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       FileCheck - Flexible pattern matching file verifier

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

       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  particularly	 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  dif-
       ferent 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	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 op-
	      tions), the --check-prefix argument allows you to	specify	(with-
	      out  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

       --check-prefixes	prefix1,prefix2,...
	      An  alias	 of --check-prefix that	allows multiple	prefixes to be
	      specified	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  de-

	      These   default	comment	  prefixes   can   be	overridden  by
	      --comment-prefixes if they are not appropriate for your  testing
	      environment.  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, con-
	      sider proposing a	change to the  default	comment	 prefixes  in-

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

	      By default, FileCheck allows matches of anywhere on a line. This
	      option 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 {{^}}
	      before, and {{ *$}} or {{$}} after every positive	check pattern.

	      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  dis-
	      ables  this behavior. End-of-line	sequences are canonicalized to
	      UNIX-style \n in all modes.

	      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	 with-
	      out 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:

       --dump-input <value>
	      Dump  input to stderr, adding annotations	representing currently
	      enabled diagnostics.  When there	are  multiple  occurrences  of
	      this option, the <value> that appears earliest in	the list below
	      has precedence.  The default is fail.

	      o	help   - Explain input dump and	quit

	      o	always - Always	dump input

	      o	fail   - Dump input on failure

	      o	never  - Never dump input

       --dump-input-context <N>
	      In the dump requested by --dump-input, print <N> input lines be-
	      fore and <N> input lines after any lines specified by --dump-in-
	      put-filter.  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 de-
	      fault  is	 error	when  --dump-input=fail,  and  it's  all  when

	      o	all		- All input lines

	      o	annotation-full	- Input	lines with annotations

	      o	annotation	- Input	lines with starting points of  annota-

	      o	error		 -  Input  lines with starting points of error

	      Enables scope for	regex variables.

	      Variables	with names that	start with $ are considered global and
	      remain set throughout the	file.

	      All   other  variables  get  undefined  after  each  encountered

	      Sets a filecheck pattern variable	VAR with value VALUE that  can
	      be used in CHECK:	lines.

	      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 Expressions for details on supported numeric expressions.

	      Show the version number of this program.

       -v     Print good directive pattern  matches.   However,	 if  -dump-in-
	      put=fail or -dump-input=always, add those	matches	as input anno-
	      tations instead.

       -vv    Print information	helpful	in diagnosing internal	FileCheck  is-
	      sues, such as discarded overlapping CHECK-DAG: matches, implicit
	      EOF pattern matches, and CHECK-NOT: patterns that	 do  not  have
	      matches.	Implies	-v.  However, if -dump-input=fail or -dump-in-
	      put=always, just add that	information as input  annotations  in-

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

	      Use colors in output (autodetected by default).

       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.

       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	speci-
       fied 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) {
	  ; 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) {
	  ; 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  output  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
       whitespace 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 unless there is a "subl" in between those labels.  If	it ex-
       isted somewhere else in the file, that would  not  count:  "grep	 subl"
       matches if "subl" exists	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 example, 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
       entirely, 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
       directive  syntax  mangling  to	prevent	FileCheck from recognizing the
       commented occurrences of	"X32:" and "X64:" above	as  directives.	 More-
       over,  FileCheck	 diagnostics  have  been  proposed that	might complain
       about the above occurrences of "X64" that don't have the	 trailing  ":"
       because	they look like directive 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:

       o "COM:"	 within	 another  directive's pattern does not comment out the
	 remainder 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.

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

       o FileCheck  does  not recognize	"COM", "RUN", or any user-defined com-
	 ment prefix as	a comment directive if it's combined with one  of  the
	 usual	check  directive  suffixes,  such as "-NEXT:" or "-NOT:", dis-
	 cussed	below.	FileCheck treats such a	combination as plain text  in-
	 stead.	 If it needs to	act as a comment directive for your test envi-
	 ronment, 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  ex-

	  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
       newline 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 be-
       tween it	and the	previous directive.  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
       whitespace, you can use the "CHECK-EMPTY:" directive.

	  declare void @foo()

	  declare void @bar()
	  ; CHECK: foo
	  ; 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 directive in a file.

   The CHECK-NOT: directive
       The "CHECK-NOT:"	directive is used to verify that a string doesn't  oc-
       cur  between  two matches (or before the	first match, or	after the last
       match).	For example, to	verify that a load is removed by a transforma-
       tion, 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 se-
       quential	order, "CHECK-DAG:" could be used to verify them  between  two
       matches (or before the first match, or after the	last match). For exam-
       ple, 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 ex-
       clude strings between the surrounding CHECK-DAG:	directives. As	a  re-
       sult,  the  surrounding CHECK-DAG: directives cannot be reordered, i.e.
       all occurrences matching	CHECK-DAG: before CHECK-NOT: must not fall be-
       hind occurrences	matching CHECK-DAG: after CHECK-NOT:. For example,


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

       With  captured variables, CHECK-DAG: is able to match valid topological
       orderings 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 sequences	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

       A CHECK-DAG: directive skips matches that overlap the  matches  of  any
       preceding 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 example, 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
       entries 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-LABEL:"  directive  can  be used.	It is treated identically to a
       normal CHECK directive except that FileCheck makes  an  additional  as-
       sumption	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 divides  the	 input	stream	into  separate
       blocks,	each  of which is processed independently, preventing a	CHECK:
       directive in one	block matching a line  in  another  block.   If	 --en-
       able-var-scope is in effect, all	local variables	are cleared at the be-
       ginning of the block.

       For example,

	  define %struct.C* @C_ctor_base(%struct.C* %this, i32 %x) {
	  ; 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) {
	  ; 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	multi-
       ple test	failures 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  lan-
       guage:  they must simply	uniquely match a single	line in	the file being

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

   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	imple-
       ments  a	 POSIX	regular	expression matcher; it supports	Extended POSIX
       regular expressions (ERE). Because 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
       visually	 distinct,  and	you don't need to use escape characters	within
       the double 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  repeti-
       tion  count  syntax, 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 dou-

   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 al-
       low any register, but verify that that register	is  used  consistently
       later.	To do this, FileCheck supports string substitution blocks that
       allow string variables to be defined  and  substituted  into  patterns.
       Here is a simple	example:

	  ; 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
       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; oth-
       erwise, 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
       numeric variables and checking for numeric values that  satisfy	a  nu-
       meric expression	constraint based on those variables via	a numeric sub-
       stitution. This allows CHECK: directives	to verify a  numeric  relation
       between	two  numbers, such as the need for consecutive registers to be

       The syntax to define a numeric  variable	 is  [[#%<fmtspec>,<NUMVAR>:]]

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

       o <NUMVAR> is the name of the numeric variable to define	to the	match-
	 ing value.

       For example:

	  ; CHECK: mov r[[#REG:]], 0x[[#%X,IMM:]]

       would  match  mov  r5, 0xF0F0 and set REG to the	value 5	and IMM	to the
       value 0xF0F0.

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

       o %<fmtspec>  is	the same matching format specifier as for defining nu-
	 meric variables but acting as a printf-style format to	indicate how a
	 numeric  expression  value should be matched against.	If absent, the
	 format	specifier is inferred from the matching	format of the  numeric
	 variable(s) used by the expression constraint if any, and defaults to
	 %u if no numeric variable is  used.   In  case	 of  conflict  between
	 matching formats of several numeric variables the format specifier is

       o <constraint> is the constraint	describing how the value to match must
	 relate	to the value of	the numeric expression.	The only currently ac-
	 cepted	constraint is == for an	exact match  and  is  the  default  if
	 <constraint>  is  not provided. No matching constraint	must be	speci-
	 fied when the <expr> is empty.

       o <expr>	is an expression. An expression	is in turn recursively defined

	 o a numeric operand, or

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

	 A  numeric operand is a previously defined numeric variable, an inte-
	 ger literal, or a function. Spaces are	accepted before, after and be-
	 tween	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 or-

       The supported operators are:

	  o + -	Returns	the sum	of its two operands.

	  o - -	Returns	the difference of its two operands.

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

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

	 o add - Returns the sum of its	two operands.

	 o div - Returns the quotient of its two operands.

	 o max - Returns the largest of	its two	operands.

	 o min - Returns the smallest of its two operands.

	 o mul - Returns the product of	its two	operands.

	 o sub - Returns the difference	of its two operands.

       o <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.

       The  syntax  also  supports  an empty expression, equivalent to writing
       {{[0-9]+}}, for cases where the input must contain a numeric value  but
       the value itself	does not matter:

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

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

       A  numeric  variable can	also be	defined	to the result of a numeric ex-
       pression, in which case the numeric expression  constraint  is  checked
       and if verified the variable is assigned	to the value. The unified syn-
       tax for both defining numeric variables and checking a numeric  expres-
       sion  is	 thus  [[#%<fmtspec>,<NUMVAR>: <constraint> <expr>]] with each
       element 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	intro-
       duces  a	 certain  fragility  of	 the match file	structure, as "CHECK:"
       lines contain absolute 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
       numeric variable	which evaluates	to the line number of the  CHECK  pat-
       tern where it is	found.

       This way	match patterns can be put near the relevant test lines and in-
       clude 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".

       Maintained by the LLVM Team (

       2003-2021, LLVM Project

11				  2021-02-28			  FILECHECK(1)


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