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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Can't fold a reload if spill size doesn't match use size"
href="https://llvm.org/bugs/show_bug.cgi?id=30832">30832</a>
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<th>Summary</th>
<td>Can't fold a reload if spill size doesn't match use size
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
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<th>OS</th>
<td>Linux
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
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<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>Backend: X86
</td>
</tr>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
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<th>Reporter</th>
<td>mkuper@google.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr>
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>This is something we currently explicitly don't do because targets aren't
required to support it (InlinerSpiller::foldMemoryOperand()).
So for:
target triple = "x86_64-unknown-linux-gnu"
define i32 @foo(i64 %add, i32 %ret) {
entry:
tail call void asm sideeffect "",
"~{rax},~{rbx},~{rcx},~{rdx},~{rdi},~{rbp},~{r8},~{r9},~{r10},~{r11},~{r12},~{r13},~{r14},~{r15},~{dirflag},~{fpsr},~{flags}"()
%conv3 = zext i32 %ret to i64
%sub = sub i64 %conv3, %add
%conv1 = trunc i64 %sub to i32
ret i32 %conv1
}
we generate:
[...]
movq %rdi, -8(%rsp) # 8-byte Spill
movq -8(%rsp), %rax # 8-byte Reload
subl %eax, %esi
[...]
The same also happens for vector registers (spill ymm, reload ymm, use xmm).</pre>
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</p>
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