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authorLaurent Vivier <laurent@vivier.eu>2017-06-14 22:39:05 +0200
committerLaurent Vivier <laurent@vivier.eu>2017-06-15 08:50:30 +0200
commit043b936ef6fe53396b3c6b8f5562ea3e238a071d (patch)
treed50b1901e4860edc71820bf786302cf4caabd256 /target
parent3f0602927b120a480b35dcf58cf6f95435b3ae91 (diff)
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')
-rw-r--r--target/m68k/translate.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/target/m68k/translate.c b/target/m68k/translate.c
index ad4d4efb8d..52653f67e5 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);