JDK14/Java14源码在线阅读
/*
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* 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
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*
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* 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).
*
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* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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#include "precompiled.hpp"
#include "memory/allocation.inline.hpp"
#include "opto/addnode.hpp"
#include "opto/connode.hpp"
#include "opto/convertnode.hpp"
#include "opto/memnode.hpp"
#include "opto/mulnode.hpp"
#include "opto/phaseX.hpp"
#include "opto/subnode.hpp"
// Portions of code courtesy of Clifford Click
//=============================================================================
//------------------------------hash-------------------------------------------
// Hash function over MulNodes. Needs to be commutative; i.e., I swap
// (commute) inputs to MulNodes willy-nilly so the hash function must return
// the same value in the presence of edge swapping.
uint MulNode::hash() const {
return (uintptr_t)in(1) + (uintptr_t)in(2) + Opcode();
}
//------------------------------Identity---------------------------------------
// Multiplying a one preserves the other argument
Node* MulNode::Identity(PhaseGVN* phase) {
const Type *one = mul_id(); // The multiplicative identity
if( phase->type( in(1) )->higher_equal( one ) ) return in(2);
if( phase->type( in(2) )->higher_equal( one ) ) return in(1);
return this;
}
//------------------------------Ideal------------------------------------------
// We also canonicalize the Node, moving constants to the right input,
// and flatten expressions (so that 1+x+2 becomes x+3).
Node *MulNode::Ideal(PhaseGVN *phase, bool can_reshape) {
const Type *t1 = phase->type( in(1) );
const Type *t2 = phase->type( in(2) );
Node *progress = NULL; // Progress flag
// We are OK if right is a constant, or right is a load and
// left is a non-constant.
if( !(t2->singleton() ||
(in(2)->is_Load() && !(t1->singleton() || in(1)->is_Load())) ) ) {
if( t1->singleton() || // Left input is a constant?
// Otherwise, sort inputs (commutativity) to help value numbering.
(in(1)->_idx > in(2)->_idx) ) {
swap_edges(1, 2);
const Type *t = t1;
t1 = t2;
t2 = t;
progress = this; // Made progress
}
}
// If the right input is a constant, and the left input is a product of a
// constant, flatten the expression tree.
uint op = Opcode();
if( t2->singleton() && // Right input is a constant?
op != Op_MulF && // Float & double cannot reassociate
op != Op_MulD ) {
if( t2 == Type::TOP ) return NULL;
Node *mul1 = in(1);
#ifdef ASSERT
// Check for dead loop
int op1 = mul1->Opcode();
if( phase->eqv( mul1, this ) || phase->eqv( in(2), this ) ||
( ( op1 == mul_opcode() || op1 == add_opcode() ) &&
( phase->eqv( mul1->in(1), this ) || phase->eqv( mul1->in(2), this ) ||
phase->eqv( mul1->in(1), mul1 ) || phase->eqv( mul1->in(2), mul1 ) ) ) )
assert(false, "dead loop in MulNode::Ideal");
#endif
if( mul1->Opcode() == mul_opcode() ) { // Left input is a multiply?
// Mul of a constant?
const Type *t12 = phase->type( mul1->in(2) );
if( t12->singleton() && t12 != Type::TOP) { // Left input is an add of a constant?
// Compute new constant; check for overflow
const Type *tcon01 = ((MulNode*)mul1)->mul_ring(t2,t12);
if( tcon01->singleton() ) {
// The Mul of the flattened expression
set_req(1, mul1->in(1));
set_req(2, phase->makecon( tcon01 ));
t2 = tcon01;
progress = this; // Made progress
}
}
}
// If the right input is a constant, and the left input is an add of a
// constant, flatten the tree: (X+con1)*con0 ==> X*con0 + con1*con0
const Node *add1 = in(1);
if( add1->Opcode() == add_opcode() ) { // Left input is an add?
// Add of a constant?
const Type *t12 = phase->type( add1->in(2) );
if( t12->singleton() && t12 != Type::TOP ) { // Left input is an add of a constant?
assert( add1->in(1) != add1, "dead loop in MulNode::Ideal" );
// Compute new constant; check for overflow
const Type *tcon01 = mul_ring(t2,t12);
if( tcon01->singleton() ) {
// Convert (X+con1)*con0 into X*con0
Node *mul = clone(); // mul = ()*con0
mul->set_req(1,add1->in(1)); // mul = X*con0
mul = phase->transform(mul);
Node *add2 = add1->clone();
add2->set_req(1, mul); // X*con0 + con0*con1
add2->set_req(2, phase->makecon(tcon01) );
progress = add2;
}
}
} // End of is left input an add
} // End of is right input a Mul
return progress;
}
//------------------------------Value-----------------------------------------
const Type* MulNode::Value(PhaseGVN* phase) const {
const Type *t1 = phase->type( in(1) );
const Type *t2 = phase->type( in(2) );
// Either input is TOP ==> the result is TOP
if( t1 == Type::TOP ) return Type::TOP;
if( t2 == Type::TOP ) return Type::TOP;
// Either input is ZERO ==> the result is ZERO.
// Not valid for floats or doubles since +0.0 * -0.0 --> +0.0
int op = Opcode();
if( op == Op_MulI || op == Op_AndI || op == Op_MulL || op == Op_AndL ) {
const Type *zero = add_id(); // The multiplicative zero
if( t1->higher_equal( zero ) ) return zero;
if( t2->higher_equal( zero ) ) return zero;
}
// Either input is BOTTOM ==> the result is the local BOTTOM
if( t1 == Type::BOTTOM || t2 == Type::BOTTOM )
return bottom_type();
#if defined(IA32)
// Can't trust native compilers to properly fold strict double
// multiplication with round-to-zero on this platform.
if (op == Op_MulD && phase->C->method()->is_strict()) {
return TypeD::DOUBLE;
}
#endif
return mul_ring(t1,t2); // Local flavor of type multiplication
}
//=============================================================================
//------------------------------Ideal------------------------------------------
// Check for power-of-2 multiply, then try the regular MulNode::Ideal
Node *MulINode::Ideal(PhaseGVN *phase, bool can_reshape) {
// Swap constant to right
jint con;
if ((con = in(1)->find_int_con(0)) != 0) {
swap_edges(1, 2);
// Finish rest of method to use info in 'con'
} else if ((con = in(2)->find_int_con(0)) == 0) {
return MulNode::Ideal(phase, can_reshape);
}
// Now we have a constant Node on the right and the constant in con
if (con == 0) return NULL; // By zero is handled by Value call
if (con == 1) return NULL; // By one is handled by Identity call
// Check for negative constant; if so negate the final result
bool sign_flip = false;
unsigned int abs_con = uabs(con);
if (abs_con != (unsigned int)con) {
sign_flip = true;
}
// Get low bit; check for being the only bit
Node *res = NULL;
unsigned int bit1 = abs_con & (0-abs_con); // Extract low bit
if (bit1 == abs_con) { // Found a power of 2?
res = new LShiftINode(in(1), phase->intcon(log2_uint(bit1)));
} else {
// Check for constant with 2 bits set
unsigned int bit2 = abs_con-bit1;
bit2 = bit2 & (0-bit2); // Extract 2nd bit
if (bit2 + bit1 == abs_con) { // Found all bits in con?
Node *n1 = phase->transform( new LShiftINode(in(1), phase->intcon(log2_uint(bit1))));
Node *n2 = phase->transform( new LShiftINode(in(1), phase->intcon(log2_uint(bit2))));
res = new AddINode(n2, n1);
} else if (is_power_of_2(abs_con+1)) {
// Sleezy: power-of-2 -1. Next time be generic.
unsigned int temp = abs_con + 1;
Node *n1 = phase->transform(new LShiftINode(in(1), phase->intcon(log2_uint(temp))));
res = new SubINode(n1, in(1));
} else {
return MulNode::Ideal(phase, can_reshape);
}
}
if (sign_flip) { // Need to negate result?
res = phase->transform(res);// Transform, before making the zero con
res = new SubINode(phase->intcon(0),res);
}
return res; // Return final result
}
//------------------------------mul_ring---------------------------------------
// Compute the product type of two integer ranges into this node.
const Type *MulINode::mul_ring(const Type *t0, const Type *t1) const {
const TypeInt *r0 = t0->is_int(); // Handy access
const TypeInt *r1 = t1->is_int();
// Fetch endpoints of all ranges
jint lo0 = r0->_lo;
double a = (double)lo0;
jint hi0 = r0->_hi;
double b = (double)hi0;
jint lo1 = r1->_lo;
double c = (double)lo1;
jint hi1 = r1->_hi;
double d = (double)hi1;
// Compute all endpoints & check for overflow
int32_t A = java_multiply(lo0, lo1);
if( (double)A != a*c ) return TypeInt::INT; // Overflow?
int32_t B = java_multiply(lo0, hi1);
if( (double)B != a*d ) return TypeInt::INT; // Overflow?
int32_t C = java_multiply(hi0, lo1);
if( (double)C != b*c ) return TypeInt::INT; // Overflow?
int32_t D = java_multiply(hi0, hi1);
if( (double)D != b*d ) return TypeInt::INT; // Overflow?
if( A < B ) { lo0 = A; hi0 = B; } // Sort range endpoints
else { lo0 = B; hi0 = A; }
if( C < D ) {
if( C < lo0 ) lo0 = C;
if( D > hi0 ) hi0 = D;
} else {
if( D < lo0 ) lo0 = D;
if( C > hi0 ) hi0 = C;
}
return TypeInt::make(lo0, hi0, MAX2(r0->_widen,r1->_widen));
}
//=============================================================================
//------------------------------Ideal------------------------------------------
// Check for power-of-2 multiply, then try the regular MulNode::Ideal
Node *MulLNode::Ideal(PhaseGVN *phase, bool can_reshape) {
// Swap constant to right
jlong con;
if ((con = in(1)->find_long_con(0)) != 0) {
swap_edges(1, 2);
// Finish rest of method to use info in 'con'
} else if ((con = in(2)->find_long_con(0)) == 0) {
return MulNode::Ideal(phase, can_reshape);
}
// Now we have a constant Node on the right and the constant in con
if (con == CONST64(0)) return NULL; // By zero is handled by Value call
if (con == CONST64(1)) return NULL; // By one is handled by Identity call
// Check for negative constant; if so negate the final result
bool sign_flip = false;
julong abs_con = uabs(con);
if (abs_con != (julong)con) {
sign_flip = true;
}
// Get low bit; check for being the only bit
Node *res = NULL;
julong bit1 = abs_con & (0-abs_con); // Extract low bit
if (bit1 == abs_con) { // Found a power of 2?
res = new LShiftLNode(in(1), phase->intcon(log2_long(bit1)));
} else {
// Check for constant with 2 bits set
julong bit2 = abs_con-bit1;
bit2 = bit2 & (0-bit2); // Extract 2nd bit
if (bit2 + bit1 == abs_con) { // Found all bits in con?
Node *n1 = phase->transform(new LShiftLNode(in(1), phase->intcon(log2_long(bit1))));
Node *n2 = phase->transform(new LShiftLNode(in(1), phase->intcon(log2_long(bit2))));
res = new AddLNode(n2, n1);
} else if (is_power_of_2_long(abs_con+1)) {
// Sleezy: power-of-2 -1. Next time be generic.
julong temp = abs_con + 1;
Node *n1 = phase->transform( new LShiftLNode(in(1), phase->intcon(log2_long(temp))));
res = new SubLNode(n1, in(1));
} else {
return MulNode::Ideal(phase, can_reshape);
}
}
if (sign_flip) { // Need to negate result?
res = phase->transform(res);// Transform, before making the zero con
res = new SubLNode(phase->longcon(0),res);
}
return res; // Return final result
}
//------------------------------mul_ring---------------------------------------
// Compute the product type of two integer ranges into this node.
const Type *MulLNode::mul_ring(const Type *t0, const Type *t1) const {
const TypeLong *r0 = t0->is_long(); // Handy access
const TypeLong *r1 = t1->is_long();
// Fetch endpoints of all ranges
jlong lo0 = r0->_lo;
double a = (double)lo0;
jlong hi0 = r0->_hi;
double b = (double)hi0;
jlong lo1 = r1->_lo;
double c = (double)lo1;
jlong hi1 = r1->_hi;
double d = (double)hi1;
// Compute all endpoints & check for overflow
jlong A = java_multiply(lo0, lo1);
if( (double)A != a*c ) return TypeLong::LONG; // Overflow?
jlong B = java_multiply(lo0, hi1);
if( (double)B != a*d ) return TypeLong::LONG; // Overflow?
jlong C = java_multiply(hi0, lo1);
if( (double)C != b*c ) return TypeLong::LONG; // Overflow?
jlong D = java_multiply(hi0, hi1);
if( (double)D != b*d ) return TypeLong::LONG; // Overflow?
if( A < B ) { lo0 = A; hi0 = B; } // Sort range endpoints
else { lo0 = B; hi0 = A; }
if( C < D ) {
if( C < lo0 ) lo0 = C;
if( D > hi0 ) hi0 = D;
} else {
if( D < lo0 ) lo0 = D;
if( C > hi0 ) hi0 = C;
}
return TypeLong::make(lo0, hi0, MAX2(r0->_widen,r1->_widen));
}
//=============================================================================
//------------------------------mul_ring---------------------------------------
// Compute the product type of two double ranges into this node.
const Type *MulFNode::mul_ring(const Type *t0, const Type *t1) const {
if( t0 == Type::FLOAT || t1 == Type::FLOAT ) return Type::FLOAT;
return TypeF::make( t0->getf() * t1->getf() );
}
//=============================================================================
//------------------------------mul_ring---------------------------------------
// Compute the product type of two double ranges into this node.
const Type *MulDNode::mul_ring(const Type *t0, const Type *t1) const {
if( t0 == Type::DOUBLE || t1 == Type::DOUBLE ) return Type::DOUBLE;
// We must be multiplying 2 double constants.
return TypeD::make( t0->getd() * t1->getd() );
}
//=============================================================================
//------------------------------Value------------------------------------------
const Type* MulHiLNode::Value(PhaseGVN* phase) const {
// Either input is TOP ==> the result is TOP
const Type *t1 = phase->type( in(1) );
const Type *t2 = phase->type( in(2) );
if( t1 == Type::TOP ) return Type::TOP;
if( t2 == Type::TOP ) return Type::TOP;
// Either input is BOTTOM ==> the result is the local BOTTOM
const Type *bot = bottom_type();
if( (t1 == bot) || (t2 == bot) ||
(t1 == Type::BOTTOM) || (t2 == Type::BOTTOM) )
return bot;
// It is not worth trying to constant fold this stuff!
return TypeLong::LONG;
}
//=============================================================================
//------------------------------mul_ring---------------------------------------
// Supplied function returns the product of the inputs IN THE CURRENT RING.
// For the logical operations the ring's MUL is really a logical AND function.
// This also type-checks the inputs for sanity. Guaranteed never to
// be passed a TOP or BOTTOM type, these are filtered out by pre-check.
const Type *AndINode::mul_ring( const Type *t0, const Type *t1 ) const {
const TypeInt *r0 = t0->is_int(); // Handy access
const TypeInt *r1 = t1->is_int();
int widen = MAX2(r0->_widen,r1->_widen);
// If either input is a constant, might be able to trim cases
if( !r0->is_con() && !r1->is_con() )
return TypeInt::INT; // No constants to be had
// Both constants? Return bits
if( r0->is_con() && r1->is_con() )
return TypeInt::make( r0->get_con() & r1->get_con() );
if( r0->is_con() && r0->get_con() > 0 )
return TypeInt::make(0, r0->get_con(), widen);
if( r1->is_con() && r1->get_con() > 0 )
return TypeInt::make(0, r1->get_con(), widen);
if( r0 == TypeInt::BOOL || r1 == TypeInt::BOOL ) {
return TypeInt::BOOL;
}
return TypeInt::INT; // No constants to be had
}
//------------------------------Identity---------------------------------------
// Masking off the high bits of an unsigned load is not required
Node* AndINode::Identity(PhaseGVN* phase) {
// x & x => x
if (phase->eqv(in(1), in(2))) return in(1);
Node* in1 = in(1);
uint op = in1->Opcode();
const TypeInt* t2 = phase->type(in(2))->isa_int();
if (t2 && t2->is_con()) {
int con = t2->get_con();
// Masking off high bits which are always zero is useless.
const TypeInt* t1 = phase->type( in(1) )->isa_int();
if (t1 != NULL && t1->_lo >= 0) {
jint t1_support = right_n_bits(1 + log2_jint(t1->_hi));
if ((t1_support & con) == t1_support)
return in1;
}
// Masking off the high bits of a unsigned-shift-right is not
// needed either.
if (op == Op_URShiftI) {
const TypeInt* t12 = phase->type(in1->in(2))->isa_int();
if (t12 && t12->is_con()) { // Shift is by a constant
int shift = t12->get_con();
shift &= BitsPerJavaInteger - 1; // semantics of Java shifts
int mask = max_juint >> shift;
if ((mask & con) == mask) // If AND is useless, skip it
return in1;
}
}
}
return MulNode::Identity(phase);
}
//------------------------------Ideal------------------------------------------
Node *AndINode::Ideal(PhaseGVN *phase, bool can_reshape) {
// Special case constant AND mask
const TypeInt *t2 = phase->type( in(2) )->isa_int();
if( !t2 || !t2->is_con() ) return MulNode::Ideal(phase, can_reshape);
const int mask = t2->get_con();
Node *load = in(1);
uint lop = load->Opcode();
// Masking bits off of a Character? Hi bits are already zero.
if( lop == Op_LoadUS &&
(mask & 0xFFFF0000) ) // Can we make a smaller mask?
return new AndINode(load,phase->intcon(mask&0xFFFF));
// Masking bits off of a Short? Loading a Character does some masking
if (can_reshape &&
load->outcnt() == 1 && load->unique_out() == this) {
if (lop == Op_LoadS && (mask & 0xFFFF0000) == 0 ) {
Node* ldus = load->as_Load()->convert_to_unsigned_load(*phase);
ldus = phase->transform(ldus);
return new AndINode(ldus, phase->intcon(mask & 0xFFFF));
}
// Masking sign bits off of a Byte? Do an unsigned byte load plus
// an and.
if (lop == Op_LoadB && (mask & 0xFFFFFF00) == 0) {
Node* ldub = load->as_Load()->convert_to_unsigned_load(*phase);
ldub = phase->transform(ldub);
return new AndINode(ldub, phase->intcon(mask));
}
}
// Masking off sign bits? Dont make them!
if( lop == Op_RShiftI ) {
const TypeInt *t12 = phase->type(load->in(2))->isa_int();
if( t12 && t12->is_con() ) { // Shift is by a constant
int shift = t12->get_con();
shift &= BitsPerJavaInteger-1; // semantics of Java shifts
const int sign_bits_mask = ~right_n_bits(BitsPerJavaInteger - shift);
// If the AND'ing of the 2 masks has no bits, then only original shifted
// bits survive. NO sign-extension bits survive the maskings.
if( (sign_bits_mask & mask) == 0 ) {
// Use zero-fill shift instead
Node *zshift = phase->transform(new URShiftINode(load->in(1),load->in(2)));
return new AndINode( zshift, in(2) );
}
}
}
// Check for 'negate/and-1', a pattern emitted when someone asks for
// 'mod 2'. Negate leaves the low order bit unchanged (think: complement
// plus 1) and the mask is of the low order bit. Skip the negate.
if( lop == Op_SubI && mask == 1 && load->in(1) &&
phase->type(load->in(1)) == TypeInt::ZERO )
return new AndINode( load->in(2), in(2) );
return MulNode::Ideal(phase, can_reshape);
}
//=============================================================================
//------------------------------mul_ring---------------------------------------
// Supplied function returns the product of the inputs IN THE CURRENT RING.
// For the logical operations the ring's MUL is really a logical AND function.
// This also type-checks the inputs for sanity. Guaranteed never to
// be passed a TOP or BOTTOM type, these are filtered out by pre-check.
const Type *AndLNode::mul_ring( const Type *t0, const Type *t1 ) const {
const TypeLong *r0 = t0->is_long(); // Handy access
const TypeLong *r1 = t1->is_long();
int widen = MAX2(r0->_widen,r1->_widen);
// If either input is a constant, might be able to trim cases
if( !r0->is_con() && !r1->is_con() )
return TypeLong::LONG; // No constants to be had
// Both constants? Return bits
if( r0->is_con() && r1->is_con() )
return TypeLong::make( r0->get_con() & r1->get_con() );
if( r0->is_con() && r0->get_con() > 0 )
return TypeLong::make(CONST64(0), r0->get_con(), widen);
if( r1->is_con() && r1->get_con() > 0 )
return TypeLong::make(CONST64(0), r1->get_con(), widen);
return TypeLong::LONG; // No constants to be had
}
//------------------------------Identity---------------------------------------
// Masking off the high bits of an unsigned load is not required
Node* AndLNode::Identity(PhaseGVN* phase) {
// x & x => x
if (phase->eqv(in(1), in(2))) return in(1);
Node *usr = in(1);
const TypeLong *t2 = phase->type( in(2) )->isa_long();
if( t2 && t2->is_con() ) {
jlong con = t2->get_con();
// Masking off high bits which are always zero is useless.
const TypeLong* t1 = phase->type( in(1) )->isa_long();
if (t1 != NULL && t1->_lo >= 0) {
int bit_count = log2_long(t1->_hi) + 1;
jlong t1_support = jlong(max_julong >> (BitsPerJavaLong - bit_count));
if ((t1_support & con) == t1_support)
return usr;
}
uint lop = usr->Opcode();
// Masking off the high bits of a unsigned-shift-right is not
// needed either.
if( lop == Op_URShiftL ) {
const TypeInt *t12 = phase->type( usr->in(2) )->isa_int();
if( t12 && t12->is_con() ) { // Shift is by a constant
int shift = t12->get_con();
shift &= BitsPerJavaLong - 1; // semantics of Java shifts
jlong mask = max_julong >> shift;
if( (mask&con) == mask ) // If AND is useless, skip it
return usr;
}
}
}
return MulNode::Identity(phase);
}
//------------------------------Ideal------------------------------------------
Node *AndLNode::Ideal(PhaseGVN *phase, bool can_reshape) {
// Special case constant AND mask
const TypeLong *t2 = phase->type( in(2) )->isa_long();
if( !t2 || !t2->is_con() ) return MulNode::Ideal(phase, can_reshape);
const jlong mask = t2->get_con();
Node* in1 = in(1);
uint op = in1->Opcode();
// Are we masking a long that was converted from an int with a mask
// that fits in 32-bits? Commute them and use an AndINode. Don't
// convert masks which would cause a sign extension of the integer
// value. This check includes UI2L masks (0x00000000FFFFFFFF) which
// would be optimized away later in Identity.
if (op == Op_ConvI2L && (mask & UCONST64(0xFFFFFFFF80000000)) == 0) {
Node* andi = new AndINode(in1->in(1), phase->intcon(mask));
andi = phase->transform(andi);
return new ConvI2LNode(andi);
}
// Masking off sign bits? Dont make them!
if (op == Op_RShiftL) {
const TypeInt* t12 = phase->type(in1->in(2))->isa_int();
if( t12 && t12->is_con() ) { // Shift is by a constant
int shift = t12->get_con();
shift &= BitsPerJavaLong - 1; // semantics of Java shifts
const jlong sign_bits_mask = ~(((jlong)CONST64(1) << (jlong)(BitsPerJavaLong - shift)) -1);
// If the AND'ing of the 2 masks has no bits, then only original shifted
// bits survive. NO sign-extension bits survive the maskings.
if( (sign_bits_mask & mask) == 0 ) {
// Use zero-fill shift instead
Node *zshift = phase->transform(new URShiftLNode(in1->in(1), in1->in(2)));
return new AndLNode(zshift, in(2));
}
}
}
return MulNode::Ideal(phase, can_reshape);
}
//=============================================================================
static int getShiftCon(PhaseGVN *phase, Node *shiftNode, int retVal) {
const Type *t = phase->type(shiftNode->in(2));
if (t == Type::TOP) return retVal; // Right input is dead.
const TypeInt *t2 = t->isa_int();
if (!t2 || !t2->is_con()) return retVal; // Right input is a constant.
return t2->get_con();
}
static int maskShiftAmount(PhaseGVN *phase, Node *shiftNode, int nBits) {
int shift = getShiftCon(phase, shiftNode, 0);
int maskedShift = shift & (nBits - 1);
if (maskedShift == 0) return 0; // Let Identity() handle 0 shift count.
if (shift != maskedShift) {
shiftNode->set_req(2, phase->intcon(maskedShift)); // Replace shift count with masked value.
phase->igvn_rehash_node_delayed(shiftNode);
}
return maskedShift;
}
//------------------------------Identity---------------------------------------
Node* LShiftINode::Identity(PhaseGVN* phase) {
return ((getShiftCon(phase, this, -1) & (BitsPerJavaInteger - 1)) == 0) ? in(1) : this;
}
//------------------------------Ideal------------------------------------------
// If the right input is a constant, and the left input is an add of a
// constant, flatten the tree: (X+con1)<<con0 ==> X<<con0 + con1<<con0
Node *LShiftINode::Ideal(PhaseGVN *phase, bool can_reshape) {
int con = maskShiftAmount(phase, this, BitsPerJavaInteger);
if (con == 0) {
return NULL;
}
// Left input is an add of a constant?
Node *add1 = in(1);
int add1_op = add1->Opcode();
if( add1_op == Op_AddI ) { // Left input is an add?
assert( add1 != add1->in(1), "dead loop in LShiftINode::Ideal" );
const TypeInt *t12 = phase->type(add1->in(2))->isa_int();
if( t12 && t12->is_con() ){ // Left input is an add of a con?
// Transform is legal, but check for profit. Avoid breaking 'i2s'
// and 'i2b' patterns which typically fold into 'StoreC/StoreB'.
if( con < 16 ) {
// Compute X << con0
Node *lsh = phase->transform( new LShiftINode( add1->in(1), in(2) ) );
// Compute X<<con0 + (con1<<con0)
return new AddINode( lsh, phase->intcon(t12->get_con() << con));
}
}
}
// Check for "(x>>c0)<<c0" which just masks off low bits
if( (add1_op == Op_RShiftI || add1_op == Op_URShiftI ) &&
add1->in(2) == in(2) )
// Convert to "(x & -(1<<c0))"
return new AndINode(add1->in(1),phase->intcon( -(1<<con)));
// Check for "((x>>c0) & Y)<<c0" which just masks off more low bits
if( add1_op == Op_AndI ) {
Node *add2 = add1->in(1);
int add2_op = add2->Opcode();
if( (add2_op == Op_RShiftI || add2_op == Op_URShiftI ) &&
add2->in(2) == in(2) ) {
// Convert to "(x & (Y<<c0))"
Node *y_sh = phase->transform( new LShiftINode( add1->in(2), in(2) ) );
return new AndINode( add2->in(1), y_sh );
}
}
// Check for ((x & ((1<<(32-c0))-1)) << c0) which ANDs off high bits
// before shifting them away.
const jint bits_mask = right_n_bits(BitsPerJavaInteger-con);
if( add1_op == Op_AndI &&
phase->type(add1->in(2)) == TypeInt::make( bits_mask ) )
return new LShiftINode( add1->in(1), in(2) );
return NULL;
}
//------------------------------Value------------------------------------------
// A LShiftINode shifts its input2 left by input1 amount.
const Type* LShiftINode::Value(PhaseGVN* phase) const {
const Type *t1 = phase->type( in(1) );
const Type *t2 = phase->type( in(2) );
// Either input is TOP ==> the result is TOP
if( t1 == Type::TOP ) return Type::TOP;
if( t2 == Type::TOP ) return Type::TOP;
// Left input is ZERO ==> the result is ZERO.
if( t1 == TypeInt::ZERO ) return TypeInt::ZERO;
// Shift by zero does nothing
if( t2 == TypeInt::ZERO ) return t1;
// Either input is BOTTOM ==> the result is BOTTOM
if( (t1 == TypeInt::INT) || (t2 == TypeInt::INT) ||
(t1 == Type::BOTTOM) || (t2 == Type::BOTTOM) )
return TypeInt::INT;
const TypeInt *r1 = t1->is_int(); // Handy access
const TypeInt *r2 = t2->is_int(); // Handy access
if (!r2->is_con())
return TypeInt::INT;
uint shift = r2->get_con();
shift &= BitsPerJavaInteger-1; // semantics of Java shifts
// Shift by a multiple of 32 does nothing:
if (shift == 0) return t1;
// If the shift is a constant, shift the bounds of the type,
// unless this could lead to an overflow.
if (!r1->is_con()) {
jint lo = r1->_lo, hi = r1->_hi;
if (((lo << shift) >> shift) == lo &&
((hi << shift) >> shift) == hi) {
// No overflow. The range shifts up cleanly.
return TypeInt::make((jint)lo << (jint)shift,
(jint)hi << (jint)shift,
MAX2(r1->_widen,r2->_widen));
}
return TypeInt::INT;
}
return TypeInt::make( (jint)r1->get_con() << (jint)shift );
}
//=============================================================================
//------------------------------Identity---------------------------------------
Node* LShiftLNode::Identity(PhaseGVN* phase) {
return ((getShiftCon(phase, this, -1) & (BitsPerJavaLong - 1)) == 0) ? in(1) : this;
}
//------------------------------Ideal------------------------------------------
// If the right input is a constant, and the left input is an add of a
// constant, flatten the tree: (X+con1)<<con0 ==> X<<con0 + con1<<con0
Node *LShiftLNode::Ideal(PhaseGVN *phase, bool can_reshape) {
int con = maskShiftAmount(phase, this, BitsPerJavaLong);
if (con == 0) {
return NULL;
}
// Left input is an add of a constant?
Node *add1 = in(1);
int add1_op = add1->Opcode();
if( add1_op == Op_AddL ) { // Left input is an add?
// Avoid dead data cycles from dead loops
assert( add1 != add1->in(1), "dead loop in LShiftLNode::Ideal" );
const TypeLong *t12 = phase->type(add1->in(2))->isa_long();
if( t12 && t12->is_con() ){ // Left input is an add of a con?
// Compute X << con0
Node *lsh = phase->transform( new LShiftLNode( add1->in(1), in(2) ) );
// Compute X<<con0 + (con1<<con0)
return new AddLNode( lsh, phase->longcon(t12->get_con() << con));
}
}
// Check for "(x>>c0)<<c0" which just masks off low bits
if( (add1_op == Op_RShiftL || add1_op == Op_URShiftL ) &&
add1->in(2) == in(2) )
// Convert to "(x & -(1<<c0))"
return new AndLNode(add1->in(1),phase->longcon( -(CONST64(1)<<con)));
// Check for "((x>>c0) & Y)<<c0" which just masks off more low bits
if( add1_op == Op_AndL ) {
Node *add2 = add1->in(1);
int add2_op = add2->Opcode();
if( (add2_op == Op_RShiftL || add2_op == Op_URShiftL ) &&
add2->in(2) == in(2) ) {
// Convert to "(x & (Y<<c0))"
Node *y_sh = phase->transform( new LShiftLNode( add1->in(2), in(2) ) );
return new AndLNode( add2->in(1), y_sh );
}
}
// Check for ((x & ((CONST64(1)<<(64-c0))-1)) << c0) which ANDs off high bits
// before shifting them away.
const jlong bits_mask = jlong(max_julong >> con);
if( add1_op == Op_AndL &&
phase->type(add1->in(2)) == TypeLong::make( bits_mask ) )
return new LShiftLNode( add1->in(1), in(2) );
return NULL;
}
//------------------------------Value------------------------------------------
// A LShiftLNode shifts its input2 left by input1 amount.
const Type* LShiftLNode::Value(PhaseGVN* phase) const {
const Type *t1 = phase->type( in(1) );
const Type *t2 = phase->type( in(2) );
// Either input is TOP ==> the result is TOP
if( t1 == Type::TOP ) return Type::TOP;
if( t2 == Type::TOP ) return Type::TOP;
// Left input is ZERO ==> the result is ZERO.
if( t1 == TypeLong::ZERO ) return TypeLong::ZERO;
// Shift by zero does nothing
if( t2 == TypeInt::ZERO ) return t1;
// Either input is BOTTOM ==> the result is BOTTOM
if( (t1 == TypeLong::LONG) || (t2 == TypeInt::INT) ||
(t1 == Type::BOTTOM) || (t2 == Type::BOTTOM) )
return TypeLong::LONG;
const TypeLong *r1 = t1->is_long(); // Handy access
const TypeInt *r2 = t2->is_int(); // Handy access
if (!r2->is_con())
return TypeLong::LONG;
uint shift = r2->get_con();
shift &= BitsPerJavaLong - 1; // semantics of Java shifts
// Shift by a multiple of 64 does nothing:
if (shift == 0) return t1;
// If the shift is a constant, shift the bounds of the type,
// unless this could lead to an overflow.
if (!r1->is_con()) {
jlong lo = r1->_lo, hi = r1->_hi;
if (((lo << shift) >> shift) == lo &&
((hi << shift) >> shift) == hi) {
// No overflow. The range shifts up cleanly.
return TypeLong::make((jlong)lo << (jint)shift,
(jlong)hi << (jint)shift,
MAX2(r1->_widen,r2->_widen));
}
return TypeLong::LONG;
}
return TypeLong::make( (jlong)r1->get_con() << (jint)shift );
}
//=============================================================================
//------------------------------Identity---------------------------------------
Node* RShiftINode::Identity(PhaseGVN* phase) {
int shift = getShiftCon(phase, this, -1);
if (shift == -1) return this;
if ((shift & (BitsPerJavaInteger - 1)) == 0) return in(1);
// Check for useless sign-masking
if (in(1)->Opcode() == Op_LShiftI &&
in(1)->req() == 3 &&
in(1)->in(2) == in(2)) {
shift &= BitsPerJavaInteger-1; // semantics of Java shifts
// Compute masks for which this shifting doesn't change
int lo = (-1 << (BitsPerJavaInteger - ((uint)shift)-1)); // FFFF8000
int hi = ~lo; // 00007FFF
const TypeInt *t11 = phase->type(in(1)->in(1))->isa_int();
if (!t11) return this;
// Does actual value fit inside of mask?
if (lo <= t11->_lo && t11->_hi <= hi) {
return in(1)->in(1); // Then shifting is a nop
}
}
return this;
}
//------------------------------Ideal------------------------------------------
Node *RShiftINode::Ideal(PhaseGVN *phase, bool can_reshape) {
// Inputs may be TOP if they are dead.
const TypeInt *t1 = phase->type(in(1))->isa_int();
if (!t1) return NULL; // Left input is an integer
const TypeInt *t3; // type of in(1).in(2)
int shift = maskShiftAmount(phase, this, BitsPerJavaInteger);
if (shift == 0) {
return NULL;
}
// Check for (x & 0xFF000000) >> 24, whose mask can be made smaller.
// Such expressions arise normally from shift chains like (byte)(x >> 24).
const Node *mask = in(1);
if( mask->Opcode() == Op_AndI &&
(t3 = phase->type(mask->in(2))->isa_int()) &&
t3->is_con() ) {
Node *x = mask->in(1);
jint maskbits = t3->get_con();
// Convert to "(x >> shift) & (mask >> shift)"
Node *shr_nomask = phase->transform( new RShiftINode(mask->in(1), in(2)) );
return new AndINode(shr_nomask, phase->intcon( maskbits >> shift));
}
// Check for "(short[i] <<16)>>16" which simply sign-extends
const Node *shl = in(1);
if( shl->Opcode() != Op_LShiftI ) return NULL;
if( shift == 16 &&
(t3 = phase->type(shl->in(2))->isa_int()) &&
t3->is_con(16) ) {
Node *ld = shl->in(1);
if( ld->Opcode() == Op_LoadS ) {
// Sign extension is just useless here. Return a RShiftI of zero instead
// returning 'ld' directly. We cannot return an old Node directly as
// that is the job of 'Identity' calls and Identity calls only work on
// direct inputs ('ld' is an extra Node removed from 'this'). The
// combined optimization requires Identity only return direct inputs.
set_req(1, ld);
set_req(2, phase->intcon(0));
return this;
}
else if( can_reshape &&
ld->Opcode() == Op_LoadUS &&
ld->outcnt() == 1 && ld->unique_out() == shl)
// Replace zero-extension-load with sign-extension-load
return ld->as_Load()->convert_to_signed_load(*phase);
}
// Check for "(byte[i] <<24)>>24" which simply sign-extends
if( shift == 24 &&
(t3 = phase->type(shl->in(2))->isa_int()) &&
t3->is_con(24) ) {
Node *ld = shl->in(1);
if( ld->Opcode() == Op_LoadB ) {
// Sign extension is just useless here
set_req(1, ld);
set_req(2, phase->intcon(0));
return this;
}
}
return NULL;
}
//------------------------------Value------------------------------------------
// A RShiftINode shifts its input2 right by input1 amount.
const Type* RShiftINode::Value(PhaseGVN* phase) const {
const Type *t1 = phase->type( in(1) );
const Type *t2 = phase->type( in(2) );
// Either input is TOP ==> the result is TOP
if( t1 == Type::TOP ) return Type::TOP;
if( t2 == Type::TOP ) return Type::TOP;
// Left input is ZERO ==> the result is ZERO.
if( t1 == TypeInt::ZERO ) return TypeInt::ZERO;
// Shift by zero does nothing
if( t2 == TypeInt::ZERO ) return t1;
// Either input is BOTTOM ==> the result is BOTTOM
if (t1 == Type::BOTTOM || t2 == Type::BOTTOM)
return TypeInt::INT;
if (t2 == TypeInt::INT)
return TypeInt::INT;
const TypeInt *r1 = t1->is_int(); // Handy access
const TypeInt *r2 = t2->is_int(); // Handy access
// If the shift is a constant, just shift the bounds of the type.
// For example, if the shift is 31, we just propagate sign bits.
if (r2->is_con()) {
uint shift = r2->get_con();
shift &= BitsPerJavaInteger-1; // semantics of Java shifts
// Shift by a multiple of 32 does nothing:
if (shift == 0) return t1;
// Calculate reasonably aggressive bounds for the result.
// This is necessary if we are to correctly type things
// like (x<<24>>24) == ((byte)x).
jint lo = (jint)r1->_lo >> (jint)shift;
jint hi = (jint)r1->_hi >> (jint)shift;
assert(lo <= hi, "must have valid bounds");
const TypeInt* ti = TypeInt::make(lo, hi, MAX2(r1->_widen,r2->_widen));
#ifdef ASSERT
// Make sure we get the sign-capture idiom correct.
if (shift == BitsPerJavaInteger-1) {
if (r1->_lo >= 0) assert(ti == TypeInt::ZERO, ">>31 of + is 0");
if (r1->_hi < 0) assert(ti == TypeInt::MINUS_1, ">>31 of - is -1");
}
#endif
return ti;
}
if( !r1->is_con() || !r2->is_con() )
return TypeInt::INT;
// Signed shift right
return TypeInt::make( r1->get_con() >> (r2->get_con()&31) );
}
//=============================================================================
//------------------------------Identity---------------------------------------
Node* RShiftLNode::Identity(PhaseGVN* phase) {
const TypeInt *ti = phase->type(in(2))->isa_int(); // Shift count is an int.
return (ti && ti->is_con() && (ti->get_con() & (BitsPerJavaLong - 1)) == 0) ? in(1) : this;
}
//------------------------------Value------------------------------------------
// A RShiftLNode shifts its input2 right by input1 amount.
const Type* RShiftLNode::Value(PhaseGVN* phase) const {
const Type *t1 = phase->type( in(1) );
const Type *t2 = phase->type( in(2) );
// Either input is TOP ==> the result is TOP
if( t1 == Type::TOP ) return Type::TOP;
if( t2 == Type::TOP ) return Type::TOP;
// Left input is ZERO ==> the result is ZERO.
if( t1 == TypeLong::ZERO ) return TypeLong::ZERO;
// Shift by zero does nothing
if( t2 == TypeInt::ZERO ) return t1;
// Either input is BOTTOM ==> the result is BOTTOM
if (t1 == Type::BOTTOM || t2 == Type::BOTTOM)
return TypeLong::LONG;
if (t2 == TypeInt::INT)
return TypeLong::LONG;
const TypeLong *r1 = t1->is_long(); // Handy access
const TypeInt *r2 = t2->is_int (); // Handy access
// If the shift is a constant, just shift the bounds of the type.
// For example, if the shift is 63, we just propagate sign bits.
if (r2->is_con()) {
uint shift = r2->get_con();
shift &= (2*BitsPerJavaInteger)-1; // semantics of Java shifts
// Shift by a multiple of 64 does nothing:
if (shift == 0) return t1;
// Calculate reasonably aggressive bounds for the result.
// This is necessary if we are to correctly type things
// like (x<<24>>24) == ((byte)x).
jlong lo = (jlong)r1->_lo >> (jlong)shift;
jlong hi = (jlong)r1->_hi >> (jlong)shift;
assert(lo <= hi, "must have valid bounds");
const TypeLong* tl = TypeLong::make(lo, hi, MAX2(r1->_widen,r2->_widen));
#ifdef ASSERT
// Make sure we get the sign-capture idiom correct.
if (shift == (2*BitsPerJavaInteger)-1) {
if (r1->_lo >= 0) assert(tl == TypeLong::ZERO, ">>63 of + is 0");
if (r1->_hi < 0) assert(tl == TypeLong::MINUS_1, ">>63 of - is -1");
}
#endif
return tl;
}
return TypeLong::LONG; // Give up
}
//=============================================================================
//------------------------------Identity---------------------------------------
Node* URShiftINode::Identity(PhaseGVN* phase) {
int shift = getShiftCon(phase, this, -1);
if ((shift & (BitsPerJavaInteger - 1)) == 0) return in(1);
// Check for "((x << LogBytesPerWord) + (wordSize-1)) >> LogBytesPerWord" which is just "x".
// Happens during new-array length computation.
// Safe if 'x' is in the range [0..(max_int>>LogBytesPerWord)]
Node *add = in(1);
if (add->Opcode() == Op_AddI) {
const TypeInt *t2 = phase->type(add->in(2))->isa_int();
if (t2 && t2->is_con(wordSize - 1) &&
add->in(1)->Opcode() == Op_LShiftI) {
// Check that shift_counts are LogBytesPerWord.
Node *lshift_count = add->in(1)->in(2);
const TypeInt *t_lshift_count = phase->type(lshift_count)->isa_int();
if (t_lshift_count && t_lshift_count->is_con(LogBytesPerWord) &&
t_lshift_count == phase->type(in(2))) {
Node *x = add->in(1)->in(1);
const TypeInt *t_x = phase->type(x)->isa_int();
if (t_x != NULL && 0 <= t_x->_lo && t_x->_hi <= (max_jint>>LogBytesPerWord)) {
return x;
}
}
}
}
return (phase->type(in(2))->higher_equal(TypeInt::ZERO)) ? in(1) : this;
}
//------------------------------Ideal------------------------------------------
Node *URShiftINode::Ideal(PhaseGVN *phase, bool can_reshape) {
int con = maskShiftAmount(phase, this, BitsPerJavaInteger);
if (con == 0) {
return NULL;
}
// We'll be wanting the right-shift amount as a mask of that many bits
const int mask = right_n_bits(BitsPerJavaInteger - con);
int in1_op = in(1)->Opcode();
// Check for ((x>>>a)>>>b) and replace with (x>>>(a+b)) when a+b < 32
if( in1_op == Op_URShiftI ) {
const TypeInt *t12 = phase->type( in(1)->in(2) )->isa_int();
if( t12 && t12->is_con() ) { // Right input is a constant
assert( in(1) != in(1)->in(1), "dead loop in URShiftINode::Ideal" );
const int con2 = t12->get_con() & 31; // Shift count is always masked
const int con3 = con+con2;
if( con3 < 32 ) // Only merge shifts if total is < 32
return new URShiftINode( in(1)->in(1), phase->intcon(con3) );
}
}
// Check for ((x << z) + Y) >>> z. Replace with x + con>>>z
// The idiom for rounding to a power of 2 is "(Q+(2^z-1)) >>> z".
// If Q is "X << z" the rounding is useless. Look for patterns like
// ((X<<Z) + Y) >>> Z and replace with (X + Y>>>Z) & Z-mask.
Node *add = in(1);
const TypeInt *t2 = phase->type(in(2))->isa_int();
if (in1_op == Op_AddI) {
Node *lshl = add->in(1);
if( lshl->Opcode() == Op_LShiftI &&
phase->type(lshl->in(2)) == t2 ) {
Node *y_z = phase->transform( new URShiftINode(add->in(2),in(2)) );
Node *sum = phase->transform( new AddINode( lshl->in(1), y_z ) );
return new AndINode( sum, phase->intcon(mask) );
}
}
// Check for (x & mask) >>> z. Replace with (x >>> z) & (mask >>> z)
// This shortens the mask. Also, if we are extracting a high byte and
// storing it to a buffer, the mask will be removed completely.
Node *andi = in(1);
if( in1_op == Op_AndI ) {
const TypeInt *t3 = phase->type( andi->in(2) )->isa_int();
if( t3 && t3->is_con() ) { // Right input is a constant
jint mask2 = t3->get_con();
mask2 >>= con; // *signed* shift downward (high-order zeroes do not help)
Node *newshr = phase->transform( new URShiftINode(andi->in(1), in(2)) );
return new AndINode(newshr, phase->intcon(mask2));
// The negative values are easier to materialize than positive ones.
// A typical case from address arithmetic is ((x & ~15) >> 4).
// It's better to change that to ((x >> 4) & ~0) versus
// ((x >> 4) & 0x0FFFFFFF). The difference is greatest in LP64.
}
}
// Check for "(X << z ) >>> z" which simply zero-extends
Node *shl = in(1);
if( in1_op == Op_LShiftI &&
phase->type(shl->in(2)) == t2 )
return new AndINode( shl->in(1), phase->intcon(mask) );
return NULL;
}
//------------------------------Value------------------------------------------
// A URShiftINode shifts its input2 right by input1 amount.
const Type* URShiftINode::Value(PhaseGVN* phase) const {
// (This is a near clone of RShiftINode::Value.)
const Type *t1 = phase->type( in(1) );
const Type *t2 = phase->type( in(2) );
// Either input is TOP ==> the result is TOP
if( t1 == Type::TOP ) return Type::TOP;
if( t2 == Type::TOP ) return Type::TOP;
// Left input is ZERO ==> the result is ZERO.
if( t1 == TypeInt::ZERO ) return TypeInt::ZERO;
// Shift by zero does nothing
if( t2 == TypeInt::ZERO ) return t1;
// Either input is BOTTOM ==> the result is BOTTOM
if (t1 == Type::BOTTOM || t2 == Type::BOTTOM)
return TypeInt::INT;
if (t2 == TypeInt::INT)
return TypeInt::INT;
const TypeInt *r1 = t1->is_int(); // Handy access
const TypeInt *r2 = t2->is_int(); // Handy access
if (r2->is_con()) {
uint shift = r2->get_con();
shift &= BitsPerJavaInteger-1; // semantics of Java shifts
// Shift by a multiple of 32 does nothing:
if (shift == 0) return t1;
// Calculate reasonably aggressive bounds for the result.
jint lo = (juint)r1->_lo >> (juint)shift;
jint hi = (juint)r1->_hi >> (juint)shift;
if (r1->_hi >= 0 && r1->_lo < 0) {
// If the type has both negative and positive values,
// there are two separate sub-domains to worry about:
// The positive half and the negative half.
jint neg_lo = lo;
jint neg_hi = (juint)-1 >> (juint)shift;
jint pos_lo = (juint) 0 >> (juint)shift;
jint pos_hi = hi;
lo = MIN2(neg_lo, pos_lo); // == 0
hi = MAX2(neg_hi, pos_hi); // == -1 >>> shift;
}
assert(lo <= hi, "must have valid bounds");
const TypeInt* ti = TypeInt::make(lo, hi, MAX2(r1->_widen,r2->_widen));
#ifdef ASSERT
// Make sure we get the sign-capture idiom correct.
if (shift == BitsPerJavaInteger-1) {
if (r1->_lo >= 0) assert(ti == TypeInt::ZERO, ">>>31 of + is 0");
if (r1->_hi < 0) assert(ti == TypeInt::ONE, ">>>31 of - is +1");
}
#endif
return ti;
}
//
// Do not support shifted oops in info for GC
//
// else if( t1->base() == Type::InstPtr ) {
//
// const TypeInstPtr *o = t1->is_instptr();
// if( t1->singleton() )
// return TypeInt::make( ((uint32_t)o->const_oop() + o->_offset) >> shift );
// }
// else if( t1->base() == Type::KlassPtr ) {
// const TypeKlassPtr *o = t1->is_klassptr();
// if( t1->singleton() )
// return TypeInt::make( ((uint32_t)o->const_oop() + o->_offset) >> shift );
// }
return TypeInt::INT;
}
//=============================================================================
//------------------------------Identity---------------------------------------
Node* URShiftLNode::Identity(PhaseGVN* phase) {
return ((getShiftCon(phase, this, -1) & (BitsPerJavaLong - 1)) == 0) ? in(1) : this;
}
//------------------------------Ideal------------------------------------------
Node *URShiftLNode::Ideal(PhaseGVN *phase, bool can_reshape) {
int con = maskShiftAmount(phase, this, BitsPerJavaLong);
if (con == 0) {
return NULL;
}
// We'll be wanting the right-shift amount as a mask of that many bits
const jlong mask = jlong(max_julong >> con);
// Check for ((x << z) + Y) >>> z. Replace with x + con>>>z
// The idiom for rounding to a power of 2 is "(Q+(2^z-1)) >>> z".
// If Q is "X << z" the rounding is useless. Look for patterns like
// ((X<<Z) + Y) >>> Z and replace with (X + Y>>>Z) & Z-mask.
Node *add = in(1);
const TypeInt *t2 = phase->type(in(2))->isa_int();
if (add->Opcode() == Op_AddL) {
Node *lshl = add->in(1);
if( lshl->Opcode() == Op_LShiftL &&
phase->type(lshl->in(2)) == t2 ) {
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