<div dir="ltr"><font face="arial, helvetica, sans-serif">Hi,</font><div><font face="arial, helvetica, sans-serif"><br></font></div><div><font face="arial, helvetica, sans-serif">I have below code in C -</font></div><div><font face="arial, helvetica, sans-serif"><br></font></div><div>




<font face="arial, helvetica, sans-serif"><span></span> </font><p class="gmail-p1" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-weight:normal;font-stretch:normal;line-height:normal;color:rgb(0,0,0);background-color:rgb(255,255,255)">




<font face="arial, helvetica, sans-serif"><span></span> </font></p><p class="gmail-p1" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal"><font face="arial, helvetica, sans-serif"><span class="gmail-s1" style="font-variant-ligatures:no-common-ligatures;color:rgb(52,188,38)">int</span><span class="gmail-s2" style="font-variant-ligatures:no-common-ligatures"> main() {</span></font></p>
<p class="gmail-p1" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal"><font face="arial, helvetica, sans-serif"><span class="gmail-s2" style="font-variant-ligatures:no-common-ligatures"><span class="gmail-Apple-converted-space">  </span></span><span class="gmail-s1" style="font-variant-ligatures:no-common-ligatures;color:rgb(52,188,38)">double</span><span class="gmail-s2" style="font-variant-ligatures:no-common-ligatures"> x,y;</span></font></p>
<p class="gmail-p1" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal"><font face="arial, helvetica, sans-serif"><span class="gmail-s2" style="font-variant-ligatures:no-common-ligatures"><span class="gmail-Apple-converted-space">  </span>x = </span><span class="gmail-s3" style="font-variant-ligatures:no-common-ligatures;color:rgb(195,55,32)">1e16</span><span class="gmail-s2" style="font-variant-ligatures:no-common-ligatures">;</span></font></p>
<p class="gmail-p1" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal"><font face="arial, helvetica, sans-serif"><span class="gmail-s2" style="font-variant-ligatures:no-common-ligatures"><span class="gmail-Apple-converted-space">  </span>y = (x + </span><span class="gmail-s3" style="font-variant-ligatures:no-common-ligatures;color:rgb(195,55,32)">1</span><span class="gmail-s2" style="font-variant-ligatures:no-common-ligatures">) - x;</span></font></p>
<p class="gmail-p1" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal"><font face="arial, helvetica, sans-serif"><span class="gmail-s2" style="font-variant-ligatures:no-common-ligatures"><span class="gmail-Apple-converted-space">  </span>printf(</span><span class="gmail-s3" style="font-variant-ligatures:no-common-ligatures;color:rgb(195,55,32)">"y:</span><span class="gmail-s4" style="font-variant-ligatures:no-common-ligatures;color:rgb(213,59,211)">%e\n</span><span class="gmail-s3" style="font-variant-ligatures:no-common-ligatures;color:rgb(195,55,32)">"</span><span class="gmail-s2" style="font-variant-ligatures:no-common-ligatures">, y);</span></font></p>
<p class="gmail-p2" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal;color:rgb(205,121,35)"><font face="arial, helvetica, sans-serif"><span class="gmail-s5" style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)"><span class="gmail-Apple-converted-space">  </span></span><span class="gmail-s2" style="font-variant-ligatures:no-common-ligatures">return</span><span class="gmail-s5" style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)"> </span><span class="gmail-s3" style="font-variant-ligatures:no-common-ligatures;color:rgb(195,55,32)">0</span><span class="gmail-s5" style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)">;</span></font></p>
<p class="gmail-p1" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal"><span class="gmail-s2" style="font-variant-ligatures:no-common-ligatures"><font face="arial, helvetica, sans-serif">}</font></span></p>


<font face="arial, helvetica, sans-serif"><br></font><p></p><p class="gmail-p1" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-weight:normal;font-stretch:normal;line-height:normal;color:rgb(0,0,0);background-color:rgb(255,255,255)"><font face="arial, helvetica, sans-serif">llvm bitcode looks like this for this function -</font></p><p class="gmail-p1" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-weight:normal;font-stretch:normal;line-height:normal;color:rgb(0,0,0);background-color:rgb(255,255,255)"><font face="arial, helvetica, sans-serif"><br></font></p><p class="gmail-p1" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-weight:normal;font-stretch:normal;line-height:normal;color:rgb(0,0,0);background-color:rgb(255,255,255)">




<font face="arial, helvetica, sans-serif"><span></span> </font></p><p class="gmail-p1" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal"><span class="gmail-s1" style="font-variant-ligatures:no-common-ligatures"><font face="arial, helvetica, sans-serif">; Function Attrs: nounwind uwtable</font></span></p>
<p class="gmail-p1" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal"><font face="arial, helvetica, sans-serif"><span class="gmail-s1" style="font-variant-ligatures:no-common-ligatures">define dso_local i32 @main() local_unnamed_addr #</span><span class="gmail-s2" style="font-variant-ligatures:no-common-ligatures;color:rgb(195,55,32)">0</span><span class="gmail-s1" style="font-variant-ligatures:no-common-ligatures"> {</span></font></p>
<p class="gmail-p1" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal"><span class="gmail-s1" style="font-variant-ligatures:no-common-ligatures"><font face="arial, helvetica, sans-serif">entry:</font></span></p>
<p class="gmail-p1" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal"><font face="arial, helvetica, sans-serif"><span class="gmail-s1" style="font-variant-ligatures:no-common-ligatures"><span class="gmail-Apple-converted-space">  </span>%</span><span class="gmail-s3" style="font-variant-ligatures:no-common-ligatures;color:rgb(205,121,35)">call</span><span class="gmail-s1" style="font-variant-ligatures:no-common-ligatures"> = tail </span><span class="gmail-s3" style="font-variant-ligatures:no-common-ligatures;color:rgb(205,121,35)">call</span><span class="gmail-s1" style="font-variant-ligatures:no-common-ligatures"> i32 (i8*, ...) @printf(i8* getelementptr inbounds ([</span><span class="gmail-s2" style="font-variant-ligatures:no-common-ligatures;color:rgb(195,55,32)">4</span><span class="gmail-s1" style="font-variant-ligatures:no-common-ligatures"> x i8], [</span><span class="gmail-s2" style="font-variant-ligatures:no-common-ligatures;color:rgb(195,55,32)">4</span><span class="gmail-s1" style="font-variant-ligatures:no-common-ligatures"> x i8]* @.str, i64 </span><span class="gmail-s2" style="font-variant-ligatures:no-common-ligatures;color:rgb(195,55,32)">0</span><span class="gmail-s1" style="font-variant-ligatures:no-common-ligatures">, i64 </span><span class="gmail-s2" style="font-variant-ligatures:no-common-ligatures;color:rgb(195,55,32)">0</span><span class="gmail-s1" style="font-variant-ligatures:no-common-ligatures">), double </span><span class="gmail-s2" style="font-variant-ligatures:no-common-ligatures;color:rgb(195,55,32)">0</span><span class="gmail-s1" style="font-variant-ligatures:no-common-ligatures">.000000e+</span><span class="gmail-s2" style="font-variant-ligatures:no-common-ligatures;color:rgb(195,55,32)">00</span><span class="gmail-s1" style="font-variant-ligatures:no-common-ligatures">)</span></font></p>
<p class="gmail-p1" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal"><font face="arial, helvetica, sans-serif"><span class="gmail-s1" style="font-variant-ligatures:no-common-ligatures"><span class="gmail-Apple-converted-space">  </span>ret i32 </span><span class="gmail-s2" style="font-variant-ligatures:no-common-ligatures;color:rgb(195,55,32)">0</span></font></p>
<p class="gmail-p1" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal"><span class="gmail-s1" style="font-variant-ligatures:no-common-ligatures"><font face="arial, helvetica, sans-serif">}</font></span></p>


<font face="arial, helvetica, sans-serif"><br></font><p></p><p class="gmail-p1" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-weight:normal;font-stretch:normal;line-height:normal;color:rgb(0,0,0);background-color:rgb(255,255,255)"><font face="arial, helvetica, sans-serif">I am not able to understand how addition and subtraction are performed in this code. There is no fadd or fsub instruction. How llvm knows that result of y is 0? </font></p><p class="gmail-p1" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-weight:normal;font-stretch:normal;line-height:normal;color:rgb(0,0,0);background-color:rgb(255,255,255)"><font face="arial, helvetica, sans-serif">Is there any way to disable this in llvm?</font></p><p class="gmail-p1" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-weight:normal;font-stretch:normal;line-height:normal;color:rgb(0,0,0);background-color:rgb(255,255,255)"><font face="arial, helvetica, sans-serif"><br></font></p><p class="gmail-p1" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-weight:normal;font-stretch:normal;line-height:normal;color:rgb(0,0,0);background-color:rgb(255,255,255)"><font face="arial, helvetica, sans-serif">Any help would be much appreciated.</font></p><p class="gmail-p1" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-weight:normal;font-stretch:normal;line-height:normal;color:rgb(0,0,0);background-color:rgb(255,255,255)"><font face="arial, helvetica, sans-serif"><br></font></p><p class="gmail-p1" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-weight:normal;font-stretch:normal;line-height:normal;color:rgb(0,0,0);background-color:rgb(255,255,255)"><font face="arial, helvetica, sans-serif">Regards,</font></p><p class="gmail-p1" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-weight:normal;font-stretch:normal;line-height:normal;color:rgb(0,0,0);background-color:rgb(255,255,255)"><font face="arial, helvetica, sans-serif">Sangeeta</font></p></div></div>