bool
ModuleGenerator::convertOutOfRangeBranchesToThunks()
{
masm_.haltingAlign(CodeAlignment);
// Create thunks for callsites that have gone out of range. Use a map to
// create one thunk for each callee since there is often high reuse.
OffsetMap alreadyThunked(cx_);
if (!alreadyThunked.init())
return false;
for (; lastPatchedCallsite_ < masm_.callSites().length(); lastPatchedCallsite_++) {
const CallSiteAndTarget& cs = masm_.callSites()[lastPatchedCallsite_];
if (!cs.isInternal())
continue;
uint32_t callerOffset = cs.returnAddressOffset();
MOZ_RELEASE_ASSERT(callerOffset < INT32_MAX);
if (funcIsDefined(cs.targetIndex())) {
uint32_t calleeOffset = funcEntry(cs.targetIndex());
MOZ_RELEASE_ASSERT(calleeOffset < INT32_MAX);
if (uint32_t(abs(int32_t(calleeOffset) - int32_t(callerOffset))) < JumpRange()) {
masm_.patchCall(callerOffset, calleeOffset);
continue;
}
}
OffsetMap::AddPtr p = alreadyThunked.lookupForAdd(cs.targetIndex());
if (!p) {
Offsets offsets;
offsets.begin = masm_.currentOffset();
uint32_t thunkOffset = masm_.thunkWithPatch().offset();
if (masm_.oom())
return false;
offsets.end = masm_.currentOffset();
if (!module_->codeRanges.emplaceBack(CodeRange::CallThunk, offsets))
return false;
if (!module_->callThunks.emplaceBack(thunkOffset, cs.targetIndex()))
return false;
if (!alreadyThunked.add(p, cs.targetIndex(), offsets.begin))
return false;
}
masm_.patchCall(callerOffset, p->value());
}
// Create thunks for jumps to stubs. Stubs are always generated at the end
// so unconditionally thunk all existing jump sites.
for (JumpTarget target : MakeEnumeratedRange(JumpTarget::Limit)) {
if (masm_.jumpSites()[target].empty())
continue;
for (uint32_t jumpSite : masm_.jumpSites()[target]) {
RepatchLabel label;
label.use(jumpSite);
masm_.bind(&label);
}
Offsets offsets;
offsets.begin = masm_.currentOffset();
uint32_t thunkOffset = masm_.thunkWithPatch().offset();
if (masm_.oom())
return false;
offsets.end = masm_.currentOffset();
if (!module_->codeRanges.emplaceBack(CodeRange::Inline, offsets))
return false;
if (!jumpThunks_[target].append(thunkOffset))
return false;
}
// Unlike callsites, which need to be persisted in the Module, we can simply
// flush jump sites after each patching pass.
masm_.clearJumpSites();
return true;
}
bool
ModuleGenerator::patchCallSites(TrapExitOffsetArray* maybeTrapExits)
{
masm_.haltingAlign(CodeAlignment);
// Create far jumps for calls that have relative offsets that may otherwise
// go out of range. Far jumps are created for two cases: direct calls
// between function definitions and calls to trap exits by trap out-of-line
// paths. Far jump code is shared when possible to reduce bloat. This method
// is called both between function bodies (at a frequency determined by the
// ISA's jump range) and once at the very end of a module's codegen after
// all possible calls/traps have been emitted.
OffsetMap existingCallFarJumps;
if (!existingCallFarJumps.init())
return false;
EnumeratedArray<Trap, Trap::Limit, Maybe<uint32_t>> existingTrapFarJumps;
for (; lastPatchedCallsite_ < masm_.callSites().length(); lastPatchedCallsite_++) {
const CallSiteAndTarget& cs = masm_.callSites()[lastPatchedCallsite_];
uint32_t callerOffset = cs.returnAddressOffset();
MOZ_RELEASE_ASSERT(callerOffset < INT32_MAX);
switch (cs.kind()) {
case CallSiteDesc::Dynamic:
case CallSiteDesc::Symbolic:
break;
case CallSiteDesc::Func: {
if (funcIsCompiled(cs.funcIndex())) {
uint32_t calleeOffset = funcCodeRange(cs.funcIndex()).funcNonProfilingEntry();
MOZ_RELEASE_ASSERT(calleeOffset < INT32_MAX);
if (uint32_t(abs(int32_t(calleeOffset) - int32_t(callerOffset))) < JumpRange()) {
masm_.patchCall(callerOffset, calleeOffset);
break;
}
}
OffsetMap::AddPtr p = existingCallFarJumps.lookupForAdd(cs.funcIndex());
if (!p) {
Offsets offsets;
offsets.begin = masm_.currentOffset();
uint32_t jumpOffset = masm_.farJumpWithPatch().offset();
offsets.end = masm_.currentOffset();
if (masm_.oom())
return false;
if (!metadata_->codeRanges.emplaceBack(CodeRange::FarJumpIsland, offsets))
return false;
if (!existingCallFarJumps.add(p, cs.funcIndex(), offsets.begin))
return false;
// Record calls' far jumps in metadata since they must be
// repatched at runtime when profiling mode is toggled.
if (!metadata_->callThunks.emplaceBack(jumpOffset, cs.funcIndex()))
return false;
}
masm_.patchCall(callerOffset, p->value());
break;
}
case CallSiteDesc::TrapExit: {
if (maybeTrapExits) {
uint32_t calleeOffset = (*maybeTrapExits)[cs.trap()].begin;
MOZ_RELEASE_ASSERT(calleeOffset < INT32_MAX);
if (uint32_t(abs(int32_t(calleeOffset) - int32_t(callerOffset))) < JumpRange()) {
masm_.patchCall(callerOffset, calleeOffset);
break;
}
}
if (!existingTrapFarJumps[cs.trap()]) {
Offsets offsets;
offsets.begin = masm_.currentOffset();
masm_.append(TrapFarJump(cs.trap(), masm_.farJumpWithPatch()));
offsets.end = masm_.currentOffset();
if (masm_.oom())
return false;
if (!metadata_->codeRanges.emplaceBack(CodeRange::FarJumpIsland, offsets))
return false;
existingTrapFarJumps[cs.trap()] = Some(offsets.begin);
}
masm_.patchCall(callerOffset, *existingTrapFarJumps[cs.trap()]);
break;
}
}
}
return true;
}
