qbe

Internal scc patchset buffer for QBE
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commit 436d0fc07e4551dd4265cfed0b0bc459c71ed8ce
parent 425a2ed09c08222e1254d93dba24c7a50e7a08b9
Author: Quentin Carbonneaux <quentin@c9x.me>
Date:   Tue, 16 May 2017 11:44:52 -0400

change the computation of spill costs for phis

I now take the view that a phi is "used" at the
end of all the predecessors.  (Think that copies
are made to phis at the end of all predecessors.)

Diffstat:
Mspill.c | 6++----
1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/spill.c b/spill.c @@ -68,13 +68,11 @@ fillcost(Fn *fn) } for (b=fn->start; b; b=b->link) { for (p=b->phi; p; p=p->link) { - /* todo, the cost computation - * for p->to is not great... */ + t = &fn->tmp[p->to.val]; tmpuse(p->to, 0, 0, fn); for (a=0; a<p->narg; a++) { n = p->blk[a]->loop; - assert(b->npred==p->narg && "wrong cfg"); - n /= b->npred; + t->cost += n; tmpuse(p->arg[a], 1, n, fn); } }