https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94877
Bug ID: 94877
Summary: Failure to simplify ~(x + 1) to -2 - x
Product: gcc
Version: 10.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: gabravier at gmail dot com
Target Milestone: ---
int f(int x)
{
return ~(x + 1);
}
With -O3, LLVM outputs this :
f(int): # @f(int)
mov eax, -2
sub eax, edi
ret
GCC outputs this :
f(int):
lea eax, [rdi+1]
not eax
ret
`~x - 1` is already simplified to `-2 - x`, so optimizing this looks like it
would make sense too.
