Re: [PATCH] arm/translate-a64: fix uninitialized variable warning
On 1/6/2020 10:15 AM, Richard Henderson wrote:
> On 1/6/20 11:57 AM, pannengy...@huawei.com wrote:
>> From: Pan Nengyuan
>>
>> Fixes:
>> target/arm/translate-a64.c: In function 'disas_crypto_three_reg_sha512':
>> target/arm/translate-a64.c:13625:9: error: 'genfn' may be used uninitialized
>> in this function [-Werror=maybe-uninitialized]
>> genfn(tcg_rd_ptr, tcg_rn_ptr, tcg_rm_ptr);
>> ^
>> qemu/target/arm/translate-a64.c:13609:8: error: 'feature' may be used
>> uninitialized in this function [-Werror=maybe-uninitialized]
>> if (!feature) {
>>
>> Reported-by: Euler Robot
>> Signed-off-by: Pan Nengyuan
>> Cc: Peter Maydell
>
> Are you compiling with reduced optimization? The compiler should be able to
> prove that these variables are initialized. It certainly does with -O2, on
> all
> known gcc versions.
Yes, I compile it with optimization flags (-O2) and get this warnings. The gcc
version is 8.2.1.
>
> Perhaps a better fix is to add a
>
> default:
> g_assert_not_reached();
>
> entry to the o == 0 switch. Though of course opcode must be in [0-3], based
> on
> the extraction mask, so a default label isn't actually reachable. But that's
> the only path I can see for which incomplete optimization would fail to prove
> initializatio
Yes, a default label is a better way.
>
> r~
>
Re: [PATCH] arm/translate-a64: fix uninitialized variable warning
On 1/6/20 11:57 AM, pannengy...@huawei.com wrote:
> From: Pan Nengyuan
>
> Fixes:
> target/arm/translate-a64.c: In function 'disas_crypto_three_reg_sha512':
> target/arm/translate-a64.c:13625:9: error: 'genfn' may be used uninitialized
> in this function [-Werror=maybe-uninitialized]
> genfn(tcg_rd_ptr, tcg_rn_ptr, tcg_rm_ptr);
> ^
> qemu/target/arm/translate-a64.c:13609:8: error: 'feature' may be used
> uninitialized in this function [-Werror=maybe-uninitialized]
> if (!feature) {
>
> Reported-by: Euler Robot
> Signed-off-by: Pan Nengyuan
> Cc: Peter Maydell
Are you compiling with reduced optimization? The compiler should be able to
prove that these variables are initialized. It certainly does with -O2, on all
known gcc versions.
Perhaps a better fix is to add a
default:
g_assert_not_reached();
entry to the o == 0 switch. Though of course opcode must be in [0-3], based on
the extraction mask, so a default label isn't actually reachable. But that's
the only path I can see for which incomplete optimization would fail to prove
initialization.
r~
[PATCH] arm/translate-a64: fix uninitialized variable warning
From: Pan Nengyuan
Fixes:
target/arm/translate-a64.c: In function 'disas_crypto_three_reg_sha512':
target/arm/translate-a64.c:13625:9: error: 'genfn' may be used uninitialized in
this function [-Werror=maybe-uninitialized]
genfn(tcg_rd_ptr, tcg_rn_ptr, tcg_rm_ptr);
^
qemu/target/arm/translate-a64.c:13609:8: error: 'feature' may be used
uninitialized in this function [-Werror=maybe-uninitialized]
if (!feature) {
Reported-by: Euler Robot
Signed-off-by: Pan Nengyuan
Cc: Peter Maydell
---
target/arm/translate-a64.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/target/arm/translate-a64.c b/target/arm/translate-a64.c
index d4bebbe629..211e3d813f 100644
--- a/target/arm/translate-a64.c
+++ b/target/arm/translate-a64.c
@@ -13564,8 +13564,8 @@ static void disas_crypto_three_reg_sha512(DisasContext
*s, uint32_t insn)
int rm = extract32(insn, 16, 5);
int rn = extract32(insn, 5, 5);
int rd = extract32(insn, 0, 5);
-bool feature;
-CryptoThreeOpFn *genfn;
+bool feature = false;
+CryptoThreeOpFn *genfn = NULL;
if (o == 0) {
switch (opcode) {
--
2.21.0.windows.1
