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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Incorrect code generated for dynamic alloca with alignment"
href="http://llvm.org/bugs/show_bug.cgi?id=17345">17345</a>
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<th>Summary</th>
<td>Incorrect code generated for dynamic alloca with alignment
</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>
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<th>OS</th>
<td>Linux
</td>
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>normal
</td>
</tr>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>Backend: X86
</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>zvi.rackover@intel.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvmbugs@cs.uiuc.edu
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</tr>
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>For the following test,
define i32 @A(i32 %Size) {
entry:
%A = alloca i8, i32 %Size, align 128
%A_addr = ptrtoint i8* %A to i32
ret i32 %A_addr
}
llc -mtriple=x86_64-linux generates:
1: pushq %rbp
2: movq %rsp, %rbp
3: pushq %rbx
4: andq $-128, %rsp
5: subq $128, %rsp
6: movq %rsp, %rbx
7: movq %rsp, %rax
8: andq $-128, %rax
9: movl %edi, %ecx
10: addq $15, %rcx
11: andq $-16, %rcx
12: subq %rcx, %rax
13: movq %rax, %rsp
14: leaq -8(%rbp), %rsp
15: popq %rbx
16: popq %rbp
17: ret
There is no guarantee that the returned value in %rax will be a multiple of
128, which is the required alignment (but it will be a multiple of 16).</pre>
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