[PATCH] newlib: Remove debug flag for --enable-target-optspace

[Stephanos Ioannidis]

Hi Jon,

While `-g` does not increase the actual code size since it is intended to add debug information only, `--enable-target-optspace` semantically has nothing to do with adding debug information and keeping `-g` here only introduces an unexpected and unintentional behaviour (and confusion).

As you suggested, the debug information added by `--enable-target-optspace` can be stripped, but why add it in the first place if it is not necessary?

Unless there is a good reason to keep `-g` and `-Os` together in `--enable-target-optspace`, I strongly believe `-g` should be removed and moved into a separate configuration option.

p.s. It looks like this was passed down from gcc and other GNU toolchains.

Regards,

Stephanos

-----Original Message-----
From: Jon Beniston <jon@beniston.com> 
Sent: Friday, November 29, 2019 6:56 PM
To: Stephanos Ioannidis <root@stephanos.io>; newlib@sourceware.org
Subject: RE: [PATCH] newlib: Remove debug flag for --enable-target-optspace

Hi Stephanos,

I don't think this should be required. -g generally shouldn't cause code size to be bigger when used with -Os. The resulting ELF files will be bigger, as they include debug info, but this debug info is not burnt to flash or loaded in to RAM. If you want the ELF files smaller because they need to go on the targets filesystem, then you can run the strip program on them to remove the debug info.

Cheers,
Jon

-----Original Message-----
From: newlib-owner@sourceware.org <newlib-owner@sourceware.org> On Behalf Of Stephanos Ioannidis
Sent: 29 November 2019 03:47
To: newlib@sourceware.org
Cc: Stephanos Ioannidis <root@stephanos.io>
Subject: [PATCH] newlib: Remove debug flag for --enable-target-optspace

--enable-target-optspace adds -g (debug) option flag to the CFLAGS alongside -Os (optimise for size) for no good reason.

Since the -g option flag is not required by the -Os option flag and it not contribute to what --enable-target-optspace tries to achieve (i.e.
optimise for size), this flag should be removed.

It is also worth noting that many newlib users (e.g. GNU ARM Embedded) are manually adding -Os to CFLAGS because the --enable-target-optspace does not achieve what it should.

Signed-off-by: Stephanos Ioannidis <root@stephanos.io>
---
 config/mt-ospace | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/config/mt-ospace b/config/mt-ospace index ce29ff431..95be8259d
100644
--- a/config/mt-ospace
+++ b/config/mt-ospace
@@ -1,3 +1,3 @@
 # Build libraries optimizing for space, not speed.
- CFLAGS_FOR_TARGET += -g -Os
- CXXFLAGS_FOR_TARGET += -g -Os
+ CFLAGS_FOR_TARGET += -Os
+ CXXFLAGS_FOR_TARGET += -Os
--
2.17.1