diff options
Diffstat (limited to 'results/scraper/launchpad-without-comments/1861404')
| -rw-r--r-- | results/scraper/launchpad-without-comments/1861404 | 50 |
1 files changed, 50 insertions, 0 deletions
diff --git a/results/scraper/launchpad-without-comments/1861404 b/results/scraper/launchpad-without-comments/1861404 new file mode 100644 index 000000000..7f8e0267b --- /dev/null +++ b/results/scraper/launchpad-without-comments/1861404 @@ -0,0 +1,50 @@ +AVX instruction VMOVDQU implementation error for YMM registers + +Hi, + +Tested with Qemu 4.2.0, and with git version bddff6f6787c916b0e9d63ef9e4d442114257739. + +The x86 AVX instruction VMOVDQU doesn't work properly with YMM registers (32 bytes). +It works with XMM registers (16 bytes) though. + +See the attached test case `ymm.c`: when copying from memory-to-ymm0 and then back from ymm0-to-memory using VMOVDQU, Qemu only copies the first 16 of the total 32 bytes. + +``` +user@ubuntu ~/Qemu % gcc -o ymm ymm.c -Wall -Wextra -Werror + +user@ubuntu ~/Qemu % ./ymm +00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F 10 11 12 13 14 15 16 17 18 19 1A 1B 1C 1D 1E 1F + +user@ubuntu ~/Qemu % ./x86_64-linux-user/qemu-x86_64 -cpu max ymm +00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 +``` + +This seems to be because in `translate.c > gen_sse()`, the case handling the VMOVDQU instruction calls `gen_ldo_env_A0` which always performs a 16 bytes copy using two 8 bytes load and store operations (with `tcg_gen_qemu_ld_i64` and `tcg_gen_st_i64`). + +Instead, the `gen_ldo_env_A0` function should generate a copy with a size corresponding to the used register. + + +``` +static void gen_sse(CPUX86State *env, DisasContext *s, int b, + target_ulong pc_start, int rex_r) +{ + [...] + case 0x26f: /* movdqu xmm, ea */ + if (mod != 3) { + gen_lea_modrm(env, s, modrm); + gen_ldo_env_A0(s, offsetof(CPUX86State, xmm_regs[reg])); + } else { + [...] +``` + +``` +static inline void gen_ldo_env_A0(DisasContext *s, int offset) +{ + int mem_index = s->mem_index; + tcg_gen_qemu_ld_i64(s->tmp1_i64, s->A0, mem_index, MO_LEQ); + tcg_gen_st_i64(s->tmp1_i64, cpu_env, offset + offsetof(ZMMReg, ZMM_Q(0))); + tcg_gen_addi_tl(s->tmp0, s->A0, 8); + tcg_gen_qemu_ld_i64(s->tmp1_i64, s->tmp0, mem_index, MO_LEQ); + tcg_gen_st_i64(s->tmp1_i64, cpu_env, offset + offsetof(ZMMReg, ZMM_Q(1))); +} +``` \ No newline at end of file |