------- Comment #126 from rguenther at suse dot de 2007-05-23 14:43 ------- Subject: Re: [4.0/4.1/4.2/4.3 Regression] placement new does not change the dynamic type as it should
On Wed, 23 May 2007, gdr at cs dot tamu dot edu wrote: > ------- Comment #125 from gdr at cs dot tamu dot edu 2007-05-23 14:22 ------- > Subject: Re: [4.0/4.1/4.2/4.3 Regression] placement new does not change the > dynamic type as it should > > "rguenther at suse dot de" <[EMAIL PROTECTED]> writes: > > [...] > > | But you can still perform hoisting loads of incoming pointer arguments > | and sinking stores to incoming pointer arguments. Please read comment > | #105 and come up with a testcase where we wouldn't be allowed to do > | a useful transformation we do now. So I believe making placement new > | work with our current scheme will severely pessimize placement new > | users, but if we slightly change rules for everyone we'll be all happy. > > Update. > > The only comment I have so far on the -core reflector is to the effect > that the reading that the program I posted earlier violates NO > aliasing rule. I'll follow with the proposal to bring the rules in > line with recent C99 rules. Note that it is important to retain the capability to implement memory allocators in C++ that are allowed to re-use memory for different typed objects. Which is not possible with C99 rules. Richard. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29286
