https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107060
Bug ID: 107060
Summary: -fanalyzer unbearably slow when compiling GNU Emacs
Product: gcc
Version: 12.2.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: analyzer
Assignee: dmalcolm at gcc dot gnu.org
Reporter: eggert at cs dot ucla.edu
Target Milestone: ---
Created attachment 53634
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=53634&action=edit
compressed source file that gcc -S -fanalyzer -O2 compiles verrrry slowly
For a while, gcc -fanalyzer has been so unbearably slow when compiling GNU
Emacs that we Emacs developers disable -fanalyzer unless the builder
specifically asks for it, which almost nobody does because it's sooo slow. I
haven't bothered to file a bug report because I assumed the analyzer code was
still being worked on and tuned, but I just now tried -fanalyzer again on a new
machine and it was still so slow that I am finally filing a bug report.
The biggest pole in the tent is when gcc compiles Emacs's xdisp.c file, which
is large for Emacs (38 Klines) but not that large. I am attaching the
preprocessed output as the file u.i.gz. Compile it with:
gzip -d u.i
gcc -S -fanalyzer -O2 u.i
On my older Fedora 36 desktop (AMD Phenom II X4 910e) with gcc (GCC) 12.2.1
20220819 (Red Hat 12.2.1-2) GCC takes 12 minutes 3 seconds, which is
ridiculous. On my newer Ubuntu 22.04 desktop (Intel Xeon W-1350) with gcc-12
(Ubuntu 12.1.0-2ubuntu1~22.04) 12.1.0, GCC takes 3 minutes 43 seconds, which is
still way too long.
Could you please take a look at this test case and see what's slowing down
-fanalyzer? If you can't improve GCC, is there some easy way we Emacs
developers can rewrite the source to avoid the performance issue, whatever it
is? Thanks.
