From d14a7a820afd7979f5bf176ab2c3aa2df6a822df Mon Sep 17 00:00:00 2001
From: "google-labs-jules[bot]"
 <161369871+google-labs-jules[bot]@users.noreply.github.com>
Date: Tue, 25 Aug 2026 05:24:46 +0000
Subject: [PATCH] =?UTF-8?q?=E2=9A=A1=20Bolt:=20[performance=20improvement]?=
 =?UTF-8?q?=20Remove=20redundant=20function=20lookup=20in=20VM=20loop?=
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Co-authored-by: Tcode-Motion <188012755+Tcode-Motion@users.noreply.github.com>
---
 .jules/bolt.md             |  1 +
 runtime/vm/src/executor.rs | 44 ++++++--------------------------------
 2 files changed, 7 insertions(+), 38 deletions(-)

diff --git a/.jules/bolt.md b/.jules/bolt.md
index 1592fa94..7e8ee7bc 100644
--- a/.jules/bolt.md
+++ b/.jules/bolt.md
@@ -1,3 +1,4 @@
 ## 2026-08-19 - Removed redundant instruction array lookup in VM loop
 **Learning:** The inner loop of the VM interpreter (`execute_loop`) had an expensive, redundant deep indexing operation to fetch `inst_operands` which was already available on the `inst` reference. Re-fetching it via `self.module.functions[...].chunk.instructions[...].operands` adds unnecessary bounds checks and pointer chasing in the hottest part of the VM.
 **Action:** Always prefer using existing local references over redundant deep lookups, especially in tight loops like an interpreter fetch-decode-execute loop.
+## 2026-08-19 - Reused local frame and func references in VM opcodes\n**Learning:** The VM executor repeatedly looked up the current frame via `self.frames.last()` and current function via `self.module.functions[...]` in several opcodes (LoadConst, FieldLoad, StoreLocal, etc.). This adds unnecessary bounds checking and pointer dereferencing on the hottest path since `frame` and `func` are already computed at the start of the while loop iteration.\n**Action:** Always reuse existing local references in tight loop opcodes rather than repeatedly querying collections or stacks when the target element is already known and borrowed.
diff --git a/runtime/vm/src/executor.rs b/runtime/vm/src/executor.rs
index 8b3400ec..226c2fc9 100644
--- a/runtime/vm/src/executor.rs
+++ b/runtime/vm/src/executor.rs
@@ -35,14 +35,8 @@ impl VM {
             self.profiler.record_stack_height(self.stack.len());
 
             if self.debugger.is_enabled() {
-                let current_func = &self.module.functions[self
-                    .frames
-                    .last()
-                    .ok_or(crate::error::VMError::StackUnderflow)?
-                    .function_idx
-                    as usize];
                 self.debugger.trace_instruction(
-                    current_func,
+                    func,
                     ip,
                     inst_op,
                     inst_operands,
@@ -55,13 +49,7 @@ impl VM {
 
                 Opcode::LoadConst => {
                     if let Some(Operand::ConstantIndex(c_idx)) = inst_operands.first() {
-                        let current_func = &self.module.functions[self
-                            .frames
-                            .last()
-                            .ok_or(crate::error::VMError::StackUnderflow)?
-                            .function_idx
-                            as usize];
-                        let lit = current_func
+                        let lit = func
                             .chunk
                             .constants
                             .get(*c_idx)
@@ -81,11 +69,7 @@ impl VM {
 
                 Opcode::LoadLocal => {
                     if let Some(Operand::LocalIndex(l_idx)) = inst_operands.first() {
-                        let bp = self
-                            .frames
-                            .last()
-                            .ok_or(crate::error::VMError::StackUnderflow)?
-                            .base_pointer;
+                        let bp = frame.base_pointer;
                         let val = self.stack.get(bp + *l_idx as usize)?;
                         self.stack.push(val.clone())?;
                     } else {
@@ -95,11 +79,7 @@ impl VM {
 
                 Opcode::StoreLocal => {
                     if let Some(Operand::LocalIndex(l_idx)) = inst_operands.first() {
-                        let bp = self
-                            .frames
-                            .last()
-                            .ok_or(crate::error::VMError::StackUnderflow)?
-                            .base_pointer;
+                        let bp = frame.base_pointer;
                         let val = self.stack.pop()?;
                         self.stack.set(bp + *l_idx as usize, val)?;
                     } else {
@@ -784,13 +764,7 @@ impl VM {
 
                 Opcode::FieldLoad => {
                     if let Some(Operand::ConstantIndex(c_idx)) = inst_operands.first() {
-                        let current_func = &self.module.functions[self
-                            .frames
-                            .last()
-                            .ok_or(crate::error::VMError::StackUnderflow)?
-                            .function_idx
-                            as usize];
-                        let lit = current_func
+                        let lit = func
                             .chunk
                             .constants
                             .get(*c_idx)
@@ -846,13 +820,7 @@ impl VM {
 
                 Opcode::FieldStore => {
                     if let Some(Operand::ConstantIndex(c_idx)) = inst_operands.first() {
-                        let current_func = &self.module.functions[self
-                            .frames
-                            .last()
-                            .ok_or(crate::error::VMError::StackUnderflow)?
-                            .function_idx
-                            as usize];
-                        let lit = current_func
+                        let lit = func
                             .chunk
                             .constants
                             .get(*c_idx)