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<base href="http://llvm.org/bugs/" />
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - [thumbv8] assertions fails when check for eligibility of IT block"
href="http://llvm.org/bugs/show_bug.cgi?id=18368">18368</a>
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<th>Summary</th>
<td>[thumbv8] assertions fails when check for eligibility of IT block
</td>
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<th>Product</th>
<td>new-bugs
</td>
</tr>
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<th>Version</th>
<td>trunk
</td>
</tr>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>Windows NT
</td>
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>normal
</td>
</tr>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>new bugs
</td>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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</tr>
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<th>Reporter</th>
<td>weimingz@codeaurora.org
</td>
</tr>
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<th>CC</th>
<td>llvmbugs@cs.uiuc.edu
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<th>Classification</th>
<td>Unclassified
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</tr></table>
<p>
<div>
<pre>@foo = global i32 ()* null
define i32 @t4(i32 %x, i32 ()* %p_foo) {
entry:
;CHECK-LABEL: t4:
;CHECK-V8-LABEL: t4:
%cmp = icmp slt i32 %x, 60
br i1 %cmp, label %if.then, label %if.else
if.then: ; preds = %entry
%tmp.2 = call i32 %p_foo()
%sub = add nsw i32 %x, -1
br label %return
if.else: ; preds = %entry
%sub1 = add nsw i32 %x, -120
br label %return
return: ; preds = %if.end5,
%if.then4, %if.then
%retval.0 = phi i32 [ %sub, %if.then ], [ %sub1, %if.else ]
ret i32 %retval.0
}
The above test fails when run with llc -mtriple=thumbv8
Reason:
When it attempts to check if the operand of blx is valid
for IT block, the reg should be the 3rd MOOperand. E.g.:
blx r8:
@ <MCInst #2747 tBLXr
@ <MCOperand Imm:14>
@ <MCOperand Reg:0>
@ <MCOperand Reg:74> ==> this is the operand to be checked
>
However, the default value is 0:
inline boolq(InstrType *Instr, int BLXOperandIndex = 0)
There are 2 call sites:
ARMBaseInstrInfo.cpp: return isV8EligibleForIT(MI); ==> this one is
causing the assertion
AsmParser/ARMAsmParser.cpp: !isV8EligibleForIT(&Inst, 2)) {</pre>
</div>
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