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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - X86: Signed Overflowing Multiplication incorrect codegen on 32-bit Windows"
href="https://bugs.llvm.org/show_bug.cgi?id=40289">40289</a>
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<th>Summary</th>
<td>X86: Signed Overflowing Multiplication incorrect codegen on 32-bit Windows
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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>All
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>enhancement
</td>
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<th>Priority</th>
<td>P
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<th>Component</th>
<td>Backend: X86
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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<th>Reporter</th>
<td>alex@crichton.co
</td>
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<th>CC</th>
<td>craig.topper@gmail.com, llvm-bugs@lists.llvm.org, llvm-dev@redking.me.uk, spatel+llvm@rotateright.com
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<p>
<div>
<pre>First reported to use at rust-lang/rust it looks like a regression has happened
somewhere between 7.0.0 and the current trunk. Taking a look at godbolt --
<a href="https://godbolt.org/z/xCkFO3">https://godbolt.org/z/xCkFO3</a> -- the following IR:
target datalayout = "e-m:x-p:32:32-i64:64-f80:32-n8:16:32-a:0:32-S32"
target triple = "i686-pc-windows-msvc"
define fastcc { i64, i1 } @testit(i64 %self) {
start:
%0 = tail call { i64, i1 } @llvm.smul.with.overflow.i64(i64 %self, i64 4)
ret { i64, i1 } %0
}
; Function Attrs: nounwind readnone speculatable
declare { i64, i1 } @llvm.smul.with.overflow.i64(i64, i64) #2
when compiled will `popl %esp` on trunk, but on 7.0.0 it correctly executes
`add $4, %esp`. Some local bisection using `-opt-bisect-limit` shows that this
happens during the "X86 Optimize Call Frame on function" pass.</pre>
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