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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - initialization of global var with a (sqrt) function optimized away"
href="http://llvm.org/bugs/show_bug.cgi?id=21048">21048</a>
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<th>Summary</th>
<td>initialization of global var with a (sqrt) function optimized away
</td>
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<th>Product</th>
<td>new-bugs
</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
</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>will_schmidt@vnet.ibm.com
</td>
</tr>
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<th>CC</th>
<td>llvmbugs@cs.uiuc.edu
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=13078" name="attach_13078" title="test source">attachment 13078</a> <a href="attachment.cgi?id=13078&action=edit" title="test source">[details]</a></span>
test source
The initialization of a double to NaN (by way of sqrt(-2.01)) is failing, due
to the sqrt call being optimized out.
Per debug, this appears to be occurring during the "Early CSE" pass.
opt -O1 -S -o optimized.ll llvm_debug_variable_init.ll
The llvm_debug_variable_init.ll file contains a snippet including:
define void @__cxx_global_var_init() section ".text.startup" {
entry:
%0 = call double @llvm.sqrt.f64(double -2.010000e+00), !dbg !1818
store double %0, double* getelementptr inbounds (%"NumberUnion"* @fruity ,
i32 0, i32 0), align 8, !dbg !1818
ret void, !dbg !1818
}
The optimized.ll output contains:
define void @__cxx_global_var_init() #0 section ".text.startup" {
entry:
store double 0.000000e+00, double* getelementptr inbounds (%NumberUnion*
@fruity, i64 0, i32 0), align 8
ret void
}
... with no sign of the sqrt call.
output from
"opt llvm_debug_variable_init.ll -O1 -S --print-after-all --print-before-all
<span class="quote">> optimized_debug.ll 2>&1 " will also be attached momentarily.</span ></pre>
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