no_inst_sux && inst->is_loaded()) {
// both successors identical and klass is loaded => simplify to: Goto
set_canonical(new Goto(is_inst_sux, x->is_safepoint()));
} else {
// successors differ => simplify to: IfInstanceOf
set_canonical(new IfInstanceOf(inst->klass(), inst->obj(), true, inst->bci(), is_inst_sux, no_inst_sux));
}
}
}
}