LLVM Testing Infrastructure Guide

The LLVM regression tests are driven by 'lit' and are located in - the llvm/test directory. - -

This directory contains a large array of small tests - that exercise various features of LLVM and to ensure that regressions do not - occur. The directory is broken into several sub-directories, each focused on - a particular area of LLVM. A few of the important ones are:

- -

Analysis: checks Analysis passes.
Archive: checks the Archive library.
Assembler: checks Assembly reader/writer functionality.
Bitcode: checks Bitcode reader/writer functionality.
CodeGen: checks code generation and each target.
Features: checks various features of the LLVM language.
Linker: tests bitcode linking.
Transforms: tests each of the scalar, IPO, and utility - transforms to ensure they make the right transformations.
Verifier: tests the IR verifier.

- - -

Writing new regression tests

- -

The regression test structure is very simple, but does require some - information to be set. This information is gathered via configure and - is written to a file, lit.site.cfg - in llvm/test. The llvm/test Makefile does this work for - you.

- -

In order for the regression tests to work, each directory of tests must - have a lit.local.cfg file. Lit looks for this file to determine how - to run the tests. This file is just Python code and thus is very flexible, - but we've standardized it for the LLVM regression tests. If you're adding a - directory of tests, just copy lit.local.cfg from another directory to - get running. The standard lit.local.cfg simply specifies which files - to look in for tests. Any directory that contains only directories does not - need the lit.local.cfg file. Read the - Lit documentation for more - information.

- -

The llvm-runtests function looks at each file that is passed to - it and gathers any lines together that match "RUN:". These are the "RUN" lines - that specify how the test is to be run. So, each test script must contain - RUN lines if it is to do anything. If there are no RUN lines, the - llvm-runtests function will issue an error and the test will - fail.

- -

RUN lines are specified in the comments of the test program using the - keyword RUN followed by a colon, and lastly the command (pipeline) - to execute. Together, these lines form the "script" that - llvm-runtests executes to run the test case. The syntax of the - RUN lines is similar to a shell's syntax for pipelines including I/O - redirection and variable substitution. However, even though these lines - may look like a shell script, they are not. RUN lines are interpreted - directly by the Tcl exec command. They are never executed by a - shell. Consequently the syntax differs from normal shell script syntax in a - few ways. You can specify as many RUN lines as needed.

- -

lit performs substitution on each RUN line to replace LLVM tool - names with the full paths to the executable built for each tool (in - $(LLVM_OBJ_ROOT)/$(BuildMode)/bin). This ensures that lit does not - invoke any stray LLVM tools in the user's path during testing.

- -

Each RUN line is executed on its own, distinct from other lines unless - its last character is \. This continuation character causes the RUN - line to be concatenated with the next one. In this way you can build up long - pipelines of commands without making huge line lengths. The lines ending in - \ are concatenated until a RUN line that doesn't end in \ is - found. This concatenated set of RUN lines then constitutes one execution. - Tcl will substitute variables and arrange for the pipeline to be executed. If - any process in the pipeline fails, the entire line (and test case) fails too. -

- -

Below is an example of legal RUN lines in a .ll file:

- -

-; RUN: llvm-as < %s | llvm-dis > %t1
-; RUN: llvm-dis < %s.bc-13 > %t2
-; RUN: diff %t1 %t2
-

- -

As with a Unix shell, the RUN: lines permit pipelines and I/O redirection - to be used. However, the usage is slightly different than for Bash. To check - what's legal, see the documentation for the - Tcl exec - command and the - tutorial. - The major differences are:

You can't do 2>&1. That will cause Tcl to write to a - file named &1. Usually this is done to get stderr to go through - a pipe. You can do that in tcl with |& so replace this idiom: - ... 2>&1 | grep with ... |& grep
You can only redirect to a file, not to another descriptor and not from - a here document.
tcl supports redirecting to open files with the @ syntax but you - shouldn't use that here.

- -

There are some quoting rules that you must pay attention to when writing - your RUN lines. In general nothing needs to be quoted. Tcl won't strip off any - quote characters so they will get passed to the invoked program. For - example:

- -

-... | grep 'find this string'
-

- -

This will fail because the ' characters are passed to grep. This would - instruction grep to look for 'find in the files this and - string'. To avoid this use curly braces to tell Tcl that it should - treat everything enclosed as one value. So our example would become:

- -

-... | grep {find this string}
-

- -

Additionally, the characters [ and ] are treated - specially by Tcl. They tell Tcl to interpret the content as a command to - execute. Since these characters are often used in regular expressions this can - have disastrous results and cause the entire test run in a directory to fail. - For example, a common idiom is to look for some basicblock number:

- -

-... | grep bb[2-8]
-

- -

This, however, will cause Tcl to fail because its going to try to execute - a program named "2-8". Instead, what you want is this:

- -

-... | grep {bb\[2-8\]}
-

- -

Finally, if you need to pass the \ character down to a program, - then it must be doubled. This is another Tcl special character. So, suppose - you had: - -

-... | grep 'i32\*'
-

- -

This will fail to match what you want (a pointer to i32). First, the - ' do not get stripped off. Second, the \ gets stripped off - by Tcl so what grep sees is: 'i32*'. That's not likely to match - anything. To resolve this you must use \\ and the {}, like - this:

- -

-... | grep {i32\\*}
-

- -

If your system includes GNU grep, make sure -that GREP_OPTIONS is not set in your environment. Otherwise, -you may get invalid results (both false positives and false -negatives).

- -

- - -

The FileCheck utility

- - -

- -

A powerful feature of the RUN: lines is that it allows any arbitrary commands - to be executed as part of the test harness. While standard (portable) unix - tools like 'grep' work fine on run lines, as you see above, there are a lot - of caveats due to interaction with Tcl syntax, and we want to make sure the - run lines are portable to a wide range of systems. Another major problem is - that grep is not very good at checking to verify that the output of a tools - contains a series of different output in a specific order. The FileCheck - tool was designed to help with these problems.

- -

FileCheck (whose basic command line arguments are described in the FileCheck man page is - designed to read a file to check from standard input, and the set of things - to verify from a file specified as a command line argument. 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 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 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 an 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 the first match and the beginning of the file). 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
-}
-

- -

- - -

- 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 variables "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, are named, 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, if not, it is a use.

- -

FileCheck variables can be defined multiple times, and uses always get the -latest value. Note that variables are all read at the start of a "CHECK" line -and are all defined at the end. This means that if you have something like -"CHECK: [[XYZ:.*]]x[[XYZ]]" that the check line will read the previous -value of the XYZ variable and define a new one after the match is performed. If -you need to do something like this you can probably take advantage of the fact -that FileCheck is not actually line-oriented when it matches, this allows you to -define two separate CHECK lines that match on the same line. -

- - - -

- -

- - -

Variables and substitutions

- -

With a RUN line there are a number of substitutions that are permitted. In - general, any Tcl variable that is available in the substitute - function (in test/lib/llvm.exp) can be substituted into a RUN line. - To make a substitution just write the variable's name preceded by a $. - Additionally, for compatibility reasons with previous versions of the test - library, certain names can be accessed with an alternate syntax: a % prefix. - These alternates are deprecated and may go away in a future version. -

Here are the available variable names. The alternate syntax is listed in - parentheses.

- -

$test (%s): The full path to the test case's source. This is suitable for passing - on the command line as the input to an llvm tool.
$srcdir: The source directory from where the "make check" was run.
objdir: The object directory that corresponds to the $srcdir.
subdir: A partial path from the test directory that contains the - sub-directory that contains the test source being executed.
srcroot: The root directory of the LLVM src tree.
objroot: The root directory of the LLVM object tree. This could be the same - as the srcroot.
path
-: The path to the directory that contains the test case source. This is - for locating any supporting files that are not generated by the test, but - used by the test.
tmp: The path to a temporary file name that could be used for this test case. - The file name won't conflict with other test cases. You can append to it if - you need multiple temporaries. This is useful as the destination of some - redirected output.
target_triplet (%target_triplet): The target triplet that corresponds to the current host machine (the one - running the test cases). This should probably be called "host".; - -
link (%link): This full link command used to link LLVM executables. This has all the - configured -I, -L and -l options.
shlibext (%shlibext): The suffix for the host platforms share library (dll) files. This - includes the period as the first character.

To add more variables, two things need to be changed. First, add a line in - the test/Makefile that creates the site.exp file. This will - "set" the variable as a global in the site.exp file. Second, in the - test/lib/llvm.exp file, in the substitute proc, add the variable name - to the list of "global" declarations at the beginning of the proc. That's it, - the variable can then be used in test scripts.

- - -

Other Features

- -

To make RUN line writing easier, there are several shell scripts located - in the llvm/test/Scripts directory. This directory is in the PATH - when running tests, so you can just call these scripts using their name. For - example:

ignore: This script runs its arguments and then always returns 0. This is useful - in cases where the test needs to cause a tool to generate an error (e.g. to - check the error output). However, any program in a pipeline that returns a - non-zero result will cause the test to fail. This script overcomes that - issue and nicely documents that the test case is purposefully ignoring the - result code of the tool
not: This script runs its arguments and then inverts the result code from - it. Zero result codes become 1. Non-zero result codes become 0. This is - useful to invert the result of a grep. For example "not grep X" means - succeed only if you don't find X in the input.

- -

Sometimes it is necessary to mark a test case as "expected fail" or XFAIL. - You can easily mark a test as XFAIL just by including XFAIL: on a - line near the top of the file. This signals that the test case should succeed - if the test fails. Such test cases are counted separately by the testing - tool. To specify an expected fail, use the XFAIL keyword in the comments of - the test program followed by a colon and one or more failure patterns. Each - failure pattern can be either '*' (to specify fail everywhere), or a part of a - target triple (indicating the test should fail on that platform), or the name - of a configurable feature (for example, "loadable_module"). If there is a - match, the test is expected to fail. If not, the test is expected to - succeed. To XFAIL everywhere just specify XFAIL: *. Here is an - example of an XFAIL line:

- -

-; XFAIL: darwin,sun
-

- -

To make the output more useful, the llvm_runtest function wil - scan the lines of the test case for ones that contain a pattern that matches - PR[0-9]+. This is the syntax for specifying a PR (Problem Report) number that - is related to the test case. The number after "PR" specifies the LLVM bugzilla - number. When a PR number is specified, it will be used in the pass/fail - reporting. This is useful to quickly get some context when a test fails.

- -

Finally, any line that contains "END." will cause the special - interpretation of lines to terminate. This is generally done right after the - last RUN: line. This has two side effects: (a) it prevents special - interpretation of lines that are part of the test program, not the - instructions to the test case, and (b) it speeds things up for really big test - cases by avoiding interpretation of the remainder of the file.

- -

- LLVM Testing Infrastructure Guide -

Overview

Requirements

LLVM testing infrastructure organization

Regression tests

`test-suite`

Debugging Information tests

Quick start

Regression tests

Debugging Information tests

Regression test structure

Writing new regression tests

The FileCheck utility

- The FileCheck -check-prefix option -

- The "CHECK-NEXT:" directive -

- The "CHECK-NOT:" directive -

- FileCheck Pattern Matching Syntax -

- FileCheck Variables -

Variables and substitutions

Other Features

`test-suite` Overview

`test-suite` Quickstart

`test-suite` Makefiles