Jakub Kuderski 9c6054d29d
[lldb][ADT] Fix LLDB/GDB formatters for PointerUnion after recactoring (#188483)
In #188242, we replaced `PointerUnion`'s `PointerIntPair` storage with
`PunnedPointer<void*>`. The old formatters relied on the PIP synthetic
provider (LLDB) / `get_pointer_int_pair helper` (GDB) which no longer
work.

Instead, read raw bytes from `PunnedPointer` and compute the active tag
from template argument type alignments -- the same fixed-width encoding
the C++ implementation uses. When template arg enumeration is truncated
(e.g., function-local types in GDB), the formatters fall back to showing
a tag-stripped `void*` instead of silently misdecoding.

Alternatives that didn't work out:
- Adding a C++ helper (`getActiveMemberIdx`) callable from Python: gets
optimized out even with `__attribute__((used, noinline))`, and
expression evaluation fails for synthetic children.
- Using `isa`/`dyn_cast` checks from Python: requires expression
evaluation, which does not work for local types or synthetic children
without a frame context.

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
2026-03-25 10:16:01 -04:00
..

                                                                   -*- rst -*-
This is a collection of tests to check debugging information generated by 
compiler. This test suite can be checked out inside clang/test folder. This 
will enable 'make test' for clang to pick up these tests.

Some tests (in the 'llgdb-tests' directory) are written with debugger
commands and checks for the intended debugger output in the source file,
using DEBUGGER: and CHECK: as prefixes respectively.

For example::

  define i32 @f1(i32 %i) nounwind ssp {
  ; DEBUGGER: break f1
  ; DEBUGGER: r
  ; DEBUGGER: p i 
  ; CHECK: $1 = 42 
  entry:
  }

is a testcase where the debugger is asked to break at function 'f1' and 
print value of argument 'i'. The expected value of 'i' is 42 in this case.

Other tests are written for use with the 'Dexter' tool (in the 'dexter-tests'
and 'dexter' directories respectively). These use a domain specific language
in comments to describe the intended debugger experience in a more abstract
way than debugger commands. This allows for testing integration across
multiple debuggers from one input language.

For example::

  void __attribute__((noinline, optnone)) bar(int *test) {}
  int main() {
    int test;
    test = 23;
    bar(&test); // DexLabel('before_bar')
    return test; // DexLabel('after_bar')
  }

  // DexExpectWatchValue('test', '23', on_line='before_bar')
  // DexExpectWatchValue('test', '23', on_line='after_bar')

Labels two lines with the names 'before_bar' and 'after_bar', and records that
the 'test' variable is expected to have the value 23 on both of them.