Displaying 3 results from an estimated 3 matches for "adsize16".
2015 Jul 02
2
[LLVMdev] [x86] Compiling in 32-bit mode causes 64-bit asm source to be silently converted to its 32-bit equavilent
...hardware/ff561499(v=vs.85).aspx> "jrcxz" in 32-bit mode "-m32"
previously resulted in an error,
now gets silently converted into the 32-bit equivalent instruction "jecxz".
I have bisected this change in behavior down to r225075 - [X86] Make the instructions that use AdSize16/32/64 co-exist together without using mode predicates.<http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20141229/250681.html>
I am curious if this change in behavior was an intended feature or perhaps a side effect.
Here is my methodology.
The asm test case.
$ cat j64.s
j...
2018 Mar 28
0
x86 instruction format which takes a single 64-bit immediate
...6 - 0x66 prefix required in 32-bit mode
OpSize32 - 0x66 prefix required in 16-bit mode
OpSizeIgnored - 0x66 prefix should be ignored if present.
Adsize
------
AdSizeX(default) - Address size prefix determined from memory operand registers encoded in modrm byte
AdSize16 - Need a 0x67 prefix in 32-bit mode
AdSize32 - Need a 0x67 prefix in 16-bit mode or 64-bit mode
AdSize64 - Marks the 64-bit version of AdSize16/32 instructions.
OpPrefix
--------
NoPrfx(default)
PS - Doesn't encode with a prefix, but 0x66/0xf2/0x...
2018 Mar 28
4
x86 instruction format which takes a single 64-bit immediate
I am attempting to create an instruction which takes a single 64-bit
immediate. This doesn't seem like a thing that would exist already (because
who needs an instruction which just takes an immediate?) How might I
implement this easily? Perhaps I could use a format which encodes a
register, which is then unused?
Thanks for the help.
Gus
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