https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92867
Bug ID: 92867
Summary: Use ERF_RETURNS_ARG in more places
Product: gcc
Version: 10.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: jakub at gcc dot gnu.org
Target Milestone: ---
Shouldn't we use the fact that some functions returns one of its arguments
unmodified in more places?
E.g. for tail calls:
char buf[128] = { 1 };
char *
foo (int n)
{
return __builtin_memset (buf, ' ', n);
}
char *
bar (int n)
{
__builtin_memset (buf, ' ', n);
return buf;
}
we get better code (tail call) just in the first case and not the second one.
Shouldn't we perform IPA discovery of calls that return one of their arguments?
And, shouldn't we have some user attribute which would allow to specify this?
