[llvm] add zstd to `llvm::compression` namespace

[ckissane]

Summary

• add zstd to llvm::compression namespace
• add a CMake option LLVM_ENABLE_ZSTD with behavior mirroring that of LLVM_ENABLE_ZLIB
• add tests for zstd to llvm/unittests/Support/CompressionTest.cpp
• debian users should install libzstd when using LLVM_ENABLE_ZSTD=FORCE_ON from source due to this bug https://bugs.launchpad.net/ubuntu/+source/libzstd/+bug/1941956

[MaskRay]

llvm/lib/Support/Compression.cpp

133

const size_t

llvm/unittests/Support/CompressionTest.cpp

69

delete blank line

70

static void testZstd...

73

delete blank line

99

https://llvm.org/docs/CodingStandards.html#don-t-use-braces-on-simple-single-statement-bodies-of-if-else-loop-statements

[ckissane]

tidy some code

[ckissane]

Mark handled comments from @MaskRay as done

[phosek]

llvm/lib/Support/Compression.cpp

63–65

I'd make changes to zlib separately.

87–89

Ditto here.

[ckissane]

llvm/lib/Support/Compression.cpp

63–65

Here https://reviews.llvm.org/D129698

[ckissane]

• Merge branch main

[MaskRay]

llvm/include/llvm/Support/Compression.h

54

I changed the zlib functions to use uint8_t * and ArrayRef<uint8_t> instead. This patch needs to switch to uint8_t too.

llvm/lib/Support/Compression.cpp

157

uint8_t

[ckissane]

• Merge remote-tracking branch 'origin/main' into ckissane.add-zstd
• [Support] update zstd interface to use uint8_t * and ArrayRef<uint8_t>

[MaskRay]

Why was this reverted? Please make extensive tests especially for something dealing with the build system. When reverting a commit, briefly describe what happened.

[sebastian-ne]

This breaks builds when LLVM is included with CMake’s add_subdirectory.
I think the zstd target needs to be marked as imported.
The following patch fixes the problem, although I’m not familiar enough with CMake to know if this is the right way to go:

diff --git a/llvm/cmake/modules/FindZSTD.cmake b/llvm/cmake/modules/FindZSTD.cmake
index 43ccf7232138..8e6ec6e8a988 100644
--- a/llvm/cmake/modules/FindZSTD.cmake
+++ b/llvm/cmake/modules/FindZSTD.cmake
@@ -12,6 +12,10 @@ find_package_handle_standard_args(
     ZSTD_LIBRARY ZSTD_INCLUDE_DIR)

 if(ZSTD_FOUND)
+    if(NOT TARGET Zstd::zstd)
+      add_library(Zstd::zstd UNKNOWN IMPORTED)
+      set_target_properties(Zstd::zstd PROPERTIES IMPORTED_LOCATION "${ZSTD_LIBRARY}")
+    endif()
     set(ZSTD_LIBRARIES ${ZSTD_LIBRARY})
     set(ZSTD_INCLUDE_DIRS ${ZSTD_INCLUDE_DIR})
 endif()
diff --git a/llvm/lib/Support/CMakeLists.txt b/llvm/lib/Support/CMakeLists.txt
index 52b95c5377d3..031adfa33ba8 100644
--- a/llvm/lib/Support/CMakeLists.txt
+++ b/llvm/lib/Support/CMakeLists.txt
@@ -26,7 +26,7 @@ if(LLVM_ENABLE_ZLIB)
 endif()

 if(LLVM_ENABLE_ZSTD)
-  list(APPEND imported_libs zstd)
+  list(APPEND imported_libs Zstd::zstd)
 endif()

 if( MSVC OR MINGW )

[aemerson]

I just reverted this in 6e6be5f9504d because it seems to have broken macOS builds:

llvm/lib/Support/Compression.cpp:24:10: fatal error: 'zstd.h' file not found
#include <zstd.h>
         ^~~~~~~~

[ckissane]

In D128465#3651025, @aemerson wrote:

I just reverted this in 6e6be5f9504d because it seems to have broken macOS builds:

llvm/lib/Support/Compression.cpp:24:10: fatal error: 'zstd.h' file not found
#include <zstd.h>
         ^~~~~~~~

@aemerson Could you provide the output of your cmake command?
(I can't easily reproduce because I don't have a mac on hand)

[ckissane]

@aemerson can you let me know if https://reviews.llvm.org/D129786 works on MacOS?
I am continuing work on that revision because this one has a lot of outdated unrelated history.

[jasonmolenda]

In D128465#3652525, @ckissane wrote:

In D128465#3651025, @aemerson wrote:

I just reverted this in 6e6be5f9504d because it seems to have broken macOS builds:

llvm/lib/Support/Compression.cpp:24:10: fatal error: 'zstd.h' file not found
#include <zstd.h>
         ^~~~~~~~

@aemerson Could you provide the output of your cmake command?
(I can't easily reproduce because I don't have a mac on hand)

FWIW I hit this last night on my mac desktop - it looked like I had zstd installed by homebrew (as a dependency on something I installed), and cmake was able to find it in /opt/homebrew (somehow) but when Compression.cpp was built, nothing had added -I/opt/homebrew/include so the header wasn't found. I hacked the FindZSTD.cmake to not find it, to finish what I was working on before bedtime. This might not be related to what @aemerson saw though.

[ckissane]

In D128465#3653051, @jasonmolenda wrote:

In D128465#3652525, @ckissane wrote:

In D128465#3651025, @aemerson wrote:

I just reverted this in 6e6be5f9504d because it seems to have broken macOS builds:

llvm/lib/Support/Compression.cpp:24:10: fatal error: 'zstd.h' file not found
#include <zstd.h>
         ^~~~~~~~

@aemerson Could you provide the output of your cmake command?
(I can't easily reproduce because I don't have a mac on hand)

FWIW I hit this last night on my mac desktop - it looked like I had zstd installed by homebrew (as a dependency on something I installed), and cmake was able to find it in /opt/homebrew (somehow) but when Compression.cpp was built, nothing had added -I/opt/homebrew/include so the header wasn't found. I hacked the FindZSTD.cmake to not find it, to finish what I was working on before bedtime. This might not be related to what @aemerson saw though.

@jasonmolenda Thank you for the info, I believe it is similar, could you try: https://reviews.llvm.org/D129786 for me?

[jasonmolenda]

In D128465#3653216, @ckissane wrote:

In D128465#3653051, @jasonmolenda wrote:

In D128465#3652525, @ckissane wrote:

In D128465#3651025, @aemerson wrote:

I just reverted this in 6e6be5f9504d because it seems to have broken macOS builds:

llvm/lib/Support/Compression.cpp:24:10: fatal error: 'zstd.h' file not found
#include <zstd.h>
         ^~~~~~~~

@aemerson Could you provide the output of your cmake command?
(I can't easily reproduce because I don't have a mac on hand)

FWIW I hit this last night on my mac desktop - it looked like I had zstd installed by homebrew (as a dependency on something I installed), and cmake was able to find it in /opt/homebrew (somehow) but when Compression.cpp was built, nothing had added -I/opt/homebrew/include so the header wasn't found. I hacked the FindZSTD.cmake to not find it, to finish what I was working on before bedtime. This might not be related to what @aemerson saw though.

@jasonmolenda Thank you for the info, I believe it is similar, could you try: https://reviews.llvm.org/D129786 for me?

I applied the patch from https://reviews.llvm.org/D129786 on a clean checkout, cmake ../llvm -G Ninja -DCMAKE_BUILD_TYPE=Debug -DLLVM_ENABLE_ASSERTIONS=1 -DLLVM_ENABLE_PROJECTS='llvm;lldb;clang' '-DLLVM_ENABLE_RUNTIMES=libcxx;libcxxabi' -DLLDB_ENABLE_PYTHON=1 (my normal cmake line) and got

-- Found ZSTD: /opt/homebrew/lib/libzstd.dylib  
-- Looking for ZSTD_compress
-- Looking for ZSTD_compress - found

[...]

FAILED: lib/Support/CMakeFiles/LLVMSupport.dir/Compression.cpp.o 
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/c++ -DGTEST_HAS_RTTI=0 -D_DEBUG -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -I/Users/jason/k/llvm/llvm-project/build/lib/Support -I/Users/jason/k/llvm/llvm-project/llvm/lib/Support -I/Users/jason/k/llvm/llvm-project/build/include -I/Users/jason/k/llvm/llvm-project/llvm/include -fPIC -fvisibility-inlines-hidden -Werror=date-time -Werror=unguarded-availability-new -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wmissing-field-initializers -pedantic -Wno-long-long -Wc++98-compat-extra-semi -Wimplicit-fallthrough -Wcovered-switch-default -Wno-noexcept-type -Wnon-virtual-dtor -Wdelete-non-virtual-dtor -Wsuggest-override -Wstring-conversion -Wmisleading-indentation -fdiagnostics-color  -g -arch arm64 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX12.3.sdk -std=c++14  -fno-exceptions -fno-rtti -MD -MT lib/Support/CMakeFiles/LLVMSupport.dir/Compression.cpp.o -MF lib/Support/CMakeFiles/LLVMSupport.dir/Compression.cpp.o.d -o lib/Support/CMakeFiles/LLVMSupport.dir/Compression.cpp.o -c /Users/jason/k/llvm/llvm-project/llvm/lib/Support/Compression.cpp
/Users/jason/k/llvm/llvm-project/llvm/lib/Support/Compression.cpp:24:10: fatal error: 'zstd.h' file not found
#include <zstd.h>
         ^~~~~~~~
1 error generated.

% file /opt/homebrew/lib/libzstd.dylib 
/opt/homebrew/lib/libzstd.dylib: Mach-O 64-bit dynamically linked shared library arm64
% head -2 /opt/homebrew/include/zstd.h 
/*
 * Copyright (c) Yann Collet, Facebook, Inc.
%

% grep -i zstd CMakeCache.txt 
//Use zstd for compression/decompression if available. Can be ON,
LLVM_ENABLE_ZSTD:STRING=ON
ZSTD_INCLUDE_DIR:PATH=/opt/homebrew/include
ZSTD_LIBRARY:FILEPATH=/opt/homebrew/lib/libzstd.dylib
//Details about finding ZSTD
FIND_PACKAGE_MESSAGE_DETAILS_ZSTD:INTERNAL=[/opt/homebrew/lib/libzstd.dylib][/opt/homebrew/include][v()]
//Have symbol ZSTD_compress
HAVE_ZSTD:INTERNAL=1
//ADVANCED property for variable: ZSTD_INCLUDE_DIR
ZSTD_INCLUDE_DIR-ADVANCED:INTERNAL=1
//ADVANCED property for variable: ZSTD_LIBRARY
ZSTD_LIBRARY-ADVANCED:INTERNAL=1

[MaskRay]

Instead of marking a differential [OLD] (which may confuse readers whether this is to be abandoned), you can mark a differential Request Reviews/Request Changes. Then it will not be in the green state.

I clicked "Reopen" to make it clear the patch hasn't relanded.

[ckissane]

In D128465#3660714, @MaskRay wrote:

Instead of marking a differential [OLD] (which may confuse readers whether this is to be abandoned), you can mark a differential Request Reviews/Request Changes. Then it will not be in the green state.

I clicked "Reopen" to make it clear the patch hasn't relanded.

Oh, sorry about that!
I had actually created https://reviews.llvm.org/D129786 instead of reopening this one because at the time I tried, reopening didn't seem to work.

[MaskRay]

In D128465#3660733, @ckissane wrote:

In D128465#3660714, @MaskRay wrote:

Instead of marking a differential [OLD] (which may confuse readers whether this is to be abandoned), you can mark a differential Request Reviews/Request Changes. Then it will not be in the green state.

I clicked "Reopen" to make it clear the patch hasn't relanded.

Oh, sorry about that!

That's fine :) We need to learn the web UI.

I had actually created https://reviews.llvm.org/D129786 instead of reopening this one because at the time I tried, reopening didn't seem to work.

A reverted patch by default is still in the "Closed" state. You can "reopen" it so that people know it hasn't relanded.
When repairing a differential, just reuse the existing patch. It keeps all discussions (including past suggestions and issues a previous commit did not address) in one thread.
If the new patch is very similar to this one, you probably need to abandon it in favor of this one.

---

If you revert B because you haven't done A, and A and B are somewhat not so related (e.g. B addresses an existing brittle build system issue which happens to affect some platform when A is added), then having A as a separate differential is fine.

[ckissane]

• move try_find_dependency into it's own file
• add newline to end of TryFindDependencyMacro.cmake
• clarify comment in TryFindDependencyMacro.cmake

[ckissane]

• remove extra cmake info

[MaskRay]

Does this address the macOS build failure?

[ckissane]

In D128465#3661049, @MaskRay wrote:

Does this address the macOS build failure?

I believe so! @leonardchan is double checking

[leonardchan]

LGTM tested on mac on my end

[barannikov88]

@ckissane
I took fresh sources of LLVM and when I run cmake I get the following warning:

-- Looking for compress2
-- Looking for compress2 - found
CMake Warning at cmake/config-ix.cmake:149 (find_package):
  By not providing "Findzstd.cmake" in CMAKE_MODULE_PATH this project has
  asked CMake to find a package configuration file provided by "zstd", but
  CMake did not find one.

  Could not find a package configuration file provided by "zstd" with any of
  the following names:

    zstdConfig.cmake
    zstd-config.cmake

  Add the installation prefix of "zstd" to CMAKE_PREFIX_PATH or set
  "zstd_DIR" to a directory containing one of the above files.  If "zstd"
  provides a separate development package or SDK, be sure it has been
  installed.
Call Stack (most recent call first):
  CMakeLists.txt:768 (include)

Ubuntu 22.04 LTS
cmake version 3.22.3

[phosek]

llvm/cmake/config-ix.cmake

147

Since there's no Findzstd.cmake module shipped with CMake, and we don't provide in LLVM, we should use the config mode.

[MaskRay]

I am still seeing the

zstdConfig.cmake
zstd-config.cmake

warning. @ckissane @phosek will you fix it? :)

[abrachet]

In D128465#3672515, @MaskRay wrote:

I am still seeing the

zstdConfig.cmake
zstd-config.cmake

warning. @ckissane @phosek will you fix it? :)

I've quieted the warnings in https://github.com/llvm/llvm-project/commit/a71a01bc10d509bd4e746e7d277c4613ef886875, though I'm just now seeing @phosek's suggestion to use CONFIG I'm not sure what that does

[MaskRay]

llvm/include/llvm/Support/Compression.h

47

I missed the values here. Why is -5 picked for NoCompression? What does it mean?

zstd.h says ZSTD_maxCLevel() is currently 22. The CLI program mentions 19. Why is BestSizeCompression 12?

ZSTD_CLEVEL_DEFAULT/the CLI CLI uses 3 for the default level. Why is DefaultCompression 5?

[MaskRay]

llvm/include/llvm/Support/Compression.h

47

Ping @ckissane about the choice.

[andrewrk]

if(LLVM_ENABLE_ZSTD)
  list(APPEND imported_libs zstd::libzstd_shared)
endif()

This hard codes shared linking which breaks the use case of static linking LLVM.

Also LLVM needs to now include a Findzstd.cmake file or else we get this error:

CMake Error at cmake/config-ix.cmake:144 (find_package):
  By not providing "Findzstd.cmake" in CMAKE_MODULE_PATH this project has
  asked CMake to find a package configuration file provided by "zstd", but
  CMake did not find one.

  Could not find a package configuration file provided by "zstd" with any of
  the following names:

    zstdConfig.cmake
    zstd-config.cmake

  Add the installation prefix of "zstd" to CMAKE_PREFIX_PATH or set
  "zstd_DIR" to a directory containing one of the above files.  If "zstd"
  provides a separate development package or SDK, be sure it has been
  installed.
Call Stack (most recent call first):
  CMakeLists.txt:774 (include)

It is impossible to satisfy this dependency when bootstrapping a static build of zig without patching LLVM.

[MaskRay]

zstd provides GNU Makefile, CMake, and Meson. The CMake files are only installed when configured with CMake. Debian and Ubuntu lack them.
The pkg-config file libzstd.pc probably provides the best portability on at least *NIX systems. (I have also used it for a binutils-gdb patch.)

I think we can then avoid the

zstdConfig.cmake
zstd-config.cmake

issue.

[andrewrk]

Compiler infrastructure should not assume the existence of a Linux distribution. The portable way is simple and can easily be supported. One should be able to install $prefix/lib/libzstd.a and $prefix/include/zstd.h, then have that prefix searched as part of the standard CMAKE_PREFIX_PATH.

If LLVM will not carry Findzstd.cmake then it should not use FIND_PACKAGE in the case of -DLLVM_ENABLE_ZSTD=FORCE_ON; it should just throw -lzstd on the linker line instead of throwing rakes in my path for no reason.

[phosek]

In D128465#3800479, @andrewrk wrote:

if(LLVM_ENABLE_ZSTD)
  list(APPEND imported_libs zstd::libzstd_shared)
endif()

This hard codes shared linking which breaks the use case of static linking LLVM.

This was addressed by D132870 and D133222.

Also LLVM needs to now include a Findzstd.cmake file or else we get this error:

CMake Error at cmake/config-ix.cmake:144 (find_package):
  By not providing "Findzstd.cmake" in CMAKE_MODULE_PATH this project has
  asked CMake to find a package configuration file provided by "zstd", but
  CMake did not find one.

  Could not find a package configuration file provided by "zstd" with any of
  the following names:

    zstdConfig.cmake
    zstd-config.cmake

  Add the installation prefix of "zstd" to CMAKE_PREFIX_PATH or set
  "zstd_DIR" to a directory containing one of the above files.  If "zstd"
  provides a separate development package or SDK, be sure it has been
  installed.
Call Stack (most recent call first):
  CMakeLists.txt:774 (include)

It is impossible to satisfy this dependency when bootstrapping a static build of zig without patching LLVM.

It should be possible to use CMAKE_FIND_PACKAGE_PREFER_CONFIG=ON to pick up config file that's part of the zstd installation, but I'd be also fine including Findzstd.cmake in LLVM to avoid needing that.

[mgorny]

Is anyone working on a solution that would work for people using a zstd install method that's actually supported upstream?

[phosek]

In D128465#3826150, @mgorny wrote:

Is anyone working on a solution that would work for people using a zstd install method that's actually supported upstream?

I have created D134990, it'd be great if others could test it on their system.

[aaronmondal]

Porting to bazel in https://reviews.llvm.org/D143344