search for: rem_i32

...without native div/rem instructions. when compiling expressions like (a % 3), the dagcombiner turns them into (a-(a/3)*3) which is not simplified later on. this is quite expensive since the multiply is not pipelined and the div requires a libcall while the same could have been achieved with a (S|U)REM_I32 libcall. the problem is that the involved "magic" int TargetLowering has certain requirements such as MULHU support, which is not available on my architecture. i guess the best way is to check this conditions beforehand in the DAGCombiner, right? cheers, - dietmar

On Mon, 18 Jun 2007, Chris Lattner wrote: > On Thu, 14 Jun 2007, Dietmar Ebner wrote: >> currently, the DAGCombiner unconditionally converts >> (DAGCombiner::visit(U|S)REM) expressions of the form X % C for constants >> C into X-X/C*C. this makes sense in certain cases where the div/mul >> logic will simplify X/C*X but is counterproductive in general, >>