ipa: Avoid excessive removing of SSAs (PR 113757)

ipa: Avoid excessive removing of SSAs (PR 113757)

PR 113757 shows that the code which was meant to debug-reset and
remove SSAs defined by LHSs of calls redirected to
__builtin_unreachable can trigger also when speculative
devirtualization creates a call to a noreturn function (and since it
is noreturn, it does not bother dealing with its return value).

What is more, it seems that the code handling this case is not really
necessary.  I feel slightly idiotic about this because I have a
feeling that I added it because of a failing test-case but I can
neither find the testcase nor a reason why the code in
cgraph_edge::redirect_call_stmt_to_callee would not be sufficient (it
turns the SSA name into a default-def, a bit like IPA-SRA, but any
code dominated by a call to a noreturn is not dangerous when it comes
to its side-effects).  So this patch just removes the handling.

gcc/ChangeLog:

2024-02-07  Martin Jambor  <mjambor@suse.cz>

	PR ipa/113757
	* tree-inline.cc (redirect_all_calls): Remove code adding SSAs to
	id->killed_new_ssa_names.

gcc/testsuite/ChangeLog:

2024-02-07  Martin Jambor  <mjambor@suse.cz>

	PR ipa/113757
	* g++.dg/ipa/pr113757.C: New test.