<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/142968>142968</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            Why can't "const xxx *restrict" be optimized?
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            new issue
      </td>
    </tr>

    <tr>
      <th>Assignees</th>
      <td>
      </td>
    </tr>

    <tr>
      <th>Reporter</th>
      <td>
          lvyitianshi
      </td>
    </tr>
</table>

<pre>
    Why can't "const xxx *restrict" be optimized?

I'm sorry because I can't write makedown.

This is c code:

__attribute__((malloc)) int *get();
void _interface0(int p);
void _interface1(const int *restrict p);

int entry() {
    int *p = get();

    _interface0(*p);
    _interface1(p);

    _interface0(*p);
    _interface1(p);

    _interface0(*p);
    _interface1(p);

    _interface0(*p);
    _interface1(p);

    _interface0(*p);
    _interface1(p);

    return 0;
}

This is command line:

clang -S -O3 main.c -ffreestanding

This is assemble code:

        .def    @feat.00;
        .scl    3;
        .type   0;
        .endef
        .globl  @feat.00
.set @feat.00, 0
        .file   "main.c"
        .def    entry;
        .scl    2;
        .type   32;
        .endef
        .text
        .globl  entry                           # -- Begin function entry
        .p2align        4
entry:                                  # @entry
# %bb.0:
        pushq   %rsi
        subq    $32, %rsp
        callq   get
        movq    %rax, %rsi
        movl    (%rax), %ecx
        callq   _interface0
        movq    %rsi, %rcx
        callq   _interface1
        movl    (%rsi), %ecx
        callq   _interface0
        movq    %rsi, %rcx
        callq   _interface1
        movl    (%rsi), %ecx
        callq   _interface0
        movq    %rsi, %rcx
        callq   _interface1
        movl    (%rsi), %ecx
        callq   _interface0
        movq    %rsi, %rcx
        callq   _interface1
        movl    (%rsi), %ecx
        callq   _interface0
        movq    %rsi, %rcx
        callq   _interface1
        xorl    %eax, %eax
        addq    $32, %rsp
        popq    %rsi
        retq
                                        # -- End function
        .addrsig

Why p can't be optimized into the registers？

Can someone tell me how to do it, I know "pure" does my thing, but it needs not to return void.

If no one realizes that this is a point that can be optimized, I hope someone will pay attention：）
</pre>
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