https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111763
Bug ID: 111763 Summary: `(a & ~1) | 2` could be done as `(a & ~(1 | 2)) + 2` which allows to use leal Product: gcc Version: 14.0 Status: UNCONFIRMED Keywords: missed-optimization Severity: enhancement Priority: P3 Component: target Assignee: unassigned at gcc dot gnu.org Reporter: pinskia at gcc dot gnu.org Target Milestone: --- Target: x86_64-linux-gnu Take: ``` int f1(int in) { in = (in & ~(unsigned long)1); in = in | 2; return in; } int f2(int in) { in = (in & ~(unsigned long)(1|2)); in = in + 2; return in; } ``` We currently get: ``` f1: movl %edi, %eax andl $-2, %eax orl $2, %eax ret f2: andl $-4, %edi leal 2(%rdi), %eax ret ``` The leal version is better because it saves more move due to leal not being a 2 operand but 3 operand instruction so it could improve register allocation ... I noticed this whole looking into PR 111762 (and PR 111282) and looking at clang/LLVM's code generation here . Also I don't know how often this shows up though.