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8136469: OptimizeStringConcat fails on pre-sized StringBuilder shapes

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Cut off dead if branch already during parsing (GVN).

Reviewed-by: shade, kvn, roland
This commit is contained in:
Tobias Hartmann 2016-01-12 12:55:37 +01:00
parent 69b52aa28b
commit 0e1b2cd198
3 changed files with 19 additions and 10 deletions
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17
hotspot/src/share/vm/opto/ifnode.cpp
View File

@ -1530,13 +1530,16 @@ Node* IfNode::search_identical(int dist) {
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 ||
// kill dead branch first otherwise the IfNode's control will
// have 2 control uses (the IfNode that doesn't go away because
// it still has uses and this branch of the
// If). Node::has_special_unique_user() will cause this node to
// be reprocessed once the dead branch is killed.
(always_taken(t) && in(0)->outcnt() == 1)) {
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
return in(0)->in(0);
}

2
hotspot/src/share/vm/opto/macro.cpp
View File

@ -244,7 +244,7 @@ void PhaseMacroExpand::eliminate_card_mark(Node* p2x) {
} else {
// G1 pre/post barriers
assert(p2x->outcnt() <= 2, "expects 1 or 2 users: Xor and URShift nodes");
// It could be only one user, URShift node, in Object.clone() instrinsic
// It could be only one user, URShift node, in Object.clone() intrinsic
// but the new allocation is passed to arraycopy stub and it could not
// be scalar replaced. So we don't check the case.

10
hotspot/src/share/vm/opto/stringopts.cpp
View File

@ -822,11 +822,10 @@ bool StringConcat::validate_mem_flow() {
}
} else if (ctrl->is_IfTrue()) { // null checks, class checks
iff = ctrl->in(0)->as_If();
assert(iff->is_If(), "must be if");
// Verify that the other arm is an uncommon trap
Node* otherproj = iff->proj_out(1 - ctrl->as_Proj()->_con);
CallStaticJavaNode* call = otherproj->unique_out()->isa_CallStaticJava();
assert(strcmp(call->_name, "uncommon_trap") == 0, "must be uncommond trap");
assert(strcmp(call->_name, "uncommon_trap") == 0, "must be uncommon trap");
ctrl = iff->in(0);
} else {
break;
@ -914,6 +913,13 @@ bool StringConcat::validate_control_flow() {
BoolNode* b = iff->in(1)->isa_Bool();
if (b == NULL) {
#ifndef PRODUCT
if (PrintOptimizeStringConcat) {
tty->print_cr("unexpected input to IfNode");
iff->in(1)->dump();
tty->cr();
}
#endif
fail = true;
break;
}