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dasm_imm13() accepted some non-encodable constants and returned a bogus encoding, so AND/OR/XOR with them computed a wrong result (0x5555555555555554) or emitted an illegal instruction (0x200000003). It also negated INT64_MIN in signed arithmetic. Backport the rewritten dasm_imm13() from DynASM (LuaJIT a9981441), already in master via the IR update.
ndossche
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Oct 25, 2026
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Looks like a clean backport, thanks
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Backport of the dasm_imm13() rewrite from DynASM (LuaJIT a9981441, LuaJIT/LuaJIT#1522), which landed in master with the IR update in #24298.
The old
dasm_imm13()accepts some constants that are not valid AArch64 logical immediates and returns a bogus encoding.AND/OR/XORwith such a constant then:$x & 0x5555555555555554has bit 0 set$x & 0x200000003It also negates INT64_MIN in signed arithmetic (UB).
Only
dasm_imm13()and its helpers are taken from the DynASM update; the rest of that update stays in master.