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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - [PPC64/PPC64LE] Call of __attribute__((noreturn)) generates suboptimal code"
href="https://bugs.llvm.org/show_bug.cgi?id=40021">40021</a>
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<th>Summary</th>
<td>[PPC64/PPC64LE] Call of __attribute__((noreturn)) generates suboptimal code
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<th>Product</th>
<td>libraries
</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
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<th>Priority</th>
<td>P
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<th>Component</th>
<td>Backend: PowerPC
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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<th>Reporter</th>
<td>simonas+llvm.org@kazlauskas.me
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<th>CC</th>
<td>llvm-bugs@lists.llvm.org, nemanja.i.ibm@gmail.com
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<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=21223" name="attach_21223" title="LLVM-IR test case">attachment 21223</a> <a href="attachment.cgi?id=21223&action=edit" title="LLVM-IR test case">[details]</a></span>
LLVM-IR test case
The following C code
typedef long long unsigned int uint64_t;
void __attribute__((noreturn)) test(uint64_t a, uint64_t b, uint64_t
__attribute__((noreturn)) (*cb)(uint64_t, uint64_t)) {
cb(a, b);
}
which generates the following LLVM-IR (clang 6)
define void @test(i64, i64, i64 (i64, i64)* nocapture) local_unnamed_addr #0 {
%4 = tail call i64 %2(i64 %0, i64 %1) #1
unreachable
}
results in unnecessary instructions after the call when ppc64le is targeted:
mtctr 5
mr 12, 5
std 2, 24(1) /* what for? */
bctrl
ld 2, 24(1) /* what for? */
The full LLVM-IR is attached.</pre>
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