From 88d148b46a2ff1093a3ece5db835f2c51fc03bd7 Mon Sep 17 00:00:00 2001
From: Ali Mohammad Pur <ali.mpfard@gmail.com>
Date: Mon, 6 Sep 2021 16:53:06 +0430
Subject: [PATCH] LibRegex: Avoid keeping track of checkpoints across forks

Doing so would increase memory consumption by quite a bit, since many
useless copies of the checkpoints hashmap would be created and later
thrown away.
---
 Userland/Libraries/LibRegex/RegexByteCode.cpp | 8 ++++----
 Userland/Libraries/LibRegex/RegexMatch.h      | 2 +-
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/Userland/Libraries/LibRegex/RegexByteCode.cpp b/Userland/Libraries/LibRegex/RegexByteCode.cpp
index 5d2b1eaa94d..ded6ff79ea5 100644
--- a/Userland/Libraries/LibRegex/RegexByteCode.cpp
+++ b/Userland/Libraries/LibRegex/RegexByteCode.cpp
@@ -871,17 +871,17 @@ ALWAYS_INLINE ExecutionResult OpCode_ResetRepeat::execute(MatchInput const&, Mat
     return ExecutionResult::Continue;
 }
 
-ALWAYS_INLINE ExecutionResult OpCode_Checkpoint::execute(MatchInput const&, MatchState& state) const
+ALWAYS_INLINE ExecutionResult OpCode_Checkpoint::execute(MatchInput const& input, MatchState& state) const
 {
-    state.checkpoints.set(state.instruction_position, state.string_position);
+    input.checkpoints.set(state.instruction_position, state.string_position);
     return ExecutionResult::Continue;
 }
 
-ALWAYS_INLINE ExecutionResult OpCode_JumpNonEmpty::execute(MatchInput const&, MatchState& state) const
+ALWAYS_INLINE ExecutionResult OpCode_JumpNonEmpty::execute(MatchInput const& input, MatchState& state) const
 {
     auto current_position = state.string_position;
     auto checkpoint_ip = state.instruction_position + size() + checkpoint();
-    if (state.checkpoints.get(checkpoint_ip).value_or(current_position) != current_position) {
+    if (input.checkpoints.get(checkpoint_ip).value_or(current_position) != current_position) {
         auto form = this->form();
 
         if (form == OpCodeId::Jump) {
diff --git a/Userland/Libraries/LibRegex/RegexMatch.h b/Userland/Libraries/LibRegex/RegexMatch.h
index 035a988234d..efd5bd0e4ae 100644
--- a/Userland/Libraries/LibRegex/RegexMatch.h
+++ b/Userland/Libraries/LibRegex/RegexMatch.h
@@ -513,6 +513,7 @@ struct MatchInput {
     mutable size_t fail_counter { 0 };
     mutable Vector<size_t> saved_positions;
     mutable Vector<size_t> saved_code_unit_positions;
+    mutable HashMap<u64, u64> checkpoints;
 };
 
 struct MatchState {
@@ -524,7 +525,6 @@ struct MatchState {
     Vector<Match> matches;
     Vector<Vector<Match>> capture_group_matches;
     Vector<u64> repetition_marks;
-    HashMap<u64, u64> checkpoints;
 };
 
 }