This fixes a minor oversight in the FileCheck documentation on what is
considered a valid variable name.

Global variables are prefixed with a `$`, which is explained two
paragraphs below, but this was omitted in the presented regex in this
paragraph.

The default has been false for quite a while now.

Differential Revision: https://reviews.llvm.org/D127846

Add printf-style alternate form flag to prefix hex number with 0x when
present. This works on both empty numeric expression (e.g. variable
definition from input) and when matching a numeric expression. The
syntax is as follows:

[[#%#<precision specifier><format specifier>, ...]

where <precision specifier> and <format specifier> are optional and ...
can be a variable definition or not with an empty expression or not.

This feature was requested in https://reviews.llvm.org/D81144#2075532
for llvm/test/MC/ELF/gen-dwarf64.s

Reviewed By: jdenny

Differential Revision: https://reviews.llvm.org/D97845

Introduce CHECK modifiers that change the behavior of the CHECK
directive. Also add a LITERAL modifier for cases where matching could
end requiring escaping strings interpreted as regex where only
literal/fixed string matching is desired (making the CHECK's more
difficult to write/fragile and difficult to interpret).

Differential Revision: https://reviews.llvm.org/D90621

Fixes
C:\src\llvm-project\llvm\docs\CommandGuide\FileCheck.rst:745:Bullet list ends without a blank line; unexpected unindent.

Add printf-style precision specifier to pad numbers to a given number of
digits when matching them if the value is smaller than the given
precision. This works on both empty numeric expression (e.g. variable
definition from input) and when matching a numeric expression. The
syntax is as follows:

[[#%.<precision><format specifier>, ...]

where <format specifier> is optional and ... can be a variable
definition or not with an empty expression or not. In the absence of a
precision specifier, a variable definition will accept leading zeros.

Reviewed By: jhenderson, grimar

Differential Revision: https://reviews.llvm.org/D81667

ouput -> output

Reviewed By: thopre

Differential Revision: https://reviews.llvm.org/D86504