Revert abb0075 "build: reduce CMake handling for zlib" (PR44780)

and follow-ups:
a2ca1c2 "build: disable zlib by default on Windows"
2181bf4 "[CMake] Link against ZLIB::ZLIB"
1079c68 "Attempt to fix ZLIB CMake logic on Windows"

This changed the output of llvm-config --system-libs, and more
importantly it broke stand-alone builds. Instead of piling on more fix
attempts, let's revert this to reduce the risk of more breakages.

(cherry picked from commit 916be8f)

Author: zmodem

clang/test/CMakeLists.txt

@@ -9,14 +9,23 @@ endif ()
 
 string(REPLACE ${CMAKE_CFG_INTDIR} ${LLVM_BUILD_MODE} CLANG_TOOLS_DIR ${LLVM_RUNTIME_OUTPUT_INTDIR})
 
+if(CLANG_BUILT_STANDALONE)
+  # Set HAVE_LIBZ according to recorded LLVM_ENABLE_ZLIB value. This
+  # value is forced to 0 if zlib was not found, so it is fine to use it
+  # instead of HAVE_LIBZ (not recorded).
+  if(LLVM_ENABLE_ZLIB)
+    set(HAVE_LIBZ 1)
+  endif()
+endif()
+
 llvm_canonicalize_cmake_booleans(
   CLANG_BUILD_EXAMPLES
   CLANG_ENABLE_ARCMT
   CLANG_ENABLE_STATIC_ANALYZER
   CLANG_SPAWN_CC1
   ENABLE_BACKTRACES
   ENABLE_EXPERIMENTAL_NEW_PASS_MANAGER
-  LLVM_ENABLE_ZLIB
+  HAVE_LIBZ
   LLVM_ENABLE_PER_TARGET_RUNTIME_DIR
   LLVM_ENABLE_PLUGINS
   LLVM_ENABLE_THREADS)

clang/test/lit.site.cfg.py.in

@@ -16,7 +16,7 @@ config.host_triple = "@LLVM_HOST_TRIPLE@"
 config.target_triple = "@TARGET_TRIPLE@"
 config.host_cxx = "@CMAKE_CXX_COMPILER@"
 config.llvm_use_sanitizer = "@LLVM_USE_SANITIZER@"
-config.have_zlib = @LLVM_ENABLE_ZLIB@
+config.have_zlib = @HAVE_LIBZ@
 config.clang_arcmt = @CLANG_ENABLE_ARCMT@
 config.clang_default_cxx_stdlib = "@CLANG_DEFAULT_CXX_STDLIB@"
 config.clang_staticanalyzer = @CLANG_ENABLE_STATIC_ANALYZER@

compiler-rt/test/lit.common.configured.in

@@ -50,7 +50,7 @@ if config.enable_per_target_runtime_dir:
 else:
   set_default("target_suffix", "-%s" % config.target_arch)
 
-set_default("have_zlib", "@LLVM_ENABLE_ZLIB@")
+set_default("have_zlib", "@HAVE_LIBZ@")
 set_default("libcxx_used", "@LLVM_LIBCXX_USED@")
 
 # LLVM tools dir can be passed in lit parameters, so try to

lld/test/CMakeLists.txt

@@ -4,8 +4,17 @@ set(LLVM_BUILD_MODE "%(build_mode)s")
 set(LLVM_TOOLS_DIR "${LLVM_TOOLS_BINARY_DIR}/%(build_config)s")
 set(LLVM_LIBS_DIR "${LLVM_BINARY_DIR}/lib${LLVM_LIBDIR_SUFFIX}/%(build_config)s")
 
+if(LLD_BUILT_STANDALONE)
+  # Set HAVE_LIBZ according to recorded LLVM_ENABLE_ZLIB value. This
+  # value is forced to 0 if zlib was not found, so it is fine to use it
+  # instead of HAVE_LIBZ (not recorded).
+  if(LLVM_ENABLE_ZLIB)
+    set(HAVE_LIBZ 1)
+  endif()
+endif()
+
 llvm_canonicalize_cmake_booleans(
-  LLVM_ENABLE_ZLIB
+  HAVE_LIBZ
   LLVM_LIBXML2_ENABLED
   )
 

lld/test/lit.site.cfg.py.in

@@ -14,7 +14,7 @@ config.lld_libs_dir = "@LLVM_LIBRARY_OUTPUT_INTDIR@"
 config.lld_tools_dir = "@LLVM_RUNTIME_OUTPUT_INTDIR@"
 config.target_triple = "@TARGET_TRIPLE@"
 config.python_executable = "@PYTHON_EXECUTABLE@"
-config.have_zlib = @LLVM_ENABLE_ZLIB@
+config.have_zlib = @HAVE_LIBZ@
 config.sizeof_void_p = @CMAKE_SIZEOF_VOID_P@
 
 # Support substitution of the tools and libs dirs with user parameters. This is

lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunication.cpp

@@ -50,7 +50,7 @@
 #include <compression.h>
 #endif
 
-#if LLVM_ENABLE_ZLIB
+#if defined(HAVE_LIBZ)
 #include <zlib.h>
 #endif
 
@@ -582,7 +582,7 @@ bool GDBRemoteCommunication::DecompressPacket() {
   }
 #endif
 
-#if LLVM_ENABLE_ZLIB
+#if defined(HAVE_LIBZ)
   if (decompressed_bytes == 0 && decompressed_bufsize != ULONG_MAX &&
       decompressed_buffer != nullptr &&
       m_compression_type == CompressionType::ZlibDeflate) {

lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationClient.cpp

@@ -1045,7 +1045,7 @@ void GDBRemoteCommunicationClient::MaybeEnableCompression(
   }
 #endif
 
-#if LLVM_ENABLE_ZLIB
+#if defined(HAVE_LIBZ)
   if (avail_type == CompressionType::None) {
     for (auto compression : supported_compressions) {
       if (compression == "zlib-deflate") {

llvm/CMakeLists.txt

@@ -347,13 +347,7 @@ option(LLVM_ENABLE_LIBPFM "Use libpfm for performance counters if available." ON
 
 option(LLVM_ENABLE_THREADS "Use threads if available." ON)
 
-if(CMAKE_SYSTEM_NAME STREQUAL Windows)
-  set(zlib_DEFAULT "OFF")
-else()
-  set(zlib_DEFAULT "ON")
-endif()
-
-set(LLVM_ENABLE_ZLIB "${zlib_DEFAULT}" CACHE STRING "Use zlib for compression/decompression if available. Can be ON, OFF, or FORCE_ON")
+option(LLVM_ENABLE_ZLIB "Use zlib for compression/decompression if available." ON)
 
 set(LLVM_Z3_INSTALL_DIR "" CACHE STRING "Install directory of the Z3 solver.")
 

llvm/cmake/config-ix.cmake

@@ -56,6 +56,7 @@ check_include_file(sys/types.h HAVE_SYS_TYPES_H)
 check_include_file(termios.h HAVE_TERMIOS_H)
 check_include_file(unistd.h HAVE_UNISTD_H)
 check_include_file(valgrind/valgrind.h HAVE_VALGRIND_VALGRIND_H)
+check_include_file(zlib.h HAVE_ZLIB_H)
 check_include_file(fenv.h HAVE_FENV_H)
 check_symbol_exists(FE_ALL_EXCEPT "fenv.h" HAVE_DECL_FE_ALL_EXCEPT)
 check_symbol_exists(FE_INEXACT "fenv.h" HAVE_DECL_FE_INEXACT)
@@ -117,6 +118,19 @@ endif()
 # Don't look for these libraries if we're using MSan, since uninstrumented third
 # party code may call MSan interceptors like strlen, leading to false positives.
 if(NOT LLVM_USE_SANITIZER MATCHES "Memory.*")
+  set(HAVE_LIBZ 0)
+  if(LLVM_ENABLE_ZLIB)
+    foreach(library z zlib_static zlib)
+      string(TOUPPER ${library} library_suffix)
+      check_library_exists(${library} compress2 "" HAVE_LIBZ_${library_suffix})
+      if(HAVE_LIBZ_${library_suffix})
+        set(HAVE_LIBZ 1)
+        set(ZLIB_LIBRARIES "${library}")
+        break()
+      endif()
+    endforeach()
+  endif()
+
   # Don't look for these libraries on Windows.
   if (NOT PURE_WINDOWS)
     # Skip libedit if using ASan as it contains memory leaks.
@@ -501,21 +515,10 @@ else( LLVM_ENABLE_THREADS )
   message(STATUS "Threads disabled.")
 endif()
 
-if(LLVM_ENABLE_ZLIB)
-  if(LLVM_ENABLE_ZLIB STREQUAL FORCE_ON)
-    find_package(ZLIB REQUIRED)
-  else()
-    find_package(ZLIB)
-  endif()
-
-  if(ZLIB_FOUND)
-    set(LLVM_ENABLE_ZLIB "YES" CACHE STRING
-      "Use zlib for compression/decompression if available. Can be ON, OFF, or FORCE_ON"
-      FORCE)
-  else()
-    set(LLVM_ENABLE_ZLIB "NO" CACHE STRING
-      "Use zlib for compression/decompression if available. Can be ON, OFF, or FORCE_ON"
-      FORCE)
+if (LLVM_ENABLE_ZLIB )
+  # Check if zlib is available in the system.
+  if ( NOT HAVE_ZLIB_H OR NOT HAVE_LIBZ )
+    set(LLVM_ENABLE_ZLIB 0)
   endif()
 endif()
 

llvm/include/llvm/Config/config.h.cmake

@@ -109,6 +109,9 @@
 /* Define to 1 if you have the `pthread_setname_np' function. */
 #cmakedefine HAVE_PTHREAD_SETNAME_NP ${HAVE_PTHREAD_SETNAME_NP}
 
+/* Define to 1 if you have the `z' library (-lz). */
+#cmakedefine HAVE_LIBZ ${HAVE_LIBZ}
+
 /* Define to 1 if you have the <link.h> header file. */
 #cmakedefine HAVE_LINK_H ${HAVE_LINK_H}
 
@@ -223,6 +226,9 @@
 /* Define to 1 if you have the <valgrind/valgrind.h> header file. */
 #cmakedefine HAVE_VALGRIND_VALGRIND_H ${HAVE_VALGRIND_VALGRIND_H}
 
+/* Define to 1 if you have the <zlib.h> header file. */
+#cmakedefine HAVE_ZLIB_H ${HAVE_ZLIB_H}
+
 /* Have host's _alloca */
 #cmakedefine HAVE__ALLOCA ${HAVE__ALLOCA}