When is the stack pointer unreliable?

John Wehle john@feith.com
Sun Sep 6 18:57:00 GMT 1998

>> Since reloading the stack pointer causes a stall on some processors
>> it should be avoided when possible.  Under what situations is sp
>> unreliable?
> alloca calls,

In which case current_function_calls_alloca is set.

> variable sized objects in the stack come immediately to mind.

I assume that this is always handled by allocate_dynamic_stack_space
in which case current_function_calls_alloca is set.

> You might also need to check if the compiler has optimized away
> popping of args after a function call if we unconditionally reach the
> epilogue after performing the call.

Good point.  That hadn't occurred to me.

-- John
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