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8071996: split_if accesses NULL region of ConstraintCast #649

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8071996: split_if accesses NULL region of ConstraintCast #649

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16 changes: 12 additions & 4 deletions hotspot/src/share/vm/opto/ifnode.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -145,10 +145,18 @@ static Node* split_if(IfNode *iff, PhaseIterGVN *igvn) {
Node* v = u->fast_out(k); // User of the phi
// CNC - Allow only really simple patterns.
// In particular I disallow AddP of the Phi, a fairly common pattern
if( v == cmp ) continue; // The compare is OK
if( (v->is_ConstraintCast()) &&
v->in(0)->in(0) == iff )
continue; // CastPP/II of the IfNode is OK
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();
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