From 77b4c526349a366ffa4f238530ada1f8b16d60dc Mon Sep 17 00:00:00 2001
From: Jacob Sandlund <jacob@jacobsandlund.com>
Date: Mon, 8 Sep 2025 17:59:17 -0400
Subject: [PATCH] [benchmarks] Align `buf` to cache line for consistency

---
 src/benchmark/CodepointWidth.zig | 6 +++---
 src/benchmark/GraphemeBreak.zig  | 4 ++--
 src/benchmark/IsSymbol.zig       | 4 ++--
 3 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/src/benchmark/CodepointWidth.zig b/src/benchmark/CodepointWidth.zig
index 406603ceb..a6945c8f1 100644
--- a/src/benchmark/CodepointWidth.zig
+++ b/src/benchmark/CodepointWidth.zig
@@ -109,7 +109,7 @@ fn stepWcwidth(ptr: *anyopaque) Benchmark.Error!void {
     const f = self.data_f orelse return;
     var r = std.io.bufferedReader(f.reader());
     var d: UTF8Decoder = .{};
-    var buf: [4096]u8 = undefined;
+    var buf: [4096]u8 align(std.atomic.cache_line) = undefined;
     while (true) {
         const n = r.read(&buf) catch |err| {
             log.warn("error reading data file err={}", .{err});
@@ -133,7 +133,7 @@ fn stepTable(ptr: *anyopaque) Benchmark.Error!void {
     const f = self.data_f orelse return;
     var r = std.io.bufferedReader(f.reader());
     var d: UTF8Decoder = .{};
-    var buf: [4096]u8 = undefined;
+    var buf: [4096]u8 align(std.atomic.cache_line) = undefined;
     while (true) {
         const n = r.read(&buf) catch |err| {
             log.warn("error reading data file err={}", .{err});
@@ -162,7 +162,7 @@ fn stepSimd(ptr: *anyopaque) Benchmark.Error!void {
     const f = self.data_f orelse return;
     var r = std.io.bufferedReader(f.reader());
     var d: UTF8Decoder = .{};
-    var buf: [4096]u8 = undefined;
+    var buf: [4096]u8 align(std.atomic.cache_line) = undefined;
     while (true) {
         const n = r.read(&buf) catch |err| {
             log.warn("error reading data file err={}", .{err});
diff --git a/src/benchmark/GraphemeBreak.zig b/src/benchmark/GraphemeBreak.zig
index 86661f985..8516f86fa 100644
--- a/src/benchmark/GraphemeBreak.zig
+++ b/src/benchmark/GraphemeBreak.zig
@@ -92,7 +92,7 @@ fn stepNoop(ptr: *anyopaque) Benchmark.Error!void {
     const f = self.data_f orelse return;
     var r = std.io.bufferedReader(f.reader());
     var d: UTF8Decoder = .{};
-    var buf: [4096]u8 = undefined;
+    var buf: [4096]u8 align(std.atomic.cache_line) = undefined;
     while (true) {
         const n = r.read(&buf) catch |err| {
             log.warn("error reading data file err={}", .{err});
@@ -114,7 +114,7 @@ fn stepTable(ptr: *anyopaque) Benchmark.Error!void {
     var d: UTF8Decoder = .{};
     var state: unicode.GraphemeBreakState = .{};
     var cp1: u21 = 0;
-    var buf: [4096]u8 = undefined;
+    var buf: [4096]u8 align(std.atomic.cache_line) = undefined;
     while (true) {
         const n = r.read(&buf) catch |err| {
             log.warn("error reading data file err={}", .{err});
diff --git a/src/benchmark/IsSymbol.zig b/src/benchmark/IsSymbol.zig
index 940207619..5b2ffd425 100644
--- a/src/benchmark/IsSymbol.zig
+++ b/src/benchmark/IsSymbol.zig
@@ -91,7 +91,7 @@ fn stepZiglyph(ptr: *anyopaque) Benchmark.Error!void {
     const f = self.data_f orelse return;
     var r = std.io.bufferedReader(f.reader());
     var d: UTF8Decoder = .{};
-    var buf: [4096]u8 = undefined;
+    var buf: [4096]u8 align(std.atomic.cache_line) = undefined;
     while (true) {
         const n = r.read(&buf) catch |err| {
             log.warn("error reading data file err={}", .{err});
@@ -115,7 +115,7 @@ fn stepTable(ptr: *anyopaque) Benchmark.Error!void {
     const f = self.data_f orelse return;
     var r = std.io.bufferedReader(f.reader());
     var d: UTF8Decoder = .{};
-    var buf: [4096]u8 = undefined;
+    var buf: [4096]u8 align(std.atomic.cache_line) = undefined;
     while (true) {
         const n = r.read(&buf) catch |err| {
             log.warn("error reading data file err={}", .{err});