1 files changed, 35 insertions, 28 deletions
diff --git a/llvm/docs/CommandGuide/FileCheck.rst b/llvm/docs/CommandGuide/FileCheck.rst
index bc216be35df..e54ab762cd2 100644
--- a/llvm/docs/CommandGuide/FileCheck.rst
+++ b/llvm/docs/CommandGuide/FileCheck.rst
@@ -499,8 +499,8 @@ simply uniquely match a single line in the file being verified.
 
 ``CHECK-LABEL:`` directives cannot contain variable definitions or uses.
 
-FileCheck Pattern Matching Syntax
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+FileCheck Regex Matching Syntax
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 All FileCheck directives take a pattern to match.
 For most uses of FileCheck, fixed string matching is perfectly sufficient.  For
@@ -525,14 +525,15 @@ braces like you would in C.  In the rare case that you want to match double
 braces explicitly from the input, you can use something ugly like
 ``{{[{][{]}}`` as your pattern.
 
-FileCheck Pattern Expressions
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+FileCheck String Substitution Blocks
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 It is often useful to match a pattern and then verify that it occurs again
-later in the file.  For codegen tests, this can be useful to allow any register,
-but verify that that register is used consistently later.  To do this,
-:program:`FileCheck` supports pattern expressions that allow pattern variables
-to be defined and substituted into patterns.  Here is a simple example:
+later in the file.  For codegen tests, this can be useful to allow any
+register, but verify that that register is used consistently later.  To do
+this, :program:`FileCheck` supports string substitution blocks that allow
+string variables to be defined and substituted into patterns.  Here is a simple
+example:
 
 .. code-block:: llvm
 
@@ -541,15 +542,16 @@ to be defined and substituted into patterns.  Here is a simple example:
    ; CHECK:    andw	{{.*}}[[REGISTER]]
 
 The first check line matches a regex ``%[a-z]+`` and captures it into the
-variable ``REGISTER``.  The second line verifies that whatever is in
-``REGISTER`` occurs later in the file after an "``andw``".  :program:`FileCheck`
-variable references are always contained in ``[[ ]]`` pairs, and their names can
-be formed with the regex ``[a-zA-Z_][a-zA-Z0-9_]*``.  If a colon follows the name,
-then it is a definition of the variable; otherwise, it is a use.
+string variable ``REGISTER``.  The second line verifies that whatever is in
+``REGISTER`` occurs later in the file after an "``andw``". :program:`FileCheck`
+string substitution blocks are always contained in ``[[ ]]`` pairs, and string
+variable names can be formed with the regex ``[a-zA-Z_][a-zA-Z0-9_]*``.  If a
+colon follows the name, then it is a definition of the variable; otherwise, it
+is a substitution.
 
-:program:`FileCheck` variables can be defined multiple times, and uses always
-get the latest value.  Variables can also be used later on the same line they
-were defined on. For example:
+:program:`FileCheck` variables can be defined multiple times, and substitutions
+always get the latest value.  Variables can also be substituted later on the
+same line they were defined on. For example:
 
 .. code-block:: llvm
 
@@ -565,16 +567,17 @@ CHECK-LABEL block. Global variables are not affected by CHECK-LABEL.
 This makes it easier to ensure that individual tests are not affected
 by variables set in preceding tests.
 
-FileCheck Numeric Variables and Expressions
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+FileCheck Numeric Substitution Blocks
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-:program:`FileCheck` also allows checking for numeric values that satisfy a
-numeric expression constraint based on numeric variables. This allows
-``CHECK:`` directives to verify a numeric relation between two numbers, such as
-the need for consecutive registers to be used.
+:program:`FileCheck` also supports numeric substitution blocks that allow
+checking for numeric values that satisfy a numeric expression constraint based
+on numeric variables. This allows ``CHECK:`` directives to verify a numeric
+relation between two numbers, such as the need for consecutive registers to be
+used.
 
-The syntax to check a numeric expression constraint is
-``[[#<NUMVAR><op><offset>]]`` where:
+The syntax of a numeric substitution block is ``[[#<NUMVAR><op><offset>]]``
+where:
 
 * ``<NUMVAR>`` is the name of a numeric variable defined on the command line.
 
@@ -585,6 +588,10 @@ The syntax to check a numeric expression constraint is
   the numeric operation <op>. It must be present if ``<op>`` is present,
   absent otherwise.
 
+Spaces are accepted before, after and between any of these elements.
+
+Unlike string substitution blocks, numeric substitution blocks only introduce
+numeric substitutions which substitute a numeric expression for its value.
 For example:
 
 .. code-block:: llvm
@@ -606,7 +613,7 @@ but would not match the line:
 due to ``7`` being unequal to ``5 + 1``.
 
 The ``--enable-var-scope`` option has the same effect on numeric variables as
-on pattern variables.
+on string variables.
 
 FileCheck Pseudo Numeric Variables
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@@ -632,9 +639,9 @@ relative line number references, for example:
    // CHECK-NEXT: {{^     ;}}
    int a
 
-To support legacy uses of ``@LINE`` as a special pattern variable,
-:program:`FileCheck` also accepts the following uses of ``@LINE`` with pattern
-variable syntax: ``[[@LINE]]``, ``[[@LINE+<offset>]]`` and
+To support legacy uses of ``@LINE`` as a special string variable,
+:program:`FileCheck` also accepts the following uses of ``@LINE`` with string
+substitution block syntax: ``[[@LINE]]``, ``[[@LINE+<offset>]]`` and
 ``[[@LINE-<offset>]]`` without any spaces inside the brackets and where
 ``offset`` is an integer.