[avr-libc-dev] [bug #50811] using -Wl, -u, vfprintf -lprintf_min causes program to grow a lot

[anonymous]

URL:
  <http://savannah.nongnu.org/bugs/?50811>

                 Summary: using -Wl,-u,vfprintf -lprintf_min causes program to
grow a lot
                 Project: AVR C Runtime Library
            Submitted by: None
            Submitted on: Sat 15 Apr 2017 11:38:22 PM UTC
                Category: None
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: None
                  Status: None
        Percent Complete: 0%
             Assigned to: None
        Originator Email: address@hidden
             Open/Closed: Open
         Discussion Lock: Any
                 Release: 2.0.0
           Fixed Release: None

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Details:


The documentation seems to be saying that using those flags is supposed to
save flash, but without them, a main() that does a single printf("foo\n");
gives me a 330 byte flash, while with them I get a 1330 byte flash.

If I remove the printf() call, I get flash sizes of 1228 or 228 with or
without the above mentioned printf-min flags, respectively.

It looks like somehow the printf-min flag ends up dragging in a bunch extra
code somehow?

The rest of my linker invocation looks like this:

avr-gcc -mmcu=atmega328p  -lm -Wl,-gc-sections
-Wl,-Map=program_to_upload.out.map -o program_to_upload.out main.o

I think probably the documentation ought to mention this possibility, assuming
it isn't a bug.




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