I get Illegal Instruction: 4 errors with binaries compiled with GCC 4.7.2 under Mac OS X 10.8.2 ("Mountain Lion"), when those binaries are run under Mac OS X 10.7.x ("Lion") and earlier versions. The binaries work properly under Mac OS X 10.8.x.
I added -mmacosx-version-min=10.5 to my compile flags and this seems to help resolve the issue for 10.5.x, 10.6.x and 10.7.x clients, whatever that issue is.
Which gets to my question(s):
Illegal Instruction: 4 error?-mmacosx-version-min=10.x fix this specific error on 10.x and greater clients?I'd like to apply this fix to my makefiles, but would like to know what it is doing before I pull the trigger. (Will I have larger binaries? Do I still have 64-bit binaries? Are there gotchas with this approach I should know about? Unintended side-effects? Etc.)
This question is related to
macos
gcc
osx-lion
osx-mountain-lion
osx-leopard
I'm consciously writing this answer to an old question with this in mind, because the other answers didn't help me.
I got the Illegal Instruction: 4 while running the binary on the same system I had compiled it on, so -mmacosx-version-min didn't help.
I was using gcc in Code Blocks 16 on Mac OS X 10.11.
However, turning off all of Code Blocks' compiler flags for optimization worked. So look at all the flags Code Blocks set (right-click on the Project -> "Build Properties") and turn off all the flags you are sure you don't need, especially -s and the -Oflags for optimization. That did it for me.
I recently got this error. I had compiled the binary with -O3. Google told me that this means "illegal opcode", which seemed fishy to me. I then turned off all optimizations and reran. Now the error transformed to a segfault. Hence by setting -g and running valgrind I tracked the source down and fixed it. Reenabling all optimizations showed no further appearances of illegal instruction 4.
Apparently, optimizing wrong code can yield weird results.
I found my issue was an improper
if (leaf = NULL) {...}
where it should have been
if (leaf == NULL){...}
Check those compiler warnings!
In my case, I got this while overloading
ostream & operator << (ostream &out, const MyClass &obj)
and forgot to return out. In other systems this just generates a warning, but on macos it also generated an error (although it seems to print correctly).
The error was resolved by adding the correct return value. In my case, adding the -mmacosx-version-min flag had no effect.
I got this error when attempting to build with Xcode 10. It appears to be a bug in the Swift compiler. Building with Whole Module Optimization on, resolves the issue: https://forums.swift.org/t/illegal-instruction-4-when-trying-to-compile-project/16118
This is not an ideal solution, I will continue to use Xcode 9.4.1 until this issue is resolved.
The "illegal instruction" message is simply telling you that your binaries contain instructions the version of the OS that you are attempting to run them under does not understand. I can't give you the precise meaning of 4 but I expect that is internal to Apple.
Otherwise take a look at these... they are a little old, but probably tell you what you need to know
How does 64 bit code work on OS-X 10.5?
what does macosx-version-min imply?
Source: Stackoverflow.com