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gh-129223: Do not allow the compiler to optimise away symbols for debug sections #129225

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Merged
ambv merged 4 commits into from
Jan 24, 2025
+35 −23
Merged

gh-129223: Do not allow the compiler to optimise away symbols for debug sections #129225

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bd41fda
gh-129223: Do not allow the compiler to optimise away symbols for deb…
pablogsal Jan 23, 2025
3a87da4
Don't use __builtin_mul_overflow
ambv Jan 23, 2025
3350aa0
Fix type
pablogsal Jan 23, 2025
596a58f
Fix the other problem
pablogsal Jan 24, 2025
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Don't use __builtin_mul_overflow
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@ambv
ambv committed Jan 23, 2025
commit 3a87da45a4fb2adc4bfa2f3f66634341e84ed524
15 changes: 6 additions & 9 deletions Modules/_testexternalinspection.c
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Original file line number Diff line number Diff line change
Expand Up @@ -649,16 +649,13 @@ read_py_long(pid_t pid, _Py_DebugOffsets* offsets, uintptr_t address)

long value = 0;

// In theory this can overflow, but because of llvm/llvm-project#16778
// we can't use __builtin_mul_overflow because it fails to link with
// __muloti4 on aarch64. In practice this is fine because all we're
// testing here are task numbers that would fit in a single byte.
for (ssize_t i = 0; i < size; ++i) {
long long factor;
if (__builtin_mul_overflow(digits[i], (1UL << (ssize_t)(shift * i)),
&factor)
) {
goto error;
}
if (__builtin_add_overflow(value, factor, &value)) {
goto error;
}
long long factor = digits[i] * (1UL << (ssize_t)(shift * i));
value += factor;
}
PyMem_RawFree(digits);
if (negative) {
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