[analyzer] UNREACHABLE executed at clang/lib/StaticAnalyzer/Core/RegionStore.cpp:2193

[dmantipov]

Hit by clang-tidy 21.0.0 (HEAD at 2529de5) when running make clang-analyzer for Linux kernel 6.16.0-rc3 (rename xe_gt_sriov_pf.txt to .i):
xe_gt_sriov_pf.txt
clang-tidy.log
clang-tidy-debug.log

[llvmbot]

@llvm/issue-subscribers-clang-tidy

Author: Dmitry Antipov (dmantipov)

Hit by clang-tidy 21.0.0 (HEAD at 2529de5) when running _make clang-analyzer_ for Linux kernel 6.16.0-rc3 (rename xe_gt_sriov_pf.txt to .i): [xe_gt_sriov_pf.txt](https://github.com/user-attachments/files/20944627/xe_gt_sriov_pf.txt) [clang-tidy.log](https://github.com/user-attachments/files/20944663/clang-tidy.log) [clang-tidy-debug.log](https://github.com/user-attachments/files/20944665/clang-tidy-debug.log)

[llvmbot]

@llvm/issue-subscribers-clang-static-analyzer

Author: Dmitry Antipov (dmantipov)

Hit by clang-tidy 21.0.0 (HEAD at 2529de5) when running _make clang-analyzer_ for Linux kernel 6.16.0-rc3 (rename xe_gt_sriov_pf.txt to .i): [xe_gt_sriov_pf.txt](https://github.com/user-attachments/files/20944627/xe_gt_sriov_pf.txt) [clang-tidy.log](https://github.com/user-attachments/files/20944663/clang-tidy.log) [clang-tidy-debug.log](https://github.com/user-attachments/files/20944665/clang-tidy-debug.log)

[steakhal]

Link to the unreachable line:

llvm-project/clang/lib/StaticAnalyzer/Core/RegionStore.cpp

Line 2193 in 2529de5

llvm_unreachable("Unknown default value");

[dmantipov]

Reproduced on repro-146050.txt (rename to .c) on HEAD at 629126e.

[vbvictor]

Thank you for the reduced version.
Further reduced to exclude Macros:

struct xe_reg {
  union {
    struct {
      unsigned int addr : 22;
      unsigned int vf : 1;
    };
    unsigned int raw;
  };
};

static struct xe_reg xe_reg_vf_to_pf(struct xe_reg vf_reg, unsigned int vfid,
                                     unsigned int stride) {
  struct xe_reg pf_reg = vf_reg;

  pf_reg.vf = 0;
  pf_reg.addr += stride * vfid;

  return pf_reg;
}

static void pf_clear_vf_scratch_regs(unsigned int vfid) {
  struct xe_reg scratch = xe_reg_vf_to_pf(
      ((const struct xe_reg){.addr = 0x190310 + (0) * 4, .vf = 1}), vfid, 1);
}

https://godbolt.org/z/W6ezhYo1K