[Bug target/51954] __int128_t (and long long on x86) negation can be optimized

[ubizjak at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=51954

--- Comment #6 from Uroš Bizjak <ubizjak at gmail dot com> ---
Created attachment 52481
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=52481&action=edit
Proposed patch

+;; Convert:
+;;   mov %esi, %edx
+;;   negl %eax
+;;   adcl $0, %edx
+;;   negl %edx
+;; to:
+;;   xorl %edx, %edx
+;;   negl %eax
+;;   sbbl %esi, %edx