RE: [PATCH V3] LoongArch: Add unaligned access support

David Laight
2022-10-17T13:11:35Z

From: Huacai Chen
> Sent: 17 October 2022 13:52
>
> Loongson-2 series (Loongson-2K500, Loongson-2K1000) don't support
> unaligned access in hardware, while Loongson-3 series (Loongson-3A5000,
> Loongson-3C5000) are configurable whether support unaligned access in
> hardware. This patch add unaligned access emulation for those LoongArch
> processors without hardware support.
>
.....
> + } else if (insn.reg2i12_format.opcode == fstd_op ||
> + insn.reg3_format.opcode == fstxd_op) {
> + value = read_fpr(insn.reg2i12_format.rd);
> + res = unaligned_write(addr, value, 8);
> + if (res)
> + goto fault;
> + } else if (insn.reg2i12_format.opcode == fsts_op ||
> + insn.reg3_format.opcode == fstxs_op) {
> + value = read_fpr(insn.reg2i12_format.rd);
> + res = unaligned_write(addr, value, 4);
> + if (res)
> + goto fault;

Are those right?
Shouldn't something be converting from 'double' to
'float' in there?
And generating SIGFPE (?) if the exponent is out of range.

(And the same for write_fpr().)

David

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