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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - BLX being used in ARMv4 in ARMFastIsel"
href="https://llvm.org/bugs/show_bug.cgi?id=24858">24858</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>BLX being used in ARMv4 in ARMFastIsel
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<th>OS</th>
<td>Linux
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
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<th>Component</th>
<td>Backend: ARM
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>renato.golin@linaro.org
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr>
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>Following from the bug report detected in Rust when using LLVM:
<a href="https://groups.google.com/forum/#!topic/llvm-dev/upPBDqUOLF4">https://groups.google.com/forum/#!topic/llvm-dev/upPBDqUOLF4</a>
ARMFastIsel doesn't recognise the lack of BLX in ARMv4 sub-architecture when
generating calls.
This commit has added support for global values call but forgot to consider
ARMv4 in the code:
+ if (!GV){
+ CallOpc = isThumb2 ? ARM::tBLXr : ARM::BLX;
+ CalleeReg = getRegForValue(Callee);
+ if (CalleeReg == 0) return false;
+ }
Currently, ARMFastISel::ARMEmitLibcal calls ARMSelectCallOp, which is
implemented similarly:
unsigned ARMFastISel::ARMSelectCallOp(bool UseReg) {
if (UseReg)
return isThumb2 ? ARM::tBLXr : ARM::BLX;
else
return isThumb2 ? ARM::tBL : ARM::BL;
}
which may need to be adapted to cope with ARMv4 hardware, but also be a bit
smarter about what the target is, not only the operand type.</pre>
</div>
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