[Bug c/50733] New: avr-gcc 4.3.5 generates incorrect code when using PROGMEM macro

[marcos_vc at coel dot com.br]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50733

             Bug #: 50733
           Summary: avr-gcc 4.3.5 generates incorrect code when using
                    PROGMEM macro
    Classification: Unclassified
           Product: gcc
           Version: 4.3.5
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: marcos_vc@coel.com.br


Created attachment 25505
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=25505
Preprocessed file

Hi,

     The compiler is generating incorrect code for the source code below, when
using the PROGMEM macro:

#include <avr/io.h>
#include <avr/pgmspace.h> // PROGMEM
#include <stdio.h>

static PROGMEM const char orig[6] = { 0xaa, 0xbb, 0xcc, 0xdd, 0xee, 0xff };
static char dest[6];

int main(void) {

    for(;;) {
        unsigned int loop;
        for (loop = 0; loop < sizeof(orig)/sizeof(orig[0]); loop++)
            dest[loop] = orig[loop];
    }
}

    I compiled using the folowing command line:

avr-gcc -I/usr/lib/gcc/avr/4.3.5/include -I/usr/lib/gcc/avr/4.3.5/include-fixed
-I/usr/lib/avr/include -Wall -g3 -gstabs -O0 -fpack-struct -fshort-enums
-std=gnu99 -funsigned-char -funsigned-bitfields -save-temps -Wall -Wextra
-fno-strict-aliasing -fwrapv -mmcu=atmega16 -DF_CPU=1000000UL test.c


    It should have a "lpm" instruction somewhere in the asm output. The result
is "orig" not being copied to "dest".
    The compiler generates correct code when the PROGMEM macro is removed but
it generates a copy of the constant in the SRAM which is undesirable because
I´m using large tables that fills up all the SRAM.

GCC version: 4.3.5
Host type: x86_64-linux-gnu (Ubuntu 11.04)
Target type: avr
Configure command line: ../src/configure -v --enable-languages=c,c++
--prefix=/usr/lib --infodir=/usr/share/info --mandir=/usr/share/man
--bindir=/usr/bin --libexecdir=/usr/lib --libdir=/usr/lib --enable-shared
--with-system-zlib --enable-long-long --enable-nls --without-included-gettext
--disable-checking --disable-libssp --build=x86_64-linux-gnu
--host=x86_64-linux-gnu --target=avr