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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - bool != less efficient than bool =="
href="https://bugs.llvm.org/show_bug.cgi?id=42876">42876</a>
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<th>Summary</th>
<td>bool != less efficient than bool ==
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
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<th>Version</th>
<td>trunk
</td>
</tr>
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<th>Hardware</th>
<td>PC
</td>
</tr>
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<th>OS</th>
<td>Windows NT
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>enhancement
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>Backend: RISC-V
</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>efriedma@quicinc.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org, llvm-dev@redking.me.uk, rofirrim@gmail.com
</td>
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<p>
<div>
<pre>void a(_Bool a, _Bool b, void c()) { if (a==b) c(); }
void a2(_Bool a, _Bool b, void c()) { if (a!=b) c(); }
Build with clang -O2 --target=riscv32. Output:
a: # @a
# %bb.0: # %entry
addi sp, sp, -16
sw ra, 12(sp)
bne a0, a1, .LBB0_2
[...]
a2: # @a2
# %bb.0: # %entry
addi sp, sp, -16
sw ra, 12(sp)
xor a0, a0, a1
addi a1, zero, 1
bne a0, a1, .LBB1_2
Something similar happens on some other targets; on x86 and 32-bit ARM, there's
an extra "cmp".
It looks like something weird is happening in target-independent SelectionDAG;
I haven't tried to dig further.</pre>
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</p>
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