On Fri, Jul 6, 2012 at 5:24 PM, Andi Kleen <a...@firstfloor.org> wrote: > Uros Bizjak <ubiz...@gmail.com> writes:
>> Sometimes, gcc generates: >> >> leaq (%rbx,%rax), %rax >> >> that is in fact equivalent (modulo flags reg clobber) to: >> >> addq %rbx, %rax >> >> Attached patch adds additional peephole2 patterns that convert LEA to >> ADD when second operand of PLUS RTX matches output operand. > > Are you sure this is a win? > > In the past on some CPUs this was done intentionally because the AGU > had more execution resources than the ALU. This is just a case of commutative operand handing, following existing approach. Please note that there is a separate pass that converts ADDs to LEAs when appropriate. Uros.
