https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109194
Bug ID: 109194
Summary: GCC Static Analyzer does not know "a+3 > b+1" in the
true branch of "if (a > b) ", but it knows "a+2 > b+1"
Product: gcc
Version: 13.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: analyzer
Assignee: dmalcolm at gcc dot gnu.org
Reporter: geoffreydgr at icloud dot com
Target Milestone: ---
I found a problem that GCC Static Analyzer does not know "a+3 > b+1" (line 14)
in the true branch of "if (a > b) ", but it knows "a+2 > b+1" (line 13) .
I run gcc (trunk) with options `-fanalyzer -O0`.
See it live: https://godbolt.org/z/61nMxo7Kv
Input:
```c
#include <stdint.h>
#include <stdbool.h>
int main(int a, int b, int c, int d) {
if ((a>b)){
__analyzer_eval(a>b);
__analyzer_eval(!(a>b) == false);
__analyzer_eval(-a < -b);
__analyzer_eval(0-a < 0-b);
__analyzer_eval( a+0 > b+0);
__analyzer_eval( a+1 > b+1);
__analyzer_eval( a+2 > b+2);
__analyzer_eval( a+2 > b+1);
__analyzer_eval( a+3 > b+1);
__analyzer_eval( a*0 > b*0 == false);
__analyzer_eval( a*1 > b*1);
__analyzer_eval( a*2 > b*2);
__analyzer_eval( a*3 > b*2);
}
}
```
Output:
```bash
<source>: In function 'main':
<source>:6:9: warning: implicit declaration of function '__analyzer_eval'
[-Wimplicit-function-declaration]
6 | __analyzer_eval(a>b);
| ^~~~~~~~~~~~~~~
<source>:6:9: warning: TRUE
6 | __analyzer_eval(a>b);
| ^~~~~~~~~~~~~~~~~~~~
<source>:7:9: warning: TRUE
7 | __analyzer_eval(!(a>b) == false);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
<source>:8:9: warning: TRUE
8 | __analyzer_eval(-a < -b);
| ^~~~~~~~~~~~~~~~~~~~~~~~
<source>:9:9: warning: TRUE
9 | __analyzer_eval(0-a < 0-b);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~
<source>:10:9: warning: TRUE
10 | __analyzer_eval( a+0 > b+0);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~
<source>:11:9: warning: TRUE
11 | __analyzer_eval( a+1 > b+1);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~
<source>:12:9: warning: TRUE
12 | __analyzer_eval( a+2 > b+2);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~
<source>:13:9: warning: TRUE
13 | __analyzer_eval( a+2 > b+1);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~
<source>:14:9: warning: UNKNOWN
14 | __analyzer_eval( a+3 > b+1);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~
<source>:15:9: warning: TRUE
15 | __analyzer_eval( a*0 > b*0 == false);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
<source>:16:9: warning: TRUE
16 | __analyzer_eval( a*1 > b*1);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~
<source>:17:9: warning: TRUE
17 | __analyzer_eval( a*2 > b*2);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~
<source>:18:9: warning: TRUE
18 | __analyzer_eval( a*3 > b*2);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~
Compiler returned: 0
```
