[PATCH 4.4 14/70] kbuild: Add support to generate LLVM assembly files

Greg Kroah-Hartman
2018-11-26T10:55:32Z

From: Vinícius Tinti <viniciustinti@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 <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>
---
.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
@@ -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
--- 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)