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* [Bug c++/104081] New: Variable optimized out despite -Og
@ 2022-01-18 8:32 matthias at urlichs dot de
2022-01-18 8:34 ` [Bug c++/104081] " matthias at urlichs dot de
` (4 more replies)
0 siblings, 5 replies; 6+ messages in thread
From: matthias at urlichs dot de @ 2022-01-18 8:32 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104081
Bug ID: 104081
Summary: Variable optimized out despite -Og
Product: gcc
Version: 12.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: matthias at urlichs dot de
Target Milestone: ---
I expect the optimizer, when confronted with "-Og", to keep my variables
debuggable.
(I also expect (of me) to not make terminally stupid mistakes like the one
exhibited here, but that's a different problem …)
// "data" is a std::string_view
(gdb) l
19 if(data.length() == 0)
20 throw_invalid("empty",data);
21 }
22 for (const auto& c : data) {
23 if ('0' < c || '9' > c)
24 throw_invalid("not a number",data);
25 val = val*10 + c-'0';
26 }
27 if(neg)
28 val = -val;
(gdb) p data
$1 = <optimized out>
(gdb) p c
$2 = <optimized out>
(gdb) q
Options: g++-12 -march=native -Og -g -xc++ -std=c++17 …
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug c++/104081] Variable optimized out despite -Og
2022-01-18 8:32 [Bug c++/104081] New: Variable optimized out despite -Og matthias at urlichs dot de
@ 2022-01-18 8:34 ` matthias at urlichs dot de
2022-01-18 8:37 ` [Bug middle-end/104081] " pinskia at gcc dot gnu.org
` (3 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: matthias at urlichs dot de @ 2022-01-18 8:34 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104081
--- Comment #1 from Matthias Urlichs <matthias at urlichs dot de> ---
current line is 24, after "throw_invalid" has called abort()
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug middle-end/104081] Variable optimized out despite -Og
2022-01-18 8:32 [Bug c++/104081] New: Variable optimized out despite -Og matthias at urlichs dot de
2022-01-18 8:34 ` [Bug c++/104081] " matthias at urlichs dot de
@ 2022-01-18 8:37 ` pinskia at gcc dot gnu.org
2022-01-18 8:51 ` matthias at urlichs dot de
` (2 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: pinskia at gcc dot gnu.org @ 2022-01-18 8:37 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104081
--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Can you attach the original source?
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug middle-end/104081] Variable optimized out despite -Og
2022-01-18 8:32 [Bug c++/104081] New: Variable optimized out despite -Og matthias at urlichs dot de
2022-01-18 8:34 ` [Bug c++/104081] " matthias at urlichs dot de
2022-01-18 8:37 ` [Bug middle-end/104081] " pinskia at gcc dot gnu.org
@ 2022-01-18 8:51 ` matthias at urlichs dot de
2022-01-18 9:46 ` rguenth at gcc dot gnu.org
2022-01-18 10:13 ` matthias at urlichs dot de
4 siblings, 0 replies; 6+ messages in thread
From: matthias at urlichs dot de @ 2022-01-18 8:51 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104081
--- Comment #3 from Matthias Urlichs <matthias at urlichs dot de> ---
Sure.
gcc -Og -g -std=c++17 -lstdc++ /tmp/test.cpp
#include <string_view>
#include <string>
void throw_invalid(const char *a, std::string_view b) {
(void)a; (void)b;
throw;
}
int64_t str_atoi(std::string_view data)
{
const std::string_view odata = data;
int64_t val = 0;
bool neg;
if(data.length() == 0)
throw_invalid("empty",odata);
neg = data.front() == '-';
if(neg) {
data.remove_prefix(1);
if(data.length() == 0)
throw_invalid("empty",data);
}
for (const auto& c : data) {
if (c < '0' || '9' < c)
throw_invalid("not a number",odata);
val = val*10 + c-'0';
}
if(neg)
val = -val;
return val;
}
int main() {
volatile int x = str_atoi("nope");
}
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug middle-end/104081] Variable optimized out despite -Og
2022-01-18 8:32 [Bug c++/104081] New: Variable optimized out despite -Og matthias at urlichs dot de
` (2 preceding siblings ...)
2022-01-18 8:51 ` matthias at urlichs dot de
@ 2022-01-18 9:46 ` rguenth at gcc dot gnu.org
2022-01-18 10:13 ` matthias at urlichs dot de
4 siblings, 0 replies; 6+ messages in thread
From: rguenth at gcc dot gnu.org @ 2022-01-18 9:46 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104081
--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
when I break at line 24 the data is still there but it's lost when unwinding
frames from the SIGABRT:
(gdb) bt
#0 0x00007ffff70cc18b in raise () from /lib64/libc.so.6
#1 0x00007ffff70cd585 in abort () from /lib64/libc.so.6
#2 0x00007ffff7a66016 in ?? () from /usr/lib64/libstdc++.so.6
#3 0x00007ffff7a718dc in ?? () from /usr/lib64/libstdc++.so.6
#4 0x00007ffff7a71947 in std::terminate() () from /usr/lib64/libstdc++.so.6
#5 0x00007ffff7a71c3d in __cxa_rethrow () from /usr/lib64/libstdc++.so.6
#6 0x000000000040055f in throw_invalid (a=a@entry=0x4006aa "not a number",
b=...) at t.C:6
#7 0x00000000004005f8 in str_atoi (data=...) at t.C:26
#8 0x0000000000400610 in main () at /usr/include/c++/11/bits/char_traits.h:371
is that what you mean?
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug middle-end/104081] Variable optimized out despite -Og
2022-01-18 8:32 [Bug c++/104081] New: Variable optimized out despite -Og matthias at urlichs dot de
` (3 preceding siblings ...)
2022-01-18 9:46 ` rguenth at gcc dot gnu.org
@ 2022-01-18 10:13 ` matthias at urlichs dot de
4 siblings, 0 replies; 6+ messages in thread
From: matthias at urlichs dot de @ 2022-01-18 10:13 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104081
--- Comment #5 from Matthias Urlichs <matthias at urlichs dot de> ---
> when I break at line 24 the data is still there but it's lost
> when unwinding frames from the SIGABRT:
Yes, that's exactly the problem.
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2022-01-18 10:13 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
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2022-01-18 8:32 [Bug c++/104081] New: Variable optimized out despite -Og matthias at urlichs dot de
2022-01-18 8:34 ` [Bug c++/104081] " matthias at urlichs dot de
2022-01-18 8:37 ` [Bug middle-end/104081] " pinskia at gcc dot gnu.org
2022-01-18 8:51 ` matthias at urlichs dot de
2022-01-18 9:46 ` rguenth at gcc dot gnu.org
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