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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">In order to handle register allocation of more complex functions, I have to implement the others methods from the MyArchInstrInfo.cpp.<o:p></o:p></p>
<p class="MsoNormal">The first one is the isLoadFromStack, that return the frameIndex referenced by the Machine Instruction.<o:p></o:p></p>
<p class="MsoNormal">I took a look at the implementation of this function in many others architectures. It’s always a switch/case on a few instructions of the architecture, followed by some access to the properties of the instruction parameters.<o:p></o:p></p>
<p class="MsoNormal">With my architecture, most of the selected instruction (MOV but also arithmetic instructions) will load one or even worst two operands from a Stack Slot: the Offset and Offset/Offset addressing mode.<o:p></o:p></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt;font-family:Monospace;color:#3F7F5F"><o:p> </o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt;font-family:Monospace;color:#3F7F5F">/// isLoadFromStackSlot - If the specified machine instruction is a direct</span><span style="font-size:10.0pt;font-family:Monospace"><o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt;font-family:Monospace;color:#3F7F5F">/// load from a stack slot, return the virtual or physical register number of</span><span style="font-size:10.0pt;font-family:Monospace"><o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt;font-family:Monospace;color:#3F7F5F">/// the destination along with the FrameIndex of the loaded stack slot. If</span><span style="font-size:10.0pt;font-family:Monospace"><o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt;font-family:Monospace;color:#3F7F5F">/// not, return 0. This predicate must return 0 if the instruction has</span><span style="font-size:10.0pt;font-family:Monospace"><o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt;font-family:Monospace;color:#3F7F5F">/// any side effects other than loading from the stack slot.</span><span style="font-size:10.0pt;font-family:Monospace"><o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><b><span style="font-size:10.0pt;font-family:Monospace;color:#7F0055">unsigned</span></b><span style="font-size:10.0pt;font-family:Monospace;color:black">
<b>CLPInstrInfo::isLoadFromStackSlot</b>(</span><b><span style="font-size:10.0pt;font-family:Monospace;color:#7F0055">const</span></b><span style="font-size:10.0pt;font-family:Monospace;color:black">
</span><span style="font-size:10.0pt;font-family:Monospace;color:#005032">MachineInstr</span><span style="font-size:10.0pt;font-family:Monospace;color:black"> *MI,</span><span style="font-size:10.0pt;font-family:Monospace"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:Monospace;color:black">
</span><b><span style="font-size:10.0pt;font-family:Monospace;color:#7F0055">int</span></b><span style="font-size:10.0pt;font-family:Monospace;color:black"> &FrameIndex)
</span><b><span style="font-size:10.0pt;font-family:Monospace;color:#7F0055">const</span></b><span style="font-size:10.0pt;font-family:Monospace;color:black"> {<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:Monospace;color:black"><o:p> </o:p></span></p>
<p class="MsoNormal">What is the purpose this method? Finding the highest position already allocated in the Stack?<o:p></o:p></p>
<p class="MsoNormal">In that case, for Offset/Offset addressing mode, I will have to return the highest offset.<o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:Monospace;color:black">As for other architecture, I can implement a switch/case, but it will be very large. Most of the instructions have an Offset/Offset addressing mode.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:Monospace;color:black">Do I have to implement this methods only for the MOV instructions or also for the arithmetic instructions fetching operands from Stack?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:Monospace;color:black">Is there a way to add a property to tag ‘LoadFromStackSlot’ instructions or instruction classes at the level of MyArchInstrInfo.td or MyArchInstrDef.td file?<o:p></o:p></span></p>
<p class="MsoNormal">Any suggestions suggestion are welcome…<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">TIA, Dominique Torette<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Times New Roman","serif""><img width="536" height="49" id="_x0000_i1025" src="http://www.spacebel.be/wp-content/uploads/2011/06/image-sign-sbp.jpg" alt="http://www.spacebel.be/wp-content/uploads/2011/06/image-sign-sbp.jpg"></span><span lang="FR-BE" style="font-size:12.0pt;font-family:"Times New Roman","serif""><o:p></o:p></span></p>
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<b><span lang="FR-BE" style="font-size:10.0pt">Dominique Torette</span></b><span lang="FR-BE" style="font-size:10.0pt">
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System Architect<br>
Rue des Chasseurs Ardennais - Liège Science Park - B-4031 Angleur <br>
Tel: +32 (0) 4 361 81 11 - Fax: +32 (0) 4 361 81 20 <br>
</span><span style="font-size:10.0pt"><a href="http://www.spacebel.be/"><span lang="FR-BE" style="color:blue">www.spacebel.be</span></a></span><span lang="FR-BE" style="font-size:12.0pt;font-family:"Times New Roman","serif""><o:p></o:p></span></p>
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