//------------------------------find_unswitching_candidate-----------------------------
// Find candidate "if" for unswitching
IfNode* PhaseIdealLoop::find_unswitching_candidate(const IdealLoopTree *loop) const {
// Find first invariant test that doesn't exit the loop
LoopNode *head = loop->_head->as_Loop();
IfNode* unswitch_iff = NULL;
Node* n = head->in(LoopNode::LoopBackControl);
while (n != head) {
Node* n_dom = idom(n);
if (n->is_Region()) {
if (n_dom->is_If()) {
IfNode* iff = n_dom->as_If();
if (iff->in(1)->is_Bool()) {
BoolNode* bol = iff->in(1)->as_Bool();
if (bol->in(1)->is_Cmp()) {
// If condition is invariant and not a loop exit,
// then found reason to unswitch.
if (loop->is_invariant(bol) && !loop->is_loop_exit(iff)) {
unswitch_iff = iff;
}
}
}
}
}
n = n_dom;
}
return unswitch_iff;
}
//------------------------------split_if---------------------------------------
// Look for places where we merge constants, then test on the merged value.
// If the IF test will be constant folded on the path with the constant, we
// win by splitting the IF to before the merge point.
static Node* split_if(IfNode *iff, PhaseIterGVN *igvn) {
// I could be a lot more general here, but I'm trying to squeeze this
// in before the Christmas '98 break so I'm gonna be kinda restrictive
// on the patterns I accept. CNC
// Look for a compare of a constant and a merged value
Node *i1 = iff->in(1);
if( !i1->is_Bool() ) return NULL;
BoolNode *b = i1->as_Bool();
Node *cmp = b->in(1);
if( !cmp->is_Cmp() ) return NULL;
i1 = cmp->in(1);
if( i1 == NULL || !i1->is_Phi() ) return NULL;
PhiNode *phi = i1->as_Phi();
if( phi->is_copy() ) return NULL;
Node *con2 = cmp->in(2);
if( !con2->is_Con() ) return NULL;
// See that the merge point contains some constants
Node *con1=NULL;
uint i4;
for( i4 = 1; i4 < phi->req(); i4++ ) {
con1 = phi->in(i4);
if( !con1 ) return NULL; // Do not optimize partially collapsed merges
if( con1->is_Con() ) break; // Found a constant
// Also allow null-vs-not-null checks
const TypePtr *tp = igvn->type(con1)->isa_ptr();
if( tp && tp->_ptr == TypePtr::NotNull )
break;
}
if( i4 >= phi->req() ) return NULL; // Found no constants
igvn->C->set_has_split_ifs(true); // Has chance for split-if
// Make sure that the compare can be constant folded away
Node *cmp2 = cmp->clone();
cmp2->set_req(1,con1);
cmp2->set_req(2,con2);
const Type *t = cmp2->Value(igvn);
// This compare is dead, so whack it!
igvn->remove_dead_node(cmp2);
if( !t->singleton() ) return NULL;
// No intervening control, like a simple Call
Node *r = iff->in(0);
if( !r->is_Region() ) return NULL;
if( phi->region() != r ) return NULL;
// No other users of the cmp/bool
if (b->outcnt() != 1 || cmp->outcnt() != 1) {
//tty->print_cr("many users of cmp/bool");
return NULL;
}
// Make sure we can determine where all the uses of merged values go
for (DUIterator_Fast jmax, j = r->fast_outs(jmax); j < jmax; j++) {
Node* u = r->fast_out(j);
if( u == r ) continue;
if( u == iff ) continue;
if( u->outcnt() == 0 ) continue; // use is dead & ignorable
if( !u->is_Phi() ) {
/*
if( u->is_Start() ) {
tty->print_cr("Region has inlined start use");
} else {
tty->print_cr("Region has odd use");
u->dump(2);
}*/
return NULL;
}
if( u != phi ) {
// CNC - do not allow any other merged value
//tty->print_cr("Merging another value");
//u->dump(2);
return NULL;
}
// Make sure we can account for all Phi uses
for (DUIterator_Fast kmax, k = u->fast_outs(kmax); k < kmax; k++) {
Node* v = u->fast_out(k); // User of the phi
// CNC - Allow only really simple patterns.
// In particular I disallow AddP of the Phi, a fairly common pattern
if( v == cmp ) continue; // The compare is OK
if( (v->is_ConstraintCast()) &&
v->in(0)->in(0) == iff )
continue; // CastPP/II of the IfNode is OK
// Disabled following code because I cannot tell if exactly one
// path dominates without a real dominator check. CNC 9/9/1999
//uint vop = v->Opcode();
//if( vop == Op_Phi ) { // Phi from another merge point might be OK
// Node *r = v->in(0); // Get controlling point
// if( !r ) return NULL; // Degraded to a copy
// // Find exactly one path in (either True or False doms, but not IFF)
// int cnt = 0;
// for( uint i = 1; i < r->req(); i++ )
// if( r->in(i) && r->in(i)->in(0) == iff )
// cnt++;
// if( cnt == 1 ) continue; // Exactly one of True or False guards Phi
//}
if( !v->is_Call() ) {
/*
if( v->Opcode() == Op_AddP ) {
tty->print_cr("Phi has AddP use");
} else if( v->Opcode() == Op_CastPP ) {
tty->print_cr("Phi has CastPP use");
} else if( v->Opcode() == Op_CastII ) {
tty->print_cr("Phi has CastII use");
} else {
tty->print_cr("Phi has use I cant be bothered with");
}
*/
}
return NULL;
/* CNC - Cut out all the fancy acceptance tests
// Can we clone this use when doing the transformation?
// If all uses are from Phis at this merge or constants, then YES.
if( !v->in(0) && v != cmp ) {
tty->print_cr("Phi has free-floating use");
v->dump(2);
return NULL;
}
for( uint l = 1; l < v->req(); l++ ) {
if( (!v->in(l)->is_Phi() || v->in(l)->in(0) != r) &&
!v->in(l)->is_Con() ) {
tty->print_cr("Phi has use");
v->dump(2);
return NULL;
} // End of if Phi-use input is neither Phi nor Constant
} // End of for all inputs to Phi-use
*/
} // End of for all uses of Phi
} // End of for all uses of Region
// Only do this if the IF node is in a sane state
if (iff->outcnt() != 2)
return NULL;
// Got a hit! Do the Mondo Hack!
//
//ABC a1c def ghi B 1 e h A C a c d f g i
// R - Phi - Phi - Phi Rc - Phi - Phi - Phi Rx - Phi - Phi - Phi
// cmp - 2 cmp - 2 cmp - 2
// bool bool_c bool_x
// if if_c if_x
// T F T F T F
// ..s.. ..t .. ..s.. ..t.. ..s.. ..t..
//
// Split the paths coming into the merge point into 2 separate groups of
// merges. On the left will be all the paths feeding constants into the
// Cmp's Phi. On the right will be the remaining paths. The Cmp's Phi
// will fold up into a constant; this will let the Cmp fold up as well as
// all the control flow. Below the original IF we have 2 control
// dependent regions, 's' and 't'. Now we will merge the two paths
// just prior to 's' and 't' from the two IFs. At least 1 path (and quite
// likely 2 or more) will promptly constant fold away.
PhaseGVN *phase = igvn;
// Make a region merging constants and a region merging the rest
uint req_c = 0;
Node* predicate_proj = NULL;
for (uint ii = 1; ii < r->req(); ii++) {
if (phi->in(ii) == con1) {
req_c++;
}
Node* proj = PhaseIdealLoop::find_predicate(r->in(ii));
if (proj != NULL) {
assert(predicate_proj == NULL, "only one predicate entry expected");
predicate_proj = proj;
}
}
Node* predicate_c = NULL;
Node* predicate_x = NULL;
bool counted_loop = r->is_CountedLoop();
Node *region_c = new (igvn->C, req_c + 1) RegionNode(req_c + 1);
Node *phi_c = con1;
uint len = r->req();
Node *region_x = new (igvn->C, len - req_c) RegionNode(len - req_c);
Node *phi_x = PhiNode::make_blank(region_x, phi);
for (uint i = 1, i_c = 1, i_x = 1; i < len; i++) {
if (phi->in(i) == con1) {
region_c->init_req( i_c++, r ->in(i) );
if (r->in(i) == predicate_proj)
predicate_c = predicate_proj;
} else {
region_x->init_req( i_x, r ->in(i) );
phi_x ->init_req( i_x++, phi->in(i) );
if (r->in(i) == predicate_proj)
predicate_x = predicate_proj;
}
}
if (predicate_c != NULL && (req_c > 1)) {
assert(predicate_x == NULL, "only one predicate entry expected");
predicate_c = NULL; // Do not clone predicate below merge point
}
if (predicate_x != NULL && ((len - req_c) > 2)) {
assert(predicate_c == NULL, "only one predicate entry expected");
predicate_x = NULL; // Do not clone predicate below merge point
}
// Register the new RegionNodes but do not transform them. Cannot
// transform until the entire Region/Phi conglomerate has been hacked
// as a single huge transform.
igvn->register_new_node_with_optimizer( region_c );
igvn->register_new_node_with_optimizer( region_x );
// Prevent the untimely death of phi_x. Currently he has no uses. He is
// about to get one. If this only use goes away, then phi_x will look dead.
// However, he will be picking up some more uses down below.
Node *hook = new (igvn->C, 4) Node(4);
hook->init_req(0, phi_x);
hook->init_req(1, phi_c);
phi_x = phase->transform( phi_x );
// Make the compare
Node *cmp_c = phase->makecon(t);
Node *cmp_x = cmp->clone();
cmp_x->set_req(1,phi_x);
cmp_x->set_req(2,con2);
cmp_x = phase->transform(cmp_x);
// Make the bool
Node *b_c = phase->transform(new (igvn->C, 2) BoolNode(cmp_c,b->_test._test));
Node *b_x = phase->transform(new (igvn->C, 2) BoolNode(cmp_x,b->_test._test));
// Make the IfNode
IfNode *iff_c = new (igvn->C, 2) IfNode(region_c,b_c,iff->_prob,iff->_fcnt);
igvn->set_type_bottom(iff_c);
igvn->_worklist.push(iff_c);
hook->init_req(2, iff_c);
IfNode *iff_x = new (igvn->C, 2) IfNode(region_x,b_x,iff->_prob, iff->_fcnt);
igvn->set_type_bottom(iff_x);
igvn->_worklist.push(iff_x);
hook->init_req(3, iff_x);
// Make the true/false arms
Node *iff_c_t = phase->transform(new (igvn->C, 1) IfTrueNode (iff_c));
Node *iff_c_f = phase->transform(new (igvn->C, 1) IfFalseNode(iff_c));
if (predicate_c != NULL) {
assert(predicate_x == NULL, "only one predicate entry expected");
// Clone loop predicates to each path
iff_c_t = igvn->clone_loop_predicates(predicate_c, iff_c_t, !counted_loop);
iff_c_f = igvn->clone_loop_predicates(predicate_c, iff_c_f, !counted_loop);
}
Node *iff_x_t = phase->transform(new (igvn->C, 1) IfTrueNode (iff_x));
Node *iff_x_f = phase->transform(new (igvn->C, 1) IfFalseNode(iff_x));
if (predicate_x != NULL) {
assert(predicate_c == NULL, "only one predicate entry expected");
// Clone loop predicates to each path
iff_x_t = igvn->clone_loop_predicates(predicate_x, iff_x_t, !counted_loop);
iff_x_f = igvn->clone_loop_predicates(predicate_x, iff_x_f, !counted_loop);
}
// Merge the TRUE paths
Node *region_s = new (igvn->C, 3) RegionNode(3);
igvn->_worklist.push(region_s);
region_s->init_req(1, iff_c_t);
region_s->init_req(2, iff_x_t);
igvn->register_new_node_with_optimizer( region_s );
// Merge the FALSE paths
Node *region_f = new (igvn->C, 3) RegionNode(3);
igvn->_worklist.push(region_f);
region_f->init_req(1, iff_c_f);
region_f->init_req(2, iff_x_f);
igvn->register_new_node_with_optimizer( region_f );
igvn->hash_delete(cmp);// Remove soon-to-be-dead node from hash table.
cmp->set_req(1,NULL); // Whack the inputs to cmp because it will be dead
cmp->set_req(2,NULL);
// Check for all uses of the Phi and give them a new home.
// The 'cmp' got cloned, but CastPP/IIs need to be moved.
Node *phi_s = NULL; // do not construct unless needed
Node *phi_f = NULL; // do not construct unless needed
for (DUIterator_Last i2min, i2 = phi->last_outs(i2min); i2 >= i2min; --i2) {
Node* v = phi->last_out(i2);// User of the phi
igvn->hash_delete(v); // Have to fixup other Phi users
igvn->_worklist.push(v);
uint vop = v->Opcode();
Node *proj = NULL;
if( vop == Op_Phi ) { // Remote merge point
Node *r = v->in(0);
for (uint i3 = 1; i3 < r->req(); i3++)
if (r->in(i3) && r->in(i3)->in(0) == iff) {
proj = r->in(i3);
break;
}
} else if( v->is_ConstraintCast() ) {
proj = v->in(0); // Controlling projection
} else {
assert( 0, "do not know how to handle this guy" );
}
Node *proj_path_data, *proj_path_ctrl;
if( proj->Opcode() == Op_IfTrue ) {
if( phi_s == NULL ) {
// Only construct phi_s if needed, otherwise provides
// interfering use.
phi_s = PhiNode::make_blank(region_s,phi);
phi_s->init_req( 1, phi_c );
phi_s->init_req( 2, phi_x );
hook->add_req(phi_s);
phi_s = phase->transform(phi_s);
}
proj_path_data = phi_s;
proj_path_ctrl = region_s;
} else {
if( phi_f == NULL ) {
// Only construct phi_f if needed, otherwise provides
// interfering use.
phi_f = PhiNode::make_blank(region_f,phi);
phi_f->init_req( 1, phi_c );
phi_f->init_req( 2, phi_x );
hook->add_req(phi_f);
phi_f = phase->transform(phi_f);
}
proj_path_data = phi_f;
proj_path_ctrl = region_f;
}
// Fixup 'v' for for the split
if( vop == Op_Phi ) { // Remote merge point
uint i;
for( i = 1; i < v->req(); i++ )
if( v->in(i) == phi )
break;
v->set_req(i, proj_path_data );
} else if( v->is_ConstraintCast() ) {
v->set_req(0, proj_path_ctrl );
v->set_req(1, proj_path_data );
} else
ShouldNotReachHere();
}
// Now replace the original iff's True/False with region_s/region_t.
// This makes the original iff go dead.
for (DUIterator_Last i3min, i3 = iff->last_outs(i3min); i3 >= i3min; --i3) {
Node* p = iff->last_out(i3);
assert( p->Opcode() == Op_IfTrue || p->Opcode() == Op_IfFalse, "" );
Node *u = (p->Opcode() == Op_IfTrue) ? region_s : region_f;
// Replace p with u
igvn->add_users_to_worklist(p);
for (DUIterator_Last lmin, l = p->last_outs(lmin); l >= lmin;) {
Node* x = p->last_out(l);
igvn->hash_delete(x);
uint uses_found = 0;
for( uint j = 0; j < x->req(); j++ ) {
if( x->in(j) == p ) {
x->set_req(j, u);
uses_found++;
}
}
l -= uses_found; // we deleted 1 or more copies of this edge
}
igvn->remove_dead_node(p);
}
// Force the original merge dead
igvn->hash_delete(r);
// First, remove region's dead users.
for (DUIterator_Last lmin, l = r->last_outs(lmin); l >= lmin;) {
Node* u = r->last_out(l);
if( u == r ) {
r->set_req(0, NULL);
} else {
assert(u->outcnt() == 0, "only dead users");
igvn->remove_dead_node(u);
}
l -= 1;
}
igvn->remove_dead_node(r);
// Now remove the bogus extra edges used to keep things alive
igvn->remove_dead_node( hook );
// Must return either the original node (now dead) or a new node
// (Do not return a top here, since that would break the uniqueness of top.)
return new (igvn->C, 1) ConINode(TypeInt::ZERO);
}
//=============================================================================
//------------------------------AbsNode----------------------------------------
Node *AbsNode::is_absolute( PhaseGVN *phase, Node *phi_root ) {
int chs = 0; // No need to change sign of result
int abs = 1; // Assume ABS is being performed
int typ = 0; // Assume integer ABS
// ABS ends with the merge of 2 control flow paths. Find the merge point.
Node *region = phi_root->in(0);
if( region->req() != 3 ) return NULL;
if( phi_root->req() != 3 ) return NULL;
// Next up is the true/false control bits
Node *iff = region->in(1);
if( !iff ) return NULL;
Node *ift = region->in(2);
if( !ift ) return NULL;
if( iff->Opcode() == Op_IfFalse &&
ift->Opcode() == Op_IfTrue ) {
} else if( iff->Opcode() == Op_IfTrue &&
ift->Opcode() == Op_IfFalse ) {
chs = 1-chs; // Test is reversed
} else return NULL; // Not from same IF
Node *fif = iff->in(0);
if( ift->in(0) != fif ) return NULL; // Not from same IF
// Roll up the predicate chain; get the Bool, CmpX
BoolNode *bol = fif->in(1)->is_Bool();
if (bol == NULL) return NULL; // test is dead (constant true or false)
switch( bol->_test._test ) {
case BoolTest::lt: break;
case BoolTest::le: break;
case BoolTest::gt: chs = 1-chs; break;
case BoolTest::ge: chs = 1-chs; break;
case BoolTest::eq: abs = 0; break; // Not an ABS function
case BoolTest::ne: abs = 0; chs = 1-chs; break; // Not an ABS function
}
// Test is next
Node *cmp = bol->in(1);
const Type *tzero = NULL;
switch( cmp->Opcode() ) {
case Op_CmpF: tzero = TypeF::ZERO; typ = 1; break; // Float ABS
case Op_CmpD: tzero = TypeD::ZERO; typ = 2; break; // Double ABS
default: return NULL;
}
// Left of float is value being ABS'd, right is a zero
Node *x = cmp->in(1);
if( phase->type(cmp->in(2)) != tzero ) return NULL;
// Next get the 2 pieces being selected, one is the original value
// and the other is the negated value.
Node *neg_x = phi_root->in(2);
if( phi_root->in(1) == x ) {
} else if( phi_root->in(2) == x ) {
chs = 1-chs;
neg_x = phi_root->in(1);
}
// Check negated value for really negating
int negop = neg_x->Opcode();
if( tzero == TypeF::ZERO ) {
// Allow either NegF(x) or SubF(0,X) and fail out for all others
if( !(negop == Op_NegF && neg_x->in(1) == x ) &&
!(negop == Op_SubF && neg_x->in(2) == x && phase->type(neg_x->in(1)) == tzero ) )
return NULL;
} else {
// Allow either NegD(x) or SubD(0,X) and fail out for all others
if( !(negop == Op_NegD && neg_x->in(1) == x ) &&
!(negop == Op_SubD && neg_x->in(2) == x && phase->type(neg_x->in(1)) == tzero ) )
return NULL;
}
// Yeah-ha! A Hit! Now emit either: abs or nothing, then
// a chs or nothing, of type float or double
if( abs ) { // Doing ABS, or doing ID function
if( typ == 1 ) x = new (2) AbsFNode(x);
else x = new (2) AbsDNode(x);
if( chs ) x = phase->transform(x); // transform all "new" interior nodes
}
if( chs ) { // Simply negating result?
if( typ == 1 ) x = new (2) NegFNode(x);
else x = new (2) NegDNode(x);
}
return x;
}
//------------------------------is_range_check---------------------------------
// Return 0 if not a range check. Return 1 if a range check and set index and
// offset. Return 2 if we had to negate the test. Index is NULL if the check
// is versus a constant.
int IfNode::is_range_check(Node* &range, Node* &index, jint &offset) {
Node* b = in(1);
if (b == NULL || !b->is_Bool()) return 0;
BoolNode* bn = b->as_Bool();
Node* cmp = bn->in(1);
if (cmp == NULL) return 0;
if (cmp->Opcode() != Op_CmpU) return 0;
Node* l = cmp->in(1);
Node* r = cmp->in(2);
int flip_test = 1;
if (bn->_test._test == BoolTest::le) {
l = cmp->in(2);
r = cmp->in(1);
flip_test = 2;
} else if (bn->_test._test != BoolTest::lt) {
return 0;
}
if (l->is_top()) return 0; // Top input means dead test
if (r->Opcode() != Op_LoadRange) return 0;
// We have recognized one of these forms:
// Flip 1: If (Bool[<] CmpU(l, LoadRange)) ...
// Flip 2: If (Bool[<=] CmpU(LoadRange, l)) ...
// Make sure it's a real range check by requiring an uncommon trap
// along the OOB path. Otherwise, it's possible that the user wrote
// something which optimized to look like a range check but behaves
// in some other way.
Node* iftrap = proj_out(flip_test == 2 ? true : false);
bool found_trap = false;
if (iftrap != NULL) {
Node* u = iftrap->unique_ctrl_out();
if (u != NULL) {
// It could be a merge point (Region) for uncommon trap.
if (u->is_Region()) {
Node* c = u->unique_ctrl_out();
if (c != NULL) {
iftrap = u;
u = c;
}
}
if (u->in(0) == iftrap && u->is_CallStaticJava()) {
int req = u->as_CallStaticJava()->uncommon_trap_request();
if (Deoptimization::trap_request_reason(req) ==
Deoptimization::Reason_range_check) {
found_trap = true;
}
}
}
}
if (!found_trap) return 0; // sorry, no cigar
// Look for index+offset form
Node* ind = l;
jint off = 0;
if (l->is_top()) {
return 0;
} else if (l->is_Add()) {
if ((off = l->in(1)->find_int_con(0)) != 0) {
ind = l->in(2);
} else if ((off = l->in(2)->find_int_con(0)) != 0) {
ind = l->in(1);
}
} else if ((off = l->find_int_con(-1)) >= 0) {
// constant offset with no variable index
ind = NULL;
} else {
// variable index with no constant offset (or dead negative index)
off = 0;
}
// Return all the values:
index = ind;
offset = off;
range = r;
return flip_test;
}