[llvm-branch-commits] [TableGen] Slightly improve error location for a fatal error (PR #170790)

[via llvm-branch-commits]

github-actions[bot] wrote:

<!--PREMERGE ADVISOR COMMENT: Linux-->
# :penguin: Linux x64 Test Results

* 166773 tests passed
* 2909 tests skipped
* 1 test failed

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

### LLVM
<details>
<summary>LLVM.TableGen/RegClassByHwMode.td</summary>

```
Exit Code: 2

Command Output (stdout):
--
# RUN: at line 1
/home/gha/actions-runner/_work/llvm-project/llvm-project/build/bin/llvm-tblgen -gen-instr-info   -I /home/gha/actions-runner/_work/llvm-project/llvm-project/llvm/test/TableGen -I /home/gha/actions-runner/_work/llvm-project/llvm-project/llvm/test/TableGen/../../include /home/gha/actions-runner/_work/llvm-project/llvm-project/llvm/test/TableGen/RegClassByHwMode.td -o - | /home/gha/actions-runner/_work/llvm-project/llvm-project/build/bin/FileCheck -check-prefix=INSTRINFO /home/gha/actions-runner/_work/llvm-project/llvm-project/llvm/test/TableGen/RegClassByHwMode.td
# executed command: /home/gha/actions-runner/_work/llvm-project/llvm-project/build/bin/llvm-tblgen -gen-instr-info -I /home/gha/actions-runner/_work/llvm-project/llvm-project/llvm/test/TableGen -I /home/gha/actions-runner/_work/llvm-project/llvm-project/llvm/test/TableGen/../../include /home/gha/actions-runner/_work/llvm-project/llvm-project/llvm/test/TableGen/RegClassByHwMode.td -o -
# .---command stderr------------
# | /home/gha/actions-runner/_work/llvm-project/llvm-project/llvm/test/TableGen/RegClassByHwMode.td:330:71: error: Variable not defined: 'X4'
# | def XRegs : RegisterClass<"MyTarget", [i64], 64, (add X0, X1, X2, X3, X4, X5, X6)>;
# |                                                                       ^
# `-----------------------------
# error: command failed with exit status: 1
# executed command: /home/gha/actions-runner/_work/llvm-project/llvm-project/build/bin/FileCheck -check-prefix=INSTRINFO /home/gha/actions-runner/_work/llvm-project/llvm-project/llvm/test/TableGen/RegClassByHwMode.td
# .---command stderr------------
# | FileCheck error: '<stdin>' is empty.
# | FileCheck command line:  /home/gha/actions-runner/_work/llvm-project/llvm-project/build/bin/FileCheck -check-prefix=INSTRINFO /home/gha/actions-runner/_work/llvm-project/llvm-project/llvm/test/TableGen/RegClassByHwMode.td
# `-----------------------------
# error: command failed with exit status: 2

--

```
</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/170790