commit ef7c6d42fe163a5e49a478c43e655ce4633fa5ba

Author: Florian Weimer <fweimer@redhat.com>

Date:   Fri Jan 14 16:09:20 2022 +0100

    Generate gcc-macros.h

    The file can be used to check the effect of the default compiler

    flags on code generation even in areas of the build that uses

    non-default compiler flags.

    Reviewed-by: H.J. Lu <hjl.tools@gmail.com>

diff --git a/Makeconfig b/Makeconfig

index 8bc5540292c7b6fa..99898a632a64be91 100644

--- a/Makeconfig

+++ b/Makeconfig

@@ -1202,6 +1202,15 @@ $(common-objpfx)dl-tunable-list.stmp: \

 	touch $@

 endif

+# Dump the GCC macros used by the default compiler flags to a header

+# file, so that they can be inspected when using different compiler

+# flags.  Add the GCCMACRO prefix to make these macro names unique.

+$(common-objpfx)gcc-macros.h.in: $(common-objpfx)config.status

+	$(CC) $(CFLAGS) $(CPPFLAGS) -E -dM -x c -o $@ /dev/null

+$(common-objpfx)gcc-macros.h: $(common-objpfx)gcc-macros.h.in

+	sed 's/^#define /#define GCCMACRO/' < $< > $@

+before-compile += $(common-objpfx)gcc-macros.h

+

 # Generate version maps, but wait until sysdep-subdirs is known

 ifeq ($(sysd-sorted-done),t)

 ifeq ($(build-shared),yes)