Module x86_encoding 

Byte-level rewrites for setcc / cmovcc on x86 / x86_64.

All functions in this module take the raw byte sequence of the original instruction (as read via r2smt_ir::BytePatcher::read_bytes) and produce a same-length replacement that preserves any prefix bytes, ModR/M, SIB, and displacement bytes. Same-length output is enforced because the patcher writes back over the original footprint; a longer or shorter instruction would either clobber the next instruction or leave invalid bytes behind.

Encoding references:

• SETcc r/m8 — [REX]? 0F 9x /0 r/m8
• MOV r/m8, imm8 — [REX]? C6 /0 r/m8 imm8
• CMOVcc r, r/m — [REX]? 0F 4x /r
• MOV r, r/m — [REX]? 8B /r

Both pairs share their addressing-byte layout (ModR/M + optional SIB + optional displacement), so the rewrites only swap opcode bytes and either append imm8 (setcc) or a nop (cmovcc).

Functions

nop_buffer

Return a buffer of len NOPs (0x90). Used both for fully-NOPed setcc / cmovcc instructions (always-false outcome) and for NOP-padding shorter replacements.

nop_byte

Single-byte NOP opcode used for padding patched instructions.

patch_cmovcc_to_mov

Rewrite a CMOVcc instruction as an unconditional MOV r, r/m.

patch_setcc

Rewrite a SETcc instruction so it unconditionally writes value as u8 to its destination operand.