Add count_insns feature to VM

ncc/count_insns.sh

@@ -0,0 +1 @@
+RUST_BACKTRACE=1 cargo run -- $* && cd ../vm && cargo run --features count_insns ../ncc/out.asm && cd ../vm

vm/Cargo.toml

@@ -9,6 +9,9 @@ edition = "2021"
 sdl2 = "0.35.2"
 libc = "0.2"
 
+[features]
+count_insns = []
+
 [profile.dev]
 debug = true
 opt-level = 1

vm/src/main.rs

@@ -6,6 +6,7 @@
 mod vm;
 mod sys;
 mod asm;
+mod utils;
 
 extern crate sdl2;
 extern crate libc;
@@ -17,6 +18,7 @@ use std::sync::{Arc, Mutex};
 use crate::vm::{VM, Value, MemBlock, ExitReason};
 use crate::asm::{Assembler};
 use crate::sys::{SysState};
+use crate::utils::{thousands_sep};
 
 /// Command-line options
 #[derive(Debug, Clone)]
@@ -155,5 +157,12 @@ fn main()
     let mut mutex = SysState::get_mutex(vm);
     let ret_val = run_program(&mut mutex);
 
+    #[cfg(feature = "count_insns")]
+    {
+        let mut vm = mutex.lock().unwrap();
+        let insn_count = vm.get_insn_count();
+        println!("insns executed: {}", thousands_sep(insn_count));
+    }
+
     exit(ret_val.as_i32());
 }

vm/src/utils.rs

@@ -0,0 +1,18 @@
+/// Produce a string with comma separator for thousands for an integer
+pub fn thousands_sep(n: u64) -> String
+{
+    let num_chars: Vec<char> = n.to_string().chars().rev().collect();
+
+    let mut chars_sep = Vec::new();
+
+    for idx in 0..num_chars.len() {
+        chars_sep.push(num_chars[idx]);
+        if (idx % 3) == 2 && idx < num_chars.len() - 1 {
+            chars_sep.push(',');
+        }
+    }
+
+    let num_str: String = chars_sep.into_iter().rev().collect();
+
+    num_str
+}

vm/src/vm.rs

@@ -526,6 +526,10 @@ pub struct VM
 
     // List of stack frames (activation records)
     frames: Vec<StackFrame>,
+
+    // Count of executed instructions
+    #[cfg(feature = "count_insns")]
+    insn_count: u64,
 }
 
 impl VM
@@ -545,9 +549,17 @@ impl VM
             heap,
             stack: Vec::default(),
             frames: Vec::default(),
+            #[cfg(feature = "count_insns")]
+            insn_count: 0,
         }
     }
 
+    #[cfg(feature = "count_insns")]
+    pub fn get_insn_count(&self) -> u64
+    {
+        self.insn_count
+    }
+
     pub fn stack_size(&self) -> usize
     {
         self.stack.len()
@@ -676,6 +688,11 @@ impl VM
         // For each instruction to execute
         loop
         {
+            #[cfg(feature = "count_insns")]
+            {
+                self.insn_count += 1;
+            }
+
             if pc >= self.code.len() {
                 panic!("pc outside bounds of code space")
             }