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8016696: PPC64 (part 4): add relocation for trampoline stubs

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A trampoline allows to encode a small branch in the code, even if there is the chance that this branch can not reach all possible code locations. If the relocation finds that a branch is too far for the instruction in the code, it can patch it to jump to the trampoline where is sufficient space for a far branch. Needed on PPC.

Reviewed-by: kvn, bdelsart, jrose
This commit is contained in:
Goetz Lindenmaier 2013-07-04 10:51:31 +02:00
parent 16f3142152
commit c12f5a0180
2 changed files with 77 additions and 2 deletions
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37
hotspot/src/share/vm/code/relocInfo.cpp
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@ -582,6 +582,18 @@ void static_stub_Relocation::unpack_data() {
_static_call = address_from_scaled_offset(unpack_1_int(), base);
}
void trampoline_stub_Relocation::pack_data_to(CodeSection* dest ) {
short* p = (short*) dest->locs_end();
CodeSection* insts = dest->outer()->insts();
normalize_address(_owner, insts);
p = pack_1_int_to(p, scaled_offset(_owner, insts->start()));
dest->set_locs_end((relocInfo*) p);
}
void trampoline_stub_Relocation::unpack_data() {
address base = binding()->section_start(CodeBuffer::SECT_INSTS);
_owner = address_from_scaled_offset(unpack_1_int(), base);
}
void external_word_Relocation::pack_data_to(CodeSection* dest) {
short* p = (short*) dest->locs_end();
@ -811,6 +823,25 @@ address static_call_Relocation::static_stub() {
return NULL;
}
// Finds the trampoline address for a call. If no trampoline stub is
// found NULL is returned which can be handled by the caller.
address trampoline_stub_Relocation::get_trampoline_for(address call, nmethod* code) {
// There are no relocations available when the code gets relocated
// because of CodeBuffer expansion.
if (code->relocation_size() == 0)
return NULL;
RelocIterator iter(code, call);
while (iter.next()) {
if (iter.type() == relocInfo::trampoline_stub_type) {
if (iter.trampoline_stub_reloc()->owner() == call) {
return iter.addr();
}
}
}
return NULL;
}
void static_stub_Relocation::clear_inline_cache() {
// Call stub is only used when calling the interpreted code.
@ -975,6 +1006,12 @@ void RelocIterator::print_current() {
tty->print(" | [static_call=" INTPTR_FORMAT "]", r->static_call());
break;
}
case relocInfo::trampoline_stub_type:
{
trampoline_stub_Relocation* r = (trampoline_stub_Relocation*) reloc();
tty->print(" | [trampoline owner=" INTPTR_FORMAT "]", r->owner());
break;
}
}
tty->cr();
}