https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105838
Bug ID: 105838
Summary: g++ 12.1.0 runs out of memory or time when building
const std::vector of std::strings
Product: gcc
Version: 12.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: eisjmbjdfcukqlaely at nthrl dot com
Target Milestone: ---
Created attachment 53078
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=53078&action=edit
Output of "g++ -E tmp_in.cpp > tmp_in.ii"
While porting a Wordle-like game from an interpreted language to C++
(ironically, in an attempt at getting better performance from a compiled
language!) it was found that g++ 12.1.0 cannot even initialize a const
std::vector of known fixed-length words.
Here is g++ 12.1.0 running out of memory (16GB RAM + 8GB swap) with -O1, after
about a minute:
```
$ g++ tmp_in.cpp -O1
g++: fatal error: Killed signal terminated program cc1plus
compilation terminated.
```
If optimization is disabled in an attempt to save memory, g++ takes
unreasonably long and gets killed after 300 seconds:
```
$ timeout 300 g++ tmp_in.cpp # gets killed after 300 seconds with no a.out
```
Output of g++ -v:
```
$ g++ -v
Using built-in specs.
COLLECT_GCC=g++
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-pc-linux-gnu/12.1.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: /build/gcc/src/gcc/configure
--enable-languages=c,c++,ada,fortran,go,lto,objc,obj-c++ --enable-bootstrap
--prefix=/usr --libdir=/usr/lib --libexecdir=/usr/lib --mandir=/usr/share/man
--infodir=/usr/share/info --with-bugurl=https://bugs.archlinux.org/
--with-linker-hash-style=gnu --with-system-zlib --enable-__cxa_atexit
--enable-cet=auto --enable-checking=release --enable-clocale=gnu
--enable-default-pie --enable-default-ssp --enable-gnu-indirect-function
--enable-gnu-unique-object --enable-linker-build-id --enable-lto
--enable-multilib --enable-plugin --enable-shared --enable-threads=posix
--disable-libssp --disable-libstdcxx-pch --disable-werror
--with-build-config=bootstrap-lto --enable-link-serialization=1
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 12.1.0 (GCC)
```
For comparison, here is clang++ 13.0.1 building in about 5 seconds without
optimization:
```
$ /usr/bin/time --verbose clang++ tmp_in.cpp
tmp_in.cpp:1797:19: warning: format specifies type 'int' but the argument has
type 'std::vector::size_type' (aka 'unsigned long') [-Wformat]
printf ("%d\n", lst.size());
~~ ^~~~~~~~~~
%zu
1 warning generated.
Command being timed: "clang++ tmp_in.cpp"
User time (seconds): 4.69
System time (seconds): 0.17
$ ./a.out
21437
```
If optimization is enabled with -O1, clang++ 13.0.1 still successfully compiles
it, though it takes just over 2 minutes and almost 4GB RAM:
```
$ /usr/bin/time --verbose clang++ tmp_in.cpp -O1
tmp_in.cpp:1797:19: warning: format specifies type 'int' but the argument has
type 'std::vector::size_type' (aka 'unsigned long') [-Wformat]
printf ("%d\n", lst.size());
~~ ^~~~~~~~~~
%zu
1 warning generated.
Command being timed: "clang++ tmp_in.cpp -O1"
User time (seconds): 125.31
System time (seconds): 0.81
Maximum resident set size (kbytes): 3675076
$ ./a.out
21437
```
Output of clang++ -v for completeness:
```
clang++ -v
clang version 13.0.1
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/bin
Found candidate GCC installation:
/usr/bin/../lib/gcc/x86_64-pc-linux-gnu/12.1.0
Found candidate GCC installation:
/usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/12.1.0
Selected GCC installation: /usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/12.1.0
Candidate multilib: .;@m64
Candidate multilib: 32;@m32
Selected multilib: .;@m64
```
