6667588: Don't generate duplicated CMP for float/double values
Summary: float CMove generation add duplicated CMPF if there are more then one Move depending on the condition.
Reviewed-by: jrose, never, rasbold
--- a/hotspot/src/share/vm/opto/loopopts.cpp Fri Feb 29 11:22:27 2008 -0800
+++ b/hotspot/src/share/vm/opto/loopopts.cpp Fri Feb 29 19:07:15 2008 -0800
@@ -435,9 +435,11 @@
// Check profitability
int cost = 0;
+ int phis = 0;
for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
Node *out = region->fast_out(i);
if( !out->is_Phi() ) continue; // Ignore other control edges, etc
+ phis++;
PhiNode* phi = out->as_Phi();
switch (phi->type()->basic_type()) {
case T_LONG:
@@ -489,6 +491,12 @@
}
}
if( cost >= ConditionalMoveLimit ) return NULL; // Too much goo
+ Node* bol = iff->in(1);
+ assert( bol->Opcode() == Op_Bool, "" );
+ int cmp_op = bol->in(1)->Opcode();
+ // It is expensive to generate flags from a float compare.
+ // Avoid duplicated float compare.
+ if( phis > 1 && (cmp_op == Op_CmpF || cmp_op == Op_CmpD)) return NULL;
// --------------
// Now replace all Phis with CMOV's