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8000805: JMM issue: short loads are non-atomic

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Perform transforms during IGVN phase when Load has a single user.

Reviewed-by: jrose, kvn, twisti
This commit is contained in:
Vladimir Ivanov 2012-10-22 11:44:30 -07:00
parent e57ac83cac
commit 7f87237400
2 changed files with 108 additions and 18 deletions
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41
hotspot/src/share/vm/opto/mulnode.cpp
View file

@ -479,24 +479,27 @@ Node *AndINode::Ideal(PhaseGVN *phase, bool can_reshape) {
return new (phase->C) AndINode(load,phase->intcon(mask&0xFFFF));
// Masking bits off of a Short? Loading a Character does some masking
if (lop == Op_LoadS && (mask & 0xFFFF0000) == 0 ) {
Node *ldus = new (phase->C) LoadUSNode(load->in(MemNode::Control),
load->in(MemNode::Memory),
load->in(MemNode::Address),
load->adr_type());
ldus = phase->transform(ldus);
return new (phase->C) AndINode(ldus, phase->intcon(mask & 0xFFFF));
}
if (can_reshape &&
load->outcnt() == 1 && load->unique_out() == this) {
if (lop == Op_LoadS && (mask & 0xFFFF0000) == 0 ) {
Node *ldus = new (phase->C) LoadUSNode(load->in(MemNode::Control),
load->in(MemNode::Memory),
load->in(MemNode::Address),
load->adr_type());
ldus = phase->transform(ldus);
return new (phase->C) 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 = new (phase->C) LoadUBNode(load->in(MemNode::Control),
load->in(MemNode::Memory),
load->in(MemNode::Address),
load->adr_type());
ldub = phase->transform(ldub);
return new (phase->C) AndINode(ldub, phase->intcon(mask));
// Masking sign bits off of a Byte? Do an unsigned byte load plus
// an and.
if (lop == Op_LoadB && (mask & 0xFFFFFF00) == 0) {
Node* ldub = new (phase->C) LoadUBNode(load->in(MemNode::Control),
load->in(MemNode::Memory),
load->in(MemNode::Address),
load->adr_type());
ldub = phase->transform(ldub);
return new (phase->C) AndINode(ldub, phase->intcon(mask));
}
}
// Masking off sign bits? Dont make them!
@ -923,7 +926,9 @@ Node *RShiftINode::Ideal(PhaseGVN *phase, bool can_reshape) {
set_req(2, phase->intcon(0));
return this;
}
else if( ld->Opcode() == Op_LoadUS )
else if( can_reshape &&
ld->Opcode() == Op_LoadUS &&
ld->outcnt() == 1 && ld->unique_out() == shl)
// Replace zero-extension-load with sign-extension-load
return new (phase->C) LoadSNode( ld->in(MemNode::Control),
ld->in(MemNode::Memory),