Fix runtime error: left shift of negative value #4957
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This patch fixes jerryscript-project#4701 JerryScript-DCO-1.0-Signed-off-by: Daniel Batiz [email protected]
ossy-szeged
approved these changes
Jan 18, 2022
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https://262.ecma-international.org/12.0/#sec-numeric-types-number-leftShift
The latest spec defines this operation: "Return the result of left shifting lnum by shiftCount bits. The mathematical value of the result is exactly representable as a 32-bit two's complement bit string."
With two's complement, the signed and unsigned left shift is exactly the same operation. To avoid the undefined behavior I think it is the right fix is doing unsigned left shift here and then interpreting the results as signed int. The PR exactly does it, so LGTM.
dbatyai
approved these changes
Jan 20, 2022
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This patch fixes #4701
JerryScript-DCO-1.0-Signed-off-by: Daniel Batiz [email protected]