https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68219
Bug ID: 68219
Summary: ICF could fold functions called via a table of
function pointers
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: enhancement
Priority: P3
Component: ipa
Assignee: unassigned at gcc dot gnu.org
Reporter: jay.foad at gmail dot com
Target Milestone: ---
Consider this simplified example:
$ cat x.cpp
namespace {
template<int N>
int f() { return 0; }
}
int g(int n) {
static int (*const t[4])() = { f<0>, f<1>, f<2>, f<3> };
return t[n]();
}
I can see from the output of "gcc -S -o - -O3 x.cpp" that GCC
generates four separate but identical function bodies for f<0>, f<1>,
f<2> and f<3>. It would be nice if it could generate just one copy.
(I realise that there might be concerns about the standard specifying
that different functions should have different addresses; but in a
case like this the compiler should be able to prove that the addresses
of the functions don't escape.)
