Skip to content

Commit

Permalink
Rename ChangeTracker/Tracker::start function and make it return m…
Browse files Browse the repository at this point in the history 
…ore clear status
  • Loading branch information
@asl
asl committed Feb 23, 2024
1 parent 4e18733 commit a656740
Showing 1 changed file with 115 additions and 85 deletions.
200 changes: 115 additions & 85 deletions ir/visitor.cpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -36,6 +36,8 @@ limitations under the License.
#include "lib/log.h"
#include "lib/map.h"

enum class VisitStatus : unsigned { New, Revisit, Busy, Done };

/** @class Visitor::ChangeTracker
* @brief Assists visitors in traversing the IR.
Expand All @@ -58,15 +60,23 @@ class Visitor::ChangeTracker {
public:
/** Begin tracking @n during a visiting pass. Use `finish(@n)` to mark @n as
* visited once the pass completes.
*
* @return Status of the node @n wrt visit: whether node is currently being
* visited (`VisitStatus::Busy`), or if node was already visited
* (`VisitStatus::Done`), node was never seen before (`VisitStatus::New`) or
* seen, but should be revisited (`VisitStatus::Revisit`).
*/
[[nodiscard]] std::pair<bool, bool> start(const IR::Node *n, bool defaultVisitOnce) {
[[nodiscard]] VisitStatus try_start(const IR::Node *n, bool defaultVisitOnce) {
// Initialization
auto [it, inserted] = visited.emplace(n, visit_info_t{true, defaultVisitOnce, n});

bool busy = !inserted && it->second.visit_in_progress;
bool done = !inserted && !it->second.visit_in_progress && it->second.visitOnce;
if (!inserted) { // We already seen this node, determine its status
if (it->second.visit_in_progress) return VisitStatus::Busy;
if (it->second.visitOnce) return VisitStatus::Done;
return VisitStatus::Revisit;
}

return {busy, done};
return VisitStatus::New;
}

/** Mark the process of visiting @orig as finished, with @final being the
Expand Down Expand Up @@ -202,15 +212,24 @@ class Visitor::Tracker {

/** Begin tracking @n during a visiting pass. Use `finish(@n)` to mark @n as
* visited once the pass completes.
*
* @return Status of the node @n wrt visit: whether node is currently being
* visited (`VisitStatus::Busy`), or if node was already visited
* (`VisitStatus::Done`), node was never seen before (`VisitStatus::New`) or
* seen, but should be revisited (`VisitStatus::Revisit`).
*/
[[nodiscard]] std::pair<bool, bool> start(const IR::Node *n, bool defaultVisitOnce) {
[[nodiscard]] VisitStatus try_start(const IR::Node *n, bool defaultVisitOnce) {
// Initialization
auto [it, inserted] = visited.emplace(n, info_t{false, defaultVisitOnce});

bool busy = !inserted && !it->second.done;
bool done = !inserted && it->second.done && it->second.visitOnce;
if (!inserted) { // We already seen this node, determine its status
if (!it->second.done) return VisitStatus::Busy;
if (it->second.visitOnce) return VisitStatus::Done;
return VisitStatus::Revisit;
}

return {busy, done};
return VisitStatus::New;
}

/** Mark the process of visiting @n as finished, with @final being the
Expand Down Expand Up @@ -429,26 +448,30 @@ const IR::Node *Modifier::apply_visitor(const IR::Node *n, const char *name) {
if (ctxt) ctxt->child_name = name;
if (n) {
PushContext local(ctxt, n);
auto [busy, done] = visited->start(n, visitDagOnce);
if (busy) {
n->apply_visitor_loop_revisit(*this);
// FIXME -- should have a way of updating the node? Needs to be decided
// by the visitor somehow, but it is tough
} else if (done) {
n->apply_visitor_revisit(*this, visited->result(n));
n = visited->result(n);
} else {
IR::Node *copy = n->clone();
local.current.node = copy;
if (!dontForwardChildrenBeforePreorder) {
ForwardChildren forward_children(*visited);
copy->visit_children(forward_children);
}
if (copy->apply_visitor_preorder(*this)) {
copy->visit_children(*this);
copy->apply_visitor_postorder(*this);
switch (visited->try_start(n, visitDagOnce)) {
case VisitStatus::Busy:
n->apply_visitor_loop_revisit(*this);
// FIXME -- should have a way of updating the node? Needs to be decided
// by the visitor somehow, but it is tough
break;
case VisitStatus::Done:
n->apply_visitor_revisit(*this, visited->result(n));
n = visited->result(n);
break;
default: { // New or Revisit
IR::Node *copy = n->clone();
local.current.node = copy;
if (!dontForwardChildrenBeforePreorder) {
ForwardChildren forward_children(*visited);
copy->visit_children(forward_children);
}
if (copy->apply_visitor_preorder(*this)) {
copy->visit_children(*this);
copy->apply_visitor_postorder(*this);
}
if (visited->finish(n, copy)) (n = copy)->validate();
break;
}
if (visited->finish(n, copy)) (n = copy)->validate();
}
}
if (ctxt)
Expand All @@ -462,17 +485,19 @@ const IR::Node *Inspector::apply_visitor(const IR::Node *n, const char *name) {
if (ctxt) ctxt->child_name = name;
if (n && !join_flows(n)) {
PushContext local(ctxt, n);
auto [busy, done] = visited->start(n, visitDagOnce);
if (busy) {
n->apply_visitor_loop_revisit(*this);
} else if (done) {
n->apply_visitor_revisit(*this);
} else {
if (n->apply_visitor_preorder(*this)) {
n->visit_children(*this);
n->apply_visitor_postorder(*this);
}
visited->finish(n);
switch (visited->try_start(n, visitDagOnce)) {
case VisitStatus::Busy:
n->apply_visitor_loop_revisit(*this);
break;
case VisitStatus::Done:
n->apply_visitor_revisit(*this);
break;
default: // New or Revisit
if (n->apply_visitor_preorder(*this)) {
n->visit_children(*this);
n->apply_visitor_postorder(*this);
}
visited->finish(n);
}
post_join_flows(n, n);
}
Expand All @@ -488,55 +513,60 @@ const IR::Node *Transform::apply_visitor(const IR::Node *n, const char *name) {
if (ctxt) ctxt->child_name = name;
if (n) {
PushContext local(ctxt, n);
auto [busy, done] = visited->start(n, visitDagOnce);
if (busy) {
n->apply_visitor_loop_revisit(*this);
// FIXME -- should have a way of updating the node? Needs to be decided
// by the visitor somehow, but it is tough
} else if (done) {
n->apply_visitor_revisit(*this, visited->result(n));
n = visited->result(n);
} else {
auto copy = n->clone();
local.current.node = copy;
if (!dontForwardChildrenBeforePreorder) {
ForwardChildren forward_children(*visited);
copy->visit_children(forward_children);
}
bool save_prune_flag = prune_flag;
prune_flag = false;
bool extra_clone = false;
const IR::Node *preorder_result = copy->apply_visitor_preorder(*this);
assert(preorder_result != n); // should never happen
const IR::Node *final_result = preorder_result;
if (preorder_result != copy) {
// FIXME -- not safe if the visitor resurrects the node (which it shouldn't)
// if (copy->id == IR::Node::currentId - 1)
// --IR::Node::currentId;
if (!preorder_result) {
prune_flag = true;
} else if (visited->done(preorder_result)) {
final_result = visited->result(preorder_result);
prune_flag = true;
} else {
extra_clone = true;
auto [prebusy, predone] =
visited->start(preorder_result, visited->shouldVisitOnce(n));
// Sanity check for IR loops
if (prebusy) BUG("IR loop detected ");
local.current.node = copy = preorder_result->clone();
switch (visited->try_start(n, visitDagOnce)) {
case VisitStatus::Busy:
n->apply_visitor_loop_revisit(*this);
// FIXME -- should have a way of updating the node? Needs to be decided
// by the visitor somehow, but it is tough
break;
case VisitStatus::Done:
n->apply_visitor_revisit(*this, visited->result(n));
n = visited->result(n);
break;
default: { // New or Revisit
auto *copy = n->clone();
local.current.node = copy;
if (!dontForwardChildrenBeforePreorder) {
ForwardChildren forward_children(*visited);
copy->visit_children(forward_children);
}
bool save_prune_flag = prune_flag;
prune_flag = false;
bool extra_clone = false;
const IR::Node *preorder_result = copy->apply_visitor_preorder(*this);
assert(preorder_result != n); // should never happen
const IR::Node *final_result = preorder_result;
if (preorder_result != copy) {
// FIXME -- not safe if the visitor resurrects the node (which it shouldn't)
// if (copy->id == IR::Node::currentId - 1)
// --IR::Node::currentId;
if (!preorder_result) {
prune_flag = true;
} else if (visited->done(preorder_result)) {
final_result = visited->result(preorder_result);
prune_flag = true;
} else {
extra_clone = true;
auto status =
visited->try_start(preorder_result, visited->shouldVisitOnce(n));
// Sanity check for IR loops
if (status == VisitStatus::Busy) BUG("IR loop detected ");
local.current.node = copy = preorder_result->clone();
}
}
if (!prune_flag) {
copy->visit_children(*this);
final_result = copy->apply_visitor_postorder(*this);
}
prune_flag = save_prune_flag;
if (final_result == copy && final_result != preorder_result &&
*final_result == *preorder_result)
final_result = preorder_result;
if (visited->finish(n, final_result) && (n = final_result))
final_result->validate();
if (extra_clone) visited->finish(preorder_result, final_result);
break;
}
if (!prune_flag) {
copy->visit_children(*this);
final_result = copy->apply_visitor_postorder(*this);
}
prune_flag = save_prune_flag;
if (final_result == copy && final_result != preorder_result &&
*final_result == *preorder_result)
final_result = preorder_result;
if (visited->finish(n, final_result) && (n = final_result)) final_result->validate();
if (extra_clone) visited->finish(preorder_result, final_result);
}
}
if (ctxt)
Expand Down

0 comments on commit a656740

Please sign in to comment.