[Bug target/109747] [12/13/14 Regression] SLP cost of constructors is off

[rguenth at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109747

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
void foo(int *a, int b, int c)
{
  a[0] = b;
  a[1] = c;
  a[2] = b;
  a[3] = c;
  a[4] = c;
  a[5] = b;
  a[6] = c;
  a[7] = b;
}

for a simpler testcase.  We get

node 0x583ae48 1 times vec_construct costs 24 in prologue 
node 0x583ae48 1 times vec_construct costs 24 in prologue

and that loop in x86 add_stmt_cost iterates over the whole CTOR twice
rather than just once for each subset (the actual cost is the same
here because I repeat b and c only).