linux-kernel - [PATCH v2] kbuild: simpler generation of assembly constants

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Date:	Fri, 8 Jul 2016 00:39:41 +0300
From:	Alexey Dobriyan <adobriyan@...il.com>
To:	akpm@...ux-foundation.org
Cc:	linux-kernel@...r.kernel.org
Subject: [PATCH v2] kbuild: simpler generation of assembly constants

gcc doesn't really look inside "asm" statements and more or less
directly emits it into assembly. So pretend "#define" is CPU
instruction.

Also, use C++ comment to block whatever garbage is put at the end of
the line by compiler.

Signed-off-by: Alexey Dobriyan <adobriyan@...il.com>
---

 Kbuild                    |   12 +-----------
 arch/ia64/kernel/Makefile |    8 +-------
 include/linux/kbuild.h    |    2 +-
 scripts/mod/Makefile      |   11 +----------
 4 files changed, 4 insertions(+), 29 deletions(-)

--- a/Kbuild
+++ b/Kbuild
@@ -7,14 +7,6 @@
 # 4) Check for missing system calls
 # 5) Generate constants.py (may need bounds.h)
 
-# Default sed regexp - multiline due to syntax constraints
-define sed-y
-	"/^->/{s:->#\(.*\):/* \1 */:; \
-	s:^->\([^ ]*\) [\$$#]*\([-0-9]*\) \(.*\):#define \1 \2 /* \3 */:; \
-	s:^->\([^ ]*\) [\$$#]*\([^ ]*\) \(.*\):#define \1 \2 /* \3 */:; \
-	s:->::; p;}"
-endef
-
 # Use filechk to avoid rebuilds when a header changes, but the resulting file
 # does not
 define filechk_offsets
@@ -26,9 +18,7 @@ define filechk_offsets
 	 echo " *"; \
 	 echo " * This file was generated by Kbuild"; \
 	 echo " */"; \
-	 echo ""; \
-	 sed -ne $(sed-y); \
-	 echo ""; \
+	 sed -ne '/#define/{s/\$$//;s/#//2;p;}'; \
 	 echo "#endif" )
 endef
 
--- a/arch/ia64/kernel/Makefile
+++ b/arch/ia64/kernel/Makefile
@@ -50,10 +50,6 @@ CFLAGS_traps.o  += -mfixed-range=f2-f5,f16-f31
 # The gate DSO image is built using a special linker script.
 include $(src)/Makefile.gate
 
-# Calculate NR_IRQ = max(IA64_NATIVE_NR_IRQS, XEN_NR_IRQS, ...) based on config
-define sed-y
-	"/^->/{s:^->\([^ ]*\) [\$$#]*\([^ ]*\) \(.*\):#define \1 \2 /* \3 */:; s:->::; p;}"
-endef
 quiet_cmd_nr_irqs = GEN     $@
 define cmd_nr_irqs
 	(set -e; \
@@ -65,9 +61,7 @@ define cmd_nr_irqs
 	 echo " * This file was generated by Kbuild"; \
 	 echo " *"; \
 	 echo " */"; \
-	 echo ""; \
-	 sed -ne $(sed-y) $<; \
-	 echo ""; \
+	 sed -ne '/#define/{s/\$$//;s/#//2;p;}' $<; \
 	 echo "#endif" ) > $@
 endef
 
--- a/include/linux/kbuild.h
+++ b/include/linux/kbuild.h
@@ -2,7 +2,7 @@
 #define __LINUX_KBUILD_H
 
 #define DEFINE(sym, val) \
-        asm volatile("\n->" #sym " %0 " #val : : "i" (val))
+	asm volatile ("#define " #sym " %0 //" #val :: "i" (val))
 
 #define BLANK() asm volatile("\n->" : : )
 
--- a/scripts/mod/Makefile
+++ b/scripts/mod/Makefile
@@ -7,13 +7,6 @@ modpost-objs	:= modpost.o file2alias.o sumversion.o
 
 devicetable-offsets-file := devicetable-offsets.h
 
-define sed-y
-	"/^->/{s:->#\(.*\):/* \1 */:; \
-	s:^->\([^ ]*\) [\$$#]*\([-0-9]*\) \(.*\):#define \1 \2 /* \3 */:; \
-	s:^->\([^ ]*\) [\$$#]*\([^ ]*\) \(.*\):#define \1 \2 /* \3 */:; \
-	s:->::; p;}"
-endef
-
 quiet_cmd_offsets = GEN     $@
 define cmd_offsets
 	(set -e; \
@@ -25,9 +18,7 @@ define cmd_offsets
 	 echo " * This file was generated by Kbuild"; \
 	 echo " *"; \
 	 echo " */"; \
-	 echo ""; \
-	 sed -ne $(sed-y) $<; \
-	 echo ""; \
+	 sed -ne '/#define/{s/\$$//;s/#//2;p;}' $<; \
 	 echo "#endif" ) > $@
 endef