From 6ba7dc6616ce69ef667204df29597767c1c9ebcf Mon Sep 17 00:00:00 2001
From: Masahiro Yamada <yamada.masahiro@socionext.com>
Date: Sun, 21 Jul 2019 01:27:39 +0900
Subject: [PATCH] kbuild: make bison create C file and header in a single
pattern rule
We generally expect bison to create not only a C file, but also a
header, which will be included from the lexer.
Currently, Kbuild generates them in separate rules. So, for instance,
when building Kconfig, you will notice bison is invoked twice:
HOSTCC scripts/kconfig/conf.o
HOSTCC scripts/kconfig/confdata.o
HOSTCC scripts/kconfig/expr.o
LEX scripts/kconfig/lexer.lex.c
YACC scripts/kconfig/parser.tab.h
HOSTCC scripts/kconfig/lexer.lex.o
YACC scripts/kconfig/parser.tab.c
HOSTCC scripts/kconfig/parser.tab.o
HOSTCC scripts/kconfig/preprocess.o
HOSTCC scripts/kconfig/symbol.o
HOSTLD scripts/kconfig/conf
Make handles such cases nicely in pattern rules [1]. Merge the two
rules so that one invokcation of bison can generate both of them.
HOSTCC scripts/kconfig/conf.o
HOSTCC scripts/kconfig/confdata.o
HOSTCC scripts/kconfig/expr.o
LEX scripts/kconfig/lexer.lex.c
YACC scripts/kconfig/parser.tab.[ch]
HOSTCC scripts/kconfig/lexer.lex.o
HOSTCC scripts/kconfig/parser.tab.o
HOSTCC scripts/kconfig/preprocess.o
HOSTCC scripts/kconfig/symbol.o
HOSTLD scripts/kconfig/conf
[1] Pattern rule
GNU Make manual says:
"Pattern rules may have more than one target. Unlike normal rules,
this does not act as many different rules with the same prerequisites
and recipe. If a pattern rule has multiple targets, make knows that
the rule's recipe is responsible for making all of the targets. The
recipe is executed only once to make all the targets. When searching
for a pattern rule to match a target, the target patterns of a rule
other than the one that matches the target in need of a rule are
incidental: make worries only about giving a recipe and prerequisites
to the file presently in question. However, when this file's recipe is
run, the other targets are marked as having been updated themselves."
https://www.gnu.org/software/make/manual/html_node/Pattern-Intro.html
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
---
scripts/Makefile.lib | 12 +++---------
scripts/genksyms/Makefile | 9 +--------
2 files changed, 4 insertions(+), 17 deletions(-)
diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index 41c50f9461e51..67d1165ab2ab9 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -197,18 +197,12 @@ $(obj)/%.lex.c: $(src)/%.l FORCE
# YACC
# ---------------------------------------------------------------------------
-quiet_cmd_bison = YACC $@
- cmd_bison = $(YACC) -o$@ -t -l $<
+quiet_cmd_bison = YACC $(basename $@).[ch]
+ cmd_bison = $(YACC) -o $(basename $@).c --defines=$(basename $@).h -t -l $<
-$(obj)/%.tab.c: $(src)/%.y FORCE
+$(obj)/%.tab.c $(obj)/%.tab.h: $(src)/%.y FORCE
$(call if_changed,bison)
-quiet_cmd_bison_h = YACC $@
- cmd_bison_h = $(YACC) -o/dev/null --defines=$@ -t -l $<
-
-$(obj)/%.tab.h: $(src)/%.y FORCE
- $(call if_changed,bison_h)
-
# Shipped files
# ===========================================================================
diff --git a/scripts/genksyms/Makefile b/scripts/genksyms/Makefile
index 66c314bc5933e..baf44ed0a93a9 100644
--- a/scripts/genksyms/Makefile
+++ b/scripts/genksyms/Makefile
@@ -18,16 +18,9 @@ quiet_cmd_bison_no_warn = $(quiet_cmd_bison)
cmd_bison_no_warn = $(YACC) --version >/dev/null; \
$(cmd_bison) 2>/dev/null
-$(obj)/parse.tab.c: $(src)/parse.y FORCE
+$(obj)/pars%.tab.c $(obj)/pars%.tab.h: $(src)/pars%.y FORCE
$(call if_changed,bison_no_warn)
-quiet_cmd_bison_h_no_warn = $(quiet_cmd_bison_h)
- cmd_bison_h_no_warn = $(YACC) --version >/dev/null; \
- $(cmd_bison_h) 2>/dev/null
-
-$(obj)/parse.tab.h: $(src)/parse.y FORCE
- $(call if_changed,bison_h_no_warn)
-
endif
# -I needed for generated C source (shipped source)
--
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