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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 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.


       -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  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.

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

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

       --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: patterns.

              When the check fails, dump all of the original input.

              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 CHECK-LABEL.

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

              Show the version number of this program.

       -v     Print directive pattern matches.

       -vv    Print  information  helpful  in  diagnosing  internal  FileCheck  issues,  such  as
              discarded  overlapping  CHECK-DAG:  matches,  implicit  EOF  pattern  matches,  and
              CHECK-NOT: patterns that do not have matches.  Implies -v.

              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.


       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 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) {
          ; 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

       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 existed 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 “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 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

       “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.  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.


          ; 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 directive 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-DAG:” directive
       If it’s necessary to match strings that  don’t  occur  in  a  strictly  sequential  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 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

          ; 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 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 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
       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
       --enable-var-scope  is  in effect, all local variables are cleared at the beginning of the

       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 multiple
       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 language: they must simply uniquely match a
       single line in the file being verified.

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

   FileCheck Pattern 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 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.

   FileCheck Variables
       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, FileCheck allows named 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  variable  REGISTER.
       The  second  line  verifies that whatever is in REGISTER occurs later in the file after an
       “andw”.  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.

       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:

          ; 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 Expressions
       Sometimes there’s a need to verify output which refers line numbers  of  the  match  file,
       e.g.  when testing compiler diagnostics.  This introduces 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   allows   using   [[@LINE]],  [[@LINE+<offset>]],
       [[@LINE-<offset>]] expressions in patterns. These expressions expand to a  number  of  the
       line where a pattern is located (with an optional integer offset).

       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

   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”.


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