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Fix common ARM32 assembly discrepancies #166

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Fix common ARM32 assembly discrepancies #166

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d258e08
Follow-up from jump table PR
abaresk Jun 10, 2024
1802c94
Remove excess padding after a function
abaresk Jun 10, 2024
ef2fb96
Normalize instructions without destination register
abaresk Jun 10, 2024
07d37b6
Address comments
abaresk Jun 21, 2024
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38 changes: 30 additions & 8 deletions diff.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1795,6 +1795,21 @@ def is_end_of_function(self, mnemonic: str, args: str) -> bool:
return mnemonic == "blr"


ARM32_DEST_OPTIONAL = {
"add",
"sub",
"rsb",
"sbc",
"and",
"orr",
"eor",
"bic",
"asr",
"lsl",
"lsr",
"ror",
}

# Example: "cmp r0, #0x10"
ARM32_COMPARE_IMM_PATTERN = r"cmp\s+(r[0-9]|1[0-3]),\s+#(\w+)"

Expand Down Expand Up @@ -1831,6 +1846,10 @@ def short_table_entry(
new_lines = []
lines = objdump.splitlines()
for i, jump_table_entry in self._lines_iterator(lines):
# Normalize the assembly by removing any excess padding.
if i == len(lines) - 1 and re.search(r"\.short.*0000", lines[i]):
continue

if jump_table_entry is None:
new_lines.append(lines[i])
continue
Expand Down Expand Up @@ -1895,11 +1914,21 @@ def _jump_table_entries_count(self, raw_lines: List[str], line_no: int) -> int:
for i in reversed(range(line_no)):
cmp_match = re.search(ARM32_COMPARE_IMM_PATTERN, raw_lines[i])
if cmp_match:
value = immediate_to_int(cmp_match.group(2))
value = int(cmp_match.group(2).lstrip("#"), 0)
if value > 0:
return value + 1
return 0

def pre_process(
self, mnemonic: str, args: str, next_row: Optional[str], comment: Optional[str]
) -> Tuple[str, str]:
arg_parts = args.split()
# Normalize instructions that omit the destination register.
if len(arg_parts) == 2 and any(ins in mnemonic for ins in ARM32_DEST_OPTIONAL):
arg_parts.insert(1, arg_parts[0])
return mnemonic, " ".join(arg_parts)
return mnemonic, args

def process_reloc(self, row: str, prev: str) -> Tuple[str, Optional[str]]:
arch = self.config.arch
if "R_ARM_V4BX" in row:
Expand Down Expand Up @@ -2631,13 +2660,6 @@ class ArchSettings:
]


def immediate_to_int(immediate: str) -> int:
imm_match = re.match(r"#?(0x)?([0-9a-f]+)", immediate)
assert imm_match
base = 16 if imm_match.group(1) else 10
return int(imm_match.group(2), base)


def is_hexstring(value: str) -> bool:
try:
int(value, 16)
Expand Down