[PATCH] powerpc: Avoid clang warnings around setjmp and longjmp

[David Laight]

From: Nathan Chancellor
> Sent: 28 August 2019 19:45
...
> However, I think that -fno-builtin-* would be appropriate here because
> we are providing our own setjmp implementation, meaning clang should not
> be trying to do anything with the builtin implementation like building a
> declaration for it.

Isn't implementing setjmp impossible unless you tell the compiler that
you function is 'setjmp-like' ?

For instance I think it all goes horribly wrong if the generated code
looks like:
	push local_variable
	// setup arguments to setjmp
	call setjmp
	pop local_variable
	// check return value of setjmp

With a naive compiler and simple ABI setjmp just has to save the
return address, stack pointer and caller saved registers.
With modern compilers and ABI I doubt you can implement setjmp
without some help from the compiler.

It is probably best to avoid setjmp/longjmp completely.

	David

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