Compiler crash when using -use-single-module with manual call to _startup_runtime()

[khaledh]

Context

Background: I'm just starting with Odin for bare-metal development. In this context, I'm taking over the entry point, so I need to call _startup_runtime() and _cleanup_runtime() myself (based on entry_unix.odin). I've been using -target:freestanding_amd64_sysv when I encountered this bug, but I was able to reproduce it even without cross-compiling (as in the repro steps below).

The compiler crashes with malloc: *** error for object 0x600000d60258: pointer being freed was not allocated when compiling an individual module that bootstraps the runtime itself (using _startup_runtime()) and the flag -use-single-module is in use. If this flag is removed, it compiles fine. This also happens when using -o:size or -o:speed, but I think it's just because those optimization modes use -use-single-module by default.

• Operating System: macOS Sequoia (15.4.1) (arm64)
• Odin Version: dev-2025-04-nightly:d9f990d
• Please paste odin report output:

	Odin:    dev-2025-04-nightly:d9f990d
	OS:      macOS Sequoia 15.4.1 (build 24E263, kernel 24.4.0)
	CPU:     Apple M3
	RAM:     16384 MiB
	Backend: LLVM 20.1.1

Expected Behavior

The compiler should produce a single .o file without crashing.

Current Behavior

The compiler crashes as shown below.

Failure Information (for bugs)

The crash message is:

    odin(67063,0x1fbd00c80) malloc: *** error for object 0x600000d60258: pointer being freed was not allocated
    odin(67063,0x1fbd00c80) malloc: *** set a breakpoint in malloc_error_break to debug

Steps to Reproduce

1. Create an odin file with the following content:

   package xyz
   
   import "base:runtime"
   
   foreign {
       @(link_name="__$startup_runtime")
       _startup_runtime :: proc "odin" () ---
   
       @(link_name="__$cleanup_runtime")
       _cleanup_runtime :: proc "odin" () ---
   }
   
   @export
   _start :: proc "c" () {
       context = runtime.default_context()
       #force_no_inline _startup_runtime()
       #force_no_inline _cleanup_runtime()
   }

2. Compile using:

   $ odin build nomain.odin -file -build-mode:obj -use-single-module -out:nomain.o
   odin(67063,0x1fbd00c80) malloc: *** error for object 0x600000d60258: pointer being freed was not allocated
   odin(67063,0x1fbd00c80) malloc: *** set a breakpoint in malloc_error_break to debug
   fish: Job 1, 'odin build nomain.odin -file -b…' terminated by signal SIGABRT (Abort)
   

   Sometimes I also get no output at all, the compiler just hangs.

[laytan]

You can actually just call runtime._startup_runtime() directly, without the foreign block etc.

It shouldn't crash of course, will have to look into that.

[Kelimion]

If we fix up the example to directly call runtime._*_runtime, then it works with -use-single-module.

package scratch

import "base:runtime"

@export
_start :: proc "c" () {
	context = runtime.default_context()
	#force_no_inline runtime._startup_runtime()
	#force_no_inline runtime._cleanup_runtime()
}

> odin build scratch.odin -file -build-mode:obj -out:nomain.obj -use-single-module
> echo %ERRORLEVEL%
0
> dir *.obj
07/05/2025  14:34            26.542 nomain.obj

But, without it it litters an object file for each package and doesn't create nomain.obj, even though it exited normally.

> odin build scratch.odin -file -build-mode:obj -out:nomain.obj
> echo %ERRORLEVEL%
0
> dir *.obj
07/05/2025  14:36             1.732 nomainnomain-builtin.obj
07/05/2025  14:36            31.547 nomainnomain-runtime.obj
07/05/2025  14:36             1.084 nomainnomain-scratch.obj

However, the original example does indeed crash the compiler, creating no object files of any kind.

W:\Scratch>odin build scratch.odin -file -build-mode:obj -out:nomain.obj -use-single-module

W:\Scratch>echo %ERRORLEVEL%
-1073741819

[khaledh]

You can actually just call runtime._startup_runtime() directly, without the foreign block etc.

Thanks, this works. I literally just started learning Odin yesterday 😅