https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107072
Bug ID: 107072
Summary: Analyzer call summarization not taking into account
side-effects of calls
Product: gcc
Version: 13.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: analyzer
Assignee: dmalcolm at gcc dot gnu.org
Reporter: dmalcolm at gcc dot gnu.org
Blocks: 99390, 107060
Target Milestone: ---
Created attachment 53637
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=53637&action=edit
Reproducer reduced from PR 107060
-fanalyzer-call-summaries doesn't seem to be taking account of the side-effects
of calls; it emit lots of -Wanalyzer-use-of-uninitialized-value false positives
on the reproducer for PR 107060.
Am attaching a minimized version, which emits these false positives:
$ ./xgcc -B. -S -fanalyzer ../../src/uninit.c -fanalyzer-call-summaries
../../src/uninit.c: In function ‘fetch_string_char_advance’:
../../src/uninit.c:52:7: warning: use of uninitialized value ‘chlen’ [CWE-457]
[-Wanalyzer-use-of-uninitialized-value]
52 | b += chlen;
| ^~
‘fetch_string_char_advance’: events 1-5
|
| 49 | if (STRING_MULTIBYTE(string)) {
| | ~
| | |
| | (3) following ‘true’ branch...
| 50 | int chlen;
| | ^~~~~
| | |
| | (1) region created on stack here
| | (2) capacity: 4 bytes
| 51 | output = string_char_and_length(chp, &chlen);
| | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| | |
| | (4) ...to here
| 52 | b += chlen;
| | ~~
| | |
| | (5) use of uninitialized value ‘chlen’ here
|
../../src/uninit.c: In function ‘fetch_string_char_as_multibyte_advance’:
../../src/uninit.c:70:7: warning: use of uninitialized value ‘chlen’ [CWE-457]
[-Wanalyzer-use-of-uninitialized-value]
70 | b += chlen;
| ^~
‘fetch_string_char_as_multibyte_advance’: events 1-5
|
| 67 | if (STRING_MULTIBYTE(string)) {
| | ~
| | |
| | (3) following ‘true’ branch...
| 68 | int chlen;
| | ^~~~~
| | |
| | (1) region created on stack here
| | (2) capacity: 4 bytes
| 69 | output = string_char_and_length(chp, &chlen);
| | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| | |
| | (4) ...to here
| 70 | b += chlen;
| | ~~
| | |
| | (5) use of uninitialized value ‘chlen’ here
|
...despite string_char_and_length writing back to chlen (aka *length) on every
possible outcome.
Referenced Bugs:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99390
[Bug 99390] [meta-bug] tracker bug for call summaries in -fanalyzer
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107060
[Bug 107060] -fanalyzer unbearably slow when compiling GNU Emacs
