From: Yoshinori Sato <ysato@users.sourceforge.jp>
To: Pan Nengyuan <pannengyuan@huawei.com>
Cc: zhang.zhanghailiang@huawei.com, qemu-devel@nongnu.org,
euler.robot@huawei.com
Subject: Re: [PATCH] op_helper: fix some compile warnings
Date: Mon, 20 Apr 2020 17:50:32 +0900 [thread overview]
Message-ID: <87o8rmv8vb.wl-ysato@users.sourceforge.jp> (raw)
In-Reply-To: <20200420054959.8082-1-pannengyuan@huawei.com>
On Mon, 20 Apr 2020 14:49:59 +0900,
Pan Nengyuan wrote:
>
> We got the following compile-time warnings(gcc7.3):
> /mnt/sdb//qemu/target/rx/op_helper.c: In function ‘helper_scmpu’:
> /mnt/sdb/qemu/target/rx/op_helper.c:213:24: error: ‘tmp1’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
> env->psw_c = (tmp0 >= tmp1);
> ~~~~~~^~~~~~~~
> /mnt/sdb/qemu/target/rx/op_helper.c:213:24: error: ‘tmp0’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
> /mnt/sdb/qemu/target/rx/op_helper.c: In function ‘helper_suntil’:
> /mnt/sdb/qemu/target/rx/op_helper.c:299:23: error: ‘tmp’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
> env->psw_c = (tmp <= env->regs[2]);
> ~~~~~^~~~~~~~~~~~~~~~
> /mnt/sdb/qemu/target/rx/op_helper.c: In function ‘helper_swhile’:
> /mnt/sdb/qemu/target/rx/op_helper.c:318:23: error: ‘tmp’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
> env->psw_c = (tmp <= env->regs[2]);
>
> Actually, it looks like a false-positive because it will enter the body of while loop and init it for the first time.
> Let's change 'while' to 'do .. while' to avoid it.
OK.
> Reported-by: Euler Robot <euler.robot@huawei.com>
> Signed-off-by: Pan Nengyuan <pannengyuan@huawei.com>
> ---
> target/rx/op_helper.c | 12 ++++++------
> 1 file changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/target/rx/op_helper.c b/target/rx/op_helper.c
> index f89d294f2b..b612ab1da8 100644
> --- a/target/rx/op_helper.c
> +++ b/target/rx/op_helper.c
> @@ -201,14 +201,14 @@ void helper_scmpu(CPURXState *env)
> if (env->regs[3] == 0) {
> return;
> }
> - while (env->regs[3] != 0) {
> + do {
> tmp0 = cpu_ldub_data_ra(env, env->regs[1]++, GETPC());
> tmp1 = cpu_ldub_data_ra(env, env->regs[2]++, GETPC());
> env->regs[3]--;
> if (tmp0 != tmp1 || tmp0 == '\0') {
> break;
> }
> - }
> + } while (env->regs[3] != 0);
> env->psw_z = tmp0 - tmp1;
> env->psw_c = (tmp0 >= tmp1);
> }
> @@ -287,14 +287,14 @@ void helper_suntil(CPURXState *env, uint32_t sz)
> if (env->regs[3] == 0) {
> return ;
> }
> - while (env->regs[3] != 0) {
> + do {
> tmp = cpu_ldufn[sz](env, env->regs[1], GETPC());
> env->regs[1] += 1 << sz;
> env->regs[3]--;
> if (tmp == env->regs[2]) {
> break;
> }
> - }
> + } while (env->regs[3] != 0);
> env->psw_z = tmp - env->regs[2];
> env->psw_c = (tmp <= env->regs[2]);
> }
> @@ -306,14 +306,14 @@ void helper_swhile(CPURXState *env, uint32_t sz)
> if (env->regs[3] == 0) {
> return ;
> }
> - while (env->regs[3] != 0) {
> + do {
> tmp = cpu_ldufn[sz](env, env->regs[1], GETPC());
> env->regs[1] += 1 << sz;
> env->regs[3]--;
> if (tmp != env->regs[2]) {
> break;
> }
> - }
> + } while (env->regs[3] != 0);
> env->psw_z = env->regs[3];
> env->psw_c = (tmp <= env->regs[2]);
> }
> --
> 2.18.2
>
>
It looks different result in env->regs[3] is zero.
In such a case, nothing changes.
I think that the warning of the uninitialized variable
will disappear by fixing as follows.
From 5de0c54a970e01e96b41870252d0ea54ec61c540 Mon Sep 17 00:00:00 2001
From: Yoshinori Sato <ysato@users.sourceforge.jp>
Date: Mon, 20 Apr 2020 17:41:04 +0900
Subject: [PATCH] target/rx/op_helper: Fix uninitialized warning.
Signed-off-by: Yoshinori Sato <ysato@users.sourceforge.jp>
---
target/rx/op_helper.c | 101 ++++++++++++++++++++----------------------
1 file changed, 49 insertions(+), 52 deletions(-)
diff --git a/target/rx/op_helper.c b/target/rx/op_helper.c
index f89d294f2b..f84f6c706c 100644
--- a/target/rx/op_helper.c
+++ b/target/rx/op_helper.c
@@ -284,38 +284,36 @@ void helper_suntil(CPURXState *env, uint32_t sz)
{
uint32_t tmp;
tcg_debug_assert(sz < 3);
- if (env->regs[3] == 0) {
- return ;
- }
- while (env->regs[3] != 0) {
- tmp = cpu_ldufn[sz](env, env->regs[1], GETPC());
- env->regs[1] += 1 << sz;
- env->regs[3]--;
- if (tmp == env->regs[2]) {
- break;
+ if (env->regs[3] > 0) {
+ while (env->regs[3] != 0) {
+ tmp = cpu_ldufn[sz](env, env->regs[1], GETPC());
+ env->regs[1] += 1 << sz;
+ env->regs[3]--;
+ if (tmp == env->regs[2]) {
+ break;
+ }
}
+ env->psw_z = tmp - env->regs[2];
+ env->psw_c = (tmp <= env->regs[2]);
}
- env->psw_z = tmp - env->regs[2];
- env->psw_c = (tmp <= env->regs[2]);
}
void helper_swhile(CPURXState *env, uint32_t sz)
{
uint32_t tmp;
tcg_debug_assert(sz < 3);
- if (env->regs[3] == 0) {
- return ;
- }
- while (env->regs[3] != 0) {
- tmp = cpu_ldufn[sz](env, env->regs[1], GETPC());
- env->regs[1] += 1 << sz;
- env->regs[3]--;
- if (tmp != env->regs[2]) {
- break;
+ if (env->regs[3] > 0) {
+ while (env->regs[3] != 0) {
+ tmp = cpu_ldufn[sz](env, env->regs[1], GETPC());
+ env->regs[1] += 1 << sz;
+ env->regs[3]--;
+ if (tmp != env->regs[2]) {
+ break;
+ }
}
+ env->psw_z = env->regs[3];
+ env->psw_c = (tmp <= env->regs[2]);
}
- env->psw_z = env->regs[3];
- env->psw_c = (tmp <= env->regs[2]);
}
/* accumlator operations */
@@ -325,40 +323,39 @@ void helper_rmpa(CPURXState *env, uint32_t sz)
int32_t result_h;
int64_t tmp0, tmp1;
- if (env->regs[3] == 0) {
- return;
- }
- result_l = env->regs[5];
- result_l <<= 32;
- result_l |= env->regs[4];
- result_h = env->regs[6];
- env->psw_o = 0;
+ if (env->regs[3] > 0) {
+ result_l = env->regs[5];
+ result_l <<= 32;
+ result_l |= env->regs[4];
+ result_h = env->regs[6];
+ env->psw_o = 0;
- while (env->regs[3] != 0) {
- tmp0 = cpu_ldfn[sz](env, env->regs[1], GETPC());
- tmp1 = cpu_ldfn[sz](env, env->regs[2], GETPC());
- tmp0 *= tmp1;
- prev = result_l;
- result_l += tmp0;
- /* carry / bollow */
- if (tmp0 < 0) {
- if (prev > result_l) {
- result_h--;
- }
- } else {
- if (prev < result_l) {
- result_h++;
+ while (env->regs[3] != 0) {
+ tmp0 = cpu_ldfn[sz](env, env->regs[1], GETPC());
+ tmp1 = cpu_ldfn[sz](env, env->regs[2], GETPC());
+ tmp0 *= tmp1;
+ prev = result_l;
+ result_l += tmp0;
+ /* carry / bollow */
+ if (tmp0 < 0) {
+ if (prev > result_l) {
+ result_h--;
+ }
+ } else {
+ if (prev < result_l) {
+ result_h++;
+ }
}
- }
- env->regs[1] += 1 << sz;
- env->regs[2] += 1 << sz;
+ env->regs[1] += 1 << sz;
+ env->regs[2] += 1 << sz;
+ }
+ env->psw_s = result_h;
+ env->psw_o = (result_h != 0 && result_h != -1) << 31;
+ env->regs[6] = result_h;
+ env->regs[5] = result_l >> 32;
+ env->regs[4] = result_l & 0xffffffff;
}
- env->psw_s = result_h;
- env->psw_o = (result_h != 0 && result_h != -1) << 31;
- env->regs[6] = result_h;
- env->regs[5] = result_l >> 32;
- env->regs[4] = result_l & 0xffffffff;
}
void helper_racw(CPURXState *env, uint32_t imm)
--
2.20.1
--
Yosinori Sato
next prev parent reply other threads:[~2020-04-20 8:51 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-20 5:49 [PATCH] op_helper: fix some compile warnings Pan Nengyuan
2020-04-20 3:13 ` no-reply
2020-04-20 8:50 ` Yoshinori Sato [this message]
2020-04-20 9:18 ` Pan Nengyuan
2020-04-20 9:49 ` Yoshinori Sato
2020-04-20 11:04 ` Pan Nengyuan
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