On 5/19/19 9:45 AM, Andrew Haley wrote:
> On 5/18/19 8:45 PM, Hamad Ahmed wrote:
>> How do I do that?
>
> Seriously? Go find the ABI for your processor and find out which
> registers are call clobbered. Write a subroutine in assembly language
> that zeroes those registers.
And actually, you can go one better than that: write a bunch of inline asms
that zero all of the registers, one at a time.
#define CLOBBER(reg) \
asm volatile("sub %%" #reg ", %%" #reg ::: #reg, "memory")
static inline void foo() {
CLOBBER(rax);
CLOBBER(rbx);
CLOBBER(rcx);
CLOBBER(rdx);
CLOBBER(rbp);
CLOBBER(rax);
CLOBBER(rsi);
CLOBBER(rdi);
CLOBBER(r8);
CLOBBER(r9);
CLOBBER(r10);
CLOBBER(r11);
CLOBBER(r12);
CLOBBER(r13);
CLOBBER(r14);
CLOBBER(r15);
}
This will mostly work, I think, but even then it's not 100% guaranteed.
But I still think you're making a mistake: garbage collection -- any
kind -- is only guaranteed to happen eventually, sometimes only when
the system is running low on memory, and if you really need to control
storage lifetime in a precise way you have to do so explicitly.
--
Andrew Haley
Java Platform Lead Engineer
Red Hat UK Ltd. <https://www.redhat.com>
https://keybase.io/andrewhaley
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