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FILECHECK(1)			      LLVM			    FILECHECK(1)

NAME
     FileCheck - Flexible pattern matching file verifier

SYNOPSIS
     FileCheck match-filename [--check-prefix=XXX] [--strict-whitespace]

DESCRIPTION
     FileCheck	reads  two  files (one from standard input, and one specified on
     the command line) and uses one to verify the other.  This behavior is  par-
     ticularly	useful	for the testsuite, which wants to verify that the output
     of some tool (e.g. llc) contains the expected information (for  example,  a
     movsd from esp or whatever is interesting).  This is similar to using grep,
     but it is optimized for matching multiple different inputs in one file in a
     specific order.

     The  match-filename  file	specifies the file that contains the patterns to
     match.  The  file	to  verify  is	read  from  standard  input  unless  the
     --input-file option is used.

OPTIONS
     Options  are  parsed  from the environment variable FILECHECK_OPTS and from
     the command line.

     -help  Print a summary of command line options.

     --check-prefix prefix
	    FileCheck searches the contents of match-filename  for  patterns  to
	    match.   By  default, these patterns are prefixed with "CHECK:".  If
	    you'd like to use a different prefix (e.g. because	the  same  input
	    file   is	checking   multiple  different	tool  or  options),  the
	    --check-prefix argument allows you to specify (without the	trailing
	    ":") one or more prefixes to match. Multiple prefixes are useful for
	    tests  which  might change for different run options, but most lines
	    remain the same.

	    FileCheck does not permit duplicate prefixes, even if one is a check
	    prefix and one is a comment prefix (see --comment-prefixes below).

     --check-prefixes prefix1,prefix2,...
	    An alias of --check-prefix that allows multiple prefixes to be spec-
	    ified as a comma separated list.

     --comment-prefixes prefix1,prefix2,...
	    By default, FileCheck ignores any occurrence  in  match-filename  of
	    any  check	prefix	if  it is preceded on the same line by "COM:" or
	    "RUN:". See the section The "COM:" directive for usage details.

	    These   default   comment	prefixes   can	  be	overridden    by
	    --comment-prefixes	if they are not appropriate for your testing en-
	    vironment. However, doing so is not recommended in LLVM's  LIT-based
	    test suites, which should be easier to maintain if they all follow a
	    consistent	comment style. In that case, consider proposing a change
	    to the default comment prefixes instead.

     --allow-unused-prefixes
	    This option controls the behavior when using more than one prefix as
	    specified by --check-prefix or --check-prefixes, and some  of  these
	    prefixes  are missing in the test file. If true, this is allowed, if
	    false, FileCheck will report an error, listing the missing prefixes.
	    The default value is false.

     --input-file filename
	    File to check (defaults to stdin).

     --match-full-lines
	    By default, FileCheck allows matches of anywhere on a line. This op-
	    tion will require all positive matches  to	cover  an  entire  line.
	    Leading    and    trailing	  whitespace	is    ignored,	  unless
	    --strict-whitespace is also specified. (Note: negative matches  from
	    CHECK-NOT are not affected by this option!)

	    Passing  this option is equivalent to inserting {{^ *}} or {{^}} be-
	    fore, and {{ *$}} or {{$}} after every positive check pattern.

     --strict-whitespace
	    By default,  FileCheck  canonicalizes  input  horizontal  whitespace
	    (spaces  and  tabs)  which	causes it to ignore these differences (a
	    space will match a tab).  The --strict-whitespace argument	disables
	    this behavior. End-of-line sequences are canonicalized to UNIX-style
	    \n in all modes.

     --ignore-case
	    By	default,  FileCheck  uses  case-sensitive  matching. This option
	    causes FileCheck to use case-insensitive matching.

     --implicit-check-not check-pattern
	    Adds implicit negative checks for  the  specified  patterns  between
	    positive  checks.  The  option allows writing stricter tests without
	    stuffing them with CHECK-NOTs.

	    For example, "--implicit-check-not	warning:"  can	be  useful  when
	    testing  diagnostic  messages  from  tools that don't have an option
	    similar to clang -verify. With this  option  FileCheck  will  verify
	    that  input does not contain warnings not covered by any CHECK: pat-
	    terns.

     --dump-input <value>
	    Dump input to stderr, adding annotations representing currently  en-
	    abled  diagnostics.  When there are multiple occurrences of this op-
	    tion, the <value> that appears earliest in the list below has prece-
	    dence.  The default is fail.

	    * help   - Explain input dump and quit

	    * always - Always dump input

	    * fail   - Dump input on failure

	    * never  - Never dump input

     --dump-input-context <N>
	    In the dump requested by --dump-input, print <N> input lines  before
	    and  <N>  input lines after any lines specified by --dump-input-fil-
	    ter.  When there  are  multiple  occurrences  of  this  option,  the
	    largest specified <N> has precedence.  The default is 5.

     --dump-input-filter <value>
	    In	the  dump  requested  by --dump-input, print only input lines of
	    kind <value> plus any  context  specified  by  --dump-input-context.
	    When there are multiple occurrences of this option, the <value> that
	    appears  earliest  in the list below has precedence.  The default is
	    error when --dump-input=fail, and it's all when --dump-input=always.

	    * all	      - All input lines

	    * annotation-full - Input lines with annotations

	    * annotation      - Input lines with starting points of annotations

	    * error	      - Input lines with starting points of error  anno-
	      tations

     --enable-var-scope
	    Enables scope for regex variables.

	    Variables with names that start with $ are considered global and re-
	    main set throughout the file.

	    All  other	variables get undefined after each encountered CHECK-LA-
	    BEL.

     -D<VAR=VALUE>
	    Sets a filecheck pattern variable VAR with value VALUE that  can  be
	    used in CHECK: lines.

     -D#<FMT>,<NUMVAR>=<NUMERIC EXPRESSION>
	    Sets  a  filecheck numeric variable NUMVAR of matching format FMT to
	    the result of evaluating <NUMERIC EXPRESSION> that can  be	used  in
	    CHECK:  lines.   See section FileCheck Numeric Variables and Expres-
	    sions for details on supported numeric expressions.

     -version
	    Show the version number of this program.

     -v     Print good directive pattern matches.  However, if	-dump-input=fail
	    or	-dump-input=always,  add  those matches as input annotations in-
	    stead.

     -vv    Print information helpful in diagnosing internal  FileCheck  issues,
	    such  as discarded overlapping CHECK-DAG: matches, implicit EOF pat-
	    tern matches, and CHECK-NOT: patterns that do not have matches.  Im-
	    plies -v.  However, if -dump-input=fail or -dump-input=always,  just
	    add that information as input annotations instead.

     --allow-deprecated-dag-overlap
	    Enable   overlapping   among  matches  in  a  group  of  consecutive
	    CHECK-DAG: directives.  This option is deprecated and is  only  pro-
	    vided for convenience as old tests are migrated to the new non-over-
	    lapping CHECK-DAG: implementation.

     --allow-empty
	    Allow checking empty input. By default, empty input is rejected.

     --color
	    Use colors in output (autodetected by default).

EXIT STATUS
     If FileCheck verifies that the file matches the expected contents, it exits
     with  0.	Otherwise,  if	not,  or if an error occurs, it will exit with a
     non-zero value.

TUTORIAL
     FileCheck is typically used from LLVM regression tests,  being  invoked  on
     the  RUN  line of the test.  A simple example of using FileCheck from a RUN
     line looks like this:

	; RUN: llvm-as < %s | llc -march=x86-64 | FileCheck %s

     This syntax says to pipe the current file ("%s") into  llvm-as,  pipe  that
     into  llc,  then  pipe  the  output of llc into FileCheck.  This means that
     FileCheck will be verifying its standard input (the llc output) against the
     filename argument specified (the original .ll file specified by "%s").   To
     see  how  this works, let's look at the rest of the .ll file (after the RUN
     line):

	define void @sub1(i32* %p, i32 %v) {
	entry:
	; CHECK: sub1:
	; CHECK: subl
		%0 = tail call i32 @llvm.atomic.load.sub.i32.p0i32(i32* %p, i32 %v)
		ret void
	}

	define void @inc4(i64* %p) {
	entry:
	; CHECK: inc4:
	; CHECK: incq
		%0 = tail call i64 @llvm.atomic.load.add.i64.p0i64(i64* %p, i64 1)
		ret void
	}

     Here you can see some "CHECK:" lines specified in comments.   Now	you  can
     see how the file is piped into llvm-as, then llc, and the machine code out-
     put  is what we are verifying.  FileCheck checks the machine code output to
     verify that it matches what the "CHECK:" lines specify.

     The syntax of the "CHECK:" lines is very simple:  they  are  fixed  strings
     that must occur in order.	FileCheck defaults to ignoring horizontal white-
     space  differences  (e.g. a space is allowed to match a tab) but otherwise,
     the contents of the "CHECK:" line is required to match some  thing  in  the
     test file exactly.

     One nice thing about FileCheck (compared to grep) is that it allows merging
     test  cases  together  into  logical groups.  For example, because the test
     above is checking for the "sub1:" and "inc4:" labels, it will not match un-
     less there is a "subl" in between those labels.  If  it  existed  somewhere
     else  in  the file, that would not count: "grep subl" matches if "subl" ex-
     ists anywhere in the file.

   The FileCheck -check-prefix option
     The FileCheck -check-prefix option allows multiple test  configurations  to
     be driven from one .ll file.  This is useful in many circumstances, for ex-
     ample,  testing different architectural variants with llc.  Here's a simple
     example:

	; RUN: llvm-as < %s | llc -mtriple=i686-apple-darwin9 -mattr=sse41 \
	; RUN:		    | FileCheck %s -check-prefix=X32
	; RUN: llvm-as < %s | llc -mtriple=x86_64-apple-darwin9 -mattr=sse41 \
	; RUN:		    | FileCheck %s -check-prefix=X64

	define <4 x i32> @pinsrd_1(i32 %s, <4 x i32> %tmp) nounwind {
		%tmp1 = insertelement <4 x i32>; %tmp, i32 %s, i32 1
		ret <4 x i32> %tmp1
	; X32: pinsrd_1:
	; X32:	  pinsrd $1, 4(%esp), %xmm0

	; X64: pinsrd_1:
	; X64:	  pinsrd $1, %edi, %xmm0
	}

     In this case, we're testing that we get the expected code	generation  with
     both 32-bit and 64-bit code generation.

   The "COM:" directive
     Sometimes you want to disable a FileCheck directive without removing it en-
     tirely, or you want to write comments that mention a directive by name. The
     "COM:" directive makes it easy to do this. For example, you might have:

	; X32: pinsrd_1:
	; X32:	  pinsrd $1, 4(%esp), %xmm0

	; COM: FIXME: X64 isn't working correctly yet for this part of codegen, but
	; COM: X64 will have something similar to X32:
	; COM:
	; COM:	 X64: pinsrd_1:
	; COM:	 X64:	 pinsrd $1, %edi, %xmm0

     Without "COM:", you would need to use some combination of rewording and di-
     rective syntax mangling to prevent FileCheck from recognizing the commented
     occurrences  of  "X32:" and "X64:" above as directives. Moreover, FileCheck
     diagnostics have been proposed that might complain about the  above  occur-
     rences of "X64" that don't have the trailing ":" because they look like di-
     rective typos. Dodging all these problems can be tedious for a test author,
     and  directive  syntax  mangling can make the purpose of test code unclear.
     "COM:" avoids all these problems.

     A few important usage notes:

     * "COM:" within another directive's pattern does not comment  out	the  re-
       mainder of the pattern. For example:

	  ; X32: pinsrd $1, 4(%esp), %xmm0 COM: This is part of the X32 pattern!

       If  you	need  to  temporarily comment out part of a directive's pattern,
       move it to another line. The reason is that FileCheck  parses  "COM:"  in
       the  same  manner as any other directive: only the first directive on the
       line is recognized as a directive.

     * For the sake of LIT, FileCheck treats "RUN:" just like "COM:". If this is
       not suitable for your test environment, see --comment-prefixes.

     * FileCheck does not recognize "COM", "RUN", or  any  user-defined  comment
       prefix  as  a  comment  directive  if it's combined with one of the usual
       check directive suffixes, such as "-NEXT:" or "-NOT:",  discussed  below.
       FileCheck treats such a combination as plain text instead. If it needs to
       act  as	a comment directive for your test environment, define it as such
       with --comment-prefixes.

   The "CHECK-NEXT:" directive
     Sometimes you want to match lines and would like  to  verify  that  matches
     happen  on  exactly  consecutive lines with no other lines in between them.
     In this case, you can use "CHECK:" and "CHECK-NEXT:" directives to  specify
     this.   If  you specified a custom check prefix, just use "<PREFIX>-NEXT:".
     For example, something like this works as you'd expect:

	define void @t2(<2 x double>* %r, <2 x double>* %A, double %B) {
	     %tmp3 = load <2 x double>* %A, align 16
	     %tmp7 = insertelement <2 x double> undef, double %B, i32 0
	     %tmp9 = shufflevector <2 x double> %tmp3,
				    <2 x double> %tmp7,
				    <2 x i32> < i32 0, i32 2 >
	     store <2 x double> %tmp9, <2 x double>* %r, align 16
	     ret void

	; CHECK:	  t2:
	; CHECK:	     movl    8(%esp), %eax
	; CHECK-NEXT:	     movapd  (%eax), %xmm0
	; CHECK-NEXT:	     movhpd  12(%esp), %xmm0
	; CHECK-NEXT:	     movl    4(%esp), %eax
	; CHECK-NEXT:	     movapd  %xmm0, (%eax)
	; CHECK-NEXT:	     ret
	}

     "CHECK-NEXT:" directives reject the input unless there is exactly one  new-
     line  between it and the previous directive.  A "CHECK-NEXT:" cannot be the
     first directive in a file.

   The "CHECK-SAME:" directive
     Sometimes you want to match lines and would like  to  verify  that  matches
     happen  on  the same line as the previous match.  In this case, you can use
     "CHECK:" and "CHECK-SAME:" directives to specify this.  If you specified  a
     custom check prefix, just use "<PREFIX>-SAME:".

     "CHECK-SAME:"  is	particularly  powerful	in conjunction with "CHECK-NOT:"
     (described below).

     For example, the following works like you'd expect:

	!0 = !DILocation(line: 5, scope: !1, inlinedAt: !2)

	; CHECK:       !DILocation(line: 5,
	; CHECK-NOT:		   column:
	; CHECK-SAME:		   scope: ![[SCOPE:[0-9]+]]

     "CHECK-SAME:" directives reject the input if there are any newlines between
     it and the previous directive.

     "CHECK-SAME:" is also useful  to  avoid  writing  matchers  for  irrelevant
     fields. For example, suppose you're writing a test which parses a tool that
     generates output like this:

	Name: foo
	Field1: ...
	Field2: ...
	Field3: ...
	Value: 1

	Name: bar
	Field1: ...
	Field2: ...
	Field3: ...
	Value: 2

	Name: baz
	Field1: ...
	Field2: ...
	Field3: ...
	Value: 1

     To  write	a  test that verifies foo has the value 1, you might first write
     this:

	CHECK: Name: foo
	CHECK: Value: 1{{$}}

     However, this would be a bad test: if the value for foo changes,  the  test
     would  still  pass because the "CHECK: Value: 1" line would match the value
     from baz. To fix this, you could add CHECK-NEXT matchers for every  FieldN:
     line,  but  that  would  be  verbose, and need to be updated when Field4 is
     added. A more succinct way  to  write  the  test  using  the  "CHECK-SAME:"
     matcher would be as follows:

	CHECK:	    Name: foo
	CHECK:	    Value:
	CHECK-SAME:	   {{ 1$}}

     This verifies that the next time "Value:" appears in the output, it has the
     value 1.

     Note: a "CHECK-SAME:" cannot be the first directive in a file.

   The "CHECK-EMPTY:" directive
     If  you need to check that the next line has nothing on it, not even white-
     space, you can use the "CHECK-EMPTY:" directive.

	declare void @foo()

	declare void @bar()
	; CHECK: foo
	; CHECK-EMPTY:
	; CHECK-NEXT: bar

     Just like "CHECK-NEXT:" the directive will fail if there is more  than  one
     newline before it finds the next blank line, and it cannot be the first di-
     rective in a file.

   The "CHECK-NOT:" directive
     The  "CHECK-NOT:"	directive  is used to verify that a string doesn't occur
     between two matches (or before the first match, or after the  last  match).
     For  example,  to verify that a load is removed by a transformation, a test
     like this can be used:

	define i8 @coerce_offset0(i32 %V, i32* %P) {
	  store i32 %V, i32* %P

	  %P2 = bitcast i32* %P to i8*
	  %P3 = getelementptr i8* %P2, i32 2

	  %A = load i8* %P3
	  ret i8 %A
	; CHECK: @coerce_offset0
	; CHECK-NOT: load
	; CHECK: ret i8
	}

   The "CHECK-COUNT:" directive
     If you need to match multiple lines with the same	pattern  over  and  over
     again  you can repeat a plain CHECK: as many times as needed. If that looks
     too boring you can instead use a counted check "CHECK-COUNT-<num>:",  where
     <num> is a positive decimal number. It will match the pattern exactly <num>
     times,  no  more  and no less. If you specified a custom check prefix, just
     use "<PREFIX>-COUNT-<num>:" for the same effect.  Here is a simple example:

	Loop at depth 1
	Loop at depth 1
	Loop at depth 1
	Loop at depth 1
	  Loop at depth 2
	    Loop at depth 3

	; CHECK-COUNT-6: Loop at depth {{[0-9]+}}
	; CHECK-NOT:	 Loop at depth {{[0-9]+}}

   The "CHECK-DAG:" directive
     If it's necessary to match strings that don't occur in a  strictly  sequen-
     tial  order,  "CHECK-DAG:" could be used to verify them between two matches
     (or before the first match, or after the last match).  For  example,  clang
     emits  vtable  globals  in reverse order. Using CHECK-DAG:, we can keep the
     checks in the natural order:

	// RUN: %clang_cc1 %s -emit-llvm -o - | FileCheck %s

	struct Foo { virtual void method(); };
	Foo f;	// emit vtable
	// CHECK-DAG: @_ZTV3Foo =

	struct Bar { virtual void method(); };
	Bar b;
	// CHECK-DAG: @_ZTV3Bar =

     CHECK-NOT: directives could be mixed with CHECK-DAG: directives to  exclude
     strings  between  the  surrounding  CHECK-DAG: directives. As a result, the
     surrounding CHECK-DAG: directives cannot be reordered, i.e. all occurrences
     matching CHECK-DAG: before CHECK-NOT:  must  not  fall  behind  occurrences
     matching CHECK-DAG: after CHECK-NOT:. For example,

	; CHECK-DAG: BEFORE
	; CHECK-NOT: NOT
	; CHECK-DAG: AFTER

     This case will reject input strings where BEFORE occurs after AFTER.

     With  captured variables, CHECK-DAG: is able to match valid topological or-
     derings of a DAG with edges from the definition of a variable to  its  use.
     It's  useful, e.g., when your test cases need to match different output se-
     quences from the instruction scheduler. For example,

	; CHECK-DAG: add [[REG1:r[0-9]+]], r1, r2
	; CHECK-DAG: add [[REG2:r[0-9]+]], r3, r4
	; CHECK:     mul r5, [[REG1]], [[REG2]]

     In this case, any order of that two add instructions will be allowed.

     If you are defining and using variables in the same  CHECK-DAG:  block,  be
     aware that the definition rule can match after its use.

     So, for instance, the code below will pass:

	; CHECK-DAG: vmov.32 [[REG2:d[0-9]+]][0]
	; CHECK-DAG: vmov.32 [[REG2]][1]
	vmov.32 d0[1]
	vmov.32 d0[0]

     While this other code, will not:

	; CHECK-DAG: vmov.32 [[REG2:d[0-9]+]][0]
	; CHECK-DAG: vmov.32 [[REG2]][1]
	vmov.32 d1[1]
	vmov.32 d0[0]

     While  this can be very useful, it's also dangerous, because in the case of
     register sequence, you must have a strong order (read  before  write,  copy
     before  use, etc). If the definition your test is looking for doesn't match
     (because of a bug in the compiler), it may match further away from the use,
     and mask real bugs away.

     In those cases, to enforce the  order,  use  a  non-DAG  directive  between
     DAG-blocks.

     A	CHECK-DAG:  directive skips matches that overlap the matches of any pre-
     ceding CHECK-DAG: directives in the same CHECK-DAG:  block.   Not	only  is
     this  non-overlapping  behavior  consistent with other directives, but it's
     also necessary to handle sets of non-unique strings or patterns.  For exam-
     ple, the following directives look for unordered log entries for two  tasks
     in a parallel program, such as the OpenMP runtime:

	// CHECK-DAG: [[THREAD_ID:[0-9]+]]: task_begin
	// CHECK-DAG: [[THREAD_ID]]: task_end
	//
	// CHECK-DAG: [[THREAD_ID:[0-9]+]]: task_begin
	// CHECK-DAG: [[THREAD_ID]]: task_end

     The  second  pair of directives is guaranteed not to match the same log en-
     tries as the first pair even though the patterns are identical and even  if
     the  text	of the log entries is identical because the thread ID manages to
     be reused.

   The "CHECK-LABEL:" directive
     Sometimes in a file containing multiple tests divided into logical  blocks,
     one  or  more CHECK: directives may inadvertently succeed by matching lines
     in a later block. While an error will usually eventually be generated,  the
     check  flagged  as causing the error may not actually bear any relationship
     to the actual source of the problem.

     In order to produce better error messages in these  cases,  the  "CHECK-LA-
     BEL:"  directive  can  be used. It is treated identically to a normal CHECK
     directive except that FileCheck makes an additional assumption that a  line
     matched  by the directive cannot also be matched by any other check present
     in match-filename; this is intended to be used for lines containing  labels
     or  other unique identifiers. Conceptually, the presence of CHECK-LABEL di-
     vides the input stream into separate blocks, each of which is processed in-
     dependently, preventing a CHECK: directive in one block matching a line  in
     another block.  If --enable-var-scope is in effect, all local variables are
     cleared at the beginning of the block.

     For example,

	define %struct.C* @C_ctor_base(%struct.C* %this, i32 %x) {
	entry:
	; CHECK-LABEL: C_ctor_base:
	; CHECK: mov [[SAVETHIS:r[0-9]+]], r0
	; CHECK: bl A_ctor_base
	; CHECK: mov r0, [[SAVETHIS]]
	  %0 = bitcast %struct.C* %this to %struct.A*
	  %call = tail call %struct.A* @A_ctor_base(%struct.A* %0)
	  %1 = bitcast %struct.C* %this to %struct.B*
	  %call2 = tail call %struct.B* @B_ctor_base(%struct.B* %1, i32 %x)
	  ret %struct.C* %this
	}

	define %struct.D* @D_ctor_base(%struct.D* %this, i32 %x) {
	entry:
	; CHECK-LABEL: D_ctor_base:

     The  use  of  CHECK-LABEL:  directives  in this case ensures that the three
     CHECK: directives only accept  lines  corresponding  to  the  body  of  the
     @C_ctor_base  function, even if the patterns match lines found later in the
     file. Furthermore, if one of these three CHECK: directives fail,  FileCheck
     will  recover by continuing to the next block, allowing multiple test fail-
     ures to be detected in a single invocation.

     There is no requirement that CHECK-LABEL: directives contain  strings  that
     correspond  to actual syntactic labels in a source or output language: they
     must simply uniquely match a single line in the file being verified.

     CHECK-LABEL: directives cannot contain variable definitions or uses.

   Directive modifiers
     A directive modifier can be append to a directive by following  the  direc-
     tive  with  {<modifier>}  where  the only supported value for <modifier> is
     LITERAL.

     The LITERAL directive modifier can be used to perform a literal match.  The
     modifier  results	in  the  directive not recognizing any syntax to perform
     regex matching, variable capture or any substitutions. This is useful  when
     the  text to match would require excessive escaping otherwise. For example,
     the following will perform literal matches rather than considering these as
     regular expressions:

	Input: [[[10, 20]], [[30, 40]]]
	Output %r10: [[10, 20]]
	Output %r10: [[30, 40]]

	; CHECK{LITERAL}: [[[10, 20]], [[30, 40]]]
	; CHECK-DAG{LITERAL}: [[30, 40]]
	; CHECK-DAG{LITERAL}: [[10, 20]]

   FileCheck Regex Matching Syntax
     All FileCheck directives take  a  pattern	to  match.   For  most	uses  of
     FileCheck, fixed string matching is perfectly sufficient.	For some things,
     a	more  flexible	form of matching is desired.  To support this, FileCheck
     allows you to specify regular expressions in matching  strings,  surrounded
     by  double  braces: {{yourregex}}. FileCheck implements a POSIX regular ex-
     pression matcher; it supports Extended POSIX regular expressions (ERE). Be-
     cause we want to use fixed string matching for a majority of  what  we  do,
     FileCheck	has  been  designed  to support mixing and matching fixed string
     matching with regular expressions.  This allows you to  write  things  like
     this:

	; CHECK: movhpd      {{[0-9]+}}(%esp), {{%xmm[0-7]}}

     In this case, any offset from the ESP register will be allowed, and any xmm
     register will be allowed.

     Because regular expressions are enclosed with double braces, they are visu-
     ally  distinct, and you don't need to use escape characters within the dou-
     ble 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.  Or if you are using the repetition count  syn-
     tax,  for	example [[:xdigit:]]{8} to match exactly 8 hex digits, you would
     need to add parentheses like this {{([[:xdigit:]]{8})}} to avoid  confusion
     with FileCheck's closing double-brace.

   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 reg-
     ister, but verify that that register is used  consistently  later.   To  do
     this, FileCheck supports string substitution blocks that allow string vari-
     ables  to be defined and substituted into patterns.  Here is a simple exam-
     ple:

	; CHECK: test5:
	; CHECK:    notw     [[REGISTER:%[a-z]+]]
	; CHECK:    andw     {{.*}}[[REGISTER]]

     The first check line matches a regex  %[a-z]+  and  captures  it  into  the
     string  variable  REGISTER.   The	second line verifies that whatever is in
     REGISTER occurs later in the file after an "andw". FileCheck string substi-
     tution 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.

     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:

	; CHECK: op [[REG:r[0-9]+]], [[REG]]

     Can  be  useful if you want the operands of op to be the same register, and
     don't care exactly which register it is.

     If --enable-var-scope is in effect, variables with names that start with  $
     are  considered  to  be  global. All others variables are local.  All local
     variables get undefined at the beginning of each 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 Substitution Blocks
     FileCheck also supports numeric substitution blocks that allow defining nu-
     meric variables and checking for numeric values that satisfy a numeric  ex-
     pression  constraint  based  on those variables via a numeric substitution.
     This allows CHECK: directives to verify a numeric relation between two num-
     bers, such as the need for consecutive registers to be used.

     The syntax to capture a numeric value is [[#%<fmtspec>,<NUMVAR>:]] where:

     * %<fmtspec>, is an optional format specifier to indicate what number  for-
       mat to match and the minimum number of digits to expect.

     * <NUMVAR>:  is  an  optional definition of variable <NUMVAR> from the cap-
       tured value.

     The syntax of <fmtspec> is: #.<precision><conversion specifier> where:

     * # is an optional flag available for hex values  (see  <conversion  speci-
       fier> below) which requires the value matched to be prefixed by 0x.

     * .<precision>  is  an  optional  printf-style precision specifier in which
       <precision> indicates the minimum number of digits that the value matched
       must have, expecting leading zeros if needed.

     * <conversion specifier> is an optional scanf-style conversion specifier to
       indicate what number format to match (e.g. hex  number).   Currently  ac-
       cepted  format  specifiers  are %u, %d, %x and %X.  If absent, the format
       specifier defaults to %u.

     For example:

	; CHECK: mov r[[#REG:]], 0x[[#%.8X,ADDR:]]

     would match mov r5, 0x0000FEFE and set REG to the value 5 and ADDR  to  the
     value 0xFEFE. Note that due to the precision it would fail to match mov r5,
     0xFEFE.

     As a result of the numeric variable definition being optional, it is possi-
     ble  to  only check that a numeric value is present in a given format. This
     can be useful when the value itself is not useful, for instance:

	; CHECK-NOT: mov r0, r[[#]]

     to check that a value is synthesized rather than moved around.

     The  syntax  of  a  numeric  substitution	is  [[#%<fmtspec>,  <constraint>
     <expr>]] where:

     * <fmtspec>  is the same format specifier as for defining a variable but in
       this context indicating how a numeric expression value should be  matched
       against.  If absent, both components of the format specifier are inferred
       from the matching format of the numeric variable(s) used by  the  expres-
       sion  constraint  if  any,  and	defaults to %u if no numeric variable is
       used, denoting that the value should be unsigned with no  leading  zeros.
       In  case  of  conflict between format specifiers of several numeric vari-
       ables, the conversion specifier becomes mandatory but the precision spec-
       ifier remains optional.

     * <constraint> is the constraint describing how the value to match must re-
       late to the value of the numeric expression. The only currently	accepted
       constraint is == for an exact match and is the default if <constraint> is
       not provided. No matching constraint must be specified when the <expr> is
       empty.

     * <expr> is an expression. An expression is in turn recursively defined as:

       * a numeric operand, or

       * an expression followed by an operator and a numeric operand.

       A  numeric  operand  is a previously defined numeric variable, an integer
       literal, or a function. Spaces are accepted before, after and between any
       of these elements. Numeric operands have 64-bit precision.  Overflow  and
       underflow  are rejected. There is no support for operator precedence, but
       parentheses can be used to change the evaluation order.

     The supported operators are:

	* + - Returns the sum of its two operands.

	* - - Returns the difference of its two operands.

     The syntax of a function call is <name>(<arguments>) where:

     * name is a predefined string literal. Accepted values are:

       * add - Returns the sum of its two operands.

       * div - Returns the quotient of its two operands.

       * max - Returns the largest of its two operands.

       * min - Returns the smallest of its two operands.

       * mul - Returns the product of its two operands.

       * sub - Returns the difference of its two operands.

     * <arguments> is a comma separated list of expressions.

     For example:

	; CHECK: load r[[#REG:]], [r0]
	; CHECK: load r[[#REG+1]], [r1]
	; CHECK: Loading from 0x[[#%x,ADDR:]]
	; CHECK-SAME: to 0x[[#ADDR + 7]]

     The above example would match the text:

	load r5, [r0]
	load r6, [r1]
	Loading from 0xa0463440 to 0xa0463447

     but would not match the text:

	load r5, [r0]
	load r7, [r1]
	Loading from 0xa0463440 to 0xa0463443

     Due to 7 being unequal to 5 + 1 and a0463443 being unequal to a0463440 + 7.

     A numeric variable can also be defined to the result of a	numeric  expres-
     sion,  in	which  case  the numeric expression constraint is checked and if
     verified the variable is assigned to the value. The unified syntax for both
     checking a numeric expression and capturing its value into a numeric  vari-
     able  is  thus [[#%<fmtspec>,<NUMVAR>: <constraint> <expr>]] with each ele-
     ment as described previously. One can use this syntax to  make  a	testcase
     more self-describing by using variables instead of values:

	; CHECK: mov r[[#REG_OFFSET:]], 0x[[#%X,FIELD_OFFSET:12]]
	; CHECK-NEXT: load r[[#]], [r[[#REG_BASE:]], r[[#REG_OFFSET]]]

     which would match:

	mov r4, 0xC
	load r6, [r5, r4]

     The  --enable-var-scope  option has the same effect on numeric variables as
     on string variables.

     Important note: In its current implementation, an expression cannot  use  a
     numeric variable defined earlier in the same CHECK directive.

   FileCheck Pseudo Numeric Variables
     Sometimes there's a need to verify output that contains line numbers of the
     match file, e.g. when testing compiler diagnostics.  This introduces a cer-
     tain  fragility  of the match file structure, as "CHECK:" lines contain ab-
     solute line numbers in the same file, which have  to  be  updated	whenever
     line numbers change due to text addition or deletion.

     To support this case, FileCheck expressions understand the @LINE pseudo nu-
     meric  variable  which  evaluates	to  the line number of the CHECK pattern
     where it is found.

     This way match patterns can be put near the relevant test lines and include
     relative line number references, for example:

	// CHECK: test.cpp:[[# @LINE + 4]]:6: error: expected ';' after top level declarator
	// CHECK-NEXT: {{^int a}}
	// CHECK-NEXT: {{^     \^}}
	// CHECK-NEXT: {{^     ;}}
	int a

     To support legacy uses of @LINE as a  special  string  variable,  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.

   Matching Newline Characters
     To  match	newline  characters  in  regular expressions the character class
     [[:space:]] can be used. For example, the following pattern:

	// CHECK: DW_AT_location [DW_FORM_sec_offset] ([[DLOC:0x[0-9a-f]+]]){{[[:space:]].*}}"intd"

     matches output of the form (from llvm-dwarfdump):

	DW_AT_location [DW_FORM_sec_offset]   (0x00000233)
	DW_AT_name [DW_FORM_strp]  ( .debug_str[0x000000c9] = "intd")

     letting us set the FileCheck variable DLOC to the desired value 0x00000233,
     extracted from the line immediately preceding "intd".

AUTHOR
     Maintained by the LLVM Team (https://llvm.org/).

COPYRIGHT
     2003-2026, LLVM Project

19				   2026-08-04			    FILECHECK(1)

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