Differences in *.elc files (was: Re: How to make aot native-compilation and pdmp creation reproduceable)

[Ulrich Mueller]

Not sure if it is related, but when I compile Emacs with make -j1 and
with make -j8 (both for commit 336c3674119 on master), it results in the
file emacs-lisp/eieio-opt.elc having a different size:

-rw-r--r-- 1 ulm users 8716 Oct 10 12:14 eieio-opt.elc-j1
-rw-r--r-- 1 ulm users 9102 Oct 10 12:23 eieio-opt.elc-j8

Is there a good way to compare byte-compiled files? diff outputs the
following for the first hunk:

$ diff -a -U0 eieio-opt.elc-{j1,j8} | head -n5
--- eieio-opt.elc-j1     2023-10-10 12:14:29.447911151 +0200
+++ eieio-opt.elc-j8     2023-10-10 12:23:58.083301315 +0200
@@ -19 +19 @@
-(defalias 'eieio-browse-tree #[771 
"\300!\204\301\302\303\304E\"\210\305!\306N\211\307H\262\310P\311P\312P\313\261\210A\203<\314@#\210A\262\202)\205F\314@#\207"
 [class-p signal wrong-type-argument class this-root symbol-name cl--class 6 "  
+--" "  |  " "     " "\n" eieio-browse-tree] 12 (#$ . 890)])
+(defalias 'eieio-browse-tree #[771 
"\301!\204\302\303\304\305E\"\210\306!\307N\310>\204#\302\303\311D\"\210\211\312H\262\313P\314P\315P\316\261\210A\203K\317@#\210A\262\2028\205U\317@#\207"
 [cl-struct-eieio--class-tags class-p signal wrong-type-argument class 
this-root symbol-name cl--class type-of eieio--class 6 "  +--" "  |  " "     " 
"\n" eieio-browse-tree] 12 (#$ . 890)])

After this there are many more differences because all the positions
have changed.

Parallel build problem because of a missing prerequisite?