[clang] Assertion `Disp.getOpcode() == ISD::TargetGlobalAddress || Disp.getOpcode() == ISD::TargetGlobalTLSAddress || Disp.getOpcode() == ISD::TargetConstantPool || Disp.getOpcode() == ISD::TargetJumpTable` failed.

The following code:

```c
void binding_to_label_loc() {
char *b = &&MyLabel; // expected-note {{'b' initialized here}}
MyLabel:
*b = 0;
}
```

Resulted in this output:
```
/tmp/test.c:20:36: warning: pragma STDC FENV_ROUND is not supported [-Wunknown-pragmas]
20 | #pragma STDC FENV_ROUND FE_DOWNWARD
| ^
clang: /home/fuzz/WorkSpace/fusion-fuzz/projects/clang/llvm-project/llvm/lib/Target/PowerPC/PPCISelLowering.cpp:20891: llvm::PPC::AddrMode llvm::PPCTargetLowering::SelectOptimalAddrMode(const llvm::SDNode*, llvm::SDValue, llvm::SDValue&, llvm::SDValue&, llvm::SelectionDAG&, llvm::MaybeAlign) const: Assertion `Disp.getOpcode() == ISD::TargetGlobalAddress || Disp.getOpcode() == ISD::TargetGlobalTLSAddress || Disp.getOpcode() == ISD::TargetConstantPool || Disp.getOpcode() == ISD::TargetJumpTable' failed.
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace and dumped files.
Stack dump:
0. Program arguments: /home/fuzz/WorkSpace/fusion-fuzz/projects/clang/llvm-clang-install/bin/clang -c -o /dev/null -O3 -Wno-implicit-function-declaration -Wno-implicit-int -fblocks -fno-inline -g -target powerpc -ffreestanding /tmp/test.c
1. parser at end of file
2. Code generation
3. Running pass 'Function Pass Manager' on module '/tmp/test.c'.
4. Running pass 'PowerPC DAG->DAG Pattern Instruction Selection' on function '@binding_to_label_loc'
Stack dump without symbol names (ensure you have llvm-symbolizer in your PATH or set the environment var `LLVM_SYMBOLIZER_PATH` to point to it):
0 clang 0x000056e637651329 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) + 121
1 clang 0x000056e63764dfec llvm::sys::RunSignalHandlers() + 76
2 clang 0x000056e63764e8a8 llvm::sys::CleanupOnSignal(unsigned long) + 216
3 clang 0x000056e637590218
4 libc.so.6 0x000079c186e86520
5 libc.so.6 0x000079c186eda9bc pthread_kill + 300
6 libc.so.6 0x000079c186e86476 raise + 22
7 libc.so.6 0x000079c186e6c7f3 abort + 211
8 libc.so.6 0x000079c186e6c71b
9 libc.so.6 0x000079c186e7de96
10 clang 0x000056e63645284e
11 clang 0x000056e6363f28a2
12 clang 0x000056e638db9d6e llvm::SelectionDAGISel::SelectCodeCommon(llvm::SDNode*, unsigned char const*, unsigned int, unsigned char const*) + 3934
13 clang 0x000056e636411efe
14 clang 0x000056e638db57e1 llvm::SelectionDAGISel::DoInstructionSelection() + 913
15 clang 0x000056e638dc2a3e llvm::SelectionDAGISel::CodeGenAndEmitDAG() + 3102
16 clang 0x000056e638dc5d9b llvm::SelectionDAGISel::SelectAllBasicBlocks(llvm::Function const&) + 2347
17 clang 0x000056e638dc77f3 llvm::SelectionDAGISel::runOnMachineFunction(llvm::MachineFunction&) + 259
18 clang 0x000056e636418afb
19 clang 0x000056e638db0168 llvm::SelectionDAGISelLegacy::runOnMachineFunction(llvm::MachineFunction&) + 168
20 clang 0x000056e6369782ec
21 clang 0x000056e6370312e5 llvm::FPPassManager::runOnFunction(llvm::Function&) + 1397
22 clang 0x000056e6370318c9 llvm::FPPassManager::runOnModule(llvm::Module&) + 57
23 clang 0x000056e6370322b2
24 clang 0x000056e6370329eb llvm::legacy::PassManagerImpl::run(llvm::Module&) + 219
25 clang 0x000056e637a7415f
26 clang 0x000056e637a88ecf
27 clang 0x000056e637a892f3 clang::emitBackendOutput(clang::CompilerInstance&, clang::CodeGenOptions&, llvm::StringRef, llvm::Module*, clang::BackendAction, llvm::IntrusiveRefCntPtr, std::unique_ptr>, clang::BackendConsumer*) + 483
28 clang 0x000056e6381783ca clang::BackendConsumer::HandleTranslationUnit(clang::ASTContext&) + 1866
29 clang 0x000056e639e4784c clang::ParseAST(clang::Sema&, bool, bool) + 1068
30 clang 0x000056e6384e8061 clang::FrontendAction::Execute() + 65
31 clang 0x000056e638471e65 clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) + 1589
32 clang 0x000056e6385bfde3 clang::ExecuteCompilerInvocation(clang::CompilerInstance*) + 467
33 clang 0x000056e63541b33e cc1_main(llvm::ArrayRef, char const*, void*) + 7166
34 clang 0x000056e63541113a
35 clang 0x000056e6354112cf
36 clang 0x000056e6381f6cfd
37 clang 0x000056e637590630 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref) + 160
38 clang 0x000056e6381f7b53
39 clang 0x000056e6381ac607 clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&, clang::driver::Command const*&, bool) const + 167
40 clang 0x000056e6381b0ef0 clang::driver::Compilation::ExecuteJobs(clang::driver::JobList const&, llvm::SmallVectorImpl>&, bool) const + 304
41 clang 0x000056e6381bf004 clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&, llvm::SmallVectorImpl>&) + 404
42 clang 0x000056e635416923 clang_main(int, char**, llvm::ToolContext const&) + 7315
43 clang 0x000056e6353527f1 main + 113
44 libc.so.6 0x000079c186e6dd90
45 libc.so.6 0x000079c186e6de40 __libc_start_main + 128
46 clang 0x000056e635410765 _start + 37
clang: error: clang frontend command failed due to signal (use -v to see invocation)
clang version 24.0.0git (https://github.com/llvm/llvm-project.git 0976d75180f482c1175ea1f204f9bfd56dd163b1)
Target: powerpc
Thread model: posix
InstalledDir: /home/fuzz/WorkSpace/fusion-fuzz/projects/clang/llvm-clang-install/bin
Build config: +assertions
clang: note: diagnostic msg:
********************

PLEASE ATTACH THE FOLLOWING CRASH REPRODUCER FILES TO THE BUG REPORT:
clang: note: diagnostic msg: /tmp/test-997128.c
clang: note: diagnostic msg: /tmp/test-997128.sh
clang: note: diagnostic msg:

********************
Aborted (core dumped)
```

To reproduce:
```
/home/fuzz/WorkSpace/fusion-fuzz/projects/clang/llvm-clang-install/bin/clang -O3 -target powerpc ./test.c
```

Trunk: https://godbolt.org/z/e4nq4qj6f

Compiler version:
```
clang version 24.0.0git (https://github.com/llvm/llvm-project.git 0976d75180f482c1175ea1f204f9bfd56dd163b1)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /home/fuzz/WorkSpace/fusion-fuzz/projects/clang/llvm-clang-install/bin
Build config: +assertions
```

*This bug was found by [fusion-fuzz](https://github.com/fusion-fuzz/fusion-fuzz)*

The crash is in llvm/lib/Target/PowerPC/PPCISelLowering.cpp, in SelectOptimalAddrMode. Start by reproducing it with test.c and the clang -O3 -target powerpc command, then inspect the failing assertion. Done means this input no longer aborts during code generation and the case is covered by a regression test.

Written by the indexing model from the issue text.