[clang] [Clang] Implement `__builtin_start_lifetime_as` for C++23 P2590R2 (PR #196502)

[via cfe-commits]

github-actions[bot] wrote:

<!--PREMERGE ADVISOR COMMENT: Windows-->
# :window: Windows x64 Test Results

* 53886 tests passed
* 1202 tests skipped
* 1 test failed

## Failed Tests
(click on a test name to see its output)

### Clang
<details>
<summary>Clang.CodeGenCXX/builtin-start-lifetime-as.cpp</summary>

```
Exit Code: 1

Command Output (stdout):
--
# RUN: at line 1
c:\_work\llvm-project\llvm-project\build\bin\clang.exe -cc1 -internal-isystem C:\_work\llvm-project\llvm-project\build\lib\clang\23\include -nostdsysteminc -std=c++23 -emit-llvm -disable-llvm-passes -o - C:\_work\llvm-project\llvm-project\clang\test\CodeGenCXX\builtin-start-lifetime-as.cpp | c:\_work\llvm-project\llvm-project\build\bin\filecheck.exe C:\_work\llvm-project\llvm-project\clang\test\CodeGenCXX\builtin-start-lifetime-as.cpp
# executed command: 'c:\_work\llvm-project\llvm-project\build\bin\clang.exe' -cc1 -internal-isystem 'C:\_work\llvm-project\llvm-project\build\lib\clang\23\include' -nostdsysteminc -std=c++23 -emit-llvm -disable-llvm-passes -o - 'C:\_work\llvm-project\llvm-project\clang\test\CodeGenCXX\builtin-start-lifetime-as.cpp'
# note: command had no output on stdout or stderr
# executed command: 'c:\_work\llvm-project\llvm-project\build\bin\filecheck.exe' 'C:\_work\llvm-project\llvm-project\clang\test\CodeGenCXX\builtin-start-lifetime-as.cpp'
# .---command stderr------------
# | C:\_work\llvm-project\llvm-project\clang\test\CodeGenCXX\builtin-start-lifetime-as.cpp:5:17: error: CHECK-LABEL: expected string not found in input
# | // CHECK-LABEL: define {{.*}}@_Z12test_trivialPv(
# |                 ^
# | <stdin>:1:1: note: scanning from here
# | ; ModuleID = 'C:\_work\llvm-project\llvm-project\clang\test\CodeGenCXX\builtin-start-lifetime-as.cpp'
# | ^
# | <stdin>:7:18: note: possible intended match here
# | define dso_local noundef ptr @"?test_trivial@@YAPEAUTrivial@@PEAX at Z"(ptr noundef %p) #0 {
# |                  ^
# | 
# | Input file: <stdin>
# | Check file: C:\_work\llvm-project\llvm-project\clang\test\CodeGenCXX\builtin-start-lifetime-as.cpp
# | 
# | -dump-input=help explains the following input dump.
# | 
# | Input was:
# | <<<<<<
# |            1: ; ModuleID = 'C:\_work\llvm-project\llvm-project\clang\test\CodeGenCXX\builtin-start-lifetime-as.cpp' 
# | label:5'0     X~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ error: no match found
# |            2: source_filename = "C:\\_work\\llvm-project\\llvm-project\\clang\\test\\CodeGenCXX\\builtin-start-lifetime-as.cpp" 
# | label:5'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# |            3: target datalayout = "e-m:w-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128" 
# | label:5'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# |            4: target triple = "x86_64-pc-windows-msvc" 
# | label:5'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# |            5:  
# | label:5'0     ~
# |            6: ; Function Attrs: mustprogress noinline nounwind optnone 
# | label:5'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# |            7: define dso_local noundef ptr @"?test_trivial@@YAPEAUTrivial@@PEAX at Z"(ptr noundef %p) #0 { 
# | label:5'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# | label:5'1                      ?                                                                         possible intended match
# |            8: entry: 
# | label:5'0     ~~~~~~~
# |            9:  %p.addr = alloca ptr, align 8 
# | label:5'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# |           10:  store ptr %p, ptr %p.addr, align 8 
# | label:5'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# |           11:  %0 = load ptr, ptr %p.addr, align 8 
# | label:5'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# |           12:  ret ptr %0 
# | label:5'0     ~~~~~~~~~~~~
# |            .
# |            .
# |            .
# | >>>>>>
# `-----------------------------
# error: command failed with exit status: 1

--

```
</details>

If these failures are unrelated to your changes (for example tests are broken or flaky at HEAD), please open an issue at https://github.com/llvm/llvm-project/issues and add the `infrastructure` label.

https://github.com/llvm/llvm-project/pull/196502