On 04/28/2011 03:50 PM, Diego Novillo wrote:
This patch from Silvius Rus adds a new flag (-fstrict-enum-precision).
While porting the patch to 4.6, I noticed that the C++ FE now has a
similar flag that seems to have similar semantics (-fstrict-enums).
Silvius's patch is used to disable some switch() optimizations that
assume enum types can *only* take values within that enum (Silvius,
please correct me if I got this wrong).
Jason, your -fstrict-enums only applies to the C++ front end.
Silvius's variant affects VRP and gimplification of switches. Would
it be better if we simply moved -fstrict-enums to common options and
used that to decide whether to optimize switches in VRP and the
gimplifier?
We use it internally to disable this optimization for code that
generates values outside of enum ranges.
It seems that to me that this patch changes optimizations to not believe
the lies of the C++ front end, whereas my patch changes the front end to
not lie in the first place, making this patch unnecessary.
Jason
