-no-crt and assembly compilation on darwin

4 files changed, 39 insertions, 6 deletions

diff --git a/core/runtime/entry_unix.odin b/core/runtime/entry_unix.odin
index 0c718445a..78e545c22 100644
--- a/core/runtime/entry_unix.odin
+++ b/core/runtime/entry_unix.odin
@@ -26,8 +26,13 @@ when ODIN_BUILD_MODE == .Dynamic {
 		// to retrieve argc and argv from the stack
 		when ODIN_ARCH == .amd64 {
 			@require foreign import entry "entry_unix_no_crt_amd64.asm"
+			SYS_exit :: 60
 		} else when ODIN_ARCH == .i386 {
 			@require foreign import entry "entry_unix_no_crt_i386.asm"
+			SYS_exit :: 1
+		} else when ODIN_OS == .Darwin && ODIN_ARCH == .arm64 {
+			@require foreign import entry "entry_unix_no_crt_darwin_arm64.asm"
+			SYS_exit :: 1
 		}
 		@(link_name="_start_odin", linkage="strong", require)
 		_start_odin :: proc "c" (argc: i32, argv: [^]cstring) -> ! {
@@ -36,11 +41,7 @@ when ODIN_BUILD_MODE == .Dynamic {
 			#force_no_inline _startup_runtime()
 			intrinsics.__entry_point()
 			#force_no_inline _cleanup_runtime()
-			when ODIN_ARCH == .amd64 {
-				intrinsics.syscall(/*SYS_exit = */60)
-			} else when ODIN_ARCH == .i386 {
-				intrinsics.syscall(/*SYS_exit = */1)
-			}
+			intrinsics.syscall(SYS_exit, 0)
 			unreachable()
 		}
 	} else {
diff --git a/core/runtime/entry_unix_no_crt_darwin_arm64.asm b/core/runtime/entry_unix_no_crt_darwin_arm64.asm
new file mode 100644
index 000000000..0f71fbdf8
--- /dev/null
+++ b/core/runtime/entry_unix_no_crt_darwin_arm64.asm
@@ -0,0 +1,20 @@
+	.section __TEXT,__text
+
+	; NOTE(laytan): this should ideally be the -minimum-os-version flag but there is no nice way of preprocessing assembly in Odin.
+	; 10 seems to be the lowest it goes and I don't see it mess with any targeted os version so this seems fine.
+	.build_version macos, 10, 0
+
+	.extern __start_odin
+
+	.global _main
+	.align 2
+_main:
+	mov x5, sp       ; use x5 as the stack pointer
+
+	str x0, [x5]     ; get argc into x0 (kernel passes 32-bit int argc as 64-bits on stack to keep alignment)
+	str x1, [x5, #8] ; get argv into x1
+
+	and sp, x5, #~15 ; force 16-byte alignment of the stack
+	
+	bl __start_odin  ; call into Odin entry point
+	ret              ; should never get here
diff --git a/core/runtime/os_specific_any.odin b/core/runtime/os_specific_any.odin
index afa106138..5fffceeeb 100644
--- a/core/runtime/os_specific_any.odin
+++ b/core/runtime/os_specific_any.odin
@@ -1,4 +1,4 @@
-//+build !freestanding !wasi !windows !js
+//+build !freestanding !wasi !windows !js !darwin
 package runtime
 
 import "core:os"
diff --git a/core/runtime/os_specific_darwin.odin b/core/runtime/os_specific_darwin.odin
new file mode 100644
index 000000000..33136c92f
--- /dev/null
+++ b/core/runtime/os_specific_darwin.odin
@@ -0,0 +1,12 @@
+//+build darwin
+package runtime
+
+import "core:intrinsics"
+
+_os_write :: proc "contextless" (data: []byte) -> (int, _OS_Errno) {
+	ret := intrinsics.syscall(4, 1, uintptr(raw_data(data)), uintptr(len(data)))
+	if ret < 0 {
+		return 0, _OS_Errno(-ret)
+	}
+	return int(ret), 0
+}