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nuttx/boards/arm/lpc17xx_40xx/olimex-lpc1766stk/configs
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chao.an b88561299b make/expression: improving up asm/C/C++ compile times 
In the current compilation environment, the recursive assignment(=) for compile
flags will be delayed until every file is actually need to be compile.

For example:
--------------------------------------------------------------------------------
arch/arm/src/Makefile:

INCLUDES += ${shell $(INCDIR) "$(CC)" $(ARCH_SRCDIR)$(DELIM)chip}
INCLUDES += ${shell $(INCDIR) "$(CC)" $(ARCH_SRCDIR)$(DELIM)common}
INCLUDES += ${shell $(INCDIR) "$(CC)" $(ARCH_SRCDIR)$(DELIM)$(ARCH_SUBDIR)}
INCLUDES += ${shell $(INCDIR) "$(CC)" $(TOPDIR)$(DELIM)sched}

CPPFLAGS += $(INCLUDES) $(EXTRAFLAGS)
CFLAGS += $(INCLUDES) $(EXTRAFLAGS)
CXXFLAGS += $(INCLUDES) $(EXTRAFLAGS)
AFLAGS += $(INCLUDES) $(EXTRAFLAGS)
--------------------------------------------------------------------------------

All compilation options will be included recursively,
which will be delayed until the compilation options are actually used:

tools/Config.mk:

--------------------------------------------------------------------------------
define COMPILE
  @echo "CC: $1"
  $(Q) $(CC) -c $(CFLAGS) $($(strip $1)_CFLAGS) $1 -o $2
endef
--------------------------------------------------------------------------------

All compile flags to be reexecuted $(INCDIR) as long as one file needs to be compiled,
but in fact, the compilation options have not changed in the current directory.

So the we recommand to change the syntax of assignment
From
    Recursive (=)
To
    Simple    (:=)

In this way, we can ensure that all compilation options are expanded only once and reducing repeated works.

Signed-off-by: chao.an <anchao@xiaomi.com>
2020-11-02 07:53:53 -08:00
..
ftpc libc/stdio: Allocate file_struct dynamically 2020-09-11 17:58:17 +08:00
hidkbd libc/stdio: Allocate file_struct dynamically 2020-09-11 17:58:17 +08:00
hidmouse libc/stdio: Allocate file_struct dynamically 2020-09-11 17:58:17 +08:00
nettest libc/stdio: Allocate file_struct dynamically 2020-09-11 17:58:17 +08:00
nsh libc/stdio: Allocate file_struct dynamically 2020-09-11 17:58:17 +08:00
slip-httpd libc/stdio: Allocate file_struct dynamically 2020-09-11 17:58:17 +08:00
thttpd-binfs make/expression: improving up asm/C/C++ compile times 2020-11-02 07:53:53 -08:00
thttpd-nxflat make/expression: improving up asm/C/C++ compile times 2020-11-02 07:53:53 -08:00
usbmsc libc/stdio: Allocate file_struct dynamically 2020-09-11 17:58:17 +08:00
usbserial Change all 'Nuttx' to 'NuttX' 2020-10-20 01:45:06 -07:00
zmodem libc/stdio: Allocate file_struct dynamically 2020-09-11 17:58:17 +08:00