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;
| ^~~~
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
---
target/m68k/translate.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/target/m68k/translate.c b/target/m68k/translate.c
index 200018ae6a6..5cdd026a4b2 100644
--- a/target/m68k/translate.c
+++ b/target/m68k/translate.c
@@ -1826,7 +1826,7 @@ DISAS_INSN(abcd_reg)
DISAS_INSN(abcd_mem)
{
- TCGv src, dest, addr;
+ TCGv src, dest;
gen_flush_flags(s); /* !Z is sticky */
@@ -1835,11 +1835,11 @@ DISAS_INSN(abcd_mem)
src = gen_ea_mode(env, s, 4, REG(insn, 0), OS_BYTE,
NULL_QREG, NULL, EA_LOADU, IS_USER(s));
dest = gen_ea_mode(env, s, 4, REG(insn, 9), OS_BYTE,
- NULL_QREG, &addr, EA_LOADU, IS_USER(s));
+ NULL_QREG, NULL, EA_LOADU, IS_USER(s));
bcd_add(dest, src);
- gen_ea_mode(env, s, 4, REG(insn, 9), OS_BYTE, dest, &addr,
+ gen_ea_mode(env, s, 4, REG(insn, 9), OS_BYTE, dest, NULL,
EA_STORE, IS_USER(s));
bcd_flags(dest);
@@ -1863,7 +1863,7 @@ DISAS_INSN(sbcd_reg)
DISAS_INSN(sbcd_mem)
{
- TCGv src, dest, addr;
+ TCGv src, dest;
gen_flush_flags(s); /* !Z is sticky */
@@ -1872,11 +1872,11 @@ DISAS_INSN(sbcd_mem)
src = gen_ea_mode(env, s, 4, REG(insn, 0), OS_BYTE,
NULL_QREG, NULL, EA_LOADU, IS_USER(s));
dest = gen_ea_mode(env, s, 4, REG(insn, 9), OS_BYTE,
- NULL_QREG, &addr, EA_LOADU, IS_USER(s));
+ NULL_QREG, NULL, EA_LOADU, IS_USER(s));
bcd_sub(dest, src);
- gen_ea_mode(env, s, 4, REG(insn, 9), OS_BYTE, dest, &addr,
+ gen_ea_mode(env, s, 4, REG(insn, 9), OS_BYTE, dest, NULL,
EA_STORE, IS_USER(s));
bcd_flags(dest);
--
2.26.3
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... Thanks, Laurent
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). Thanks, Laurent
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?
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