[llvm] [GlobalISel][TableGen] MIR Pattern Variadics (PR #100563)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `clang-x86_64-debian-fast` running on `gribozavr4` while building `llvm` at step 6 "test-build-unified-tree-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/56/builds/3838

Here is the relevant piece of the build log for the reference:
```
Step 6 (test-build-unified-tree-check-all) failure: test (failure)
******************** TEST 'LLVM :: TableGen/GlobalISelCombinerEmitter/variadic-errors.td' FAILED ********************
Exit Code: 1

Command Output (stderr):
--
RUN: at line 1: not /b/1/clang-x86_64-debian-fast/llvm.obj/bin/llvm-tblgen -I /b/1/clang-x86_64-debian-fast/llvm.src/llvm/test/TableGen/GlobalISelCombinerEmitter/../../../include -gen-global-isel-combiner      -combiners=MyCombiner /b/1/clang-x86_64-debian-fast/llvm.src/llvm/test/TableGen/GlobalISelCombinerEmitter/variadic-errors.td 2>&1|  /b/1/clang-x86_64-debian-fast/llvm.obj/bin/FileCheck /b/1/clang-x86_64-debian-fast/llvm.src/llvm/test/TableGen/GlobalISelCombinerEmitter/variadic-errors.td -implicit-check-not=error:
+ /b/1/clang-x86_64-debian-fast/llvm.obj/bin/FileCheck /b/1/clang-x86_64-debian-fast/llvm.src/llvm/test/TableGen/GlobalISelCombinerEmitter/variadic-errors.td -implicit-check-not=error:
+ not /b/1/clang-x86_64-debian-fast/llvm.obj/bin/llvm-tblgen -I /b/1/clang-x86_64-debian-fast/llvm.src/llvm/test/TableGen/GlobalISelCombinerEmitter/../../../include -gen-global-isel-combiner -combiners=MyCombiner /b/1/clang-x86_64-debian-fast/llvm.src/llvm/test/TableGen/GlobalISelCombinerEmitter/variadic-errors.td
/b/1/clang-x86_64-debian-fast/llvm.src/llvm/test/TableGen/GlobalISelCombinerEmitter/variadic-errors.td:30:11: error: CHECK: expected string not found in input
// CHECK: :[[@LINE+1]]:{{[0-9]+}}: error: Failed to parse pattern: '(G_BUILD_VECTOR ?:$dst, anonymous_8021:$a)'
          ^
<stdin>:16:211: note: scanning from here
/b/1/clang-x86_64-debian-fast/llvm.src/llvm/test/TableGen/GlobalISelCombinerEmitter/variadic-errors.td:31:5: error: cannot parse operand type: minimum number of arguments must be greater than zero in GIVariadic
                                                                                                                                                                                                                  ^
<stdin>:16:211: note: with "@LINE+1" equal to "31"
/b/1/clang-x86_64-debian-fast/llvm.src/llvm/test/TableGen/GlobalISelCombinerEmitter/variadic-errors.td:31:5: error: cannot parse operand type: minimum number of arguments must be greater than zero in GIVariadic
                                                                                                                                                                                                                  ^
<stdin>:19:102: note: possible intended match here
/b/1/clang-x86_64-debian-fast/llvm.src/llvm/test/TableGen/GlobalISelCombinerEmitter/variadic-errors.td:31:5: error: Failed to parse pattern: '(G_BUILD_VECTOR ?:$dst, anonymous_8022:$a)'
                                                                                                     ^

Input file: <stdin>
Check file: /b/1/clang-x86_64-debian-fast/llvm.src/llvm/test/TableGen/GlobalISelCombinerEmitter/variadic-errors.td

-dump-input=help explains the following input dump.

Input was:
<<<<<<
            .
            .
            .
           11: def ConflictingInference : GICombineRule< 
           12:  ^ 
           13: /b/1/clang-x86_64-debian-fast/llvm.src/llvm/test/TableGen/GlobalISelCombinerEmitter/variadic-errors.td:24:5: note: 'args' seen with type 'GIVariadic<2,4>' in '__ConflictingInference_match_0' 
           14: def ConflictingInference : GICombineRule< 
           15:  ^ 
           16: /b/1/clang-x86_64-debian-fast/llvm.src/llvm/test/TableGen/GlobalISelCombinerEmitter/variadic-errors.td:31:5: error: cannot parse operand type: minimum number of arguments must be greater than zero in GIVariadic 
check:30'0                                                                                                                                                                                                                       X error: no match found
check:30'1                                                                                                                                                                                                                         with "@LINE+1" equal to "31"
           17: def InvalidBounds0 : GICombineRule< 
check:30'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
           18:  ^ 
check:30'0     ~~~
           19: /b/1/clang-x86_64-debian-fast/llvm.src/llvm/test/TableGen/GlobalISelCombinerEmitter/variadic-errors.td:31:5: error: Failed to parse pattern: '(G_BUILD_VECTOR ?:$dst, anonymous_8022:$a)' 
check:30'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
check:30'2                                                                                                          ?                                                                                     possible intended match
           20: def InvalidBounds0 : GICombineRule< 
check:30'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
           21:  ^ 
check:30'0     ~~~
...

```

https://github.com/llvm/llvm-project/pull/100563