[llvm-commits] [llvm] r161463 - in /llvm/trunk: include/llvm/CodeGen/MachineBasicBlock.h include/llvm/CodeGen/MachineBranchProbabilityInfo.h lib/CodeGen/MachineBasicBlock.cpp lib/CodeGen/MachineBranchProbabilityInfo.cpp

[Chandler Carruth]

Can you send me a test case for the quadratic behavior? I'm happy to help
with fixing it
On Aug 7, 2012 6:12 PM, "Jakob Stoklund Olesen" <stoklund at 2pi.dk> wrote:

> Author: stoklund
> Date: Tue Aug  7 20:10:31 2012
> New Revision: 161463
>
> URL: http://llvm.org/viewvc/llvm-project?rev=161463&view=rev
> Log:
> Revert "Fix a quadratic algorithm in MachineBranchProbabilityInfo."
>
> It caused an assertion failure when compiling consumer-typeset.
>
> Modified:
>     llvm/trunk/include/llvm/CodeGen/MachineBasicBlock.h
>     llvm/trunk/include/llvm/CodeGen/MachineBranchProbabilityInfo.h
>     llvm/trunk/lib/CodeGen/MachineBasicBlock.cpp
>     llvm/trunk/lib/CodeGen/MachineBranchProbabilityInfo.cpp
>
> Modified: llvm/trunk/include/llvm/CodeGen/MachineBasicBlock.h
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/CodeGen/MachineBasicBlock.h?rev=161463&r1=161462&r2=161463&view=diff
>
> ==============================================================================
> --- llvm/trunk/include/llvm/CodeGen/MachineBasicBlock.h (original)
> +++ llvm/trunk/include/llvm/CodeGen/MachineBasicBlock.h Tue Aug  7
> 20:10:31 2012
> @@ -572,7 +572,7 @@
>    /// getSuccWeight - Return weight of the edge from this block to MBB.
> This
>    /// method should NOT be called directly, but by using getEdgeWeight
> method
>    /// from MachineBranchProbabilityInfo class.
> -  uint32_t getSuccWeight(const_succ_iterator Succ) const;
> +  uint32_t getSuccWeight(const MachineBasicBlock *succ) const;
>
>
>    // Methods used to maintain doubly linked list of blocks...
>
> Modified: llvm/trunk/include/llvm/CodeGen/MachineBranchProbabilityInfo.h
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/CodeGen/MachineBranchProbabilityInfo.h?rev=161463&r1=161462&r2=161463&view=diff
>
> ==============================================================================
> --- llvm/trunk/include/llvm/CodeGen/MachineBranchProbabilityInfo.h
> (original)
> +++ llvm/trunk/include/llvm/CodeGen/MachineBranchProbabilityInfo.h Tue Aug
>  7 20:10:31 2012
> @@ -16,12 +16,14 @@
>  #define LLVM_CODEGEN_MACHINEBRANCHPROBABILITYINFO_H
>
>  #include "llvm/Pass.h"
> -#include "llvm/CodeGen/MachineBasicBlock.h"
>  #include "llvm/Support/BranchProbability.h"
>  #include <climits>
>
>  namespace llvm {
>
> +class raw_ostream;
> +class MachineBasicBlock;
> +
>  class MachineBranchProbabilityInfo : public ImmutablePass {
>    virtual void anchor();
>
> @@ -50,11 +52,6 @@
>    uint32_t getEdgeWeight(const MachineBasicBlock *Src,
>                           const MachineBasicBlock *Dst) const;
>
> -  // Same thing, but using a const_succ_iterator from Src. This is faster
> when
> -  // the iterator is already available.
> -  uint32_t getEdgeWeight(const MachineBasicBlock *Src,
> -                         MachineBasicBlock::const_succ_iterator Dst)
> const;
> -
>    // Get sum of the block successors' weights, potentially scaling them
> to fit
>    // within 32-bits. If scaling is required, sets Scale based on the
> necessary
>    // adjustment. Any edge weights used with the sum should be divided by
> Scale.
>
> Modified: llvm/trunk/lib/CodeGen/MachineBasicBlock.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/MachineBasicBlock.cpp?rev=161463&r1=161462&r2=161463&view=diff
>
> ==============================================================================
> --- llvm/trunk/lib/CodeGen/MachineBasicBlock.cpp (original)
> +++ llvm/trunk/lib/CodeGen/MachineBasicBlock.cpp Tue Aug  7 20:10:31 2012
> @@ -912,11 +912,12 @@
>
>  /// getSuccWeight - Return weight of the edge from this block to MBB.
>  ///
> -uint32_t MachineBasicBlock::getSuccWeight(const_succ_iterator Succ) const
> {
> +uint32_t MachineBasicBlock::getSuccWeight(const MachineBasicBlock *succ)
> const {
>    if (Weights.empty())
>      return 0;
>
> -  return *getWeightIterator(Succ);
> +  const_succ_iterator I = std::find(Successors.begin(), Successors.end(),
> succ);
> +  return *getWeightIterator(I);
>  }
>
>  /// getWeightIterator - Return wight iterator corresonding to the I
> successor
>
> Modified: llvm/trunk/lib/CodeGen/MachineBranchProbabilityInfo.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/MachineBranchProbabilityInfo.cpp?rev=161463&r1=161462&r2=161463&view=diff
>
> ==============================================================================
> --- llvm/trunk/lib/CodeGen/MachineBranchProbabilityInfo.cpp (original)
> +++ llvm/trunk/lib/CodeGen/MachineBranchProbabilityInfo.cpp Tue Aug  7
> 20:10:31 2012
> @@ -38,7 +38,7 @@
>    Scale = 1;
>    for (MachineBasicBlock::const_succ_iterator I = MBB->succ_begin(),
>         E = MBB->succ_end(); I != E; ++I) {
> -    uint32_t Weight = getEdgeWeight(MBB, I);
> +    uint32_t Weight = getEdgeWeight(MBB, *I);
>      Sum += Weight;
>    }
>
> @@ -53,30 +53,22 @@
>    Sum = 0;
>    for (MachineBasicBlock::const_succ_iterator I = MBB->succ_begin(),
>         E = MBB->succ_end(); I != E; ++I) {
> -    uint32_t Weight = getEdgeWeight(MBB, I);
> +    uint32_t Weight = getEdgeWeight(MBB, *I);
>      Sum += Weight / Scale;
>    }
>    assert(Sum <= UINT32_MAX);
>    return Sum;
>  }
>
> -uint32_t MachineBranchProbabilityInfo::
> -getEdgeWeight(const MachineBasicBlock *Src,
> -              MachineBasicBlock::const_succ_iterator Dst) const {
> +uint32_t
> +MachineBranchProbabilityInfo::getEdgeWeight(const MachineBasicBlock *Src,
> +                                            const MachineBasicBlock *Dst)
> const {
>    uint32_t Weight = Src->getSuccWeight(Dst);
>    if (!Weight)
>      return DEFAULT_WEIGHT;
>    return Weight;
>  }
>
> -uint32_t MachineBranchProbabilityInfo::
> -getEdgeWeight(const MachineBasicBlock *Src,
> -              const MachineBasicBlock *Dst) const {
> -  // This is a linear search. Try to use the const_succ_iterator version
> when
> -  // possible.
> -  return getEdgeWeight(Src, std::find(Src->succ_begin(), Src->succ_end(),
> Dst));
> -}
> -
>  bool MachineBranchProbabilityInfo::isEdgeHot(MachineBasicBlock *Src,
>                                               MachineBasicBlock *Dst)
> const {
>    // Hot probability is at least 4/5 = 80%
> @@ -90,7 +82,7 @@
>    MachineBasicBlock *MaxSucc = 0;
>    for (MachineBasicBlock::const_succ_iterator I = MBB->succ_begin(),
>         E = MBB->succ_end(); I != E; ++I) {
> -    uint32_t Weight = getEdgeWeight(MBB, I);
> +    uint32_t Weight = getEdgeWeight(MBB, *I);
>      if (Weight > MaxWeight) {
>        MaxWeight = Weight;
>        MaxSucc = *I;
>
>
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