[Gm2] latest changes to gcc-trunk

[Gaius Mulley]

Hi,

I've checked in some additions to the gcc-trunk which allow the compiler
to detect range errors caused by calculating the modulus of whole
numbers.  Runtime checking code is generated and compile time detection
is attempted with the plugin - currently this can be seen when using
-fpim2 -fsoft-check-all -O2.

Eventually -fiso, -fpim4 will also detect modulus overflow but it
requires different modulus detection code (floor vs truncate),




regards,
Gaius