On 5/6/21 12:29 PM, Laurent Vivier wrote: > Le 05/05/2021 à 18:43, Laurent Vivier a écrit : >> Le 05/05/2021 à 18:03, Philippe Mathieu-Daudé a écrit : >>> The ABCD / SBCD memory opcodes (introduced in commit fb5543d8200) >>> don't use their "addr" variable. >>> >>> Remove the unused variable and pass a NULL argument instead to >>> gen_ea_mode(). This fixes warnings generated when building with >>> CFLAGS=-O3 (using GCC 10.2.1 20201125): >>> >>> target/m68k/translate.c: In function ‘disas_sbcd_mem’: >>> target/m68k/translate.c:897:13: warning: ‘addr’ may be used uninitialized >>> in this function [-Wmaybe-uninitialized] >>> 897 | delay_set_areg(s, reg0, tmp, false); >>> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ >>> target/m68k/translate.c:1866:21: note: ‘addr’ was declared here >>> 1866 | TCGv src, dest, addr; >>> | ^~~~ >>> >>> target/m68k/translate.c: In function ‘disas_abcd_mem’: >>> target/m68k/translate.c:897:13: warning: ‘addr’ may be used uninitialized >>> in this function [-Wmaybe-uninitialized] >>> 897 | delay_set_areg(s, reg0, tmp, false); >>> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ >>> target/m68k/translate.c:1829:21: note: ‘addr’ was declared here >>> 1829 | TCGv src, dest, addr; >>> | ^~~~ >>> >> >> It's really strange because ABCD and SBCD support indirect predecrement >> (mode 4, "-(Ay),-(Ax)"), and >> if you look into gen_ea_mode() &addr (addrp) is used with mode 4, it is >> initialized on EA_LOADU to >> be reused on EA_STORE. >> >> The bug is somewhere else... >> > > I think I see what is the problem: as the mode is indirect pre-decrement, the > register doesn't need > to be updated and thus the addr is not needed. > > But if we replace addrp by NULL, gen_lea_mode() will be called twice and the > register will be > decremented twice (on load and store, rather than only on load).
Ah OK I see. Well, I guess I'll let you have a look, you clearly have better understanding :P Would it help if I fill a GitLab issue?
