target/i386: Fix andn instruction

In commit 7073fbada733c8d10992f00772c9b9299d740e9b, the `andn` instruction
was implemented via `tcg_gen_andc` but passes the operands in the wrong
order:
- X86 defines `andn dest,src1,src2` as: dest = ~src1 & src2
- TCG defines `andc dest,src1,src2` as: dest = src1 & ~src2

The following simple test shows the issue:

int main(void) {
uint32_t ret = 0;
__asm (
"mov $0xFF00, %%ecx\n"
"mov $0x0F0F, %%eax\n"
"andn %%ecx, %%eax, %%ecx\n"
"mov %%ecx, %0\n"
: "=r" (ret));
printf("%08X\n", ret);
return 0;
}

This patch fixes the problem by simply swapping the order of the two last
arguments in `tcg_gen_andc_tl`.

Backports commit 5cd10051c2e02b7a86eae49919d6c65a87dbea46 from qemu
This commit is contained in:
Alexandro Sanchez Bach 2018-04-10 08:47:50 -04:00 committed by Lioncash
parent e0903adacf
commit 4a1de154ef
No known key found for this signature in database
GPG key ID: 4E3C3CC1031BA9C7

View file

@ -4363,7 +4363,7 @@ static void gen_sse(CPUX86State *env, DisasContext *s, int b,
}
ot = mo_64_32(s->dflag);
gen_ldst_modrm(env, s, modrm, ot, OR_TMP0, 0);
tcg_gen_andc_tl(tcg_ctx, cpu_T0, cpu_regs[s->vex_v], cpu_T0);
tcg_gen_andc_tl(tcg_ctx, cpu_T0, cpu_T0, cpu_regs[s->vex_v]);
gen_op_mov_reg_v(tcg_ctx, ot, reg, cpu_T0);
gen_op_update1_cc(tcg_ctx);
set_cc_op(s, CC_OP_LOGICB + ot);