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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Floating point asm constraint for arm target without floating point should give error"
href="https://bugs.llvm.org/show_bug.cgi?id=42641">42641</a>
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<th>Summary</th>
<td>Floating point asm constraint for arm target without floating point should give error
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<th>Product</th>
<td>clang
</td>
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<th>Version</th>
<td>trunk
</td>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>Linux
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>enhancement
</td>
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<th>Priority</th>
<td>P
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<th>Component</th>
<td>Frontend
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
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<th>Reporter</th>
<td>john.brawn@arm.com
</td>
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<th>CC</th>
<td>llvm-bugs@lists.llvm.org, neeilans@live.com, richard-llvm@metafoo.co.uk
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<p>
<div>
<pre>If you have some inline asm that has a constraint that specifies a
floating-point register, e.g.
float func(float t)
{
__asm__ ( "" : "=w" (t) );
return t;
}
then compiling for an arm cpu without floating point (e.g. --target=arm
-mcpu=cortex-m3) using a build of clang with asserts enabled you get
llvm/lib/CodeGen/SelectionDAG/LegalizeFloatTypes.cpp:65: bool
llvm::DAGTypeLegalizer::SoftenFloatResult(llvm::SDNode*, unsigned int):
Assertion `isLegalInHWReg(N->getValueType(ResNo)) && "Unsupported
SoftenFloatRes opcode!"' failed.
or with a build without asserts you end up in an endless loop in SelectionDAG.
We should be rejecting this code early and giving an error. It looks like
ARMTargetInfo::validateAsmConstraint is probably the place to do this.</pre>
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