asm: comprehend 1-, 2-, and 3-byte opcodes #10232
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How IA-32e describes and encodes opcodes is a bit confusing, but section 2.1.2 in the reference manual does a decent job explaining how the various prefixes, escape bytes, and primary/secondary opcodes may be used. This change uses this explanation to create what is essentially a parser for `[u8]`; this allows us to compactly express instruction definitions, e.g., `rex([0x66, 0x25])`. Improper use of this DSL syntax should result in an immediate compilation error when attempting to generate the assembler.
alexcrichton
approved these changes
Feb 14, 2025
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How IA-32e describes and encodes opcodes is a bit confusing, but section 2.1.2 in the reference manual does a decent job explaining how the various prefixes, escape bytes, and primary/secondary opcodes may be used. This change uses this explanation to create what is essentially a parser for
[u8]; this allows us to compactly express instruction definitions, e.g.,rex([0x66, 0x25]). Improper use of this DSL syntax should result in an immediate compilation error when attempting to generate the assembler.