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<p class="MsoNormal">Hi,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I’ve found a bug in the way LLVM creates a call to __chkstk.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">The assemble instruction created for this is:<o:p></o:p></p>
<p class="MsoNormal">call <imm32><o:p></o:p></p>
<p class="MsoNormal">Where imm32 is the address of __chkstk. On 64 bit OS the address can 64 bits and <imm32> is not big enough to contain the full address.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">The solution for 64 bits is to save the address to r11 and call r11:<o:p></o:p></p>
<p class="MsoNormal">mov r11, <imm64><o:p></o:p></p>
<p class="MsoNormal">call r11<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I’ve added a patch with the solution and a LIT test making sure we do not create “call __chkstk” instructions on 64 bit OS.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Please let me know if you want me to open a bug on this issue.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Thank you,<o:p></o:p></p>
<p class="MsoNormal">Marina.<o:p></o:p></p>
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