void SrcRec::patch(Asm* a, IncomingBranch branch, TCA dest) {
if (branch.m_type == IncomingBranch::ADDR) {
// Note that this effectively ignores a
atomic_release_store(branch.m_addr, dest);
return;
}
// modifying reachable code
switch(branch.m_type) {
case IncomingBranch::JMP: {
CodeCursor cg(*a, branch.m_src);
TranslatorX64::smashJmp(*a, branch.m_src, dest);
break;
}
case IncomingBranch::JCC: {
// patch destination, but preserve the condition code
int32_t delta = safe_cast<int32_t>((dest - branch.m_src) -
TranslatorX64::kJmpccLen);
int32_t* addr = (int32_t*)(branch.m_src + TranslatorX64::kJmpccLen - 4);
atomic_release_store(addr, delta);
break;
}
default:
not_implemented();
}
}
void SrcRec::replaceOldTranslations() {
// Everyone needs to give up on old translations; send them to the anchor,
// which is a REQ_RETRANSLATE.
m_translations.clear();
m_tailFallbackJumps.clear();
atomic_release_store(&m_topTranslation, static_cast<TCA>(0));
/*
* It may seem a little weird that we're about to point every
* incoming branch at the anchor, since that's going to just
* unconditionally retranslate this SrcKey and never patch the
* incoming branch to do something else.
*
* The reason this is ok is this mechanism is only used in
* non-RepoAuthoritative mode, and the granularity of code
* invalidation there is such that we'll only have incoming branches
* like this basically within the same file since we don't have
* whole program analysis.
*
* This means all these incoming branches are about to go away
* anyway ...
*
* If we ever change that we'll have to change this to patch to
* some sort of rebind requests.
*/
assert(!RuntimeOption::RepoAuthoritative || RuntimeOption::EvalJitPGO);
patchIncomingBranches(m_anchorTranslation);
}
void SrcRec::replaceOldTranslations(Asm& a, Asm& astubs) {
// Everyone needs to give up on old translations; send them to the anchor,
// which is a REQ_RETRANSLATE
m_translations.clear();
m_tailFallbackJumps.clear();
atomic_release_store(&m_topTranslation, static_cast<TCA>(0));
patchIncomingBranches(a, astubs, m_anchorTranslation);
}
void SrcRec::patch(IncomingBranch branch, TCA dest) {
switch (branch.type()) {
case IncomingBranch::Tag::JMP: {
auto& a = tx64->getAsmFor(branch.toSmash());
CodeCursor cg(a, branch.toSmash());
TranslatorX64::smashJmp(a, branch.toSmash(), dest);
break;
}
case IncomingBranch::Tag::JCC: {
// patch destination, but preserve the condition code
int32_t delta = safe_cast<int32_t>((dest - branch.toSmash()) - kJmpccLen);
int32_t* addr = (int32_t*)(branch.toSmash() + kJmpccLen - 4);
atomic_release_store(addr, delta);
break;
}
case IncomingBranch::Tag::ADDR:
// Note that this effectively ignores a
atomic_release_store(reinterpret_cast<TCA*>(branch.toSmash()), dest);
}
}
void SrcRec::addDebuggerGuard(TCA dbgGuard, TCA dbgBranchGuardSrc) {
assert(!m_dbgBranchGuardSrc);
TRACE(1, "SrcRec(%p)::addDebuggerGuard @%p, "
"%zd incoming branches to rechain\n",
this, dbgGuard, m_incomingBranches.size());
patchIncomingBranches(dbgGuard);
// Set m_dbgBranchGuardSrc after patching, so we don't try to patch
// the debug guard.
m_dbgBranchGuardSrc = dbgBranchGuardSrc;
atomic_release_store(&m_topTranslation, dbgGuard);
}
void SrcRec::patch(IncomingBranch branch, TCA dest) {
switch (branch.type()) {
case IncomingBranch::Tag::JMP: {
JIT::smashJmp(branch.toSmash(), dest);
break;
}
case IncomingBranch::Tag::JCC: {
JIT::smashJcc(branch.toSmash(), dest);
break;
}
case IncomingBranch::Tag::ADDR:
// Note that this effectively ignores a
atomic_release_store(reinterpret_cast<TCA*>(branch.toSmash()), dest);
}
}
void SrcRec::patch(Asm* a, IncomingBranch branch, TCA dest) {
if (branch.m_type == IncomingBranch::ADDR) {
// Note that this effectively ignores a
atomic_release_store(branch.m_addr, dest);
return;
}
CodeCursor cg(*a, branch.m_src);
// modifying reachable code
switch(branch.m_type) {
case IncomingBranch::JMP:
TranslatorX64::smash(*a, branch.m_src, dest);
break;
case IncomingBranch::JCC:
ASSERT(TranslatorX64::isSmashable(*a,
TranslatorX64::kJmpccLen));
a->jcc(branch.m_cc, dest);
break;
default:
not_implemented();
}
}
void SrcRec::newTranslation(Asm& a, Asm &astubs, TCA newStart) {
// When translation punts due to hitting limit, will generate one
// more translation that will call the interpreter.
ASSERT(m_translations.size() <= kMaxTranslations);
TRACE(1, "SrcRec(%p)::newTranslation @%p, ", this, newStart);
m_translations.push_back(newStart);
if (!m_topTranslation) {
atomic_release_store(&m_topTranslation, newStart);
patchIncomingBranches(a, astubs, newStart);
}
/*
* Link all the jumps from the current tail translation to this new
* guy.
*
* It's (mostly) ok if someone is running in this code while we do
* this: we hold the write lease, they'll instead jump to the anchor
* and do REQ_RETRANSLATE and failing to get the write lease they'll
* interp. FIXME: Unfortunately, right now, in an unlikely race
* another thread could create another translation with the same
* type specialization that we just created in this case. (If we
* happen to release the write lease after they jump but before they
* get into REQ_RETRANSLATE, they'll acquire it and generate a
* translation possibly for this same situation.)
*/
for (size_t i = 0; i < m_tailFallbackJumps.size(); ++i) {
Asm& as = Asm::Choose(a, astubs, m_tailFallbackJumps[i].m_src);
patch(&as, m_tailFallbackJumps[i], newStart);
}
// This is the new tail translation, so store the fallback jump list
// in case we translate this again.
m_tailFallbackJumps.swap(m_inProgressTailJumps);
m_inProgressTailJumps.clear();
}