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<p class="MsoNormal">I cannot get Clang to add noalias via a cast operation. This code does not produce any warnings, and I believe it’s legal, but the restrict qualifier is lost. Am I incorrect about this code being legal? Any idea why the qualifier is stripped?
(It is a contrived example. You could imagine address checking and two separate loops.)<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">#define NOALIAS __restrict<o:p></o:p></p>
<p class="MsoNormal">//#define NOALIAS __attribute__((noalias))<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">void move(<o:p></o:p></p>
<p class="MsoNormal"> int* velocity_x, int* velocity_y, int* velocity_z,<o:p></o:p></p>
<p class="MsoNormal"> int* position_x,int* position_y,int* position_z,<o:p></o:p></p>
<p class="MsoNormal"> int* acceleration_x, int* acceleration_y, int* acceleration_z,<o:p></o:p></p>
<p class="MsoNormal"> int time_step, <o:p></o:p></p>
<p class="MsoNormal"> int count, <o:p></o:p></p>
<p class="MsoNormal"> int stride )<o:p></o:p></p>
<p class="MsoNormal">{<o:p></o:p></p>
<p class="MsoNormal"> {<o:p></o:p></p>
<p class="MsoNormal"> int* NOALIAS r_acceleration_x = (int* NOALIAS)acceleration_x;<o:p></o:p></p>
<p class="MsoNormal"> int* NOALIAS r_velocity_x = (int* NOALIAS)velocity_x;<o:p></o:p></p>
<p class="MsoNormal"> int* NOALIAS r_position_x = (int* NOALIAS)position_x;<o:p></o:p></p>
<p class="MsoNormal"> int* NOALIAS r_acceleration_y = (int* NOALIAS)acceleration_y;<o:p></o:p></p>
<p class="MsoNormal"> int* NOALIAS r_velocity_y = (int* NOALIAS)velocity_y;<o:p></o:p></p>
<p class="MsoNormal"> int* NOALIAS r_position_y = (int* NOALIAS)position_y;<o:p></o:p></p>
<p class="MsoNormal"> int* NOALIAS r_acceleration_z = (int* NOALIAS)acceleration_z;<o:p></o:p></p>
<p class="MsoNormal"> int* NOALIAS r_velocity_z = (int* NOALIAS)velocity_z;<o:p></o:p></p>
<p class="MsoNormal"> int* NOALIAS r_position_z = (int* NOALIAS)position_z;<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"> for (int i=0;i<count*stride;i+=stride)<o:p></o:p></p>
<p class="MsoNormal"> {<o:p></o:p></p>
<p class="MsoNormal"> r_velocity_x[i] += r_acceleration_x[i] * time_step;<o:p></o:p></p>
<p class="MsoNormal"> r_velocity_y[i] += r_acceleration_y[i] * time_step;<o:p></o:p></p>
<p class="MsoNormal"> r_velocity_z[i] += r_acceleration_z[i] * time_step;<o:p></o:p></p>
<p class="MsoNormal"> r_position_x[i] += r_velocity_x[i] * time_step;<o:p></o:p></p>
<p class="MsoNormal"> r_position_y[i] += r_velocity_y[i] * time_step;<o:p></o:p></p>
<p class="MsoNormal"> r_position_z[i] += r_velocity_z[i] * time_step;<o:p></o:p></p>
<p class="MsoNormal"> }<o:p></o:p></p>
<p class="MsoNormal"> }<o:p></o:p></p>
<p class="MsoNormal">}<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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