Re: [Qemu-devel] [RFC v2 08/24] riscv: tcg-target: Add the immediate encoders

[Richard Henderson]

On 11/27/18 1:07 PM, Alistair Francis wrote:
> +void tb_target_set_jmp_target(uintptr_t tc_ptr, uintptr_t jmp_addr,
> +                              uintptr_t addr)
> +{
> +    intptr_t offset = (intptr_t)addr - (intptr_t)jmp_addr;
> +    tcg_debug_assert(offset == (int32_t)offset);
> +
> +    int32_t hi20 = ((offset + 0x800) >> 12) << 12;
> +    int32_t lo12 = offset - hi20;
> +
> +    atomic_set((uint32_t *)jmp_addr, encode_uimm20(hi20));
> +    atomic_set((uint32_t *)jmp_addr + 4, encode_imm12(lo12));
> +
> +    flush_icache_range(jmp_addr, jmp_addr + 8);
> +}

Two atomic_sets do not help.  You want a single 64-bit atomic_set updating both
insns simultaneously.  But since you're currently setting

> +#define TCG_TARGET_HAS_direct_jump      0

this code isn't used at all.  Better to simply remove it for now.

Otherwise,
Reviewed-by: Richard Henderson <address@hidden>


r~