Add support for x32-abi

Detect x32-abi through CMakeCompilerABI infrastruture and use this
information at runtime to determine the correct library paths with
`FIND_LIBRARY_USE_LIBX32_PATHS`.

Fixes: #15994

Help/command/find_library.rst

@@ -53,7 +53,8 @@ If the :variable:`CMAKE_FIND_LIBRARY_CUSTOM_LIB_SUFFIX` variable is set all
 search paths will be tested as normal, with the suffix appended, and with
 all matches of ``lib/`` replaced with
 ``lib${CMAKE_FIND_LIBRARY_CUSTOM_LIB_SUFFIX}/``.  This variable overrides
-the :prop_gbl:`FIND_LIBRARY_USE_LIB32_PATHS`
+the :prop_gbl:`FIND_LIBRARY_USE_LIB32_PATHS`,
+:prop_gbl:`FIND_LIBRARY_USE_LIBX32_PATHS`,
 and :prop_gbl:`FIND_LIBRARY_USE_LIB64_PATHS` global properties.
 
 If the :prop_gbl:`FIND_LIBRARY_USE_LIB32_PATHS` global property is set
@@ -63,6 +64,13 @@ automatically set for the platforms that are known to need it if at
 least one of the languages supported by the :command:`project` command
 is enabled.
 
+If the :prop_gbl:`FIND_LIBRARY_USE_LIBX32_PATHS` global property is set
+all search paths will be tested as normal, with ``x32/`` appended, and
+with all matches of ``lib/`` replaced with ``libx32/``.  This property is
+automatically set for the platforms that are known to need it if at
+least one of the languages supported by the :command:`project` command
+is enabled.
+
 If the :prop_gbl:`FIND_LIBRARY_USE_LIB64_PATHS` global property is set
 all search paths will be tested as normal, with ``64/`` appended, and
 with all matches of ``lib/`` replaced with ``lib64/``.  This property is

Help/manual/cmake-properties.7.rst

@@ -26,6 +26,7 @@ Properties of Global Scope
    /prop_gbl/ENABLED_LANGUAGES
    /prop_gbl/FIND_LIBRARY_USE_LIB32_PATHS
    /prop_gbl/FIND_LIBRARY_USE_LIB64_PATHS
+   /prop_gbl/FIND_LIBRARY_USE_LIBX32_PATHS
    /prop_gbl/FIND_LIBRARY_USE_OPENBSD_VERSIONING
    /prop_gbl/GLOBAL_DEPENDS_DEBUG_MODE
    /prop_gbl/GLOBAL_DEPENDS_NO_CYCLES

Help/prop_gbl/FIND_LIBRARY_USE_LIBX32_PATHS.rst

@@ -0,0 +1,12 @@
+FIND_LIBRARY_USE_LIBX32_PATHS
+-----------------------------
+
+Whether the :command:`find_library` command should automatically search
+``libx32`` directories.
+
+``FIND_LIBRARY_USE_LIBX32_PATHS`` is a boolean specifying whether the
+:command:`find_library` command should automatically search the ``libx32``
+variant of directories called ``lib`` in the search path when building
+x32-abi binaries.
+
+See also the :variable:`CMAKE_FIND_LIBRARY_CUSTOM_LIB_SUFFIX` variable.

Help/variable/CMAKE_FIND_LIBRARY_CUSTOM_LIB_SUFFIX.rst

@@ -9,3 +9,4 @@ This overrides the behavior of related global properties:
 
 * :prop_gbl:`FIND_LIBRARY_USE_LIB32_PATHS`
 * :prop_gbl:`FIND_LIBRARY_USE_LIB64_PATHS`
+* :prop_gbl:`FIND_LIBRARY_USE_LIBX32_PATHS`

Modules/CMakeCompilerABI.h

@@ -25,6 +25,10 @@ const char info_sizeof_dptr[] = {
 #elif defined(__GNU__) && defined(__ELF__) && defined(__ARMEL__)
 #define ABI_ID "ELF ARM"
 
+#elif defined(__linux__) && defined(__ELF__) && defined(__amd64__) &&         \
+  defined(__ILP32__)
+#define ABI_ID "ELF X32"
+
 #elif defined(__ELF__)
 #define ABI_ID "ELF"
 #endif

Modules/FindPkgConfig.cmake

@@ -312,6 +312,10 @@ macro(_pkg_check_modules_internal _is_required _is_silent _no_cmake_path _no_cma
           if(uselib64 AND CMAKE_SIZEOF_VOID_P EQUAL 8)
             list(APPEND _lib_dirs "lib64/pkgconfig")
           endif()
+          get_property(uselibx32 GLOBAL PROPERTY FIND_LIBRARY_USE_LIBX32_PATHS)
+          if(uselibx32 AND CMAKE_INTERNAL_PLATFORM_ABI STREQUAL "ELF X32")
+            list(APPEND _lib_dirs "libx32/pkgconfig")
+          endif()
         endif()
       endif()
       list(APPEND _lib_dirs "lib/pkgconfig")

Modules/Platform/UnixPaths.cmake

@@ -86,3 +86,4 @@ list(APPEND CMAKE_CXX_IMPLICIT_INCLUDE_DIRECTORIES
 # Enable use of lib32 and lib64 search path variants by default.
 set_property(GLOBAL PROPERTY FIND_LIBRARY_USE_LIB32_PATHS TRUE)
 set_property(GLOBAL PROPERTY FIND_LIBRARY_USE_LIB64_PATHS TRUE)
+set_property(GLOBAL PROPERTY FIND_LIBRARY_USE_LIBX32_PATHS TRUE)

Source/cmExportInstallFileGenerator.cxx

@@ -195,8 +195,10 @@ void cmExportInstallFileGenerator::GenerateImportPrefix(std::ostream& os)
        << " \"${CMAKE_CURRENT_LIST_FILE}\" PATH)\n";
     if (cmHasLiteralPrefix(absDestS.c_str(), "/lib/") ||
         cmHasLiteralPrefix(absDestS.c_str(), "/lib64/") ||
+        cmHasLiteralPrefix(absDestS.c_str(), "/libx32/") ||
         cmHasLiteralPrefix(absDestS.c_str(), "/usr/lib/") ||
-        cmHasLiteralPrefix(absDestS.c_str(), "/usr/lib64/")) {
+        cmHasLiteralPrefix(absDestS.c_str(), "/usr/lib64/") ||
+        cmHasLiteralPrefix(absDestS.c_str(), "/usr/libx32/")) {
       // Handle "/usr move" symlinks created by some Linux distros.
       /* clang-format off */
       os <<

Source/cmFindLibraryCommand.cxx

@@ -43,7 +43,8 @@ bool cmFindLibraryCommand::InitialPass(std::vector<std::string> const& argsIn,
     return true;
   }
 
-  // add custom lib<qual> paths instead of using fixed lib32 or lib64
+  // add custom lib<qual> paths instead of using fixed lib32, lib64 or
+  // libx32
   if (const char* customLib = this->Makefile->GetDefinition(
         "CMAKE_FIND_LIBRARY_CUSTOM_LIB_SUFFIX")) {
     this->AddArchitecturePaths(customLib);
@@ -60,6 +61,12 @@ bool cmFindLibraryCommand::InitialPass(std::vector<std::string> const& argsIn,
              "FIND_LIBRARY_USE_LIB64_PATHS")) {
     this->AddArchitecturePaths("64");
   }
+  // add special 32 bit paths if this is an x32 compile.
+  else if (this->Makefile->PlatformIsx32() &&
+           this->Makefile->GetState()->GetGlobalPropertyAsBool(
+             "FIND_LIBRARY_USE_LIBX32_PATHS")) {
+    this->AddArchitecturePaths("x32");
+  }
 
   std::string library = this->FindLibrary();
   if (library != "") {

Source/cmFindPackageCommand.cxx

@@ -92,6 +92,7 @@ cmFindPackageCommand::cmFindPackageCommand()
   this->DebugMode = false;
   this->UseLib32Paths = false;
   this->UseLib64Paths = false;
+  this->UseLibx32Paths = false;
   this->PolicyScope = true;
   this->VersionMajor = 0;
   this->VersionMinor = 0;
@@ -173,6 +174,13 @@ bool cmFindPackageCommand::InitialPass(std::vector<std::string> const& args,
     this->UseLib64Paths = true;
   }
 
+  // Lookup whether libx32 paths should be used.
+  if (this->Makefile->PlatformIsx32() &&
+      this->Makefile->GetState()->GetGlobalPropertyAsBool(
+        "FIND_LIBRARY_USE_LIBX32_PATHS")) {
+    this->UseLibx32Paths = true;
+  }
+
   // Check if User Package Registry should be disabled
   if (this->Makefile->IsOn("CMAKE_FIND_PACKAGE_NO_PACKAGE_REGISTRY")) {
     this->NoUserRegistry = true;
@@ -2002,6 +2010,9 @@ bool cmFindPackageCommand::SearchPrefix(std::string const& prefix_in)
   if (this->UseLib64Paths) {
     common.push_back("lib64");
   }
+  if (this->UseLibx32Paths) {
+    common.push_back("libx32");
+  }
   common.push_back("lib");
   common.push_back("share");
 

Source/cmFindPackageCommand.h

@@ -169,6 +169,7 @@ private:
   bool DebugMode;
   bool UseLib32Paths;
   bool UseLib64Paths;
+  bool UseLibx32Paths;
   bool PolicyScope;
   std::string LibraryArchitecture;
   std::vector<std::string> Names;

Source/cmMakefile.cxx

@@ -2149,6 +2149,12 @@ bool cmMakefile::IsSet(const std::string& name) const
 
 bool cmMakefile::PlatformIs32Bit() const
 {
+  if (const char* plat_abi =
+        this->GetDefinition("CMAKE_INTERNAL_PLATFORM_ABI")) {
+    if (strcmp(plat_abi, "ELF X32") == 0) {
+      return false;
+    }
+  }
   if (const char* sizeof_dptr = this->GetDefinition("CMAKE_SIZEOF_VOID_P")) {
     return atoi(sizeof_dptr) == 4;
   }
@@ -2163,6 +2169,17 @@ bool cmMakefile::PlatformIs64Bit() const
   return false;
 }
 
+bool cmMakefile::PlatformIsx32() const
+{
+  if (const char* plat_abi =
+        this->GetDefinition("CMAKE_INTERNAL_PLATFORM_ABI")) {
+    if (strcmp(plat_abi, "ELF X32") == 0) {
+      return true;
+    }
+  }
+  return false;
+}
+
 bool cmMakefile::PlatformIsAppleIos() const
 {
   std::string sdkRoot;

Source/cmMakefile.h

@@ -436,6 +436,8 @@ public:
 
   /** Return whether the target platform is 64-bit.  */
   bool PlatformIs64Bit() const;
+  /** Return whether the target platform is x32.  */
+  bool PlatformIsx32() const;
 
   /** Return whether the target platform is Apple iOS.  */
   bool PlatformIsAppleIos() const;