[PATCH AUTOSEL 5.4 19/24] kbuild: improve cc-option to clean up all temporary files

Sasha Levin
2020-06-23T17:39:29Z

From: Masahiro Yamada <masahiroy@kernel.org>

[ Upstream commit f2f02ebd8f3833626642688b2d2c6a7b3c141fa9 ]

When cc-option and friends evaluate compiler flags, the temporary file
$$TMP is created as an output object, and automatically cleaned up.
The actual file path of $$TMP is .<pid>.tmp, here <pid> is the process
ID of $(shell ...) invoked from cc-option. (Please note $$$$ is the
escape sequence of $$).

Such garbage files are cleaned up in most cases, but some compiler flags
create additional output files.

For example, -gsplit-dwarf creates a .dwo file.

When CONFIG_DEBUG_INFO_SPLIT=y, you will see a bunch of .<pid>.dwo files
left in the top of build directories. You may not notice them unless you
do 'ls -a', but the garbage files will increase every time you run 'make'.

This commit changes the temporary object path to .tmp_<pid>/tmp, and
removes .tmp_<pid> directory when exiting. Separate build artifacts such
as *.dwo will be cleaned up all together because their file paths are
usually determined based on the base name of the object.

Another example is -ftest-coverage, which outputs the coverage data into
<base-name-of-object>.gcno

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
scripts/Kbuild.include | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include
index d1dd4a6b6adb6..7da10afc92c61 100644
--- a/scripts/Kbuild.include
+++ b/scripts/Kbuild.include
@@ -82,20 +82,21 @@ cc-cross-prefix = $(firstword $(foreach c, $(1), \
$(if $(shell command -v -- $(c)gcc 2>/dev/null), $(c))))

# output directory for tests below
-TMPOUT := $(if $(KBUILD_EXTMOD),$(firstword $(KBUILD_EXTMOD))/)
+TMPOUT = $(if $(KBUILD_EXTMOD),$(firstword $(KBUILD_EXTMOD))/).tmp_$$$$

# try-run
# Usage: option = $(call try-run, $(CC)...-o "$$TMP",option-ok,otherwise)
# Exit code chooses option. "$$TMP" serves as a temporary file and is
# automatically cleaned up.
try-run = $(shell set -e; \
- TMP="$(TMPOUT).$$$$.tmp"; \
- TMPO="$(TMPOUT).$$$$.o"; \
+ TMP=$(TMPOUT)/tmp; \
+ TMPO=$(TMPOUT)/tmp.o; \
+ mkdir -p $(TMPOUT); \
+ trap "rm -rf $(TMPOUT)" EXIT; \
if ($(1)) >/dev/null 2>&1; \
then echo "$(2)"; \
else echo "$(3)"; \
- fi; \
- rm -f "$$TMP" "$$TMPO")
+ fi)

# as-option
# Usage: cflags-y += $(call as-option,-Wa$(comma)-isa=foo,)
--
2.25.1