https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112687
Bug ID: 112687
Summary: missed-optimization: switch statement does not
simplify to it's expression
Product: gcc
Version: 13.2.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: goon.pri.low at gmail dot com
Target Milestone: ---
This following code:
int unopt(int v) {
switch (v & 3) {
case 0: return 0;
case 1: return 1;
case 2: return 2;
case 3: return 3;
default: __builtin_unreachable();
}
}
unopt:
mov eax, edi
and eax, 3
lea edx, [rax-1]
cmp edx, 3
mov edx, 0
cmovnb eax, edx
ret
Ought to be optimized to:
int opt(int v) {
return v & 3;
}
opt:
mov eax, edi
and eax, 3
ret
Note: I decided to separate this problem from
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112645 since it was unrelated to
the main bug, though Richard offers some initial insight into the problem.
