Immediate Values - x86 Optimization
x86 optimization of the immediate values which uses a movl with code patching
to set/unset the value used to populate the register used as variable source.
Changelog:
- Use text_poke_early with cr0 WP save/restore to patch the bypass. We are doing
non atomic writes to a code region only touched by us (nobody can execute it
since we are protected by the immediate_mutex).
- Put immediate_set and _immediate_set in the architecture independent header.
- Use $0 instead of %2 with (0) operand.
- Add x86_64 support, ready for i386+x86_64 -> x86 merge.
- Use asm-x86/asm.h.
Ok, so the most flexible solution that I see, that should fit for both
i386 and x86_64 would be :
1 byte : "=Q" : Any register accessible as rh: a, b, c, and d.
2, 4 bytes : "=R" : Legacy registerâthe eight integer registers available
on all i386 processors (a, b, c, d, si, di, bp, sp). 8
bytes : (only for x86_64)
"=r" : A register operand is allowed provided that it is in a
general register.
That should make sure x86_64 won't try to use REX prefixed opcodes for
1, 2 and 4 bytes values.