On 08/27/2015 05:21 AM, Kai Tietz wrote:
2015-08-27 4:57 GMT+02:00 Jason Merrill <ja...@redhat.com>:
Why does fold_simple fold so many patterns? I thought we wanted something
that would just fold conversions and negations of constant values.
Yes, initial variant was handling much less patterns. But actually we
need for functions (eg. like build_vec_init in init.c) a simple
routine to perform basic constant-value arithmetics (sizeof * / + -
trunc, etc) to avoid call of maybe_constant_value. Also for
overflow-diagnostics we want at least to resolve such simple patterns
for constant-values only. We could change those calls to use
maybe_constant_value instead, but the overhead (and some of its
folding) leads much further then working on constant-values only (as
fold_simple does).
For build_vec_init, since whether maxindex is constant has semantic
meaning, I think we want maybe_constant_value.
I think we also want it for overflow warnings, to get better diagnostics.
Jason
