The toolchain writes the source immediate straight into imm[31:12]
(riscv64.s: AUIPC 24287, X10 encodes 7ffff517), and rejects values
beyond the signed 20-bit span; the encoder divided by 4096 instead and
truncated silently, so the high bits of every large AUIPC and LUI were
lost.
Assisted-by: GLM 5.3 Flash
SLLI $64 assembled with the amount silently masked into the six-bit
field where the toolchain rejects it, and the word forms took 0-63 where
they take 0-31. Both families now validate against their own width and
the check reads the immediate at full width, so a value the source
spelled beyond int32 cannot wrap into the range; the boundary is pinned
in a test.
Assisted-by: GLM 5.3 Flash
WORD and BYTE read their immediate through the truncating helper, so the
int32 wrap turned WORD $0xffffffff into -1 and rejected it, while WORD
$0x100000000 and BYTE $0x100000001 arrived pre-truncated and slipped
past the range check as small values. Both statements now read the
immediate the source wrote and bound it at the toolchain's own limits:
[0, 0xffffffff] for WORD, [0, 0xff] for BYTE, with the bounds pinned in
a test.
Assisted-by: GLM 5.3 Flash
petrbalvin