Re: [PATCH] Improve gimplification of constructors with RANGE_EXPRs (PR c++/82294, PR c++/87436)

[Jakub Jelinek <jakub at redhat dot com>]

On Fri, Dec 14, 2018 at 12:22:28PM +0100, Richard Biener wrote:
> > Still need to wait for the FE patch if I want to commit the testcases, those
> > depend on both patches.
> > I've added size32plus effective target to the larger test, as 384MB is too
> > much for 16 or 20 bit address targets.
> > And, I'll gather statistics on how often this makes a difference during
> > gimplification during my next bootstraps/regtests.

Besides those 2 new testcases it only made a difference on:
g++.dg/torture/pr60746.C
which has
{[0 ... 4]={[0 ... 1]={._vptr.One=&_ZTV3One + 16}}}
ctor (80 bytes), but only at -O0, so comparing the assembly in that case
is kind of pointless.  If I modify the testcase to pass list_arry address
to external function and compile with -O2, the resulting assembly is
identical before/after this commit, as we inline the copy from the constant
ctor and unroll the loops.
If I modify it to:
class One
{
public:
  virtual unsigned long getSize () const;
};

class Two
{
  virtual int run ();
};

void bar (One (*)[2]);

int
Two::run ()
{
  One list_arry[1000][2];
  bar (list_arry);
  return 0;
}
it is similar difference to the other testcases, either 16000 bytes
long .rodata initializer with memcpy from it, or a small loop.

	Jakub