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<p>In addition to my previous letter. I'm very concerned that we may have no chance to analyze a big chunk of code in this case:<br>
</p>
<blockquote style="margin: 0 0 0 40px; border: none; padding: 0px;">
<div><span style="font-family: Consolas, monospace; font-size: 9pt;"></span></div>
<div><span style="font-size: 9pt;"><span style="font-family: Consolas, monospace;"><span style="font-family: Consolas, monospace;">void clang_analyzer_warnIfReached();</span></span><br style="font-family: Consolas, monospace;">
<span style="font-family: Consolas, monospace;"><span style="font-family: Consolas, monospace;">int f()</span></span><br style="font-family: Consolas, monospace;">
<span style="font-family: Consolas, monospace;"><span style="font-family: Consolas, monospace;">{</span></span><br style="font-family: Consolas, monospace;">
<span style="font-family: Consolas, monospace;"><span style="font-family: Consolas, monospace;"> int i = 0;</span></span><br style="font-family: Consolas, monospace;">
<span style="font-family: Consolas, monospace;"><span style="font-family: Consolas, monospace;"> for(int i = 0; i < 100; i++){</span></span><br style="font-family: Consolas, monospace;">
<span style="font-family: Consolas, monospace;"><span style="font-family: Consolas, monospace;"> if(i > 10){</span></span><br style="font-family: Consolas, monospace;">
<span style="font-family: Consolas, monospace;"><span style="font-family: Consolas, monospace;"> clang_analyzer_warnIfReached();</span></span><br style="font-family: Consolas, monospace;">
<span style="font-family: Consolas, monospace;"><span style="font-family: Consolas, monospace;"> // a lot of code will never be analyzed</span></span><br style="font-family: Consolas, monospace;">
<span style="font-family: Consolas, monospace;"><span style="font-family: Consolas, monospace;"> }</span></span><br style="font-family: Consolas, monospace;">
<span style="font-family: Consolas, monospace;"><span style="font-family: Consolas, monospace;"> }</span></span><br style="font-family: Consolas, monospace;">
<span style="font-family: Consolas, monospace;"><span style="font-family: Consolas, monospace;">}</span></span></span></div>
</blockquote>
<p>Why don't we analyze loop bodies as functions, just substitute a var `i` <span style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);">
with </span><span style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);">s</span><span style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);">ymbols(or
constraint ranges)</span> after reaching the limits, not generating a sinks instead?<br>
</p>
<p>Or there are somewhere already disscussed plans for improvement?<br>
</p>
<p><br>
</p>
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<div><b>Denys Petrov</b></div>
<div>Senior ó++ Developer | Kharkiv, Ukraine</div>
<div><br>
</div>
<div></div>
</div>
</div>
<div style="color: rgb(33, 33, 33);">
<hr tabindex="-1" style="display:inline-block; width:98%">
<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" color="#000000" style="font-size:11pt"><b>ïÔ:</b> Artem Dergachev <noqnoqneo@gmail.com><br>
<b>ïÔÐÒÁ×ÌÅÎÏ:</b> 28 ÉÀÌÑ 2020 Ç. 22:34<br>
<b>ëÏÍÕ:</b> Denis Petrov; cfe-dev<br>
<b>ôÅÍÁ:</b> Re: [cfe-dev] [analyzer] How to analyzer the code after an indefinite loop?</font>
<div> </div>
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<div>Here's how you can find this out with the help of ExprInspection:<br>
<br>
<br>
$ cat test.c<br>
<br>
int f(int x, int flag)<br>
{<br>
int i = 0;<br>
while(i < x)<br>
i++;<br>
<br>
clang_analyzer_warnIfReached();<br>
}<br>
<br>
<br>
$ clang --analyze -Xclang -analyzer-checker=debug.ExprInspection test.c<br>
<br>
test.c:7:3: warning: REACHABLE [debug.ExprInspection]<br>
clang_analyzer_warnIfReached();<br>
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~<br>
1 warning generated.<br>
<br>
<br>
Here's a slightly more interesting experiment:<br>
<br>
<br>
$ cat test.c<br>
<br>
int f(int x, int flag)<br>
{<br>
int i = 0;<br>
while(i < x)<br>
i++;<br>
<br>
if (flag) {<br>
clang_analyzer_warnIfReached();<br>
clang_analyzer_numTimesReached();<br>
return i;<br>
} else {<br>
clang_analyzer_warnIfReached();<br>
clang_analyzer_numTimesReached();<br>
return 0;<br>
}<br>
}<br>
<br>
<br>
$ clang --analyze -Xclang -analyzer-checker=debug.ExprInspection test.c<br>
<br>
test.c:8:5: warning: REACHABLE [debug.ExprInspection]<br>
clang_analyzer_warnIfReached();<br>
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~<br>
test.c:9:5: warning: 4 [debug.ExprInspection]<br>
clang_analyzer_numTimesReached();<br>
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~<br>
test.c:12:5: warning: REACHABLE [debug.ExprInspection]<br>
clang_analyzer_warnIfReached();<br>
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~<br>
test.c:13:5: warning: 1 [debug.ExprInspection]<br>
clang_analyzer_numTimesReached();<br>
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~<br>
4 warnings generated.<br>
<br>
<br>
Will you be able to figure out why is one branch reached 4 times while the other branch is reached only once? You can find all your answers on the exploded graph dump.<br>
<br>
<br>
<div class="moz-cite-prefix">On 7/28/20 5:59 AM, Denis Petrov via cfe-dev wrote:<br>
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<p>Hi, community!<br>
</p>
<p><br>
</p>
<p>A quick question.<br>
</p>
<p><br>
</p>
<p>Is CSA Core able to analyze the code after some indefinite loop?<br>
</p>
<p>E.g.<br>
</p>
<div><span style="font-family:Consolas,monospace; font-size:9pt"><span style="font-family:Consolas,monospace"><span style="font-family:Consolas,monospace"><span style="font-family:Consolas,monospace">void f(int x)</span></span></span></span></div>
<div><span style="font-family:Consolas,monospace; font-size:9pt"><span style="font-family:Consolas,monospace"><span style="font-family:Consolas,monospace"><span style="font-family:Consolas,monospace"><span style="font-family:Consolas,monospace">{</span></span></span></span><br style="font-family:Consolas,monospace">
</span></div>
<div><span style="font-family:Consolas,monospace; font-size:9pt"><span style="font-family:Consolas,monospace"><span style="font-family:Consolas,monospace"><span style="font-family:Consolas,monospace"><span style="font-family:Consolas,monospace"> int i = 0;</span></span></span></span><br style="font-family:Consolas,monospace">
</span></div>
<div><span style="font-family:Consolas,monospace; font-size:9pt"><span style="font-family:Consolas,monospace"><span style="font-family:Consolas,monospace"><span style="font-family:Consolas,monospace"> while(i < x)</span></span></span></span></div>
<div><span style="font-size:9pt"><span style="font-family:Consolas,monospace"><span style="font-family:Consolas,monospace"> i++;</span></span><br style="font-family:Consolas,monospace">
</span></div>
<div><span style="font-family:Consolas,monospace; font-size:9pt"><span style="font-family:Consolas,monospace"><span style="font-family:Consolas,monospace"><span style="font-family:Consolas,monospace"><span style="font-family:Consolas,monospace"> // Interested
in some code here!!</span></span></span></span><br style="font-family:Consolas,monospace">
</span></div>
<div><span style="font-family:Consolas,monospace; font-size:9pt"><span style="font-family:Consolas,monospace"><span style="font-family:Consolas,monospace"><span style="font-family:Consolas,monospace">}</span></span></span></span><br>
</div>
<p><br>
</p>
<p>I found that Exploded graph grows going through the loop 4 times and then stops to analyze the code further.<br>
</p>
<p>P.S. I know about -<span style="color:rgb(36,41,46); font-family:SFMono-Regular,Consolas,"Liberation Mono",Menlo,monospace; font-size:12px; white-space:pre; background-color:rgb(255,255,255)">analyzer-max-loop</span>(4).<br>
</p>
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<div><b>Denys Petrov</b></div>
<div>Senior ó++ Developer | Kharkiv, Ukraine</div>
<div><br>
</div>
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