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| author | Laurent Vivier <laurent@vivier.eu> | 2017-06-14 22:39:05 +0200 |
|---|---|---|
| committer | Laurent Vivier <laurent@vivier.eu> | 2017-06-15 08:50:30 +0200 |
| commit | 043b936ef6fe53396b3c6b8f5562ea3e238a071d (patch) | |
| tree | d50b1901e4860edc71820bf786302cf4caabd256 /target/m68k | |
| parent | 3f0602927b120a480b35dcf58cf6f95435b3ae91 (diff) | |
| download | qemu-043b936ef6fe53396b3c6b8f5562ea3e238a071d.zip qemu-043b936ef6fe53396b3c6b8f5562ea3e238a071d.tar.gz qemu-043b936ef6fe53396b3c6b8f5562ea3e238a071d.tar.bz2 | |
target/m68k: fix V flag for CC_OP_SUBx
V flag for subtraction is:
v = (res ^ src1) & (src1 ^ src2)
(see COMPUTE_CCR() in target/m68k/helper.c)
But gen_flush_flags() uses:
v = (res ^ src2) & (src1 ^ src2)
The problem has been found with the following program:
.global _start
_start:
move.l #-2147483648,%d0
subq.l #1,%d0
jvc 1f
move.l #1,%d1
move.l #1,%d0
trap #0
1:
move.l #0,%d1
move.l #1,%d0
trap #0
It works fine (exit(1)) on real hardware, and with "-singlestep".
"-singlestep" uses gen_helper_flush_flags(), whereas
without "-singlestep", V flag is computed directly in
gen_flush_flags().
This patch updates gen_flush_flags() to have the same result
as with gen_helper_flush_flags().
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Message-Id: <20170614203905.19657-1-laurent@vivier.eu>
Diffstat (limited to 'target/m68k')
| -rw-r--r-- | target/m68k/translate.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/target/m68k/translate.c b/target/m68k/translate.c index ad4d4ef..52653f6 100644 --- a/target/m68k/translate.c +++ b/target/m68k/translate.c @@ -565,7 +565,7 @@ static void gen_flush_flags(DisasContext *s) t1 = tcg_temp_new(); tcg_gen_add_i32(t0, QREG_CC_N, QREG_CC_V); gen_ext(t0, t0, s->cc_op - CC_OP_SUBB, 1); - tcg_gen_xor_i32(t1, QREG_CC_N, QREG_CC_V); + tcg_gen_xor_i32(t1, QREG_CC_N, t0); tcg_gen_xor_i32(QREG_CC_V, QREG_CC_V, t0); tcg_temp_free(t0); tcg_gen_and_i32(QREG_CC_V, QREG_CC_V, t1); |