void region_prune_arcs(RegionDesc& region) {
FTRACE(4, "region_prune_arcs\n");
region.sortBlocks();
auto const sortedBlocks = region.blocks();
// Maps region block ids to their RPO ids.
auto blockToRPO = std::unordered_map<RegionDesc::BlockId,uint32_t>{};
auto blockInfos = std::vector<BlockInfo>(sortedBlocks.size());
auto workQ = dataflow_worklist<uint32_t>(sortedBlocks.size());
for (auto rpoID = uint32_t{0}; rpoID < sortedBlocks.size(); ++rpoID) {
auto const& b = sortedBlocks[rpoID];
auto& binfo = blockInfos[rpoID];
binfo.blockID = b->id();
blockToRPO[binfo.blockID] = rpoID;
}
workQ.push(0);
blockInfos[0].in = entry_state(region);
FTRACE(4, "Iterating:\n");
do {
auto const rpoID = workQ.pop();
auto& binfo = blockInfos[rpoID];
FTRACE(4, "B{}\n", binfo.blockID);
binfo.out = binfo.in;
apply_transfer_function(
binfo.out,
region.block(binfo.blockID)->postConds()
);
for (auto& succ : region.succs(binfo.blockID)) {
auto const succRPO = blockToRPO.find(succ);
assertx(succRPO != end(blockToRPO));
auto& succInfo = blockInfos[succRPO->second];
if (preconds_may_pass(*region.block(succInfo.blockID), binfo.out)) {
if (merge_into(succInfo.in, binfo.out)) {
FTRACE(5, " -> {}\n", succInfo.blockID);
workQ.push(succRPO->second);
}
}
}
} while (!workQ.empty());
FTRACE(2, "\nPostConds fixed point:\n{}\n",
[&] () -> std::string {
auto ret = std::string{};
for (auto& s : blockInfos) {
folly::format(&ret, "B{}:\n{}", s.blockID, show(s.in));
}
return ret;
}()
);
// Now remove any edge that looks like it will unconditionally fail type
// predictions, and completely remove any block that can't be reached.
using ArcIDs = std::pair<RegionDesc::BlockId,RegionDesc::BlockId>;
auto toRemove = std::vector<ArcIDs>{};
for (auto rpoID = uint32_t{0}; rpoID < sortedBlocks.size(); ++rpoID) {
auto const& binfo = blockInfos[rpoID];
for (auto& succ : region.succs(binfo.blockID)) {
auto const succRPO = blockToRPO.find(succ);
assertx(succRPO != end(blockToRPO));
auto const& succInfo = blockInfos[succRPO->second];
if (!binfo.in.initialized ||
!succInfo.in.initialized ||
!preconds_may_pass(*region.block(succInfo.blockID), binfo.out)) {
FTRACE(2, "Pruning arc: B{} -> B{}\n",
binfo.blockID,
succInfo.blockID);
toRemove.emplace_back(binfo.blockID, succInfo.blockID);
}
}
for (auto& r : toRemove) region.removeArc(r.first, r.second);
toRemove.clear();
}
// Get rid of the completely unreachable blocks, now that any arcs to/from
// them are gone.
for (auto rpoID = uint32_t{0}; rpoID < sortedBlocks.size(); ++rpoID) {
auto const& binfo = blockInfos[rpoID];
if (!binfo.in.initialized) {
FTRACE(2, "Pruning block: B{}\n", binfo.blockID);
region.deleteBlock(binfo.blockID);
}
}
FTRACE(2, "\n");
}
void region_prune_arcs(RegionDesc& region) {
FTRACE(4, "region_prune_arcs\n");
region.sortBlocks();
auto const sortedBlocks = region.blocks();
// Maps region block ids to their RPO ids.
auto blockToRPO = std::unordered_map<RegionDesc::BlockId,uint32_t>{};
auto blockInfos = std::vector<BlockInfo>(sortedBlocks.size());
auto workQ = dataflow_worklist<uint32_t>(sortedBlocks.size());
for (auto rpoID = uint32_t{0}; rpoID < sortedBlocks.size(); ++rpoID) {
auto const& b = sortedBlocks[rpoID];
auto& binfo = blockInfos[rpoID];
binfo.blockID = b->id();
blockToRPO[binfo.blockID] = rpoID;
}
workQ.push(0);
blockInfos[0].in = entry_state(region);
FTRACE(4, "Iterating:\n");
do {
auto const rpoID = workQ.pop();
auto& binfo = blockInfos[rpoID];
FTRACE(4, "B{}\n", binfo.blockID);
/*
* This code currently assumes inlined functions were entirely contained
* within a single profiling translation, and will need updates if we
* inline bigger things in a way visible to region selection.
*
* Note: inlined blocks /may/ have postConditions, if they are the last
* blocks from profiling translations. Currently any locations referred to
* in postconditions for these blocks are for the outermost caller, so this
* code handles that correctly.
*/
if (region.block(binfo.blockID)->inlineLevel() != 0) {
assertx(region.block(binfo.blockID)->typePreConditions().empty());
}
binfo.out = binfo.in;
apply_transfer_function(
binfo.out,
region.block(binfo.blockID)->postConds()
);
for (auto& succ : region.succs(binfo.blockID)) {
auto const succRPO = blockToRPO.find(succ);
assertx(succRPO != end(blockToRPO));
auto& succInfo = blockInfos[succRPO->second];
if (preconds_may_pass(*region.block(succInfo.blockID), binfo.out)) {
if (merge_into(succInfo.in, binfo.out)) {
FTRACE(5, " -> {}\n", succInfo.blockID);
workQ.push(succRPO->second);
}
}
}
} while (!workQ.empty());
FTRACE(2, "\nPostConds fixed point:\n{}\n",
[&] () -> std::string {
auto ret = std::string{};
for (auto& s : blockInfos) {
folly::format(&ret, "B{}:\n{}", s.blockID, show(s.in));
}
return ret;
}()
);
// Now remove any edge that looks like it will unconditionally fail type
// predictions, and completely remove any block that can't be reached.
using ArcIDs = std::pair<RegionDesc::BlockId,RegionDesc::BlockId>;
auto toRemove = std::vector<ArcIDs>{};
for (auto rpoID = uint32_t{0}; rpoID < sortedBlocks.size(); ++rpoID) {
auto const& binfo = blockInfos[rpoID];
for (auto& succ : region.succs(binfo.blockID)) {
auto const succRPO = blockToRPO.find(succ);
assertx(succRPO != end(blockToRPO));
auto const& succInfo = blockInfos[succRPO->second];
if (!binfo.in.initialized ||
!succInfo.in.initialized ||
!preconds_may_pass(*region.block(succInfo.blockID), binfo.out)) {
FTRACE(2, "Pruning arc: B{} -> B{}\n",
binfo.blockID,
succInfo.blockID);
toRemove.emplace_back(binfo.blockID, succInfo.blockID);
}
}
for (auto& r : toRemove) region.removeArc(r.first, r.second);
toRemove.clear();
}
// Get rid of the completely unreachable blocks, now that any arcs to/from
// them are gone.
for (auto rpoID = uint32_t{0}; rpoID < sortedBlocks.size(); ++rpoID) {
auto const& binfo = blockInfos[rpoID];
if (!binfo.in.initialized) {
FTRACE(2, "Pruning block: B{}\n", binfo.blockID);
region.deleteBlock(binfo.blockID);
}
}
FTRACE(2, "\n");
}