solenv/gbuild/PrecompiledHeaders.mk

   1 # -*- Mode: makefile-gmake; tab-width: 4; indent-tabs-mode: t -*-
   2 #
   3 # This file is part of the LibreOffice project.
   4 #
   5 # This Source Code Form is subject to the terms of the Mozilla Public
   6 # License, v. 2.0. If a copy of the MPL was not distributed with this
   7 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
   8 #
   9 # This file incorporates work covered by the following license notice:
  10 #
  11 #   Licensed to the Apache Software Foundation (ASF) under one or more
  12 #   contributor license agreements. See the NOTICE file distributed
  13 #   with this work for additional information regarding copyright
  14 #   ownership. The ASF licenses this file to you under the Apache
  15 #   License, Version 2.0 (the "License"); you may not use this file
  16 #   except in compliance with the License. You may obtain a copy of
  17 #   the License at http://www.apache.org/licenses/LICENSE-2.0 .
  18 #
  19
  20
  21 # PrecompiledHeader class
  22
  23 ifneq ($(gb_ENABLE_PCH),)
  24
  25 # Use different PCH file depending on whether we use debugging symbols.
  26 gb_PrecompiledHeader__get_debugdir = $(if $(call gb_LinkTarget__symbols_enabled,$(1)),debug,nodebug)
  27
  28 # IMPORTANT: Since these defines get expanded, every $ needs to be doubled to $$, except
  29 # for $(1)'s and things that are constant.
  30 # The defines are needed to get the right version of gb_PrecompiledHeader__get_debugdir.
  31
  32 # $(call gb_PrecompiledHeader_generate_rules,pchtarget,linktarget,linktargetmakefilename)
  33 define gb_PrecompiledHeader_generate_rules
  34
  35 $(call gb_PrecompiledHeader_get_dep_target,$(1),$(3)) :
  36         $$(call gb_Helper_abbreviate_dirs,\
  37                 mkdir -p $$(dir $$@) && \
  38                 echo "$$(call gb_PrecompiledHeader_get_target,$(1),$(3)) : $$(gb_Helper_PHONY)" > $$@)
  39
  40 # despite this being only one .d file, need to run concat-deps on it to
  41 # re-write external headers from UnpackedTarball
  42 $(call gb_PrecompiledHeader_get_target,$(1),$(3)) :
  43         test "$$(PCH_LINKTARGETMAKEFILENAME)" = "$(3)" \
  44                  || ( echo "Error, PCH $(1) built by $$(PCH_LINKTARGETMAKEFILENAME) instead of $(3)" >&2; exit 1)
  45         rm -f $$@
  46         $$(call gb_PrecompiledHeader__command,$$@,$(1),$$<,$$(PCH_DEFS),$$(PCH_CXXFLAGS) $$(gb_PrecompiledHeader_EXCEPTIONFLAGS),$$(INCLUDE),$(3))
  47         $$(call gb_PrecompiledHeader__sum_command,$$@,$(1),$$<,$$(PCH_DEFS),$$(PCH_CXXFLAGS) $$(gb_PrecompiledHeader_EXCEPTIONFLAGS),$$(INCLUDE),$(3))
  48         echo $$(sort $$(PCH_DEFS) $$(PCH_CXXFLAGS) $$(gb_PrecompiledHeader_EXCEPTIONFLAGS)) > $$(call gb_PrecompiledHeader_get_target,$(1),$(3)).flags
  49 ifeq ($(gb_FULLDEPS),$(true))
  50         $$(call gb_Helper_abbreviate_dirs,\
  51                 RESPONSEFILE=$$(call var2file,$$(shell $$(gb_MKTEMP)),200,$$(call gb_PrecompiledHeader_get_dep_target_tmp,$(1),$(3))) && \
  52                 $$(call gb_Executable_get_command,concat-deps) $$$${RESPONSEFILE} \
  53                         > $$(call gb_PrecompiledHeader_get_dep_target,$(1),$(3)) && \
  54                 rm -f $$$${RESPONSEFILE} $$(call gb_PrecompiledHeader_get_dep_target_tmp,$(1),$(3)))
  55 endif
  56
  57 $(call gb_PrecompiledHeader_get_for_reuse_target,$(1),$(3)) : $(call gb_LinkTarget_get_target,$(2))
  58         $$(call gb_PrecompiledHeader__create_reuse_files,$(2),$(1),$(3))
  59         mkdir -p $$(dir $$@) && touch $$@
  60
  61 .PHONY : $(call gb_PrecompiledHeader_get_clean_target,$(1))
  62 $(call gb_PrecompiledHeader_get_clean_target,$(1)) :
  63         $$(call gb_Output_announce,$(1),$(false),PCH,1)
  64         -$$(call gb_Helper_abbreviate_dirs,\
  65                 rm -f $$(call gb_PrecompiledHeader_get_target,$(1),$(3)) \
  66                         $$(call gb_PrecompiledHeader_get_target,$(1),$(3)).obj \
  67                         $$(call gb_PrecompiledHeader_get_target,$(1),$(3)).pdb \
  68                         $$(call gb_PrecompiledHeader_get_target,$(1),$(3)).sum \
  69                         $$(call gb_PrecompiledHeader_get_target,$(1),$(3)).flags \
  70                         $$(call gb_PrecompiledHeader_get_target,$(1),$(3)).reuse \
  71                         $$(call gb_PrecompiledHeader_get_dep_target,$(1),$(3)))
  72
  73 endef
  74
  75 endif
  76
  77 # $(call gb_PrecompiledHeader_generate_timestamp_rule,linktargetmakefilename)
  78 define gb_PrecompiledHeader_generate_timestamp_rule
  79 $(call gb_LinkTarget_get_pch_timestamp,$(1)) :
  80         mkdir -p $$(dir $$@) && touch $$@
  81
  82 endef
  83
  84 # $(call gb_PrecompiledHeader_check_flags,linktargetmakefilename,pchcxxfile,pchfile,flags)
  85 # When creating a PCH, the PCH's CXXFLAGS are saved to a matching .flags file. When reusing the PCH
  86 # from another linktarget, use the file to check that the linktarget uses the same CXXFLAGS as the PCH.
  87 # This complements the check in gb_CxxObject__set_pchflags.
  88 define gb_PrecompiledHeader_check_flags
  89 $$(call gb_Helper_abbreviate_dirs,\
  90         $$(if $$(strip $$(call gb_PrecompiledHeader_check_flags_internal,$$(shell cat $(3).flags),$(4),$(2))),false,true) || ( \
  91                 echo Error reusing $(2) by $(1). >&2 && \
  92                 echo -n " precompiled header flags : ">&2 && \
  93                 cat $(3).flags >&2 && \
  94                 echo    "            object flags  : "$$(sort $(4)) >&2 && \
  95                 echo    " reason : $$(call gb_PrecompiledHeader_check_flags_internal,$$(shell cat $(3).flags),$(4),$(2))" >&2 && \
  96                 echo Incorrect precompiled header setup or internal gbuild error. >&2 ; \
  97                 exit 1) \
  98 )
  99
 100 endef
 101
 102 # When trying to reuse one PCH between multiple linktargets, there is a problem that we have
 103 # various defines that cause mismatch in the check above, but these defines actually should not affect the PCH.
 104 # Specifically, there are 3 kinds:
 105 # - -DXXX_DLLIMPLEMENTATION - they are used only in our headers, should not affect system headers.
 106 # - -DSYSTEM_XXX - they are used only by our code (if at all), should not affect system headers
 107 # - various LO configuration defines - they again should only be used by our code and not system headers
 108 # Technically, different compilers handle additional defines like this:
 109 # - GCC
 110 #   * It is explicitly allowed to have different macros, as long as they do not affect the PCH.
 111 #   * With -Winvalid-pch GCC will even warn if there is a change in a macro affecting the PCH.
 112 #   * https://gcc.gnu.org/onlinedocs/gcc/Precompiled-Headers.html
 113 # - Clang
 114 #   * I could not find an official statement on what happens if definitions are different.
 115 #   * In practice a conflict does not seem to be detected, but the PCH and all the code in it
 116 #     acts according to the settings it was built with. Using a PCH and adding more defines
 117 #     seems to be functionally equivalent to creating the definitions only after the PCH inclusion.
 118 #   * As a side-effect, macros defined on the command line not present in the PCH suddenly
 119 #     trigger the -Wunused-macros warning. See bottom of pch/inc/clangfix.hxx .
 120 # - MSVC
 121 #   * MSVC explicitly states that the definitions must be the same, but they are not checked,
 122 #     and "unpredictable results can occur" if files depend on them.
 123 #   * In practice the situation seems to be the same as with Clang, the PCH and the code from it
 124 #     act according to the settings it was built with.
 125 #   * https://docs.microsoft.com/en-us/cpp/build/creating-precompiled-header-files
 126 # So while this is officially tricky, in practice it seems to work to allow PCH reuse if the linktarget
 127 # has more defines than the PCH was built with, as long as the defines do not affect the PCH.
 128 gb_PrecompiledHeader_ignore_flags_system := \
 129 -DFASTSAX_DLLIMPLEMENTATION \
 130 -DSAX_DLLIMPLEMENTATION \
 131 -DSCQAHELPER_DLLIMPLEMENTATION \
 132 -DVCLPLUG_WIN_IMPLEMENTATION \
 133 -DVCLPLUG_GEN_IMPLEMENTATION \
 134 -DSYSTEM_EXPAT \
 135 -DSYSTEM_LIBXML \
 136 -DSYSTEM_ZLIB \
 137 -DHAVE_VALGRIND_HEADERS \
 138 -DUSE_RANDR \
 139 -DUSE_XINERAMA_XORG \
 140 -DDISABLE_CVE_TESTS \
 141 -DCPPUNIT_PLUGIN_EXPORT='extern "C" SAL_DLLPUBLIC_EXPORT' \
 142 -DOOO_DLLIMPLEMENTATION_TEST \
 143 -include $(SRCDIR)/pch/inc/clangfix.hxx \
 144
 145 # Probably also update pch/inc/clangfix.hxx if you extend the list.
 146
 147 # $(call gb_PrecompiledHeader_check_flags_internal,pchfileflags,flags,pchcxxfile)
 148 # Check if two sets of flags are compatible, allowing reuse of the PCH. Flags are compatible if
 149 # - they are the same
 150 # - the PCH is precompiled_system and the linktarget has additional defines listed above
 151 define gb_PrecompiledHeader_check_flags_internal
 152 $(if $(filter-out $(2),$(1)),$(filter-out $(2),$(1)), \
 153         $(if $(filter-out $(1),$(2)),\
 154                 $(if $(filter-out precompiled_system,$(notdir $(3))),$(filter-out $(1),$(2)), \
 155                         $(foreach flag,$(filter-out $(1),$(2)),$(filter-out $(gb_PrecompiledHeader_ignore_flags_system),$(flag))) \
 156                 ) \
 157         ,) \
 158 )
 159 endef
 160
 161 # vim: set noet sw=4: