From 670fcf59d8c8cb97f8aa1e113a9614564f377bb3 Mon Sep 17 00:00:00 2001
From: Ayke van Laethem <aykevanlaethem@gmail.com>
Date: Thu, 4 Nov 2021 20:35:13 +0100
Subject: [PATCH] linux: reduce binary size in the common case

This commit changes the runtime.putchar implementation to directly call
the `write` system call. This reduces the binary size by around 2.7kB.
---
 src/runtime/runtime_unix.go | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/src/runtime/runtime_unix.go b/src/runtime/runtime_unix.go
index e53ff357..684063b4 100644
--- a/src/runtime/runtime_unix.go
+++ b/src/runtime/runtime_unix.go
@@ -7,8 +7,8 @@ import (
 	"unsafe"
 )
 
-//export putchar
-func _putchar(c int) int
+//export write
+func libc_write(fd int32, buf unsafe.Pointer, count uint) int
 
 //export usleep
 func usleep(usec uint) int
@@ -145,7 +145,8 @@ func syscall_runtime_envs() []string {
 }
 
 func putchar(c byte) {
-	_putchar(int(c))
+	buf := [1]byte{c}
+	libc_write(1, unsafe.Pointer(&buf[0]), 1)
 }
 
 func ticksToNanoseconds(ticks timeUnit) int64 {