x86: printing of 8-bit immediate values

[vbgl]

The pretty-printing to x86 asm is not compatible with recent assemblers.

Here is an example program:

export
fn test(reg u64 p) -> reg u128 {
  reg u128 r;
  r = #AESKEYGENASSIST((u128)[p], 128);
  return r;
}

It is translated to the following assembly listing (AT&T syntax):

        .att_syntax
        .text
        .p2align        5
        .globl  _test
        .globl  test
_test:
test:
        aeskeygenassist $-128, (%rdi), %xmm0
        ret

for completeness, here it is in Intel syntax:

        .intel_syntax noprefix
        .text
        .p2align        5
        .globl  _test
        .globl  test
_test:
test:
        aeskeygenassist xmm0, xmmword ptr[rdi], -128
        ret

These assembly listings are accepted by GNU binutils 2.40, but at version 2.41, the following error arises:

….s:8: Error: operand type mismatch for `aeskeygenassist'