<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/68746>68746</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            no lifetime markers emitted for compound literals
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            c,
            clang:codegen
      </td>
    </tr>

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

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

<pre>
    C23 6.2.4 Storage durations of objects:

> 5 An object whose identifier is declared with no linkage and without the storage-class specifier static
has automatic storage duration, as do some compound literals. The result of attempting to indirectly
access an object with automatic storage duration from a thread other than the one with which the
object is associated is implementation-defined.
6 For such an object that does not have a variable length array type, its lifetime extends from entry
into the block with which it is associated until execution of that block ends in any way

as noted here: https://reviews.llvm.org/D74094#4647616

example:
```c
struct foo { long long x, y, z; int w; };

void bar (struct foo);

void baz (void) {
    {
        bar((struct foo){
            .x = 42,
 .y = 25,
            .z = 77,
        });
    }
    {
 bar((struct foo){
            .x = 42,
            .y = 25,
 .z = 77,
        });
    }
}
```
we should emit lifetime markers for those `alloca`s as we should be able to reuse their stack slots.  That should help us reduce stack usage for C codebases. cc @rjmccall @ilovepi 
</pre>
<img width="1px" height="1px" alt="" src="http://email.email.llvm.org/o/eJykVd1y6jgMfhpzo2kmOCHARS76s7zAnhdQbIX41LEZSymlT7_jhB447dmb3QwTbMn69EmRZGR2x0DUqs2T0jo482qJcfLBUWKltdq8rHCSIab2i3LVRXtpn3UFTaGLGv6WmPBIYKeE4mJgiD3E7icZYVU9qvJFlZ_v6i_YwGO4quE8RCZwloK43lECx2DJeExk4exkgBDBu_Ca8TEssjgJyEDAi98H45EZ-ERmwWBBcWZxOCADThLHLPq0-MVU6WdABhuB40hg4niKU7DgnVBCzwX8GAgS8eQlB4UiNJ7EhSNIBBesS2TEXxZfaAwxA96iywH8u3foUxwBQYZEaCHKQAlkwDBHFwMtAOfBmSGLFi9XbMeAzNE4FLJ558aTp5GCzNgPlnoXyBaLUQOHmIAnM9zRkwEFbCSGEAUGfCNAeMPksPMEnsIx008JLyCXE-VkOWHwridxIwG9CwXLSxgUJF3z4ILEOYTOR_N6H4T7ynsK4jzQO5lpzkjsF1aL5YzuAmC4wBkv94WEM2myMFAiVT3CIHKaq00flD4kenN05sL7t7GI6aj04WVbl_ta6apu6m2zbu7R6B1z9m7F2pTL71pFLGkyAn2MoLZP4GM4Lq_3nJRLfn2o6glcEDjnhdq-qOrp3sVbdBY6TKD07gan9P7P5z7yubxWep99LkoA-H2Tnw6T0rtvsF-P5ad4B1W9QK2Vfr5qi8ss0pub6N7gY9Zut9-0OcI78p-iP9D8f_zutd-p_jd-t8Xnd162ZwIe4uQt0OjkVugjpldKDH3M_ZknlmpK9D4aVE2ZCxpuph3B3D8SIdHElDvBzUPJvAL7KFwA_MhFfjUYyJ9gYkhkJ0PXgxPnSZEdPoOJljpk4gKMAVWX6edoDHqf187HNzo5WNm2svtqjytq182-2W_rst6thrbfdju76cvedOttQ3a_rxqiurFIiJvdZuVaXepqXa5Lvc42xdrUu0531HW63mFjVF3SiM7_6qaVY56obXbbull57Mjz9Rox-eLQz3nlMRxV9ZjJHylcL5TUZoyHbjqyqkvvWG49uhInntp54H9JfP4cudlzPr4N6dWUfPt7-x-dDFNXmDgqfcj417-HU4p59Cl9mENgpQ9zFP8EAAD__wBpMIE">