This PR shows adhoc support for symbolic opcodes.

Changes

• The op argument to dis_decode_entry is changed from value to sym type. This change cascades throughout the dis functions.
• Extend the sym_inmask implementation with simplification rules.
• Adds some operations on masks to primops.
• Hacks in an asli :adhoc command for testing purposes. We would need an actual user interface if we were going to land this.
• (Unfortunately, my editor has also polluted the PR by removing whitespace and end of lines.)

Example

For comparison, when you ask for semantics for a concrete add immediate:

asm: add x7, x8, #291
opcode: 91048d07

Decoding instruction A64 91048d07
__array _R [ 7 ] = add_bits.0 {{ 64 }} ( __array _R [ 8 ],'0000000000000000000000000000000000000000000000000000000100100011' ) ;

ASLp can now execute opcodes that are expressions. For example the assembly template add x7, x8, #<imm> would be the opcode concatenation 0x244:imm:0x107. It now gives the semantics:

__array _R [ 7 ] = add_bits.0 {{ 64 }} ( __array _R [ 8 ],append_bits.0 {{ 52,12 }} ( '0000000000000000000000000000000000000000000000000000',imm [ 0 +: 12 ] ) ) ;