[PATCH 4.9 18/59] kbuild: Add support to generate LLVM assembly files

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Vinícius Tinti <viniciusti...@gmail.com>

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 <viniciusti...@gmail.com>
Signed-off-by: Behan Webster <beh...@converseincode.com>
Signed-off-by: Matthias Kaehlcke <m...@chromium.org>
Signed-off-by: Masahiro Yamada <yamada.masah...@socionext.com>
Signed-off-by: Nick Desaulniers <ndesaulni...@google.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
 .gitignore             |    1 +
 Makefile               |    5 +++++
 scripts/Makefile.build |    8 ++++++++
 3 files changed, 14 insertions(+)

--- a/.gitignore
+++ b/.gitignore
@@ -33,6 +33,7 @@
 *.lzo
 *.patch
 *.gcno
+*.ll
 modules.builtin
 Module.symvers
 *.dwo
--- a/Makefile
+++ b/Makefile
@@ -1390,6 +1390,8 @@ 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'
@@ -1574,6 +1576,7 @@ clean: $(clean-dirs)
                -o -name '*.symtypes' -o -name 'modules.order' \
                -o -name modules.builtin -o -name '.tmp_*.o.*' \
                -o -name '*.c.[012]*.*' \
+               -o -name '*.ll' \
                -o -name '*.gcno' \) -type f -print | xargs rm -f
 
 # Generate tags for editors
@@ -1677,6 +1680,8 @@ 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
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -176,6 +176,14 @@ 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)