From 9bf23e2abf74d70b77726a4300917c78bc8035e7 Mon Sep 17 00:00:00 2001
From: nsfisis <nsfisis@gmail.com>
Date: Thu, 14 Mar 2024 00:32:30 +0900
Subject: perf: cache current frame

---
 benchmarks/20240314-0030.log    |  4 ++++
 src/Execution/Stack.php         | 17 +++++++++++++++--
 traces/20240314-0030.stderr.log |  8 ++++++++
 3 files changed, 27 insertions(+), 2 deletions(-)
 create mode 100644 benchmarks/20240314-0030.log
 create mode 100644 traces/20240314-0030.stderr.log

diff --git a/benchmarks/20240314-0030.log b/benchmarks/20240314-0030.log
new file mode 100644
index 0000000..9ab0496
--- /dev/null
+++ b/benchmarks/20240314-0030.log
@@ -0,0 +1,4 @@
+Benchmark 1: make run
+  Time (mean ± σ):      4.500 s ±  0.060 s    [User: 4.418 s, System: 0.082 s]
+  Range (min … max):    4.427 s …  4.598 s    10 runs
+ 
diff --git a/src/Execution/Stack.php b/src/Execution/Stack.php
index 396cb29..a96a875 100644
--- a/src/Execution/Stack.php
+++ b/src/Execution/Stack.php
@@ -13,6 +13,8 @@ final class Stack
      */
     private array $frames = [];
 
+    private ?Frame $currentFrame = null;
+
     /**
      * @param list<int|float|Ref|Frame|Label> $entries
      */
@@ -25,6 +27,7 @@ final class Stack
     {
         $this->push($frame);
         $this->frames[] = $frame;
+        $this->currentFrame = $frame;
     }
 
     public function pushLabel(Label $label): void
@@ -62,6 +65,11 @@ final class Stack
         $result = $this->pop();
         assert($result instanceof Frame);
         array_pop($this->frames);
+        if (count($this->frames) === 0) {
+            $this->currentFrame = null;
+        } else {
+            $this->currentFrame = end($this->frames);
+        }
         return $result;
     }
 
@@ -137,6 +145,11 @@ final class Stack
             }
         }
         array_pop($this->frames);
+        if (count($this->frames) === 0) {
+            $this->currentFrame = null;
+        } else {
+            $this->currentFrame = end($this->frames);
+        }
     }
 
     public function top(): int|float|Ref|Frame|Label|null
@@ -157,8 +170,8 @@ final class Stack
 
     public function currentFrame(): Frame
     {
-        assert(count($this->frames) !== 0);
-        return $this->frames[count($this->frames) - 1];
+        assert($this->currentFrame !== null);
+        return $this->currentFrame;
     }
 
     private function push(int|float|Ref|Frame|Label $entry): void
diff --git a/traces/20240314-0030.stderr.log b/traces/20240314-0030.stderr.log
new file mode 100644
index 0000000..dae98f4
--- /dev/null
+++ b/traces/20240314-0030.stderr.log
@@ -0,0 +1,8 @@
+Decoding...
+Instantiating...
+Executing...
+
+Exit code: 0
+Memory peak usage: 195983240
+
+
-- 
cgit v1.2.3-70-g09d2