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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.

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

              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.

              Show the version number of this program.


       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-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.

   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.  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
       The "CHECK:" and "CHECK-NOT:" directives both 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}}.
       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.

   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


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