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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - The memclr call generated by the compiler optimization cannot be disabled."
href="https://bugs.llvm.org/show_bug.cgi?id=46180">46180</a>
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<th>Summary</th>
<td>The memclr call generated by the compiler optimization cannot be disabled.
</td>
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<th>Product</th>
<td>clang
</td>
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<th>Version</th>
<td>8.0
</td>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>Windows NT
</td>
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<th>Status</th>
<td>NEW
</td>
</tr>
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<th>Severity</th>
<td>enhancement
</td>
</tr>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>C
</td>
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
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<th>Reporter</th>
<td>2077213809@qq.com
</td>
</tr>
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<th>CC</th>
<td>blitzrakete@gmail.com, dgregor@apple.com, erik.pilkington@gmail.com, llvm-bugs@lists.llvm.org, richard-llvm@metafoo.co.uk
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<pre>I have some code that the compiler generates calls to the libc library by
default and cannot be disabled, even if I use -ffreestanding or -fno-builtin.
My program runs in a bare-metal environment without any libc libraries, and
compiler optimizations like this cause my program to linker fail.
clang -ffreestanding -fno-builtin --target=arm-none-eabi -Oz -S test.c -o -
typedef struct {
int a;
int b;
int c;
int d;
int e;
int *p;
} A;
void __attribute__((noinline)) test(A *a){
a->e = 1;
}
int main()
{
A a = {0};
test(&a);
}
main:
.fnstart
.save {r4, r10, r11, lr}
push {r4, r10, r11, lr}
.setfp r11, sp, #8
add r11, sp, #8
.pad #24
sub sp, sp, #24
mov r4, sp
mov r1, #24
mov r0, r4
bl __aeabi_memclr4 // linker failed
mov r0, r4
bl test
sub sp, r11, #8
pop {r4, r10, r11, lr}
bx lr</pre>
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