How is the preempt stub be like?

[Patricio Chilano Mateo]

Hi,

On 1/20/25 6:41 AM, xtex wrote:
> The comment says "fp restored from the stub would be invalid" when the current
> frame is frozen. I wonder if there are any documentation about how does the
> freezing process happen and why FP is invalid but FP and return address (RA)
> loaded from the address pointed by SP is still valid?
The FP value that was restored from the stub is invalid because it 
contains a pointer to the stack that was created in the prologue before 
freezing. But when we thaw the frame, it will most likely be copied at a 
different memory address. The FP loaded from SP in the epilogue is the 
original value from the compiled caller, and it never holds a pointer to 
the stack unless PreserveFramePointer is used. In that latter case the 
value would be fixed during the thaw operation (check use of 
PreserveFramePointer).

Patricio