[all-commits] [llvm/llvm-project] bcea3a: Add test utility 'split-file'

[Fangrui Song via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: bcea3a7a288e0b5ac977f90c46e4eef7946467e7
      https://github.com/llvm/llvm-project/commit/bcea3a7a288e0b5ac977f90c46e4eef7946467e7
  Author: Fangrui Song <maskray at google.com>
  Date:   2020-08-03 (Mon, 03 Aug 2020)

  Changed paths:
    M lld/test/CMakeLists.txt
    M lld/test/ELF/linkerscript/noload.s
    M llvm/docs/TestingGuide.rst
    M llvm/test/CMakeLists.txt
    M llvm/test/lit.cfg.py
    M llvm/test/tools/gold/X86/multiple-sections.ll
    M llvm/test/tools/llvm-strings/radix.test
    A llvm/test/tools/split-file/Inputs/basic-aa.txt
    A llvm/test/tools/split-file/Inputs/basic-bb.txt
    A llvm/test/tools/split-file/Inputs/basic-cc.txt
    A llvm/test/tools/split-file/basic.test
    A llvm/test/tools/split-file/empty.test
    A llvm/test/tools/split-file/error.test
    A llvm/test/tools/split-file/help.test
    A llvm/test/tools/split-file/no-leading-lines.test
    A llvm/test/tools/split-file/output-is-special.test
    A llvm/tools/split-file/.clang-tidy
    A llvm/tools/split-file/CMakeLists.txt
    A llvm/tools/split-file/split-file.cpp
    M llvm/utils/gn/secondary/lld/test/BUILD.gn
    M llvm/utils/gn/secondary/llvm/test/BUILD.gn
    A llvm/utils/gn/secondary/llvm/tools/split-file/BUILD.gn

  Log Message:
  -----------
  Add test utility 'split-file'

See https://lists.llvm.org/pipermail/llvm-dev/2020-July/143373.html
"[llvm-dev] Multiple documents in one test file" for some discussions.

This patch has explored several alternatives. The current semantics are similar to
what @dblaikie proposed.
`split-file filename output` splits the input file into multiple parts separated by
regex `^(.|//)--- filename` and write each part to the file `output/filename`
(`filename` can include path separators).

Use case A (organizing input of different formats (e.g. linker
script+assembly) in one file).

```
# RUN: split-file %s %t
# RUN: llvm-mc %t/asm -o %t.o
# RUN: ld.lld -T %t/lds %t.o -o %t
This is sometimes better than the %S/Inputs/ approach because the user
can see the auxiliary files immediately and don't have to open another file.

# asm
...
# lds
...
```

Use case B (for utilities which don't have built-in input splitting
feature):

```
// RUN: split-file %s %t
// RUN: llc < %t/1.ll | FileCheck %s --check-prefix=CASE1
// RUN: llc < %t/2.ll | FileCheck %s --check-prefix=CASE2
Combing tests prudently can improve readability.
For example, when testing parsing errors if the recovery mechanism isn't possible,
grouping the tests in one file can more readily see test coverage/strategy.

//--- 1.ll
...
//--- 2.ll
...
```

Since this is a new utility, there is no git history concerns for
UpperCase variable names. I use lowerCase variable names like mlir/lld.

Reviewed By: jhenderson, lattner

Differential Revision: https://reviews.llvm.org/D83834