kbuild: Add support to generate LLVM assembly files

commit 433db3e260bc8134d4a46ddf20b3668937e12556 upstream.

Add rules to kbuild in order to generate LLVM assembly files with the .ll
extension when using clang.

  # from c code
  make CC=clang kernel/pid.ll

Signed-off-by: Vinícius Tinti <viniciustinti@gmail.com>
Signed-off-by: Behan Webster <behanw@converseincode.com>
Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
[nc: Fix conflicts due to lack of commit 6b90bd4ba40b3 in linux-4.4.y]
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/.gitignore b/.gitignore
index fd3a355925432f58c1bcf84b16ec3ec8bc8c5457..34fe1346aa87da5f33e76ab9f710cc4b739ea522 100644 (file)
--- a/.gitignore
+++ b/.gitignore
@@ -33,6 +33,7 @@
 *.lzo
 *.patch
 *.gcno
+*.ll
 modules.builtin
 Module.symvers
 *.dwo

diff --git a/Makefile b/Makefile
index c9e27ba9152d53061e734fccbcd97d7c02018f12..10cbd11f99ee161493c0915b0e17cca14e8ec681 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -1307,6 +1307,8 @@ help:
        @echo  '                    (default: $$(INSTALL_MOD_PATH)/lib/firmware)'
        @echo  '  dir/            - Build all files in dir and below'
        @echo  '  dir/file.[ois]  - Build specified target only'
+       @echo  '  dir/file.ll     - Build the LLVM assembly file'
+       @echo  '                    (requires compiler support for LLVM assembly generation)'
        @echo  '  dir/file.lst    - Build specified mixed source/assembly target only'
        @echo  '                    (requires a recent binutils and recent build (System.map))'
        @echo  '  dir/file.ko     - Build module including final link'
@@ -1482,6 +1484,7 @@ clean: $(clean-dirs)
                -o -name '.*.d' -o -name '.*.tmp' -o -name '*.mod.c' \
                -o -name '*.symtypes' -o -name 'modules.order' \
                -o -name modules.builtin -o -name '.tmp_*.o.*' \
+               -o -name '*.ll' \
                -o -name '*.gcno' \) -type f -print | xargs rm -f
 
 # Generate tags for editors
@@ -1585,6 +1588,8 @@ endif
        $(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)
 %.symtypes: %.c prepare scripts FORCE
        $(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)
+%.ll: %.c prepare scripts FORCE
+       $(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)
 
 # Modules
 /: prepare scripts FORCE

diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 18209917e3798ec73d5214a5e5e15d77c2dc5b00..42aef001dfdd73f8fd4970a1c8fd45cf27fbf8c6 100644 (file)
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -175,6 +175,14 @@ cmd_cc_symtypes_c =                                                         \
 $(obj)/%.symtypes : $(src)/%.c FORCE
        $(call cmd,cc_symtypes_c)
 
+# LLVM assembly
+# Generate .ll files from .c
+quiet_cmd_cc_ll_c = CC $(quiet_modtag)  $@
+      cmd_cc_ll_c = $(CC) $(c_flags) -emit-llvm -S -o $@ $<
+
+$(obj)/%.ll: $(src)/%.c FORCE
+       $(call if_changed_dep,cc_ll_c)
+
 # C (.c) files
 # The C file is compiled and updated dependency information is generated.
 # (See cmd_cc_o_c + relevant part of rule_cc_o_c)