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[Qemu-devel] [PULL 1/4] target/m68k: fix V flag for CC_OP_SUBx
From: |
Laurent Vivier |
Subject: |
[Qemu-devel] [PULL 1/4] target/m68k: fix V flag for CC_OP_SUBx |
Date: |
Thu, 15 Jun 2017 10:17:08 +0200 |
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 <address@hidden>
Reviewed-by: Richard Henderson <address@hidden>
Message-Id: <address@hidden>
---
target/m68k/translate.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
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);
--
2.9.4