<html>
<head>
<base href="https://bugs.llvm.org/">
</head>
<body><table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Suboptimal code for llvm.ssub.sat.i32"
href="https://bugs.llvm.org/show_bug.cgi?id=43649">43649</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>Suboptimal code for llvm.ssub.sat.i32
</td>
</tr>
<tr>
<th>Product</th>
<td>new-bugs
</td>
</tr>
<tr>
<th>Version</th>
<td>unspecified
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<th>OS</th>
<td>Linux
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>enhancement
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>new bugs
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>tspiteri@ieee.org
</td>
</tr>
<tr>
<th>CC</th>
<td>htmldeveloper@gmail.com, llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>The following IR:
define i32 @_ZN7example14saturating_sub17h23583ee3c8b034a4E(i32 %a, i32 %b)
unnamed_addr #0 !dbg !5 {
start:
%0 = tail call i32 @llvm.ssub.sat.i32(i32 %a, i32 %b) #2, !dbg !8
ret i32 %0, !dbg !15
}
declare i32 @llvm.ssub.sat.i32(i32, i32) #1
attributes #0 = { nounwind nonlazybind readnone uwtable
"probe-stack"="__rust_probestack" "target-cpu"="x86-64" }
attributes #1 = { nounwind readnone speculatable }
attributes #2 = { nounwind }
results in the following asm:
example::saturating_sub:
xor eax, eax
mov ecx, edi
sub ecx, esi
setns al
add eax, 2147483647
sub edi, esi
cmovno eax, edi
ret
I think the `mov ecx, edi` and `sub ecx, esi` instructions should be replaced
by a `cmp esi, edi` instruction.</pre>
</div>
</p>
<hr>
<span>You are receiving this mail because:</span>
<ul>
<li>You are on the CC list for the bug.</li>
</ul>
</body>
</html>