dwarf2 eh for alpha, mark 3

[Richard Henderson <rth at cygnus dot com>]

Two relevant changes here, other than merging with Bernd's
flow patch (which is still needed for lame targets):

  * Back to using an offset for adjusting the SP,

  * Using virtual register instantiation to find the CFA.  I think
    this is a far superior way to go about getting hold of this,
    since the method of plucking frame_pointer_rtx makes erroneous
    assumptions.  Here we let the target tell us where the CFA is,
    and as a bonus we get (slightly) smaller code.

The patch passes the testsuite with flying colors on Alpha.  The
other three platforms (sparc, mips, x86), being of wussy cpu, are
still running.  I guess I'll check in on them in the morning.

Comments, particularly on the virtual reg business?


r~

d-axp-eh-5.gz