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/*
* Copyright (c) 2000, 2022, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*
*/
#include "precompiled.hpp"
#include "ci/ciTypeFlow.hpp"
#include "memory/allocation.inline.hpp"
#include "memory/resourceArea.hpp"
#include "opto/addnode.hpp"
#include "opto/castnode.hpp"
#include "opto/cfgnode.hpp"
#include "opto/connode.hpp"
#include "opto/loopnode.hpp"
#include "opto/phaseX.hpp"
#include "opto/runtime.hpp"
#include "opto/rootnode.hpp"
#include "opto/subnode.hpp"
// Portions of code courtesy of Clifford Click
// Optimization - Graph Style
#ifndef PRODUCT
extern int explicit_null_checks_elided;
#endif
//=============================================================================
//------------------------------Value------------------------------------------
// Return a tuple for whichever arm of the IF is reachable
const Type* IfNode::Value(PhaseGVN* phase) const {
if( !in(0) ) return Type::TOP;
if( phase->type(in(0)) == Type::TOP )
return Type::TOP;
const Type *t = phase->type(in(1));
if( t == Type::TOP ) // data is undefined
return TypeTuple::IFNEITHER; // unreachable altogether
if( t == TypeInt::ZERO ) // zero, or false
return TypeTuple::IFFALSE; // only false branch is reachable
if( t == TypeInt::ONE ) // 1, or true
return TypeTuple::IFTRUE; // only true branch is reachable
assert( t == TypeInt::BOOL, "expected boolean type" );
return TypeTuple::IFBOTH; // No progress
}
const RegMask &IfNode::out_RegMask() const {
return RegMask::Empty;
}
//------------------------------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();
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() || r->is_Loop() || phi->region() != r || r->as_Region()->is_copy()) {
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()) {
// If the cast is derived from data flow edges, it may not have a control edge.
// If so, it should be safe to split. But follow-up code can not deal with
// this (l. 359). So skip.
if (v->in(0) == NULL) {
return NULL;
}
if (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 can't 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;
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) {
// Bail out if splitting through a region with a predicate input (could
// also be a loop header before loop opts creates a LoopNode for it).
return NULL;
}
}
// If all the defs of the phi are the same constant, we already have the desired end state.
// Skip the split that would create empty phi and region nodes.
if ((r->req() - req_c) == 1) {
return NULL;
}
// At this point we know that we can apply the split if optimization. If the region is still on the worklist,
// we should wait until it is processed. The region might be removed which makes this optimization redundant.
// This also avoids the creation of dead data loops when rewiring data nodes below when a region is dying.
if (igvn->_worklist.member(r)) {
igvn->_worklist.push(iff); // retry split if later again
return NULL;
}
Node *region_c = new RegionNode(req_c + 1);
Node *phi_c = con1;
uint len = r->req();
Node *region_x = new 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) );
} else {
region_x->init_req( i_x, r ->in(i) );
phi_x ->init_req( i_x++, phi->in(i) );
}
}
// 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 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 BoolNode(cmp_c,b->_test._test));
Node *b_x = phase->transform(new BoolNode(cmp_x,b->_test._test));
// Make the IfNode
IfNode* iff_c = iff->clone()->as_If();
iff_c->set_req(0, region_c);
iff_c->set_req(1, b_c);
igvn->set_type_bottom(iff_c);
igvn->_worklist.push(iff_c);
hook->init_req(2, iff_c);
IfNode* iff_x = iff->clone()->as_If();
iff_x->set_req(0, region_x);
iff_x->set_req(1, b_x);
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 IfTrueNode (iff_c));
Node *iff_c_f = phase->transform(new IfFalseNode(iff_c));
Node *iff_x_t = phase->transform(new IfTrueNode (iff_x));
Node *iff_x_f = phase->transform(new IfFalseNode(iff_x));
// Merge the TRUE paths
Node *region_s = new 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 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->rehash_node_delayed(v); // Have to fixup other Phi users
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" );
}
guarantee(proj != NULL, "sanity");
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 ConINode(TypeInt::ZERO);
}
// if this IfNode follows a range check pattern return the projection
// for the failed path
ProjNode* IfNode::range_check_trap_proj(int& flip_test, Node*& l, Node*& r) {
if (outcnt() != 2) {
return NULL;
}
Node* b = in(1);
if (b == NULL || !b->is_Bool()) return NULL;
BoolNode* bn = b->as_Bool();
Node* cmp = bn->in(1);
if (cmp == NULL) return NULL;
if (cmp->Opcode() != Op_CmpU) return NULL;
l = cmp->in(1);
r = cmp->in(2);
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 NULL;
}
if (l->is_top()) return NULL; // Top input means dead test
if (r->Opcode() != Op_LoadRange && !is_RangeCheck()) return NULL;
// We have recognized one of these forms:
// Flip 1: If (Bool[<] CmpU(l, LoadRange)) ...
// Flip 2: If (Bool[<=] CmpU(LoadRange, l)) ...
ProjNode* iftrap = proj_out_or_null(flip_test == 2 ? true : false);
return iftrap;
}
//------------------------------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 RangeCheckNode::is_range_check(Node* &range, Node* &index, jint &offset) {
int flip_test = 0;
Node* l = NULL;
Node* r = NULL;
ProjNode* iftrap = range_check_trap_proj(flip_test, l, r);
if (iftrap == NULL) {
return 0;
}
// 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.
if (iftrap->is_uncommon_trap_proj(Deoptimization::Reason_range_check) == NULL) {
return 0;
}
// Look for index+offset form
Node* ind = l;
jint off = 0;
if (l->is_top()) {
return 0;
} else if (l->Opcode() == Op_AddI) {
if ((off = l->in(1)->find_int_con(0)) != 0) {
ind = l->in(2)->uncast();
} else if ((off = l->in(2)->find_int_con(0)) != 0) {
ind = l->in(1)->uncast();
}
} 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;
}
//------------------------------adjust_check-----------------------------------
// Adjust (widen) a prior range check
static void adjust_check(Node* proj, Node* range, Node* index,
int flip, jint off_lo, PhaseIterGVN* igvn) {
PhaseGVN *gvn = igvn;
// Break apart the old check
Node *iff = proj->in(0);
Node *bol = iff->in(1);
if( bol->is_top() ) return; // In case a partially dead range check appears
// bail (or bomb[ASSERT/DEBUG]) if NOT projection-->IfNode-->BoolNode
DEBUG_ONLY( if( !bol->is_Bool() ) { proj->dump(3); fatal("Expect projection-->IfNode-->BoolNode"); } )
if( !bol->is_Bool() ) return;
Node *cmp = bol->in(1);
// Compute a new check
Node *new_add = gvn->intcon(off_lo);
if( index ) {
new_add = off_lo ? gvn->transform(new AddINode( index, new_add )) : index;
}
Node *new_cmp = (flip == 1)
? new CmpUNode( new_add, range )
: new CmpUNode( range, new_add );
new_cmp = gvn->transform(new_cmp);
// See if no need to adjust the existing check
if( new_cmp == cmp ) return;
// Else, adjust existing check
Node *new_bol = gvn->transform( new BoolNode( new_cmp, bol->as_Bool()->_test._test ) );
igvn->rehash_node_delayed( iff );
iff->set_req_X( 1, new_bol, igvn );
}
//------------------------------up_one_dom-------------------------------------
// Walk up the dominator tree one step. Return NULL at root or true
// complex merges. Skips through small diamonds.
Node* IfNode::up_one_dom(Node *curr, bool linear_only) {
Node *dom = curr->in(0);
if( !dom ) // Found a Region degraded to a copy?
return curr->nonnull_req(); // Skip thru it
if( curr != dom ) // Normal walk up one step?
return dom;
// Use linear_only if we are still parsing, since we cannot
// trust the regions to be fully filled in.
if (linear_only)
return NULL;
if( dom->is_Root() )
return NULL;
// Else hit a Region. Check for a loop header
if( dom->is_Loop() )
return dom->in(1); // Skip up thru loops
// Check for small diamonds
Node *din1, *din2, *din3, *din4;
if( dom->req() == 3 && // 2-path merge point
(din1 = dom ->in(1)) && // Left path exists
(din2 = dom ->in(2)) && // Right path exists
(din3 = din1->in(0)) && // Left path up one
(din4 = din2->in(0)) ) { // Right path up one
if( din3->is_Call() && // Handle a slow-path call on either arm
(din3 = din3->in(0)) )
din3 = din3->in(0);
if( din4->is_Call() && // Handle a slow-path call on either arm
(din4 = din4->in(0)) )
din4 = din4->in(0);
if (din3 != NULL && din3 == din4 && din3->is_If()) // Regions not degraded to a copy
return din3; // Skip around diamonds
}
// Give up the search at true merges
return NULL; // Dead loop? Or hit root?
}
//------------------------------filtered_int_type--------------------------------
// Return a possibly more restrictive type for val based on condition control flow for an if
const TypeInt* IfNode::filtered_int_type(PhaseGVN* gvn, Node* val, Node* if_proj) {
assert(if_proj &&
(if_proj->Opcode() == Op_IfTrue || if_proj->Opcode() == Op_IfFalse), "expecting an if projection");
if (if_proj->in(0) && if_proj->in(0)->is_If()) {
IfNode* iff = if_proj->in(0)->as_If();
if (iff->in(1) && iff->in(1)->is_Bool()) {
BoolNode* bol = iff->in(1)->as_Bool();
if (bol->in(1) && bol->in(1)->is_Cmp()) {
const CmpNode* cmp = bol->in(1)->as_Cmp();
if (cmp->in(1) == val) {
const TypeInt* cmp2_t = gvn->type(cmp->in(2))->isa_int();
if (cmp2_t != NULL) {
jint lo = cmp2_t->_lo;
jint hi = cmp2_t->_hi;
BoolTest::mask msk = if_proj->Opcode() == Op_IfTrue ? bol->_test._test : bol->_test.negate();
switch (msk) {
case BoolTest::ne: {
// If val is compared to its lower or upper bound, we can narrow the type
const TypeInt* val_t = gvn->type(val)->isa_int();
if (val_t != NULL && !val_t->singleton() && cmp2_t->is_con()) {
if (val_t->_lo == lo) {
return TypeInt::make(val_t->_lo + 1, val_t->_hi, val_t->_widen);
} else if (val_t->_hi == hi) {
return TypeInt::make(val_t->_lo, val_t->_hi - 1, val_t->_widen);
}
}
// Can't refine type
return NULL;
}
case BoolTest::eq:
return cmp2_t;
case BoolTest::lt:
lo = TypeInt::INT->_lo;
if (hi != min_jint) {
hi = hi - 1;
}
break;
case BoolTest::le:
lo = TypeInt::INT->_lo;
break;
case BoolTest::gt:
if (lo != max_jint) {
lo = lo + 1;
}
hi = TypeInt::INT->_hi;
break;
case BoolTest::ge:
// lo unchanged
hi = TypeInt::INT->_hi;
break;
default:
break;
}
const TypeInt* rtn_t = TypeInt::make(lo, hi, cmp2_t->_widen);
return rtn_t;
}
}
}
}
}
return NULL;
}
//------------------------------fold_compares----------------------------
// See if a pair of CmpIs can be converted into a CmpU. In some cases
// the direction of this if is determined by the preceding if so it
// can be eliminate entirely.
//
// Given an if testing (CmpI n v) check for an immediately control
// dependent if that is testing (CmpI n v2) and has one projection
// leading to this if and the other projection leading to a region
// that merges one of this ifs control projections.
//
// If
// / |
// / |
// / |
// If |
// /\ |
// / \ |
// / \ |
// / Region
//
// Or given an if testing (CmpI n v) check for a dominating if that is
// testing (CmpI n v2), both having one projection leading to an
// uncommon trap. Allow Another independent guard in between to cover
// an explicit range check:
// if (index < 0 || index >= array.length) {
// which may need a null check to guard the LoadRange
//
// If
// / \
// / \
// / \
// If unc
// /\
// / \
// / \
// / unc
//
// Is the comparison for this If suitable for folding?
bool IfNode::cmpi_folds(PhaseIterGVN* igvn, bool fold_ne) {
return in(1) != NULL &&
in(1)->is_Bool() &&
in(1)->in(1) != NULL &&
in(1)->in(1)->Opcode() == Op_CmpI &&
in(1)->in(1)->in(2) != NULL &&
in(1)->in(1)->in(2) != igvn->C->top() &&
(in(1)->as_Bool()->_test.is_less() ||
in(1)->as_Bool()->_test.is_greater() ||
(fold_ne && in(1)->as_Bool()->_test._test == BoolTest::ne));
}
// Is a dominating control suitable for folding with this if?
bool IfNode::is_ctrl_folds(Node* ctrl, PhaseIterGVN* igvn) {
return ctrl != NULL &&
ctrl->is_Proj() &&
ctrl->in(0) != NULL &&
ctrl->in(0)->Opcode() == Op_If &&
ctrl->in(0)->outcnt() == 2 &&
ctrl->in(0)->as_If()->cmpi_folds(igvn, true) &&
// Must compare same value
ctrl->in(0)->in(1)->in(1)->in(1) != NULL &&
ctrl->in(0)->in(1)->in(1)->in(1) != igvn->C->top() &&
ctrl->in(0)->in(1)->in(1)->in(1) == in(1)->in(1)->in(1);
}
// Do this If and the dominating If share a region?
bool IfNode::has_shared_region(ProjNode* proj, ProjNode*& success, ProjNode*& fail) {
ProjNode* otherproj = proj->other_if_proj();
Node* otherproj_ctrl_use = otherproj->unique_ctrl_out_or_null();
RegionNode* region = (otherproj_ctrl_use != NULL && otherproj_ctrl_use->is_Region()) ? otherproj_ctrl_use->as_Region() : NULL;
success = NULL;
fail = NULL;
if (otherproj->outcnt() == 1 && region != NULL && !region->has_phi()) {
for (int i = 0; i < 2; i++) {
ProjNode* proj = proj_out(i);
if (success == NULL && proj->outcnt() == 1 && proj->unique_out() == region) {
success = proj;
} else if (fail == NULL) {
fail = proj;
} else {
success = fail = NULL;
}
}
}
return success != NULL && fail != NULL;
}
bool IfNode::is_dominator_unc(CallStaticJavaNode* dom_unc, CallStaticJavaNode* unc) {
// Different methods and methods containing jsrs are not supported.
ciMethod* method = unc->jvms()->method();
ciMethod* dom_method = dom_unc->jvms()->method();
if (method != dom_method || method->has_jsrs()) {
return false;
}
// Check that both traps are in the same activation of the method (instead
// of two activations being inlined through different call sites) by verifying
// that the call stacks are equal for both JVMStates.
JVMState* dom_caller = dom_unc->jvms()->caller();
JVMState* caller = unc->jvms()->caller();
if ((dom_caller == NULL) != (caller == NULL)) {
// The current method must either be inlined into both dom_caller and
// caller or must not be inlined at all (top method). Bail out otherwise.
return false;
} else if (dom_caller != NULL && !dom_caller->same_calls_as(caller)) {
return false;
}
// Check that the bci of the dominating uncommon trap dominates the bci
// of the dominated uncommon trap. Otherwise we may not re-execute
// the dominated check after deoptimization from the merged uncommon trap.
ciTypeFlow* flow = dom_method->get_flow_analysis();
int bci = unc->jvms()->bci();
int dom_bci = dom_unc->jvms()->bci();
if (!flow->is_dominated_by(bci, dom_bci)) {
return false;
}
return true;
}
// Return projection that leads to an uncommon trap if any
ProjNode* IfNode::uncommon_trap_proj(CallStaticJavaNode*& call) const {
for (int i = 0; i < 2; i++) {
call = proj_out(i)->is_uncommon_trap_proj(Deoptimization::Reason_none);
if (call != NULL) {
return proj_out(i);
}
}
return NULL;
}
// Do this If and the dominating If both branch out to an uncommon trap
bool IfNode::has_only_uncommon_traps(ProjNode* proj, ProjNode*& success, ProjNode*& fail, PhaseIterGVN* igvn) {
ProjNode* otherproj = proj->other_if_proj();
CallStaticJavaNode* dom_unc = otherproj->is_uncommon_trap_proj(Deoptimization::Reason_none);
if (otherproj->outcnt() == 1 && dom_unc != NULL) {
// We need to re-execute the folded Ifs after deoptimization from the merged traps
if (!dom_unc->jvms()->should_reexecute()) {
return false;
}
CallStaticJavaNode* unc = NULL;
ProjNode* unc_proj = uncommon_trap_proj(unc);
if (unc_proj != NULL && unc_proj->outcnt() == 1) {
if (dom_unc == unc) {
// Allow the uncommon trap to be shared through a region
RegionNode* r = unc->in(0)->as_Region();
if (r->outcnt() != 2 || r->req() != 3 || r->find_edge(otherproj) == -1 || r->find_edge(unc_proj) == -1) {
return false;
}
assert(r->has_phi() == NULL, "simple region shouldn't have a phi");
} else if (dom_unc->in(0) != otherproj || unc->in(0) != unc_proj) {
return false;
}
if (!is_dominator_unc(dom_unc, unc)) {
return false;
}
// See merge_uncommon_traps: the reason of the uncommon trap
// will be changed and the state of the dominating If will be
// used. Checked that we didn't apply this transformation in a
// previous compilation and it didn't cause too many traps
ciMethod* dom_method = dom_unc->jvms()->method();
int dom_bci = dom_unc->jvms()->bci();
if (!igvn->C->too_many_traps(dom_method, dom_bci, Deoptimization::Reason_unstable_fused_if) &&
!igvn->C->too_many_traps(dom_method, dom_bci, Deoptimization::Reason_range_check) &&
// Return true if c2 manages to reconcile with UnstableIf optimization. See the comments for it.
igvn->C->remove_unstable_if_trap(dom_unc, true/*yield*/)) {
success = unc_proj;
fail = unc_proj->other_if_proj();
return true;
}
}
}
return false;
}
// Check that the 2 CmpI can be folded into as single CmpU and proceed with the folding
bool IfNode::fold_compares_helper(ProjNode* proj, ProjNode* success, ProjNode* fail, PhaseIterGVN* igvn) {
Node* this_cmp = in(1)->in(1);
BoolNode* this_bool = in(1)->as_Bool();
IfNode* dom_iff = proj->in(0)->as_If();
BoolNode* dom_bool = dom_iff->in(1)->as_Bool();
Node* lo = dom_iff->in(1)->in(1)->in(2);
Node* hi = this_cmp->in(2);
Node* n = this_cmp->in(1);
ProjNode* otherproj = proj->other_if_proj();
const TypeInt* lo_type = IfNode::filtered_int_type(igvn, n, otherproj);
const TypeInt* hi_type = IfNode::filtered_int_type(igvn, n, success);
BoolTest::mask lo_test = dom_bool->_test._test;
BoolTest::mask hi_test = this_bool->_test._test;
BoolTest::mask cond = hi_test;
// convert:
//
// dom_bool = x {<,<=,>,>=} a
// / \
// proj = {True,False} / \ otherproj = {False,True}
// /
// this_bool = x {<,<=} b
// / \
// fail = {True,False} / \ success = {False,True}
// /
//
// (Second test guaranteed canonicalized, first one may not have
// been canonicalized yet)
//
// into:
//
// cond = (x - lo) {<u,<=u,>u,>=u} adjusted_lim
// / \
// fail / \ success
// /
//
// Figure out which of the two tests sets the upper bound and which
// sets the lower bound if any.
Node* adjusted_lim = NULL;
if (lo_type != NULL && hi_type != NULL && hi_type->_lo > lo_type->_hi &&
hi_type->_hi == max_jint && lo_type->_lo == min_jint && lo_test != BoolTest::ne) {
assert((dom_bool->_test.is_less() && !proj->_con) ||
(dom_bool->_test.is_greater() && proj->_con), "incorrect test");
// this_bool = <
// dom_bool = >= (proj = True) or dom_bool = < (proj = False)
// x in [a, b[ on the fail (= True) projection, b > a-1 (because of hi_type->_lo > lo_type->_hi test above):
// lo = a, hi = b, adjusted_lim = b-a, cond = <u
// dom_bool = > (proj = True) or dom_bool = <= (proj = False)
// x in ]a, b[ on the fail (= True) projection, b > a:
// lo = a+1, hi = b, adjusted_lim = b-a-1, cond = <u
// this_bool = <=
// dom_bool = >= (proj = True) or dom_bool = < (proj = False)
// x in [a, b] on the fail (= True) projection, b+1 > a-1:
// lo = a, hi = b, adjusted_lim = b-a+1, cond = <u
// lo = a, hi = b, adjusted_lim = b-a, cond = <=u doesn't work because b = a - 1 is possible, then b-a = -1
// dom_bool = > (proj = True) or dom_bool = <= (proj = False)
// x in ]a, b] on the fail (= True) projection b+1 > a:
// lo = a+1, hi = b, adjusted_lim = b-a, cond = <u
// lo = a+1, hi = b, adjusted_lim = b-a-1, cond = <=u doesn't work because a = b is possible, then b-a-1 = -1
if (hi_test == BoolTest::lt) {
if (lo_test == BoolTest::gt || lo_test == BoolTest::le) {
lo = igvn->transform(new AddINode(lo, igvn->intcon(1)));
}
} else if (hi_test == BoolTest::le) {
if (lo_test == BoolTest::ge || lo_test == BoolTest::lt) {
adjusted_lim = igvn->transform(new SubINode(hi, lo));
adjusted_lim = igvn->transform(new AddINode(adjusted_lim, igvn->intcon(1)));
cond = BoolTest::lt;
} else if (lo_test == BoolTest::gt || lo_test == BoolTest::le) {
adjusted_lim = igvn->transform(new SubINode(hi, lo));
lo = igvn->transform(new AddINode(lo, igvn->intcon(1)));
cond = BoolTest::lt;
} else {
assert(false, "unhandled lo_test: %d", lo_test);
return false;
}
} else {
assert(igvn->_worklist.member(in(1)) && in(1)->Value(igvn) != igvn->type(in(1)), "unhandled hi_test: %d", hi_test);
return false;
}
// this test was canonicalized
assert(this_bool->_test.is_less() && fail->_con, "incorrect test");
} else if (lo_type != NULL && hi_type != NULL && lo_type->_lo > hi_type->_hi &&
lo_type->_hi == max_jint && hi_type->_lo == min_jint && lo_test != BoolTest::ne) {
// this_bool = <
// dom_bool = < (proj = True) or dom_bool = >= (proj = False)
// x in [b, a[ on the fail (= False) projection, a > b-1 (because of lo_type->_lo > hi_type->_hi above):
// lo = b, hi = a, adjusted_lim = a-b, cond = >=u
// dom_bool = <= (proj = True) or dom_bool = > (proj = False)
// x in [b, a] on the fail (= False) projection, a+1 > b-1:
// lo = b, hi = a, adjusted_lim = a-b+1, cond = >=u
// lo = b, hi = a, adjusted_lim = a-b, cond = >u doesn't work because a = b - 1 is possible, then b-a = -1
// this_bool = <=
// dom_bool = < (proj = True) or dom_bool = >= (proj = False)
// x in ]b, a[ on the fail (= False) projection, a > b:
// lo = b+1, hi = a, adjusted_lim = a-b-1, cond = >=u
// dom_bool = <= (proj = True) or dom_bool = > (proj = False)
// x in ]b, a] on the fail (= False) projection, a+1 > b:
// lo = b+1, hi = a, adjusted_lim = a-b, cond = >=u
// lo = b+1, hi = a, adjusted_lim = a-b-1, cond = >u doesn't work because a = b is possible, then b-a-1 = -1
swap(lo, hi);
swap(lo_type, hi_type);
swap(lo_test, hi_test);
assert((dom_bool->_test.is_less() && proj->_con) ||
(dom_bool->_test.is_greater() && !proj->_con), "incorrect test");
cond = (hi_test == BoolTest::le || hi_test == BoolTest::gt) ? BoolTest::gt : BoolTest::ge;
if (lo_test == BoolTest::lt) {
if (hi_test == BoolTest::lt || hi_test == BoolTest::ge) {
cond = BoolTest::ge;
} else if (hi_test == BoolTest::le || hi_test == BoolTest::gt) {
adjusted_lim = igvn->transform(new SubINode(hi, lo));
adjusted_lim = igvn->transform(new AddINode(adjusted_lim, igvn->intcon(1)));
cond = BoolTest::ge;
} else {
assert(false, "unhandled hi_test: %d", hi_test);
return false;
}
} else if (lo_test == BoolTest::le) {
if (hi_test == BoolTest::lt || hi_test == BoolTest::ge) {
lo = igvn->transform(new AddINode(lo, igvn->intcon(1)));
cond = BoolTest::ge;
} else if (hi_test == BoolTest::le || hi_test == BoolTest::gt) {
adjusted_lim = igvn->transform(new SubINode(hi, lo));
lo = igvn->transform(new AddINode(lo, igvn->intcon(1)));
cond = BoolTest::ge;
} else {
assert(false, "unhandled hi_test: %d", hi_test);
return false;
}
} else {
assert(igvn->_worklist.member(in(1)) && in(1)->Value(igvn) != igvn->type(in(1)), "unhandled lo_test: %d", lo_test);
return false;
}
// this test was canonicalized
assert(this_bool->_test.is_less() && !fail->_con, "incorrect test");
} else {
const TypeInt* failtype = filtered_int_type(igvn, n, proj);
if (failtype != NULL) {
const TypeInt* type2 = filtered_int_type(igvn, n, fail);
if (type2 != NULL) {
failtype = failtype->join(type2)->is_int();
if (failtype->_lo > failtype->_hi) {
// previous if determines the result of this if so
// replace Bool with constant
igvn->replace_input_of(this, 1, igvn->intcon(success->_con));
return true;
}
}
}
lo = NULL;
hi = NULL;
}
if (lo && hi) {
Node* hook = new Node(1);
hook->init_req(0, lo); // Add a use to lo to prevent him from dying
// Merge the two compares into a single unsigned compare by building (CmpU (n - lo) (hi - lo))
Node* adjusted_val = igvn->transform(new SubINode(n, lo));
if (adjusted_lim == NULL) {
adjusted_lim = igvn->transform(new SubINode(hi, lo));
}
hook->destruct(igvn);
int lo = igvn->type(adjusted_lim)->is_int()->_lo;
if (lo < 0) {
// If range check elimination applies to this comparison, it includes code to protect from overflows that may
// cause the main loop to be skipped entirely. Delay this transformation.
// Example:
// for (int i = 0; i < limit; i++) {
// if (i < max_jint && i > min_jint) {...
// }
// Comparisons folded as:
// i - min_jint - 1 <u -2
// when RC applies, main loop limit becomes:
// min(limit, max(-2 + min_jint + 1, min_jint))
// = min(limit, min_jint)
// = min_jint
if (!igvn->C->post_loop_opts_phase()) {
if (adjusted_val->outcnt() == 0) {
igvn->remove_dead_node(adjusted_val);
}
if (adjusted_lim->outcnt() == 0) {
igvn->remove_dead_node(adjusted_lim);
}
igvn->C->record_for_post_loop_opts_igvn(this);
return false;
}
}
Node* newcmp = igvn->transform(new CmpUNode(adjusted_val, adjusted_lim));
Node* newbool = igvn->transform(new BoolNode(newcmp, cond));
igvn->replace_input_of(dom_iff, 1, igvn->intcon(proj->_con));
igvn->replace_input_of(this, 1, newbool);
return true;
}
return false;
}
// Merge the branches that trap for this If and the dominating If into
// a single region that branches to the uncommon trap for the
// dominating If
Node* IfNode::merge_uncommon_traps(ProjNode* proj, ProjNode* success, ProjNode* fail, PhaseIterGVN* igvn) {
Node* res = this;
assert(success->in(0) == this, "bad projection");
ProjNode* otherproj = proj->other_if_proj();
CallStaticJavaNode* unc = success->is_uncommon_trap_proj(Deoptimization::Reason_none);
CallStaticJavaNode* dom_unc = otherproj->is_uncommon_trap_proj(Deoptimization::Reason_none);
if (unc != dom_unc) {
Node* r = new RegionNode(3);
r->set_req(1, otherproj);
r->set_req(2, success);
r = igvn->transform(r);
assert(r->is_Region(), "can't go away");
// Make both If trap at the state of the first If: once the CmpI
// nodes are merged, if we trap we don't know which of the CmpI
// nodes would have caused the trap so we have to restart
// execution at the first one
igvn->replace_input_of(dom_unc, 0, r);
igvn->replace_input_of(unc, 0, igvn->C->top());
}
int trap_request = dom_unc->uncommon_trap_request();
Deoptimization::DeoptReason reason = Deoptimization::trap_request_reason(trap_request);
Deoptimization::DeoptAction action = Deoptimization::trap_request_action(trap_request);
int flip_test = 0;
Node* l = NULL;
Node* r = NULL;
if (success->in(0)->as_If()->range_check_trap_proj(flip_test, l, r) != NULL) {
// If this looks like a range check, change the trap to
// Reason_range_check so the compiler recognizes it as a range
// check and applies the corresponding optimizations
trap_request = Deoptimization::make_trap_request(Deoptimization::Reason_range_check, action);
improve_address_types(l, r, fail, igvn);
res = igvn->transform(new RangeCheckNode(in(0), in(1), _prob, _fcnt));
} else if (unc != dom_unc) {
// If we trap we won't know what CmpI would have caused the trap
// so use a special trap reason to mark this pair of CmpI nodes as
// bad candidate for folding. On recompilation we won't fold them
// and we may trap again but this time we'll know what branch
// traps
trap_request = Deoptimization::make_trap_request(Deoptimization::Reason_unstable_fused_if, action);
}
igvn->replace_input_of(dom_unc, TypeFunc::Parms, igvn->intcon(trap_request));
return res;
}
// If we are turning 2 CmpI nodes into a CmpU that follows the pattern
// of a rangecheck on index i, on 64 bit the compares may be followed
// by memory accesses using i as index. In that case, the CmpU tells
// us something about the values taken by i that can help the compiler
// (see Compile::conv_I2X_index())
void IfNode::improve_address_types(Node* l, Node* r, ProjNode* fail, PhaseIterGVN* igvn) {
#ifdef _LP64
ResourceMark rm;
Node_Stack stack(2);
assert(r->Opcode() == Op_LoadRange, "unexpected range check");
const TypeInt* array_size = igvn->type(r)->is_int();
stack.push(l, 0);
while(stack.size() > 0) {
Node* n = stack.node();
uint start = stack.index();
uint i = start;
for (; i < n->outcnt(); i++) {
Node* use = n->raw_out(i);
if (stack.size() == 1) {
if (use->Opcode() == Op_ConvI2L) {
const TypeLong* bounds = use->as_Type()->type()->is_long();
if (bounds->_lo <= array_size->_lo && bounds->_hi >= array_size->_hi &&
(bounds->_lo != array_size->_lo || bounds->_hi != array_size->_hi)) {
stack.set_index(i+1);
stack.push(use, 0);
break;
}
}
} else if (use->is_Mem()) {
Node* ctrl = use->in(0);
for (int i = 0; i < 10 && ctrl != NULL && ctrl != fail; i++) {
ctrl = up_one_dom(ctrl);
}
if (ctrl == fail) {
Node* init_n = stack.node_at(1);
assert(init_n->Opcode() == Op_ConvI2L, "unexpected first node");
// Create a new narrow ConvI2L node that is dependent on the range check
Node* new_n = igvn->C->conv_I2X_index(igvn, l, array_size, fail);
// The type of the ConvI2L may be widen and so the new
// ConvI2L may not be better than an existing ConvI2L
if (new_n != init_n) {
for (uint j = 2; j < stack.size(); j++) {
Node* n = stack.node_at(j);
Node* clone = n->clone();
int rep = clone->replace_edge(init_n, new_n, igvn);
assert(rep > 0, "can't find expected node?");
clone = igvn->transform(clone);
init_n = n;
new_n = clone;
}
igvn->hash_delete(use);
int rep = use->replace_edge(init_n, new_n, igvn);
assert(rep > 0, "can't find expected node?");
igvn->transform(use);
if (init_n->outcnt() == 0) {
igvn->_worklist.push(init_n);
}
}
}
} else if (use->in(0) == NULL && (igvn->type(use)->isa_long() ||
igvn->type(use)->isa_ptr())) {
stack.set_index(i+1);
stack.push(use, 0);
break;
}
}
if (i == n->outcnt()) {
stack.pop();
}
}
#endif
}
bool IfNode::is_cmp_with_loadrange(ProjNode* proj) {
if (in(1) != NULL &&
in(1)->in(1) != NULL &&
in(1)->in(1)->in(2) != NULL) {
Node* other = in(1)->in(1)->in(2);
if (other->Opcode() == Op_LoadRange &&
((other->in(0) != NULL && other->in(0) == proj) ||
(other->in(0) == NULL &&
other->in(2) != NULL &&
other->in(2)->is_AddP() &&
other->in(2)->in(1) != NULL &&
other->in(2)->in(1)->Opcode() == Op_CastPP &&
other->in(2)->in(1)->in(0) == proj))) {
return true;
}
}
return false;
}
bool IfNode::is_null_check(ProjNode* proj, PhaseIterGVN* igvn) {
Node* other = in(1)->in(1)->in(2);
if (other->in(MemNode::Address) != NULL &&
proj->in(0)->in(1) != NULL &&
proj->in(0)->in(1)->is_Bool() &&
proj->in(0)->in(1)->in(1) != NULL &&
proj->in(0)->in(1)->in(1)->Opcode() == Op_CmpP &&
proj->in(0)->in(1)->in(1)->in(2) != NULL &&
proj->in(0)->in(1)->in(1)->in(1) == other->in(MemNode::Address)->in(AddPNode::Address)->uncast() &&
igvn->type(proj->in(0)->in(1)->in(1)->in(2)) == TypePtr::NULL_PTR) {
return true;
}
return false;
}
// Check that the If that is in between the 2 integer comparisons has
// no side effect
bool IfNode::is_side_effect_free_test(ProjNode* proj, PhaseIterGVN* igvn) {
if (proj == NULL) {
return false;
}
CallStaticJavaNode* unc = proj->is_uncommon_trap_if_pattern(Deoptimization::Reason_none);
if (unc != NULL && proj->outcnt() <= 2) {
if (proj->outcnt() == 1 ||
// Allow simple null check from LoadRange
(is_cmp_with_loadrange(proj) && is_null_check(proj, igvn))) {
CallStaticJavaNode* unc = proj->is_uncommon_trap_if_pattern(Deoptimization::Reason_none);
CallStaticJavaNode* dom_unc = proj->in(0)->in(0)->as_Proj()->is_uncommon_trap_if_pattern(Deoptimization::Reason_none);
assert(dom_unc != NULL, "is_uncommon_trap_if_pattern returned NULL");
// reroute_side_effect_free_unc changes the state of this
// uncommon trap to restart execution at the previous
// CmpI. Check that this change in a previous compilation didn't
// cause too many traps.
int trap_request = unc->uncommon_trap_request();
Deoptimization::DeoptReason reason = Deoptimization::trap_request_reason(trap_request);
if (igvn->C->too_many_traps(dom_unc->jvms()->method(), dom_unc->jvms()->bci(), reason)) {
return false;
}
if (!is_dominator_unc(dom_unc, unc)) {
return false;
}
return true;
}
}
return false;
}
// Make the If between the 2 integer comparisons trap at the state of
// the first If: the last CmpI is the one replaced by a CmpU and the
// first CmpI is eliminated, so the test between the 2 CmpI nodes
// won't be guarded by the first CmpI anymore. It can trap in cases
// where the first CmpI would have prevented it from executing: on a
// trap, we need to restart execution at the state of the first CmpI
void IfNode::reroute_side_effect_free_unc(ProjNode* proj, ProjNode* dom_proj, PhaseIterGVN* igvn) {
CallStaticJavaNode* dom_unc = dom_proj->is_uncommon_trap_if_pattern(Deoptimization::Reason_none);
ProjNode* otherproj = proj->other_if_proj();
CallStaticJavaNode* unc = proj->is_uncommon_trap_if_pattern(Deoptimization::Reason_none);
Node* call_proj = dom_unc->unique_ctrl_out();
Node* halt = call_proj->unique_ctrl_out();
Node* new_unc = dom_unc->clone();
call_proj = call_proj->clone();
halt = halt->clone();
Node* c = otherproj->clone();
c = igvn->transform(c);
new_unc->set_req(TypeFunc::Parms, unc->in(TypeFunc::Parms));
new_unc->set_req(0, c);
new_unc = igvn->transform(new_unc);
call_proj->set_req(0, new_unc);
call_proj = igvn->transform(call_proj);
halt->set_req(0, call_proj);
halt = igvn->transform(halt);
igvn->replace_node(otherproj, igvn->C->top());
igvn->C->root()->add_req(halt);
}
Node* IfNode::fold_compares(PhaseIterGVN* igvn) {
if (Opcode() != Op_If) return NULL;
if (cmpi_folds(igvn)) {
Node* ctrl = in(0);
if (is_ctrl_folds(ctrl, igvn) && ctrl->outcnt() == 1) {
// A integer comparison immediately dominated by another integer
// comparison
ProjNode* success = NULL;
ProjNode* fail = NULL;
ProjNode* dom_cmp = ctrl->as_Proj();
if (has_shared_region(dom_cmp, success, fail) &&
// Next call modifies graph so must be last
fold_compares_helper(dom_cmp, success, fail, igvn)) {
return this;
}
if (has_only_uncommon_traps(dom_cmp, success, fail, igvn) &&
// Next call modifies graph so must be last
fold_compares_helper(dom_cmp, success, fail, igvn)) {
return merge_uncommon_traps(dom_cmp, success, fail, igvn);
}
return NULL;
} else if (ctrl->in(0) != NULL &&
ctrl->in(0)->in(0) != NULL) {
ProjNode* success = NULL;
ProjNode* fail = NULL;
Node* dom = ctrl->in(0)->in(0);
ProjNode* dom_cmp = dom->isa_Proj();
ProjNode* other_cmp = ctrl->isa_Proj();
// Check if it's an integer comparison dominated by another
// integer comparison with another test in between
if (is_ctrl_folds(dom, igvn) &&
has_only_uncommon_traps(dom_cmp, success, fail, igvn) &&
is_side_effect_free_test(other_cmp, igvn) &&
// Next call modifies graph so must be last
fold_compares_helper(dom_cmp, success, fail, igvn)) {
reroute_side_effect_free_unc(other_cmp, dom_cmp, igvn);
return merge_uncommon_traps(dom_cmp, success, fail, igvn);
}
}
}
return NULL;
}
//------------------------------remove_useless_bool----------------------------
// Check for people making a useless boolean: things like
// if( (x < y ? true : false) ) { ... }
// Replace with if( x < y ) { ... }
static Node *remove_useless_bool(IfNode *iff, PhaseGVN *phase) {
Node *i1 = iff->in(1);
if( !i1->is_Bool() ) return NULL;
BoolNode *bol = i1->as_Bool();
Node *cmp = bol->in(1);
if( cmp->Opcode() != Op_CmpI ) return NULL;
// Must be comparing against a bool
const Type *cmp2_t = phase->type( cmp->in(2) );
if( cmp2_t != TypeInt::ZERO &&
cmp2_t != TypeInt::ONE )
return NULL;
// Find a prior merge point merging the boolean
i1 = cmp->in(1);
if( !i1->is_Phi() ) return NULL;
PhiNode *phi = i1->as_Phi();
if( phase->type( phi ) != TypeInt::BOOL )
return NULL;
// Check for diamond pattern
int true_path = phi->is_diamond_phi();
if( true_path == 0 ) return NULL;
// Make sure that iff and the control of the phi are different. This
// should really only happen for dead control flow since it requires
// an illegal cycle.
if (phi->in(0)->in(1)->in(0) == iff) return NULL;
// phi->region->if_proj->ifnode->bool->cmp
BoolNode *bol2 = phi->in(0)->in(1)->in(0)->in(1)->as_Bool();
// Now get the 'sense' of the test correct so we can plug in
// either iff2->in(1) or its complement.
int flip = 0;
if( bol->_test._test == BoolTest::ne ) flip = 1-flip;
else if( bol->_test._test != BoolTest::eq ) return NULL;
if( cmp2_t == TypeInt::ZERO ) flip = 1-flip;
const Type *phi1_t = phase->type( phi->in(1) );
const Type *phi2_t = phase->type( phi->in(2) );
// Check for Phi(0,1) and flip
if( phi1_t == TypeInt::ZERO ) {
if( phi2_t != TypeInt::ONE ) return NULL;
flip = 1-flip;
} else {
// Check for Phi(1,0)
if( phi1_t != TypeInt::ONE ) return NULL;
if( phi2_t != TypeInt::ZERO ) return NULL;
}
if( true_path == 2 ) {
flip = 1-flip;
}
Node* new_bol = (flip ? phase->transform( bol2->negate(phase) ) : bol2);
assert(new_bol != iff->in(1), "must make progress");
iff->set_req_X(1, new_bol, phase);
// Intervening diamond probably goes dead
phase->C->set_major_progress();
return iff;
}
static IfNode* idealize_test(PhaseGVN* phase, IfNode* iff);
struct RangeCheck {
Node* ctl;
jint off;
};
Node* IfNode::Ideal_common(PhaseGVN *phase, bool can_reshape) {
if (remove_dead_region(phase, can_reshape)) return this;
// No Def-Use info?
if (!can_reshape) return NULL;
// Don't bother trying to transform a dead if
if (in(0)->is_top()) return NULL;
// Don't bother trying to transform an if with a dead test
if (in(1)->is_top()) return NULL;
// Another variation of a dead test
if (in(1)->is_Con()) return NULL;
// Another variation of a dead if
if (outcnt() < 2) return NULL;
// Canonicalize the test.
Node* idt_if = idealize_test(phase, this);
if (idt_if != NULL) return idt_if;
// Try to split the IF
PhaseIterGVN *igvn = phase->is_IterGVN();
Node *s = split_if(this, igvn);
if (s != NULL) return s;
return NodeSentinel;
}
//------------------------------Ideal------------------------------------------
// Return a node which is more "ideal" than the current node. Strip out
// control copies
Node* IfNode::Ideal(PhaseGVN *phase, bool can_reshape) {
Node* res = Ideal_common(phase, can_reshape);
if (res != NodeSentinel) {
return res;
}
// Check for people making a useless boolean: things like
// if( (x < y ? true : false) ) { ... }
// Replace with if( x < y ) { ... }
Node* bol2 = remove_useless_bool(this, phase);
if (bol2) return bol2;
if (in(0) == NULL) return NULL; // Dead loop?
PhaseIterGVN* igvn = phase->is_IterGVN();
Node* result = fold_compares(igvn);
if (result != NULL) {
return result;
}
// Scan for an equivalent test
int dist = 4; // Cutoff limit for search
if (is_If() && in(1)->is_Bool()) {
Node* cmp = in(1)->in(1);
if (cmp->Opcode() == Op_CmpP &&
cmp->in(2) != NULL && // make sure cmp is not already dead
cmp->in(2)->bottom_type() == TypePtr::NULL_PTR) {
dist = 64; // Limit for null-pointer scans
}
}
Node* prev_dom = search_identical(dist);
if (prev_dom != NULL) {
// Replace dominated IfNode
return dominated_by(prev_dom, igvn);
}
return simple_subsuming(igvn);
}
//------------------------------dominated_by-----------------------------------
Node* IfNode::dominated_by(Node* prev_dom, PhaseIterGVN *igvn) {
#ifndef PRODUCT
if (TraceIterativeGVN) {
tty->print(" Removing IfNode: "); this->dump();
}
#endif
igvn->hash_delete(this); // Remove self to prevent spurious V-N
Node *idom = in(0);
// Need opcode to decide which way 'this' test goes
int prev_op = prev_dom->Opcode();
Node *top = igvn->C->top(); // Shortcut to top
// Loop predicates may have depending checks which should not
// be skipped. For example, range check predicate has two checks
// for lower and upper bounds.
ProjNode* unc_proj = proj_out(1 - prev_dom->as_Proj()->_con)->as_Proj();
if (unc_proj->is_uncommon_trap_proj(Deoptimization::Reason_predicate) != NULL ||
unc_proj->is_uncommon_trap_proj(Deoptimization::Reason_profile_predicate) != NULL) {
prev_dom = idom;
}
// Now walk the current IfNode's projections.
// Loop ends when 'this' has no more uses.
for (DUIterator_Last imin, i = last_outs(imin); i >= imin; --i) {
Node *ifp = last_out(i); // Get IfTrue/IfFalse
igvn->add_users_to_worklist(ifp);
// Check which projection it is and set target.
// Data-target is either the dominating projection of the same type
// or TOP if the dominating projection is of opposite type.
// Data-target will be used as the new control edge for the non-CFG
// nodes like Casts and Loads.
Node *data_target = (ifp->Opcode() == prev_op) ? prev_dom : top;
// Control-target is just the If's immediate dominator or TOP.
Node *ctrl_target = (ifp->Opcode() == prev_op) ? idom : top;
// For each child of an IfTrue/IfFalse projection, reroute.
// Loop ends when projection has no more uses.
for (DUIterator_Last jmin, j = ifp->last_outs(jmin); j >= jmin; --j) {
Node* s = ifp->last_out(j); // Get child of IfTrue/IfFalse
if (s->depends_only_on_test() && igvn->no_dependent_zero_check(s)) {
// For control producers.
// Do not rewire Div and Mod nodes which could have a zero divisor to avoid skipping their zero check.
igvn->replace_input_of(s, 0, data_target); // Move child to data-target
} else {
// Find the control input matching this def-use edge.
// For Regions it may not be in slot 0.
uint l;
for (l = 0; s->in(l) != ifp; l++) { }
igvn->replace_input_of(s, l, ctrl_target);
}
} // End for each child of a projection
igvn->remove_dead_node(ifp);
} // End for each IfTrue/IfFalse child of If
// Kill the IfNode
igvn->remove_dead_node(this);
// 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 ConINode(TypeInt::ZERO);
}
Node* IfNode::search_identical(int dist) {
// Setup to scan up the CFG looking for a dominating test
Node* dom = in(0);
Node* prev_dom = this;
int op = Opcode();
// Search up the dominator tree for an If with an identical test
while (dom->Opcode() != op || // Not same opcode?
dom->in(1) != in(1) || // Not same input 1?
prev_dom->in(0) != dom) { // One path of test does not dominate?
if (dist < 0) return NULL;
dist--;
prev_dom = dom;
dom = up_one_dom(dom);
if (!dom) return NULL;
}
// Check that we did not follow a loop back to ourselves
if (this == dom) {
return NULL;
}
#ifndef PRODUCT
if (dist > 2) { // Add to count of NULL checks elided
explicit_null_checks_elided++;
}
#endif
return prev_dom;
}
static int subsuming_bool_test_encode(Node*);
// Check if dominating test is subsuming 'this' one.
//
// cmp
// / \
// (r1) bool \
// / bool (r2)
// (dom) if \
// \ )
// (pre) if[TF] /
// \ /
// if (this)
// \r1
// r2\ eqT eqF neT neF ltT ltF leT leF gtT gtF geT geF
// eq t f f t f - - f f - - f
// ne f t t f t - - t t - - t
// lt f - - f t f - f f - f t
// le t - - t t - t f f t - t
// gt f - - f f - f t t f - f
// ge t - - t f t - t t - t f
//
Node* IfNode::simple_subsuming(PhaseIterGVN* igvn) {
// Table encoding: N/A (na), True-branch (tb), False-branch (fb).
static enum { na, tb, fb } s_short_circuit_map[6][12] = {
/*rel: eq+T eq+F ne+T ne+F lt+T lt+F le+T le+F gt+T gt+F ge+T ge+F*/
/*eq*/{ tb, fb, fb, tb, fb, na, na, fb, fb, na, na, fb },
/*ne*/{ fb, tb, tb, fb, tb, na, na, tb, tb, na, na, tb },
/*lt*/{ fb, na, na, fb, tb, fb, na, fb, fb, na, fb, tb },
/*le*/{ tb, na, na, tb, tb, na, tb, fb, fb, tb, na, tb },
/*gt*/{ fb, na, na, fb, fb, na, fb, tb, tb, fb, na, fb },
/*ge*/{ tb, na, na, tb, fb, tb, na, tb, tb, na, tb, fb }};
Node* pre = in(0);
if (!pre->is_IfTrue() && !pre->is_IfFalse()) {
return NULL;
}
Node* dom = pre->in(0);
if (!dom->is_If()) {
return NULL;
}
Node* bol = in(1);
if (!bol->is_Bool()) {
return NULL;
}
Node* cmp = in(1)->in(1);
if (!cmp->is_Cmp()) {
return NULL;
}
if (!dom->in(1)->is_Bool()) {
return NULL;
}
if (dom->in(1)->in(1) != cmp) { // Not same cond?
return NULL;
}
int drel = subsuming_bool_test_encode(dom->in(1));
int trel = subsuming_bool_test_encode(bol);
int bout = pre->is_IfFalse() ? 1 : 0;
if (drel < 0 || trel < 0) {
return NULL;
}
int br = s_short_circuit_map[trel][2*drel+bout];
if (br == na) {
return NULL;
}
#ifndef PRODUCT
if (TraceIterativeGVN) {
tty->print(" Subsumed IfNode: "); dump();
}
#endif
// Replace condition with constant True(1)/False(0).
bool is_always_true = br == tb;
set_req(1, igvn->intcon(is_always_true ? 1 : 0));
// Update any data dependencies to the directly dominating test. This subsumed test is not immediately removed by igvn
// and therefore subsequent optimizations might miss these data dependencies otherwise. There might be a dead loop
// ('always_taken_proj' == 'pre') that is cleaned up later. Skip this case to make the iterator work properly.
Node* always_taken_proj = proj_out(is_always_true);
if (always_taken_proj != pre) {
for (DUIterator_Fast imax, i = always_taken_proj->fast_outs(imax); i < imax; i++) {
Node* u = always_taken_proj->fast_out(i);
if (!u->is_CFG()) {
igvn->replace_input_of(u, 0, pre);
--i;
--imax;
}
}
}
if (bol->outcnt() == 0) {
igvn->remove_dead_node(bol); // Kill the BoolNode.
}
return this;
}
// Map BoolTest to local table encoding. The BoolTest (e)numerals
// { eq = 0, ne = 4, le = 5, ge = 7, lt = 3, gt = 1 }
// are mapped to table indices, while the remaining (e)numerals in BoolTest
// { overflow = 2, no_overflow = 6, never = 8, illegal = 9 }
// are ignored (these are not modeled in the table).
//
static int subsuming_bool_test_encode(Node* node) {
precond(node->is_Bool());
BoolTest::mask x = node->as_Bool()->_test._test;
switch (x) {
case BoolTest::eq: return 0;
case BoolTest::ne: return 1;
case BoolTest::lt: return 2;
case BoolTest::le: return 3;
case BoolTest::gt: return 4;
case BoolTest::ge: return 5;
case BoolTest::overflow:
case BoolTest::no_overflow:
case BoolTest::never:
case BoolTest::illegal:
default:
return -1;
}
}
//------------------------------Identity---------------------------------------
// If the test is constant & we match, then we are the input Control
Node* IfProjNode::Identity(PhaseGVN* phase) {
// Can only optimize if cannot go the other way
const TypeTuple *t = phase->type(in(0))->is_tuple();
if (t == TypeTuple::IFNEITHER || (always_taken(t) &&
// During parsing (GVN) we don't remove dead code aggressively.
// Cut off dead branch and let PhaseRemoveUseless take care of it.
(!phase->is_IterGVN() ||
// During IGVN, first wait for the dead branch to be killed.
// Otherwise, the IfNode's control will have two control uses (the IfNode
// that doesn't go away because it still has uses and this branch of the
// If) which breaks other optimizations. Node::has_special_unique_user()
// will cause this node to be reprocessed once the dead branch is killed.
in(0)->outcnt() == 1))) {
// IfNode control
if (in(0)->is_BaseCountedLoopEnd()) {
// CountedLoopEndNode may be eliminated by if subsuming, replace CountedLoopNode with LoopNode to
// avoid mismatching between CountedLoopNode and CountedLoopEndNode in the following optimization.
Node* head = unique_ctrl_out_or_null();
if (head != NULL && head->is_BaseCountedLoop() && head->in(LoopNode::LoopBackControl) == this) {
Node* new_head = new LoopNode(head->in(LoopNode::EntryControl), this);
phase->is_IterGVN()->register_new_node_with_optimizer(new_head);
phase->is_IterGVN()->replace_node(head, new_head);
}
}
return in(0)->in(0);
}
// no progress
return this;
}
#ifndef PRODUCT
//------------------------------dump_spec--------------------------------------
void IfNode::dump_spec(outputStream *st) const {
st->print("P=%f, C=%f",_prob,_fcnt);
}
#endif
//------------------------------idealize_test----------------------------------
// Try to canonicalize tests better. Peek at the Cmp/Bool/If sequence and
--> --------------------
--> maximum size reached
--> --------------------
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