1.1 --- a/src/share/vm/opto/memnode.cpp Mon Sep 09 19:53:28 2013 +0200
1.2 +++ b/src/share/vm/opto/memnode.cpp Tue Sep 10 14:51:48 2013 -0700
1.3 @@ -962,6 +962,19 @@
1.4 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address);
1.5 }
1.6
1.7 +static bool skip_through_membars(Compile::AliasType* atp, const TypeInstPtr* tp, bool eliminate_boxing) {
1.8 + if ((atp != NULL) && (atp->index() >= Compile::AliasIdxRaw)) {
1.9 + bool non_volatile = (atp->field() != NULL) && !atp->field()->is_volatile();
1.10 + bool is_stable_ary = FoldStableValues &&
1.11 + (tp != NULL) && (tp->isa_aryptr() != NULL) &&
1.12 + tp->isa_aryptr()->is_stable();
1.13 +
1.14 + return (eliminate_boxing && non_volatile) || is_stable_ary;
1.15 + }
1.16 +
1.17 + return false;
1.18 +}
1.19 +
1.20 //---------------------------can_see_stored_value------------------------------
1.21 // This routine exists to make sure this set of tests is done the same
1.22 // everywhere. We need to make a coordinated change: first LoadNode::Ideal
1.23 @@ -976,11 +989,9 @@
1.24 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
1.25 Compile::AliasType* atp = (tp != NULL) ? phase->C->alias_type(tp) : NULL;
1.26 // This is more general than load from boxing objects.
1.27 - if (phase->C->eliminate_boxing() && (atp != NULL) &&
1.28 - (atp->index() >= Compile::AliasIdxRaw) &&
1.29 - (atp->field() != NULL) && !atp->field()->is_volatile()) {
1.30 + if (skip_through_membars(atp, tp, phase->C->eliminate_boxing())) {
1.31 uint alias_idx = atp->index();
1.32 - bool final = atp->field()->is_final();
1.33 + bool final = !atp->is_rewritable();
1.34 Node* result = NULL;
1.35 Node* current = st;
1.36 // Skip through chains of MemBarNodes checking the MergeMems for
1.37 @@ -1015,7 +1026,6 @@
1.38 }
1.39 }
1.40
1.41 -
1.42 // Loop around twice in the case Load -> Initialize -> Store.
1.43 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.)
1.44 for (int trip = 0; trip <= 1; trip++) {
1.45 @@ -1577,6 +1587,40 @@
1.46 return NULL;
1.47 }
1.48
1.49 +// Try to constant-fold a stable array element.
1.50 +static const Type* fold_stable_ary_elem(const TypeAryPtr* ary, int off, BasicType loadbt) {
1.51 + assert(ary->is_stable(), "array should be stable");
1.52 +
1.53 + if (ary->const_oop() != NULL) {
1.54 + // Decode the results of GraphKit::array_element_address.
1.55 + ciArray* aobj = ary->const_oop()->as_array();
1.56 + ciConstant con = aobj->element_value_by_offset(off);
1.57 +
1.58 + if (con.basic_type() != T_ILLEGAL && !con.is_null_or_zero()) {
1.59 + const Type* con_type = Type::make_from_constant(con);
1.60 + if (con_type != NULL) {
1.61 + if (con_type->isa_aryptr()) {
1.62 + // Join with the array element type, in case it is also stable.
1.63 + int dim = ary->stable_dimension();
1.64 + con_type = con_type->is_aryptr()->cast_to_stable(true, dim-1);
1.65 + }
1.66 + if (loadbt == T_NARROWOOP && con_type->isa_oopptr()) {
1.67 + con_type = con_type->make_narrowoop();
1.68 + }
1.69 +#ifndef PRODUCT
1.70 + if (TraceIterativeGVN) {
1.71 + tty->print("FoldStableValues: array element [off=%d]: con_type=", off);
1.72 + con_type->dump(); tty->cr();
1.73 + }
1.74 +#endif //PRODUCT
1.75 + return con_type;
1.76 + }
1.77 + }
1.78 + }
1.79 +
1.80 + return NULL;
1.81 +}
1.82 +
1.83 //------------------------------Value-----------------------------------------
1.84 const Type *LoadNode::Value( PhaseTransform *phase ) const {
1.85 // Either input is TOP ==> the result is TOP
1.86 @@ -1591,8 +1635,31 @@
1.87 Compile* C = phase->C;
1.88
1.89 // Try to guess loaded type from pointer type
1.90 - if (tp->base() == Type::AryPtr) {
1.91 - const Type *t = tp->is_aryptr()->elem();
1.92 + if (tp->isa_aryptr()) {
1.93 + const TypeAryPtr* ary = tp->is_aryptr();
1.94 + const Type *t = ary->elem();
1.95 +
1.96 + // Determine whether the reference is beyond the header or not, by comparing
1.97 + // the offset against the offset of the start of the array's data.
1.98 + // Different array types begin at slightly different offsets (12 vs. 16).
1.99 + // We choose T_BYTE as an example base type that is least restrictive
1.100 + // as to alignment, which will therefore produce the smallest
1.101 + // possible base offset.
1.102 + const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
1.103 + const bool off_beyond_header = ((uint)off >= (uint)min_base_off);
1.104 +
1.105 + // Try to constant-fold a stable array element.
1.106 + if (FoldStableValues && ary->is_stable()) {
1.107 + // Make sure the reference is not into the header
1.108 + if (off_beyond_header && off != Type::OffsetBot) {
1.109 + assert(adr->is_AddP() && adr->in(AddPNode::Offset)->is_Con(), "offset is a constant");
1.110 + const Type* con_type = fold_stable_ary_elem(ary, off, memory_type());
1.111 + if (con_type != NULL) {
1.112 + return con_type;
1.113 + }
1.114 + }
1.115 + }
1.116 +
1.117 // Don't do this for integer types. There is only potential profit if
1.118 // the element type t is lower than _type; that is, for int types, if _type is
1.119 // more restrictive than t. This only happens here if one is short and the other
1.120 @@ -1613,14 +1680,7 @@
1.121 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) {
1.122 // t might actually be lower than _type, if _type is a unique
1.123 // concrete subclass of abstract class t.
1.124 - // Make sure the reference is not into the header, by comparing
1.125 - // the offset against the offset of the start of the array's data.
1.126 - // Different array types begin at slightly different offsets (12 vs. 16).
1.127 - // We choose T_BYTE as an example base type that is least restrictive
1.128 - // as to alignment, which will therefore produce the smallest
1.129 - // possible base offset.
1.130 - const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
1.131 - if ((uint)off >= (uint)min_base_off) { // is the offset beyond the header?
1.132 + if (off_beyond_header) { // is the offset beyond the header?
1.133 const Type* jt = t->join(_type);
1.134 // In any case, do not allow the join, per se, to empty out the type.
1.135 if (jt->empty() && !t->empty()) {
