decompiler: fix bit extractions with RuleShiftAnd and RuleShiftCompare#8718
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ryanmkurtz merged 1 commit intoNationalSecurityAgency:masterfrom Jan 13, 2026
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Fixes NationalSecurityAgency#8717 RuleShiftAnd previously replaced the AND opcode with COPY. This, however doesn't update the NZMask of the Varnode. As a result, following rules may assume the NZMask after the AND operation also applies to the Varnode being copied. In combination with RuleShiftCompare, an expression of the form (a & bitmask) >> const != 0, wrongfully is reduced to a != 0. Instead of replacing the AND with COPY, we now replace the input of the shift operation instead. This way, future rules will see the correct NZMask.
ryanmkurtz
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Feature: Decompiler
Status: Triage
ryanmkurtz
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Status: Internal
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Fixes #8717
RuleShiftAnd previously replaced the AND opcode with COPY. This, however doesn't update the NZMask of the Varnode. As a result, following rules may assume the NZMask after the AND operation also applies to the Varnode being copied.
In combination with RuleShiftCompare, an expression of the form (a & bitmask) >> const != 0, wrongfully is reduced to a != 0. Instead of replacing the AND with COPY, we now replace the input of the shift operation instead. This way, future rules will see the correct NZMask.