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8076758: new StringBuilder().append(String).toString() should be recognized by OptimizeStringConcat

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Reviewed-by: kvn, thartmann
This commit is contained in:
Aleksey Shipilev 2015-09-01 12:57:41 +03:00
parent 7b6480cfa4
commit e3007b79ad
1 changed files with 48 additions and 41 deletions
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11
hotspot/src/share/vm/opto/stringopts.cpp
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@ -1576,10 +1576,16 @@ void PhaseStringOpts::replace_string_concat(StringConcat* sc) {
Node* result; Node* result;
if (!kit.stopped()) { if (!kit.stopped()) {
Node* char_array = NULL;
if (sc->num_arguments() == 1 &&
(sc->mode(0) == StringConcat::StringMode ||
sc->mode(0) == StringConcat::StringNullCheckMode)) {
// Handle the case when there is only a single String argument.
// In this case, we can just pull the value from the String itself.
char_array = kit.load_String_value(kit.control(), sc->argument(0));
} else {
// length now contains the number of characters needed for the // length now contains the number of characters needed for the
// char[] so create a new AllocateArray for the char[] // char[] so create a new AllocateArray for the char[]
Node* char_array = NULL;
{ {
PreserveReexecuteState preexecs(&kit); PreserveReexecuteState preexecs(&kit);
// The original jvms is for an allocation of either a String or // The original jvms is for an allocation of either a String or
@ -1623,6 +1629,7 @@ void PhaseStringOpts::replace_string_concat(StringConcat* sc) {
ShouldNotReachHere(); ShouldNotReachHere();
} }
} }
}
// If we're not reusing an existing String allocation then allocate one here. // If we're not reusing an existing String allocation then allocate one here.
result = sc->string_alloc(); result = sc->string_alloc();