https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67075
Bug ID: 67075
Summary: Infinite GC loop with ggc-min-expand=0
Product: gcc
Version: 4.8.4
Status: UNCONFIRMED
Severity: major
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: luke-jr+gccbugs at utopios dot org
Target Milestone: ---
Created attachment 36100
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=36100&action=edit
Preprocessed source code to reproduce loop, compressed
On a low-memory system, I "need" ggc-min-expand=0 to avoid swapping. However,
it appears there are cases where this can lead to an infinite loop of the
garbage collector, I presume because more than gcc-min-heapsize memory is
actually in use. I did not encounter this in GCC 4.4 or 4.5, but it may have
been coincidence, so I am uncertain whether this is a regression or not.
I am able to reproduce this consistently with the attached preprocessed source,
and either one of these build commands:
armv7a-hardfloat-linux-gnueabi-g++ -c -O2 -pipe -mcpu=cortex-a8 -mfpu=vfpv3
-mfloat-abi=hard -mthumb -mthumb-interwork --param ggc-min-expand=0 --param
ggc-min-heapsize=32768 -fvisibility=hidden -fvisibility-inlines-hidden -Wall -W
-fPIC x.cpp
/usr/libexec/gcc/armv7a-hardfloat-linux-gnueabi/4.8.4/cc1plus -D_GNU_SOURCE
x.cpp -dumpbase x.cpp -da -mcpu=cortex-a8 -mfpu=vfpv3 -mfloat-abi=hard -mthumb
-mthumb-interwork -mtls-dialect=gnu -auxbase x -O2 -Wall -Wextra
-fvisibility=hidden -fvisibility-inlines-hidden -fPIC --param ggc-min-expand=0
--param ggc-min-heapsize=32768 -fstack-protector -o x.out
The latter of these verbosely prints:
<*free_lang_data> <visibility> <early_local_cleanups> {GC 32770k -> 32172k}
{GC 32770k -> 32480k} ............ (~forever)
