http://llvm.org/bugs/show_bug.cgi?id=19534
Bug ID: 19534
Summary: UBSan: False positive for large left shift
Product: new-bugs
Version: trunk
Hardware: PC
OS: Windows NT
Status: NEW
Severity: normal
Priority: P
Component: new bugs
Assignee: [email protected]
Reporter: [email protected]
CC: [email protected]
Classification: Unclassified
The code
int x = 0;
int y = x << 40;
When instrumented with UBSan gives the error:
"runtime error: shift exponent 40 is too large for 32-bit type 'int'"
However as far as I can tell from e.g. http://stackoverflow.com/a/3785121
It's well defined to shift left by such a large amount, as long as the left
operand (x) is zero, because the result is still representable.
So UBSan shouldn't show an error in this case.
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