https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109058
Bug ID: 109058
Summary: RFE: analyzer should elide repeated calls to strcmp in
execution paths
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
Target Milestone: ---
Seen on a diagnostic in haproxy's cfgparse-global.c: cfg_parse_global
Consider:
--------------------------------------------------------------------------
#include <string.h>
#include "analyzer-decls.h"
int test (char **args)
{
if (strcmp (args[0], "opt-001") == 0) {
do_opt (1);
} else if (strcmp (args[0], "opt-002") == 0) {
do_opt (2);
} else if (strcmp (args[0], "opt-003") == 0) {
do_opt (3);
} else if (strcmp (args[0], "opt-004") == 0) {
do_opt (4);
} else if (strcmp (args[0], "opt-005") == 0) {
do_opt (5);
} else if (strcmp (args[0], "opt-006") == 0) {
do_opt (6);
} else if (strcmp (args[0], "opt-007") == 0) {
do_opt (7);
} else if (strcmp (args[0], "opt-008") == 0) {
do_opt (8);
} else if (strcmp (args[0], "opt-009") == 0) {
do_opt (9);
} else if (strcmp (args[0], "opt-010") == 0) {
do_opt (10);
__analyzer_dump_path ();
}
}
--------------------------------------------------------------------------
for which we currently emit:
--------------------------------------------------------------------------
../../src/gcc/testsuite/gcc.dg/analyzer/strcmp-path-1.c:27:5: note: path
27 | __analyzer_dump_path ();
| ^~~~~~~~~~~~~~~~~~~~~~~
‘test’: events 1-21
|
| 7 | if (strcmp (args[0], "opt-001") == 0) {
| | ^
| | |
| | (1) following ‘false’ branch (when the strings are
non-equal)...
| 8 | do_opt (1);
| 9 | } else if (strcmp (args[0], "opt-002") == 0) {
| | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| | ||
| | |(2) ...to here
| | (3) following ‘false’ branch (when the strings are
non-equal)...
| 10 | do_opt (2);
| 11 | } else if (strcmp (args[0], "opt-003") == 0) {
| | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| | ||
| | |(4) ...to here
| | (5) following ‘false’ branch (when the strings are
non-equal)...
| 12 | do_opt (3);
| 13 | } else if (strcmp (args[0], "opt-004") == 0) {
| | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| | ||
| | |(6) ...to here
| | (7) following ‘false’ branch (when the strings are
non-equal)...
| 14 | do_opt (4);
| 15 | } else if (strcmp (args[0], "opt-005") == 0) {
| | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| | ||
| | |(8) ...to here
| | (9) following ‘false’ branch (when the strings are
non-equal)...
| 16 | do_opt (5);
| 17 | } else if (strcmp (args[0], "opt-006") == 0) {
| | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| | ||
| | |(10) ...to here
| | (11) following ‘false’ branch (when the strings are
non-equal)...
| 18 | do_opt (6);
| 19 | } else if (strcmp (args[0], "opt-007") == 0) {
| | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| | ||
| | |(12) ...to here
| | (13) following ‘false’ branch (when the strings are
non-equal)...
| 20 | do_opt (7);
| 21 | } else if (strcmp (args[0], "opt-008") == 0) {
| | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| | ||
| | |(14) ...to here
| | (15) following ‘false’ branch (when the strings are
non-equal)...
| 22 | do_opt (8);
| 23 | } else if (strcmp (args[0], "opt-009") == 0) {
| | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| | ||
| | |(16) ...to here
| | (17) following ‘false’ branch (when the strings are
non-equal)...
| 24 | do_opt (9);
| 25 | } else if (strcmp (args[0], "opt-010") == 0) {
| | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| | ||
| | |(18) ...to here
| | (19) following ‘true’ branch (when the strings are
equal)...
| 26 | do_opt (10);
| | ~~~~~~~~~~~
| | |
| | (20) ...to here
| 27 | __analyzer_dump_path ();
| | ~~~~~~~~~~~~~~~~~~~~~~~
| | |
| | (21) here
|
--------------------------------------------------------------------------
We should probably elide all the repeated :
following ‘false’ branch (when the strings are non-equal)...
...to here
events before the:
following ‘true’ branch (when the strings are equal)...
assuming that all they're checking the same string against a series of possible
values.
This would simplify the execution path to just:
--------------------------------------------------------------------------
../../src/gcc/testsuite/gcc.dg/analyzer/strcmp-path-1.c:27:5: note: path
27 | __analyzer_dump_path ();
| ^~~~~~~~~~~~~~~~~~~~~~~
‘test’: events 1-3
|
| 25 | } else if (strcmp (args[0], "opt-010") == 0) {
| | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| | |
| | (1) following ‘true’ branch (when the strings are
equal)...
| 26 | do_opt (10);
| | ~~~~~~~~~~~
| | |
| | (2) ...to here
| 27 | __analyzer_dump_path ();
| | ~~~~~~~~~~~~~~~~~~~~~~~
| | |
| | (3) here
|
--------------------------------------------------------------------------
