search for: computeexitlimitfromicmp

Hi Benjamin, > LLVM misses this optimization because ScalarEvolution's ComputeExitLimitFromICmp doesn't handle signed<= (SLE) and thus can't compute the number of times the loop is executed. I wonder if there's a reason for this, it seems like something simple to add. instsimplify could also be enhanced to clean it up in this particular case, but it would be better to make sce...

...uot;3" > ret i32 %2 > } > > The questions: > Is it possible to unroll loop with non-constant boundary using standard LLVM 3.1 facilities, and, if it is, how I can do that? Hi Nicolas, LLVM misses this optimization because ScalarEvolution's ComputeExitLimitFromICmp doesn't handle signed <= (SLE) and thus can't compute the number of times the loop is executed. I wonder if there's a reason for this, it seems like something simple to add. Attached is a completely untested patch that adds the missing logic. -------------- next part --------------...

Dear LLVM, Consider two loops with one interation - First with constant lower bound, second with usual non-constant lower bound: int main(int argc, char ** argv) { int numOfIterations= 1; int stride=1; int lowerBound = 1000; - 1st | int lowerBound = argc; - 2nd int upperBound = lowerBound + (numOfIterations - 1)*stride; int i = lowerBound;

...th low==end and stride!=1. Please find it for review. -Stepan 28.02.2012, 17:41, "Benjamin Kramer" <benny.kra at googlemail.com>: > On 27.02.2012, at 20:17, Duncan Sands wrote: > >>  Hi Benjamin, >>>  LLVM misses this optimization because ScalarEvolution's ComputeExitLimitFromICmp doesn't handle signed<= (SLE) and thus can't compute the number of times the loop is executed. I wonder if there's a reason for this, it seems like something simple to add. >>  instsimplify could also be enhanced to clean it up in this particular case, but >>  it would be...

On 27.02.2012, at 20:17, Duncan Sands wrote: > Hi Benjamin, > >> LLVM misses this optimization because ScalarEvolution's ComputeExitLimitFromICmp doesn't handle signed<= (SLE) and thus can't compute the number of times the loop is executed. I wonder if there's a reason for this, it seems like something simple to add. > > instsimplify could also be enhanced to clean it up in this particular case, but > it would be bet...

...ret i32 %2 >>       } >> >>     The questions: >>       Is it possible to unroll loop with non-constant boundary using standard LLVM 3.1 facilities, and, if it is, how I can do that? > > Hi Nicolas, > > LLVM misses this optimization because ScalarEvolution's ComputeExitLimitFromICmp doesn't handle signed <= (SLE) and thus can't compute the number of times the loop is executed. I wonder if there's a reason for this, it seems like something simple to add. > > Attached is a completely untested patch that adds the missing logic. Off the top of my head, the at...

...ind it for review. > > -Stepan > > 28.02.2012, 17:41, "Benjamin Kramer"<benny.kra at googlemail.com>: >> On 27.02.2012, at 20:17, Duncan Sands wrote: >> >>> Hi Benjamin, >>>> LLVM misses this optimization because ScalarEvolution's ComputeExitLimitFromICmp doesn't handle signed<= (SLE) and thus can't compute the number of times the loop is executed. I wonder if there's a reason for this, it seems like something simple to add. >>> instsimplify could also be enhanced to clean it up in this particular case, but >>> i...

...t;>> >>> The questions: >>> Is it possible to unroll loop with non-constant boundary using standard LLVM 3.1 facilities, and, if it is, how I can do that? >> >> Hi Nicolas, >> >> LLVM misses this optimization because ScalarEvolution's ComputeExitLimitFromICmp doesn't handle signed <= (SLE) and thus can't compute the number of times the loop is executed. I wonder if there's a reason for this, it seems like something simple to add. >> >> Attached is a completely untested patch that adds the missing logic. > > Off the top...