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m68k: fix CAS2 writeback when Dc1==Dc2

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According to Programmer's Reference Manual, if Dc1 and Dc2 specify the
same data register and the comparison fails, memory operand 1 is stored
in the data register.

The current helpers wrote Dc1 then Dc2, leaving operand 2 in the shared
register.

Swap the writeback order for cas2w/cas2l so memory operand 1 wins.

Signed-off-by: Laurent Vivier <laurent@vivier.eu>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-ID: <20251226213707.331741-1-laurent@vivier.eu>
(cherry picked from commit 11dac41f2e830bcd7ba74969dc50f5740e3ce7e7)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
This commit is contained in:
Laurent Vivier 2025-12-26 22:37:07 +01:00 • committed by Michael Tokarev
parent 920634e411
commit 359076c8a0
1 changed files with 2 additions and 2 deletions
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4
target/m68k/op_helper.c
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@ -799,8 +799,8 @@ void HELPER(cas2w)(CPUM68KState *env, uint32_t regs, uint32_t a1, uint32_t a2)
env->cc_v = c2;
}
env->cc_op = CC_OP_CMPW;
env->dregs[Dc1] = deposit32(env->dregs[Dc1], 0, 16, l1);
env->dregs[Dc2] = deposit32(env->dregs[Dc2], 0, 16, l2);
env->dregs[Dc1] = deposit32(env->dregs[Dc1], 0, 16, l1);
}
static void do_cas2l(CPUM68KState *env, uint32_t regs, uint32_t a1, uint32_t a2,
@ -861,8 +861,8 @@ static void do_cas2l(CPUM68KState *env, uint32_t regs, uint32_t a1, uint32_t a2,
env->cc_v = c2;
}
env->cc_op = CC_OP_CMPL;
env->dregs[Dc1] = l1;
env->dregs[Dc2] = l2;
env->dregs[Dc1] = l1;
}
void HELPER(cas2l)(CPUM68KState *env, uint32_t regs, uint32_t a1, uint32_t a2)