ARM EABI floatingpoint issue

Question

I have a data-conversion function in our ARM9 code which uses varargs. I've been using an arm-elf yagarto distribution from a couple of years ago, with no problems. Recently, we upgraded to the arm-eabi-none yagarto package from the yagarto site, and I'm finding that we now have problems with floating point values. What I eventually discovered is that doubles are being forced to 8-byte boundaries, and the existing varargs floating-point handler didn't expect to find gaps in the args.

I can manually check the pointer and force it up to an eight-byte boundary (in fact, I did that, and that fixed the issue entirely), but I'd like to know why this has suddenly started happening.

Is there a compiler switch that specifies data alignment on the stack, or in function calls, or something like that?? And why would it be defaulting to 8-byte boundaries on a 32-bit (4-byte) architecture??

I would appreciate any advice or insights that anyone could provide on these issues.

The code is simple:

    .....
    float floatValue = 10.0;
    int intValue = 10;
    char buffer[32];
    ...
    snprintf (buffer, 32, "%g", floatValue); /* Here we are getting junk value bcz of 8-byte*/
    snprintf (buffer, 32, "%lld", intValue); /* Here we are getting junk value bcz of 8-byte */
    ....

The version of GCC we were using is 4.7.1

Compiling options:

Toolchain compiling options:

    `mabi=aapcs-linux
    `mcpu=arm7tdmi/mcpu=arm946e-s`
    `mfloat-abi=softfp`

Application compiler option:

    `-mfloat-abi=softfp`
    `-mfpu=vfp`
    `-mstructure-size-boundary=8`
    `-fomit-frame-pointer`
    `-fshort-wchar`
    `-fno-short-enums`