ix86 code generation bug -march=pentiumpro

[grahams@rcp.co.uk]

Hi

I've identified an ix86 code generation bug in egcs-19980425 snapshot.

I've been investigating why bootstraping egcs-19980425 with
"CFLAGS=O6 -march=pentiumpro -mcpu=pentiumpro"
aborts during "make compare" due to differences in the
output of the stage1 and stage2 compilers.

I've managed to identify that its the compilation of
init_reg_sets_1() in gcc/regclass.c that results in the
differences.

Attached below is a self contained and cut-down
version of the init_reg_sets_1() routine which can
be used to demonstate the code generation bug.

graham