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Optimize instruction prefix extraction loops #88

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Optimize instruction prefix extraction loops #88

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4fcdc05
Optimize prefix extraction in IntelInstructionEscaper
r0ny123 Apr 8, 2026
fc73014
Use next() generator idiom for prefix length lookup
claude May 7, 2026
8344a60
Group _PREFIXES with class constants and extract prefix-length helper
claude May 7, 2026
af26358
Fix ruff format whitespace around slice expression
claude May 7, 2026
cc20c18
Convert _getPrefixLen to classmethod for subclassing flexibility
claude May 7, 2026
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55 changes: 15 additions & 40 deletions smda/intel/IntelInstructionEscaper.py
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Original file line number Diff line number Diff line change
Expand Up @@ -2014,6 +2014,8 @@ class IntelInstructionEscaper:
"tr7",
]

_PREFIXES = {"26", "2e", "36", "3e", "64", "65", "66", "67", "f2", "f3"}

@staticmethod
def escapeMnemonic(mnemonic):
mnemonic = mnemonic.split(" ")[-1]
Expand Down Expand Up @@ -2151,29 +2153,21 @@ def escapeOperands(ins, offsets_only=False):
)
return ", ".join(escaped_fields)

@classmethod
def _getPrefixLen(cls, ins_bytes):
prefixes = cls._PREFIXES
return next(
(i for i in range(0, len(ins_bytes), 2) if ins_bytes[i : i + 2] not in prefixes),
len(ins_bytes),
)

@staticmethod
def escapeToOpcodeOnly(ins):
escaped_sequence = ""
ins_bytes = ins.bytes
cleaned = ""
is_cleaning = True
for target_byte in [ins_bytes[i : i + 2] for i in range(0, len(ins_bytes), 2)]:
if is_cleaning and target_byte in [
"26",
"2e",
"36",
"3e",
"64",
"65",
"66",
"67",
"f2",
"f3",
]:
escaped_sequence += target_byte
else:
is_cleaning = False
cleaned += target_byte
prefix_len = IntelInstructionEscaper._getPrefixLen(ins_bytes)

escaped_sequence = ins_bytes[:prefix_len]
cleaned = ins_bytes[prefix_len:]
cap_ins = ins.getDetailed()
opcode_length = 0
if cap_ins.rex:
Expand Down Expand Up @@ -2332,23 +2326,4 @@ def escapeBinaryValue(ins, escaped_sequence, value):
@staticmethod
def getByteWithoutPrefixes(ins):
ins_bytes = ins.bytes
cleaned = ""
is_cleaning = True
for prefix_byte in [ins_bytes[i : i + 2] for i in range(0, len(ins_bytes), 2)]:
if is_cleaning and prefix_byte in [
"26",
"2e",
"36",
"3e",
"64",
"65",
"66",
"67",
"f2",
"f3",
]:
continue
else:
is_cleaning = False
cleaned += prefix_byte
return cleaned
return ins_bytes[IntelInstructionEscaper._getPrefixLen(ins_bytes) :]
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