[clang] [llvm] [Clang] Add __builtin_assume_dereferenceable to encode deref assumption. (PR #121789)

[LLVM Continuous Integration via cfe-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `lldb-arm-ubuntu` running on `linaro-lldb-arm-ubuntu` while building `clang,llvm` at step 6 "test".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/18/builds/11474

<details>
<summary>Here is the relevant piece of the build log for the reference</summary>

```
Step 6 (test) failure: build (failure)
...
PASS: lldb-api :: terminal/TestSTTYBeforeAndAfter.py (1127 of 2903)
PASS: lldb-api :: test_utils/TestDecorators.py (1128 of 2903)
PASS: lldb-api :: test_utils/TestInlineTest.py (1129 of 2903)
PASS: lldb-api :: test_utils/TestPExpectTest.py (1130 of 2903)
PASS: lldb-api :: test_utils/base/TestBaseTest.py (1131 of 2903)
PASS: lldb-api :: python_api/watchpoint/watchlocation/TestTargetWatchAddress.py (1132 of 2903)
PASS: lldb-api :: terminal/TestEditline.py (1133 of 2903)
UNSUPPORTED: lldb-api :: tools/lldb-dap/breakpoint-events/TestDAP_breakpointEvents.py (1134 of 2903)
PASS: lldb-api :: tools/lldb-dap/breakpoint/TestDAP_breakpointLocations.py (1135 of 2903)
PASS: lldb-api :: tools/lldb-dap/attach/TestDAP_attachByPortNum.py (1136 of 2903)
FAIL: lldb-api :: tools/lldb-dap/attach/TestDAP_attach.py (1137 of 2903)
******************** TEST 'lldb-api :: tools/lldb-dap/attach/TestDAP_attach.py' FAILED ********************
Script:
--
/usr/bin/python3.10 /home/tcwg-buildbot/worker/lldb-arm-ubuntu/llvm-project/lldb/test/API/dotest.py -u CXXFLAGS -u CFLAGS --env LLVM_LIBS_DIR=/home/tcwg-buildbot/worker/lldb-arm-ubuntu/build/./lib --env LLVM_INCLUDE_DIR=/home/tcwg-buildbot/worker/lldb-arm-ubuntu/build/include --env LLVM_TOOLS_DIR=/home/tcwg-buildbot/worker/lldb-arm-ubuntu/build/./bin --arch armv8l --build-dir /home/tcwg-buildbot/worker/lldb-arm-ubuntu/build/lldb-test-build.noindex --lldb-module-cache-dir /home/tcwg-buildbot/worker/lldb-arm-ubuntu/build/lldb-test-build.noindex/module-cache-lldb/lldb-api --clang-module-cache-dir /home/tcwg-buildbot/worker/lldb-arm-ubuntu/build/lldb-test-build.noindex/module-cache-clang/lldb-api --executable /home/tcwg-buildbot/worker/lldb-arm-ubuntu/build/./bin/lldb --compiler /home/tcwg-buildbot/worker/lldb-arm-ubuntu/build/./bin/clang --dsymutil /home/tcwg-buildbot/worker/lldb-arm-ubuntu/build/./bin/dsymutil --make /usr/bin/gmake --llvm-tools-dir /home/tcwg-buildbot/worker/lldb-arm-ubuntu/build/./bin --lldb-obj-root /home/tcwg-buildbot/worker/lldb-arm-ubuntu/build/tools/lldb --lldb-libs-dir /home/tcwg-buildbot/worker/lldb-arm-ubuntu/build/./lib /home/tcwg-buildbot/worker/lldb-arm-ubuntu/llvm-project/lldb/test/API/tools/lldb-dap/attach -p TestDAP_attach.py
--
Exit Code: 1

Command Output (stdout):
--
lldb version 21.0.0git (https://github.com/llvm/llvm-project.git revision 50d10b5c1c26c12570d3d31ef24b1a880fd23e26)
  clang revision 50d10b5c1c26c12570d3d31ef24b1a880fd23e26
  llvm revision 50d10b5c1c26c12570d3d31ef24b1a880fd23e26
Skipping the following test categories: ['libc++', 'dsym', 'gmodules', 'debugserver', 'objc']
========= DEBUG ADAPTER PROTOCOL LOGS =========
1739535890.685433865 --> 
Content-Length: 344

{
  "arguments": {
    "adapterID": "lldb-native",
    "clientID": "vscode",
    "columnsStartAt1": true,
    "linesStartAt1": true,
    "locale": "en-us",
    "pathFormat": "path",
    "sourceInitFile": false,
    "supportsRunInTerminalRequest": true,
    "supportsStartDebuggingRequest": true,
    "supportsVariablePaging": true,
    "supportsVariableType": true
  },
  "command": "initialize",
  "seq": 1,
  "type": "request"
}
1739535890.689916849 <-- 
Content-Length: 1631


```

</details>

https://github.com/llvm/llvm-project/pull/121789