[Bug tree-optimization/71104] [7 Regression] ICE: verify_ssa failed (with vfork / error: definition in block 3 does not dominate use in block 7 )

[rguenther at suse dot de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71104

--- Comment #8 from rguenther at suse dot de <rguenther at suse dot de> ---
On Tue, 17 May 2016, glisse at gcc dot gnu.org wrote:

> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71104
> 
> --- Comment #7 from Marc Glisse <glisse at gcc dot gnu.org> ---
> (In reply to Richard Biener from comment #6)
> > C11 6.5.16/3 suggests that the LHS "operand" is evaluated in unspecified
> > order.
> 
> It seems that C++ is moving towards specifying the order
> http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2016/p0145r1.pdf
> 
> I don't remember the status exactly, but I think this is going more or 
> less as is into C++17.

I interpret the 5. b @= a example in "4 A Solution" as applying
to assignment and op-assignment like +=.  So the gimplifier change
would agree with this (phew).

Not that I like this proposal at all (given it changes function arg
evaluation order on x86_64).