[llvm] r230619 - IRCE: only touch loops that have been shown to have a high

[Hal Finkel]

Test case?

 -Hal

----- Original Message -----
> From: "Sanjoy Das" <sanjoy at playingwithpointers.com>
> To: llvm-commits at cs.uiuc.edu
> Sent: Thursday, February 26, 2015 2:56:04 AM
> Subject: [llvm] r230619 - IRCE: only touch loops that have been shown to have	a high
> 
> Author: sanjoy
> Date: Thu Feb 26 02:56:04 2015
> New Revision: 230619
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=230619&view=rev
> Log:
> IRCE: only touch loops that have been shown to have a high
> backedge-taken count in profiliing data.
> 
> 
> Modified:
>     llvm/trunk/lib/Transforms/Scalar/InductiveRangeCheckElimination.cpp
> 
> Modified:
> llvm/trunk/lib/Transforms/Scalar/InductiveRangeCheckElimination.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/InductiveRangeCheckElimination.cpp?rev=230619&r1=230618&r2=230619&view=diff
> ==============================================================================
> ---
> llvm/trunk/lib/Transforms/Scalar/InductiveRangeCheckElimination.cpp
> (original)
> +++
> llvm/trunk/lib/Transforms/Scalar/InductiveRangeCheckElimination.cpp
> Thu Feb 26 02:56:04 2015
> @@ -82,6 +82,9 @@ static cl::opt<unsigned> LoopSizeCutoff(
>  static cl::opt<bool> PrintChangedLoops("irce-print-changed-loops",
>  cl::Hidden,
>                                         cl::init(false));
>  
> +static cl::opt<int>
> MaxExitProbReciprocal("irce-max-exit-prob-reciprocal",
> +                                          cl::Hidden, cl::init(10));
> +
>  #define DEBUG_TYPE "irce"
>  
>  namespace {
> @@ -441,7 +444,9 @@ struct LoopStructure {
>      return Result;
>    }
>  
> -  static Optional<LoopStructure> parseLoopStructure(ScalarEvolution
> &, Loop &,
> +  static Optional<LoopStructure> parseLoopStructure(ScalarEvolution
> &,
> +
>                                                    BranchProbabilityInfo
> &BPI,
> +                                                    Loop &,
>                                                      const char *&);
>  };
>  
> @@ -615,8 +620,8 @@ static bool CanBeSMin(ScalarEvolution &S
>  }
>  
>  Optional<LoopStructure>
> -LoopStructure::parseLoopStructure(ScalarEvolution &SE, Loop &L,
> -                                  const char *&FailureReason) {
> +LoopStructure::parseLoopStructure(ScalarEvolution &SE,
> BranchProbabilityInfo &BPI,
> +                                  Loop &L, const char
> *&FailureReason) {
>    assert(L.isLoopSimplifyForm() && "should follow from
>    addRequired<>");
>  
>    BasicBlock *Latch = L.getLoopLatch();
> @@ -640,6 +645,14 @@ LoopStructure::parseLoopStructure(Scalar
>  
>    unsigned LatchBrExitIdx = LatchBr->getSuccessor(0) == Header ? 1 :
>    0;
>  
> +  BranchProbability ExitProbability =
> +    BPI.getEdgeProbability(LatchBr->getParent(), LatchBrExitIdx);
> +
> +  if (ExitProbability > BranchProbability(1, MaxExitProbReciprocal))
> {
> +    FailureReason = "short running loop, not profitable";
> +    return None;
> +  }
> +
>    ICmpInst *ICI = dyn_cast<ICmpInst>(LatchBr->getCondition());
>    if (!ICI || !isa<IntegerType>(ICI->getOperand(0)->getType())) {
>      FailureReason = "latch terminator branch not conditional on
>      integral icmp";
> @@ -1340,7 +1353,7 @@ bool InductiveRangeCheckElimination::run
>  
>    const char *FailureReason = nullptr;
>    Optional<LoopStructure> MaybeLoopStructure =
> -      LoopStructure::parseLoopStructure(SE, *L, FailureReason);
> +      LoopStructure::parseLoopStructure(SE, BPI, *L, FailureReason);
>    if (!MaybeLoopStructure.hasValue()) {
>      DEBUG(dbgs() << "irce: could not parse loop structure: " <<
>      FailureReason
>                   << "\n";);
> 
> 
> _______________________________________________
> llvm-commits mailing list
> llvm-commits at cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
> 

-- 
Hal Finkel
Assistant Computational Scientist
Leadership Computing Facility
Argonne National Laboratory