From ff2c4940e92c17ddc138df202a3dd731c00bfddb Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Gustav=20S=C3=B6rn=C3=A4s?= <gustav@sornas.net>
Date: Tue, 12 Jan 2021 22:04:12 +0100
Subject: optimize pop_twice

Fibonacci runtime 0.27 -> 0.19
---
 src/vm.rs | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

(limited to 'src/vm.rs')

diff --git a/src/vm.rs b/src/vm.rs
index 68ab3b8..bc3b1e8 100644
--- a/src/vm.rs
+++ b/src/vm.rs
@@ -128,8 +128,10 @@ pub fn run_block(block: Block) -> Result<(), Error> {
 
 impl VM {
     fn pop_twice(&mut self) -> (Value, Value) {
-        let (a, b) = (self.stack.pop().unwrap(), self.stack.pop().unwrap());
-        (b, a)
+        let len = self.stack.len();
+        let res = (self.stack[len-2].clone(), self.stack[len-1].clone());
+        self.stack.truncate(len - 2);
+        res
     }
 
     fn _peek_up(&self, amount: usize) -> Option<&Value> {
-- 
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