[llvm-commits] [llvm] r153812 - in /llvm/trunk: include/llvm/Analysis/ include/llvm/Transforms/IPO/ lib/Analysis/ lib/Transforms/IPO/ test/Transforms/Inline/

David Dean david_dean at apple.com
Tue Apr 10 13:50:35 PDT 2012


Chandler,
    we're seeing a 9.92% compile time regression in MultiSource/Applications/sqlite3/sqlite3 on ARMv7 -mthumb -O3. Can you please take a look?

On 31 Mar 2012, at 5:42 AM, Chandler Carruth wrote:

> Author: chandlerc
> Date: Sat Mar 31 07:42:41 2012
> New Revision: 153812
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=153812&view=rev
> Log:
> Initial commit for the rewrite of the inline cost analysis to operate
> on a per-callsite walk of the called function's instructions, in
> breadth-first order over the potentially reachable set of basic blocks.
> 
> This is a major shift in how inline cost analysis works to improve the
> accuracy and rationality of inlining decisions. A brief outline of the
> algorithm this moves to:
> 
> - Build a simplification mapping based on the callsite arguments to the
>  function arguments.
> - Push the entry block onto a worklist of potentially-live basic blocks.
> - Pop the first block off of the *front* of the worklist (for
>  breadth-first ordering) and walk its instructions using a custom
>  InstVisitor.
> - For each instruction's operands, re-map them based on the
>  simplification mappings available for the given callsite.
> - Compute any simplification possible of the instruction after
>  re-mapping, and store that back int othe simplification mapping.
> - Compute any bonuses, costs, or other impacts of the instruction on the
>  cost metric.
> - When the terminator is reached, replace any conditional value in the
>  terminator with any simplifications from the mapping we have, and add
>  any successors which are not proven to be dead from these
>  simplifications to the worklist.
> - Pop the next block off of the front of the worklist, and repeat.
> - As soon as the cost of inlining exceeds the threshold for the
>  callsite, stop analyzing the function in order to bound cost.
> 
> The primary goal of this algorithm is to perfectly handle dead code
> paths. We do not want any code in trivially dead code paths to impact
> inlining decisions. The previous metric was *extremely* flawed here, and
> would always subtract the average cost of two successors of
> a conditional branch when it was proven to become an unconditional
> branch at the callsite. There was no handling of wildly different costs
> between the two successors, which would cause inlining when the path
> actually taken was too large, and no inlining when the path actually
> taken was trivially simple. There was also no handling of the code
> *path*, only the immediate successors. These problems vanish completely
> now. See the added regression tests for the shiny new features -- we
> skip recursive function calls, SROA-killing instructions, and high cost
> complex CFG structures when dead at the callsite being analyzed.
> 
> Switching to this algorithm required refactoring the inline cost
> interface to accept the actual threshold rather than simply returning
> a single cost. The resulting interface is pretty bad, and I'm planning
> to do lots of interface cleanup after this patch.
> 
> Several other refactorings fell out of this, but I've tried to minimize
> them for this patch. =/ There is still more cleanup that can be done
> here. Please point out anything that you see in review.
> 
> I've worked really hard to try to mirror at least the spirit of all of
> the previous heuristics in the new model. It's not clear that they are
> all correct any more, but I wanted to minimize the change in this single
> patch, it's already a bit ridiculous. One heuristic that is *not* yet
> mirrored is to allow inlining of functions with a dynamic alloca *if*
> the caller has a dynamic alloca. I will add this back, but I think the
> most reasonable way requires changes to the inliner itself rather than
> just the cost metric, and so I've deferred this for a subsequent patch.
> The test case is XFAIL-ed until then.
> 
> As mentioned in the review mail, this seems to make Clang run about 1%
> to 2% faster in -O0, but makes its binary size grow by just under 4%.
> I've looked into the 4% growth, and it can be fixed, but requires
> changes to other parts of the inliner.
> 
> Modified:
>    llvm/trunk/include/llvm/Analysis/CodeMetrics.h
>    llvm/trunk/include/llvm/Analysis/InlineCost.h
>    llvm/trunk/include/llvm/Transforms/IPO/InlinerPass.h
>    llvm/trunk/lib/Analysis/CodeMetrics.cpp
>    llvm/trunk/lib/Analysis/InlineCost.cpp
>    llvm/trunk/lib/Transforms/IPO/InlineAlways.cpp
>    llvm/trunk/lib/Transforms/IPO/InlineSimple.cpp
>    llvm/trunk/lib/Transforms/IPO/Inliner.cpp
>    llvm/trunk/test/Transforms/Inline/alloca-bonus.ll
>    llvm/trunk/test/Transforms/Inline/dynamic_alloca_test.ll
>    llvm/trunk/test/Transforms/Inline/inline_constprop.ll
>    llvm/trunk/test/Transforms/Inline/noinline-recursive-fn.ll
>    llvm/trunk/test/Transforms/Inline/ptr-diff.ll
> 
> Modified: llvm/trunk/include/llvm/Analysis/CodeMetrics.h
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Analysis/CodeMetrics.h?rev=153812&r1=153811&r2=153812&view=diff
> ==============================================================================
> --- llvm/trunk/include/llvm/Analysis/CodeMetrics.h (original)
> +++ llvm/trunk/include/llvm/Analysis/CodeMetrics.h Sat Mar 31 07:42:41 2012
> @@ -20,9 +20,13 @@
> namespace llvm {
>   class BasicBlock;
>   class Function;
> +  class Instruction;
>   class TargetData;
>   class Value;
> 
> +  /// \brief Check whether an instruction is likely to be "free" when lowered.
> +  bool isInstructionFree(const Instruction *I, const TargetData *TD = 0);
> +
>   /// \brief Check whether a call will lower to something small.
>   ///
>   /// This tests checks whether calls to this function will lower to something
> 
> Modified: llvm/trunk/include/llvm/Analysis/InlineCost.h
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Analysis/InlineCost.h?rev=153812&r1=153811&r2=153812&view=diff
> ==============================================================================
> --- llvm/trunk/include/llvm/Analysis/InlineCost.h (original)
> +++ llvm/trunk/include/llvm/Analysis/InlineCost.h Sat Mar 31 07:42:41 2012
> @@ -16,6 +16,7 @@
> 
> #include "llvm/Function.h"
> #include "llvm/ADT/DenseMap.h"
> +#include "llvm/ADT/SmallPtrSet.h"
> #include "llvm/ADT/ValueMap.h"
> #include "llvm/Analysis/CodeMetrics.h"
> #include <cassert>
> @@ -25,162 +26,105 @@
> namespace llvm {
> 
>   class CallSite;
> -  template<class PtrType, unsigned SmallSize>
> -  class SmallPtrSet;
>   class TargetData;
> 
>   namespace InlineConstants {
>     // Various magic constants used to adjust heuristics.
>     const int InstrCost = 5;
> -    const int IndirectCallBonus = -100;
> +    const int IndirectCallThreshold = 100;
>     const int CallPenalty = 25;
>     const int LastCallToStaticBonus = -15000;
>     const int ColdccPenalty = 2000;
>     const int NoreturnPenalty = 10000;
>   }
> 
> -  /// InlineCost - Represent the cost of inlining a function. This
> -  /// supports special values for functions which should "always" or
> -  /// "never" be inlined. Otherwise, the cost represents a unitless
> -  /// amount; smaller values increase the likelihood of the function
> -  /// being inlined.
> +  /// \brief Represents the cost of inlining a function.
> +  ///
> +  /// This supports special values for functions which should "always" or
> +  /// "never" be inlined. Otherwise, the cost represents a unitless amount;
> +  /// smaller values increase the likelihood of the function being inlined.
> +  ///
> +  /// Objects of this type also provide the adjusted threshold for inlining
> +  /// based on the information available for a particular callsite. They can be
> +  /// directly tested to determine if inlining should occur given the cost and
> +  /// threshold for this cost metric.
>   class InlineCost {
> -    enum Kind {
> -      Value,
> -      Always,
> -      Never
> +    enum CostKind {
> +      CK_Variable,
> +      CK_Always,
> +      CK_Never
>     };
> 
> -    // This is a do-it-yourself implementation of
> -    //   int Cost : 30;
> -    //   unsigned Type : 2;
> -    // We used to use bitfields, but they were sometimes miscompiled (PR3822).
> -    enum { TYPE_BITS = 2 };
> -    enum { COST_BITS = unsigned(sizeof(unsigned)) * CHAR_BIT - TYPE_BITS };
> -    unsigned TypedCost; // int Cost : COST_BITS; unsigned Type : TYPE_BITS;
> +    const int      Cost : 30; // The inlining cost if neither always nor never.
> +    const unsigned Kind : 2;  // The type of cost, one of CostKind above.
> 
> -    Kind getType() const {
> -      return Kind(TypedCost >> COST_BITS);
> -    }
> +    /// \brief The adjusted threshold against which this cost should be tested.
> +    const int Threshold;
> 
> -    int getCost() const {
> -      // Sign-extend the bottom COST_BITS bits.
> -      return (int(TypedCost << TYPE_BITS)) >> TYPE_BITS;
> +    // Trivial constructor, interesting logic in the factory functions below.
> +    InlineCost(int Cost, CostKind Kind, int Threshold)
> +      : Cost(Cost), Kind(Kind), Threshold(Threshold) {}
> +
> +  public:
> +    static InlineCost get(int Cost, int Threshold) {
> +      InlineCost Result(Cost, CK_Variable, Threshold);
> +      assert(Result.Cost == Cost && "Cost exceeds InlineCost precision");
> +      return Result;
> +    }
> +    static InlineCost getAlways() {
> +      return InlineCost(0, CK_Always, 0);
> +    }
> +    static InlineCost getNever() {
> +      return InlineCost(0, CK_Never, 0);
>     }
> 
> -    InlineCost(int C, int T) {
> -      TypedCost = (unsigned(C << TYPE_BITS) >> TYPE_BITS) | (T << COST_BITS);
> -      assert(getCost() == C && "Cost exceeds InlineCost precision");
> +    /// \brief Test whether the inline cost is low enough for inlining.
> +    operator bool() const {
> +      if (isAlways()) return true;
> +      if (isNever()) return false;
> +      return Cost < Threshold;
>     }
> -  public:
> -    static InlineCost get(int Cost) { return InlineCost(Cost, Value); }
> -    static InlineCost getAlways() { return InlineCost(0, Always); }
> -    static InlineCost getNever() { return InlineCost(0, Never); }
> -
> -    bool isVariable() const { return getType() == Value; }
> -    bool isAlways() const { return getType() == Always; }
> -    bool isNever() const { return getType() == Never; }
> 
> -    /// getValue() - Return a "variable" inline cost's amount. It is
> +    bool isVariable() const { return Kind == CK_Variable; }
> +    bool isAlways() const   { return Kind == CK_Always; }
> +    bool isNever() const    { return Kind == CK_Never; }
> +
> +    /// getCost() - Return a "variable" inline cost's amount. It is
>     /// an error to call this on an "always" or "never" InlineCost.
> -    int getValue() const {
> -      assert(getType() == Value && "Invalid access of InlineCost");
> -      return getCost();
> +    int getCost() const {
> +      assert(Kind == CK_Variable && "Invalid access of InlineCost");
> +      return Cost;
> +    }
> +
> +    /// \brief Get the cost delta from the threshold for inlining.
> +    /// Only valid if the cost is of the variable kind. Returns a negative
> +    /// value if the cost is too high to inline.
> +    int getCostDelta() const {
> +      return Threshold - getCost();
>     }
>   };
> 
>   /// InlineCostAnalyzer - Cost analyzer used by inliner.
>   class InlineCostAnalyzer {
> -    struct ArgInfo {
> -    public:
> -      unsigned ConstantWeight;
> -      unsigned AllocaWeight;
> -
> -      ArgInfo(unsigned CWeight, unsigned AWeight)
> -        : ConstantWeight(CWeight), AllocaWeight(AWeight)
> -          {}
> -    };
> -
> -    struct FunctionInfo {
> -      CodeMetrics Metrics;
> -
> -      /// ArgumentWeights - Each formal argument of the function is inspected to
> -      /// see if it is used in any contexts where making it a constant or alloca
> -      /// would reduce the code size.  If so, we add some value to the argument
> -      /// entry here.
> -      std::vector<ArgInfo> ArgumentWeights;
> -
> -      /// PointerArgPairWeights - Weights to use when giving an inline bonus to
> -      /// a call site due to correlated pairs of pointers.
> -      DenseMap<std::pair<unsigned, unsigned>, unsigned> PointerArgPairWeights;
> -
> -      /// countCodeReductionForConstant - Figure out an approximation for how
> -      /// many instructions will be constant folded if the specified value is
> -      /// constant.
> -      unsigned countCodeReductionForConstant(const CodeMetrics &Metrics,
> -                                             Value *V);
> -
> -      /// countCodeReductionForAlloca - Figure out an approximation of how much
> -      /// smaller the function will be if it is inlined into a context where an
> -      /// argument becomes an alloca.
> -      unsigned countCodeReductionForAlloca(const CodeMetrics &Metrics,
> -                                           Value *V);
> -
> -      /// countCodeReductionForPointerPair - Count the bonus to apply to an
> -      /// inline call site where a pair of arguments are pointers and one
> -      /// argument is a constant offset from the other. The idea is to
> -      /// recognize a common C++ idiom where a begin and end iterator are
> -      /// actually pointers, and many operations on the pair of them will be
> -      /// constants if the function is called with arguments that have
> -      /// a constant offset.
> -      void countCodeReductionForPointerPair(
> -          const CodeMetrics &Metrics,
> -          DenseMap<Value *, unsigned> &PointerArgs,
> -          Value *V, unsigned ArgIdx);
> -
> -      /// analyzeFunction - Add information about the specified function
> -      /// to the current structure.
> -      void analyzeFunction(Function *F, const TargetData *TD);
> -
> -      /// NeverInline - Returns true if the function should never be
> -      /// inlined into any caller.
> -      bool NeverInline();
> -    };
> -
> -    // The Function* for a function can be changed (by ArgumentPromotion);
> -    // the ValueMap will update itself when this happens.
> -    ValueMap<const Function *, FunctionInfo> CachedFunctionInfo;
> -
>     // TargetData if available, or null.
>     const TargetData *TD;
> 
> -    int CountBonusForConstant(Value *V, Constant *C = NULL);
> -    int ConstantFunctionBonus(CallSite CS, Constant *C);
> -    int getInlineSize(CallSite CS, Function *Callee);
> -    int getInlineBonuses(CallSite CS, Function *Callee);
>   public:
>     InlineCostAnalyzer(): TD(0) {}
> 
>     void setTargetData(const TargetData *TData) { TD = TData; }
> 
> -    /// getInlineCost - The heuristic used to determine if we should inline the
> -    /// function call or not.
> +    /// \brief Get an InlineCost object representing the cost of inlining this
> +    /// callsite.
>     ///
> -    InlineCost getInlineCost(CallSite CS);
> -    /// getCalledFunction - The heuristic used to determine if we should inline
> -    /// the function call or not.  The callee is explicitly specified, to allow
> -    /// you to calculate the cost of inlining a function via a pointer.  The
> -    /// result assumes that the inlined version will always be used.  You should
> -    /// weight it yourself in cases where this callee will not always be called.
> -    InlineCost getInlineCost(CallSite CS, Function *Callee);
> -
> -    /// getInlineFudgeFactor - Return a > 1.0 factor if the inliner should use a
> -    /// higher threshold to determine if the function call should be inlined.
> -    float getInlineFudgeFactor(CallSite CS);
> +    /// Note that threshold is passed into this function. Only costs below the
> +    /// threshold are computed with any accuracy. The threshold can be used to
> +    /// bound the computation necessary to determine whether the cost is
> +    /// sufficiently low to warrant inlining.
> +    InlineCost getInlineCost(CallSite CS, int Threshold);
> 
>     /// resetCachedFunctionInfo - erase any cached cost info for this function.
>     void resetCachedCostInfo(Function* Caller) {
> -      CachedFunctionInfo[Caller] = FunctionInfo();
>     }
> 
>     /// growCachedCostInfo - update the cached cost info for Caller after Callee
> 
> Modified: llvm/trunk/include/llvm/Transforms/IPO/InlinerPass.h
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Transforms/IPO/InlinerPass.h?rev=153812&r1=153811&r2=153812&view=diff
> ==============================================================================
> --- llvm/trunk/include/llvm/Transforms/IPO/InlinerPass.h (original)
> +++ llvm/trunk/include/llvm/Transforms/IPO/InlinerPass.h Sat Mar 31 07:42:41 2012
> @@ -65,11 +65,6 @@
>   ///
>   virtual InlineCost getInlineCost(CallSite CS) = 0;
> 
> -  // getInlineFudgeFactor - Return a > 1.0 factor if the inliner should use a
> -  // higher threshold to determine if the function call should be inlined.
> -  ///
> -  virtual float getInlineFudgeFactor(CallSite CS) = 0;
> -
>   /// resetCachedCostInfo - erase any cached cost data from the derived class.
>   /// If the derived class has no such data this can be empty.
>   /// 
> 
> Modified: llvm/trunk/lib/Analysis/CodeMetrics.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/CodeMetrics.cpp?rev=153812&r1=153811&r2=153812&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Analysis/CodeMetrics.cpp (original)
> +++ llvm/trunk/lib/Analysis/CodeMetrics.cpp Sat Mar 31 07:42:41 2012
> @@ -50,6 +50,52 @@
>   return false;
> }
> 
> +bool llvm::isInstructionFree(const Instruction *I, const TargetData *TD) {
> +  if (isa<PHINode>(I))
> +    return true;
> +
> +  // If a GEP has all constant indices, it will probably be folded with
> +  // a load/store.
> +  if (const GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(I))
> +    return GEP->hasAllConstantIndices();
> +
> +  if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) {
> +    switch (II->getIntrinsicID()) {
> +    default:
> +      return false;
> +    case Intrinsic::dbg_declare:
> +    case Intrinsic::dbg_value:
> +    case Intrinsic::invariant_start:
> +    case Intrinsic::invariant_end:
> +    case Intrinsic::lifetime_start:
> +    case Intrinsic::lifetime_end:
> +    case Intrinsic::objectsize:
> +    case Intrinsic::ptr_annotation:
> +    case Intrinsic::var_annotation:
> +      // These intrinsics don't count as size.
> +      return true;
> +    }
> +  }
> +
> +  if (const CastInst *CI = dyn_cast<CastInst>(I)) {
> +    // Noop casts, including ptr <-> int,  don't count.
> +    if (CI->isLosslessCast() || isa<IntToPtrInst>(CI) || isa<PtrToIntInst>(CI))
> +      return true;
> +    // trunc to a native type is free (assuming the target has compare and
> +    // shift-right of the same width).
> +    if (TD && isa<TruncInst>(CI) &&
> +        TD->isLegalInteger(TD->getTypeSizeInBits(CI->getType())))
> +      return true;
> +    // Result of a cmp instruction is often extended (to be used by other
> +    // cmp instructions, logical or return instructions). These are usually
> +    // nop on most sane targets.
> +    if (isa<CmpInst>(CI->getOperand(0)))
> +      return true;
> +  }
> +
> +  return false;
> +}
> +
> /// analyzeBasicBlock - Fill in the current structure with information gleaned
> /// from the specified block.
> void CodeMetrics::analyzeBasicBlock(const BasicBlock *BB,
> @@ -58,27 +104,11 @@
>   unsigned NumInstsBeforeThisBB = NumInsts;
>   for (BasicBlock::const_iterator II = BB->begin(), E = BB->end();
>        II != E; ++II) {
> -    if (isa<PHINode>(II)) continue;           // PHI nodes don't count.
> +    if (isInstructionFree(II, TD))
> +      continue;
> 
>     // Special handling for calls.
>     if (isa<CallInst>(II) || isa<InvokeInst>(II)) {
> -      if (const IntrinsicInst *IntrinsicI = dyn_cast<IntrinsicInst>(II)) {
> -        switch (IntrinsicI->getIntrinsicID()) {
> -        default: break;
> -        case Intrinsic::dbg_declare:
> -        case Intrinsic::dbg_value:
> -        case Intrinsic::invariant_start:
> -        case Intrinsic::invariant_end:
> -        case Intrinsic::lifetime_start:
> -        case Intrinsic::lifetime_end:
> -        case Intrinsic::objectsize:
> -        case Intrinsic::ptr_annotation:
> -        case Intrinsic::var_annotation:
> -          // These intrinsics don't count as size.
> -          continue;
> -        }
> -      }
> -
>       ImmutableCallSite CS(cast<Instruction>(II));
> 
>       if (const Function *F = CS.getCalledFunction()) {
> @@ -115,28 +145,6 @@
>     if (isa<ExtractElementInst>(II) || II->getType()->isVectorTy())
>       ++NumVectorInsts;
> 
> -    if (const CastInst *CI = dyn_cast<CastInst>(II)) {
> -      // Noop casts, including ptr <-> int,  don't count.
> -      if (CI->isLosslessCast() || isa<IntToPtrInst>(CI) ||
> -          isa<PtrToIntInst>(CI))
> -        continue;
> -      // trunc to a native type is free (assuming the target has compare and
> -      // shift-right of the same width).
> -      if (isa<TruncInst>(CI) && TD &&
> -          TD->isLegalInteger(TD->getTypeSizeInBits(CI->getType())))
> -        continue;
> -      // Result of a cmp instruction is often extended (to be used by other
> -      // cmp instructions, logical or return instructions). These are usually
> -      // nop on most sane targets.
> -      if (isa<CmpInst>(CI->getOperand(0)))
> -        continue;
> -    } else if (const GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(II)){
> -      // If a GEP has all constant indices, it will probably be folded with
> -      // a load/store.
> -      if (GEPI->hasAllConstantIndices())
> -        continue;
> -    }
> -
>     ++NumInsts;
>   }
> 
> 
> Modified: llvm/trunk/lib/Analysis/InlineCost.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/InlineCost.cpp?rev=153812&r1=153811&r2=153812&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Analysis/InlineCost.cpp (original)
> +++ llvm/trunk/lib/Analysis/InlineCost.cpp Sat Mar 31 07:42:41 2012
> @@ -11,659 +11,1014 @@
> //
> //===----------------------------------------------------------------------===//
> 
> +#define DEBUG_TYPE "inline-cost"
> #include "llvm/Analysis/InlineCost.h"
> +#include "llvm/Analysis/ConstantFolding.h"
> +#include "llvm/Analysis/InstructionSimplify.h"
> #include "llvm/Support/CallSite.h"
> +#include "llvm/Support/Debug.h"
> +#include "llvm/Support/InstVisitor.h"
> +#include "llvm/Support/GetElementPtrTypeIterator.h"
> +#include "llvm/Support/raw_ostream.h"
> #include "llvm/CallingConv.h"
> #include "llvm/IntrinsicInst.h"
> +#include "llvm/Operator.h"
> +#include "llvm/GlobalAlias.h"
> #include "llvm/Target/TargetData.h"
> +#include "llvm/ADT/STLExtras.h"
> +#include "llvm/ADT/SetVector.h"
> +#include "llvm/ADT/SmallVector.h"
> #include "llvm/ADT/SmallPtrSet.h"
> 
> using namespace llvm;
> 
> -unsigned InlineCostAnalyzer::FunctionInfo::countCodeReductionForConstant(
> -    const CodeMetrics &Metrics, Value *V) {
> -  unsigned Reduction = 0;
> -  SmallVector<Value *, 4> Worklist;
> -  Worklist.push_back(V);
> -  do {
> -    Value *V = Worklist.pop_back_val();
> -    for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI != E;++UI){
> -      User *U = *UI;
> -      if (isa<BranchInst>(U) || isa<SwitchInst>(U)) {
> -        // We will be able to eliminate all but one of the successors.
> -        const TerminatorInst &TI = cast<TerminatorInst>(*U);
> -        const unsigned NumSucc = TI.getNumSuccessors();
> -        unsigned Instrs = 0;
> -        for (unsigned I = 0; I != NumSucc; ++I)
> -          Instrs += Metrics.NumBBInsts.lookup(TI.getSuccessor(I));
> -        // We don't know which blocks will be eliminated, so use the average size.
> -        Reduction += InlineConstants::InstrCost*Instrs*(NumSucc-1)/NumSucc;
> -        continue;
> +namespace {
> +
> +class CallAnalyzer : public InstVisitor<CallAnalyzer, bool> {
> +  typedef InstVisitor<CallAnalyzer, bool> Base;
> +  friend class InstVisitor<CallAnalyzer, bool>;
> +
> +  // TargetData if available, or null.
> +  const TargetData *const TD;
> +
> +  // The called function.
> +  Function &F;
> +
> +  int Threshold;
> +  int Cost;
> +  const bool AlwaysInline;
> +
> +  bool IsRecursive;
> +  bool ExposesReturnsTwice;
> +  bool HasDynamicAlloca;
> +  unsigned NumInstructions, NumVectorInstructions;
> +  int FiftyPercentVectorBonus, TenPercentVectorBonus;
> +  int VectorBonus;
> +
> +  // While we walk the potentially-inlined instructions, we build up and
> +  // maintain a mapping of simplified values specific to this callsite. The
> +  // idea is to propagate any special information we have about arguments to
> +  // this call through the inlinable section of the function, and account for
> +  // likely simplifications post-inlining. The most important aspect we track
> +  // is CFG altering simplifications -- when we prove a basic block dead, that
> +  // can cause dramatic shifts in the cost of inlining a function.
> +  DenseMap<Value *, Constant *> SimplifiedValues;
> +
> +  // Keep track of the values which map back (through function arguments) to
> +  // allocas on the caller stack which could be simplified through SROA.
> +  DenseMap<Value *, Value *> SROAArgValues;
> +
> +  // The mapping of caller Alloca values to their accumulated cost savings. If
> +  // we have to disable SROA for one of the allocas, this tells us how much
> +  // cost must be added.
> +  DenseMap<Value *, int> SROAArgCosts;
> +
> +  // Keep track of values which map to a pointer base and constant offset.
> +  DenseMap<Value *, std::pair<Value *, APInt> > ConstantOffsetPtrs;
> +
> +  // Custom simplification helper routines.
> +  bool isAllocaDerivedArg(Value *V);
> +  bool lookupSROAArgAndCost(Value *V, Value *&Arg,
> +                            DenseMap<Value *, int>::iterator &CostIt);
> +  void disableSROA(DenseMap<Value *, int>::iterator CostIt);
> +  void disableSROA(Value *V);
> +  void accumulateSROACost(DenseMap<Value *, int>::iterator CostIt,
> +                          int InstructionCost);
> +  bool handleSROACandidate(bool IsSROAValid,
> +                           DenseMap<Value *, int>::iterator CostIt,
> +                           int InstructionCost);
> +  bool isGEPOffsetConstant(GetElementPtrInst &GEP);
> +  bool accumulateGEPOffset(GEPOperator &GEP, APInt &Offset);
> +  ConstantInt *stripAndComputeInBoundsConstantOffsets(Value *&V);
> +
> +  // Custom analysis routines.
> +  bool analyzeBlock(BasicBlock *BB);
> +
> +  // Disable several entry points to the visitor so we don't accidentally use
> +  // them by declaring but not defining them here.
> +  void visit(Module *);     void visit(Module &);
> +  void visit(Function *);   void visit(Function &);
> +  void visit(BasicBlock *); void visit(BasicBlock &);
> +
> +  // Provide base case for our instruction visit.
> +  bool visitInstruction(Instruction &I);
> +
> +  // Our visit overrides.
> +  bool visitAlloca(AllocaInst &I);
> +  bool visitPHI(PHINode &I);
> +  bool visitGetElementPtr(GetElementPtrInst &I);
> +  bool visitBitCast(BitCastInst &I);
> +  bool visitPtrToInt(PtrToIntInst &I);
> +  bool visitIntToPtr(IntToPtrInst &I);
> +  bool visitCastInst(CastInst &I);
> +  bool visitUnaryInstruction(UnaryInstruction &I);
> +  bool visitICmp(ICmpInst &I);
> +  bool visitSub(BinaryOperator &I);
> +  bool visitBinaryOperator(BinaryOperator &I);
> +  bool visitLoad(LoadInst &I);
> +  bool visitStore(StoreInst &I);
> +  bool visitCallSite(CallSite CS);
> +
> +public:
> +  CallAnalyzer(const TargetData *TD, Function &Callee, int Threshold)
> +    : TD(TD), F(Callee), Threshold(Threshold), Cost(0),
> +      AlwaysInline(F.hasFnAttr(Attribute::AlwaysInline)),
> +      IsRecursive(false), ExposesReturnsTwice(false), HasDynamicAlloca(false),
> +      NumInstructions(0), NumVectorInstructions(0),
> +      FiftyPercentVectorBonus(0), TenPercentVectorBonus(0), VectorBonus(0),
> +      NumConstantArgs(0), NumConstantOffsetPtrArgs(0), NumAllocaArgs(0),
> +      NumConstantPtrCmps(0), NumConstantPtrDiffs(0),
> +      NumInstructionsSimplified(0), SROACostSavings(0), SROACostSavingsLost(0) {
> +  }
> +
> +  bool analyzeCall(CallSite CS);
> +
> +  int getThreshold() { return Threshold; }
> +  int getCost() { return Cost; }
> +
> +  // Keep a bunch of stats about the cost savings found so we can print them
> +  // out when debugging.
> +  unsigned NumConstantArgs;
> +  unsigned NumConstantOffsetPtrArgs;
> +  unsigned NumAllocaArgs;
> +  unsigned NumConstantPtrCmps;
> +  unsigned NumConstantPtrDiffs;
> +  unsigned NumInstructionsSimplified;
> +  unsigned SROACostSavings;
> +  unsigned SROACostSavingsLost;
> +
> +  void dump();
> +};
> +
> +} // namespace
> +
> +/// \brief Test whether the given value is an Alloca-derived function argument.
> +bool CallAnalyzer::isAllocaDerivedArg(Value *V) {
> +  return SROAArgValues.count(V);
> +}
> +
> +/// \brief Lookup the SROA-candidate argument and cost iterator which V maps to.
> +/// Returns false if V does not map to a SROA-candidate.
> +bool CallAnalyzer::lookupSROAArgAndCost(
> +    Value *V, Value *&Arg, DenseMap<Value *, int>::iterator &CostIt) {
> +  if (SROAArgValues.empty() || SROAArgCosts.empty())
> +    return false;
> +
> +  DenseMap<Value *, Value *>::iterator ArgIt = SROAArgValues.find(V);
> +  if (ArgIt == SROAArgValues.end())
> +    return false;
> +
> +  Arg = ArgIt->second;
> +  CostIt = SROAArgCosts.find(Arg);
> +  return CostIt != SROAArgCosts.end();
> +}
> +
> +/// \brief Disable SROA for the candidate marked by this cost iterator.
> +///
> +/// This markes the candidate as no longer viable for SROA, and adds the cost
> +/// savings associated with it back into the inline cost measurement.
> +void CallAnalyzer::disableSROA(DenseMap<Value *, int>::iterator CostIt) {
> +  // If we're no longer able to perform SROA we need to undo its cost savings
> +  // and prevent subsequent analysis.
> +  Cost += CostIt->second;
> +  SROACostSavings -= CostIt->second;
> +  SROACostSavingsLost += CostIt->second;
> +  SROAArgCosts.erase(CostIt);
> +}
> +
> +/// \brief If 'V' maps to a SROA candidate, disable SROA for it.
> +void CallAnalyzer::disableSROA(Value *V) {
> +  Value *SROAArg;
> +  DenseMap<Value *, int>::iterator CostIt;
> +  if (lookupSROAArgAndCost(V, SROAArg, CostIt))
> +    disableSROA(CostIt);
> +}
> +
> +/// \brief Accumulate the given cost for a particular SROA candidate.
> +void CallAnalyzer::accumulateSROACost(DenseMap<Value *, int>::iterator CostIt,
> +                                      int InstructionCost) {
> +  CostIt->second += InstructionCost;
> +  SROACostSavings += InstructionCost;
> +}
> +
> +/// \brief Helper for the common pattern of handling a SROA candidate.
> +/// Either accumulates the cost savings if the SROA remains valid, or disables
> +/// SROA for the candidate.
> +bool CallAnalyzer::handleSROACandidate(bool IsSROAValid,
> +                                       DenseMap<Value *, int>::iterator CostIt,
> +                                       int InstructionCost) {
> +  if (IsSROAValid) {
> +    accumulateSROACost(CostIt, InstructionCost);
> +    return true;
> +  }
> +
> +  disableSROA(CostIt);
> +  return false;
> +}
> +
> +/// \brief Check whether a GEP's indices are all constant.
> +///
> +/// Respects any simplified values known during the analysis of this callsite.
> +bool CallAnalyzer::isGEPOffsetConstant(GetElementPtrInst &GEP) {
> +  for (User::op_iterator I = GEP.idx_begin(), E = GEP.idx_end(); I != E; ++I)
> +    if (!isa<Constant>(*I) && !SimplifiedValues.lookup(*I))
> +      return false;
> +
> +  return true;
> +}
> +
> +/// \brief Accumulate a constant GEP offset into an APInt if possible.
> +///
> +/// Returns false if unable to compute the offset for any reason. Respects any
> +/// simplified values known during the analysis of this callsite.
> +bool CallAnalyzer::accumulateGEPOffset(GEPOperator &GEP, APInt &Offset) {
> +  if (!TD)
> +    return false;
> +
> +  unsigned IntPtrWidth = TD->getPointerSizeInBits();
> +  assert(IntPtrWidth == Offset.getBitWidth());
> +
> +  for (gep_type_iterator GTI = gep_type_begin(GEP), GTE = gep_type_end(GEP);
> +       GTI != GTE; ++GTI) {
> +    ConstantInt *OpC = dyn_cast<ConstantInt>(GTI.getOperand());
> +    if (!OpC)
> +      if (Constant *SimpleOp = SimplifiedValues.lookup(GTI.getOperand()))
> +        OpC = dyn_cast<ConstantInt>(SimpleOp);
> +    if (!OpC)
> +      return false;
> +    if (OpC->isZero()) continue;
> +
> +    // Handle a struct index, which adds its field offset to the pointer.
> +    if (StructType *STy = dyn_cast<StructType>(*GTI)) {
> +      unsigned ElementIdx = OpC->getZExtValue();
> +      const StructLayout *SL = TD->getStructLayout(STy);
> +      Offset += APInt(IntPtrWidth, SL->getElementOffset(ElementIdx));
> +      continue;
> +    }
> +
> +    APInt TypeSize(IntPtrWidth, TD->getTypeAllocSize(GTI.getIndexedType()));
> +    Offset += OpC->getValue().sextOrTrunc(IntPtrWidth) * TypeSize;
> +  }
> +  return true;
> +}
> +
> +bool CallAnalyzer::visitAlloca(AllocaInst &I) {
> +  // FIXME: Check whether inlining will turn a dynamic alloca into a static
> +  // alloca, and handle that case.
> +
> +  // We will happily inline tatic alloca instructions or dynamic alloca
> +  // instructions in always-inline situations.
> +  if (AlwaysInline || I.isStaticAlloca())
> +    return Base::visitAlloca(I);
> +
> +  // FIXME: This is overly conservative. Dynamic allocas are inefficient for
> +  // a variety of reasons, and so we would like to not inline them into
> +  // functions which don't currently have a dynamic alloca. This simply
> +  // disables inlining altogether in the presence of a dynamic alloca.
> +  HasDynamicAlloca = true;
> +  return false;
> +}
> +
> +bool CallAnalyzer::visitPHI(PHINode &I) {
> +  // FIXME: We should potentially be tracking values through phi nodes,
> +  // especially when they collapse to a single value due to deleted CFG edges
> +  // during inlining.
> +
> +  // FIXME: We need to propagate SROA *disabling* through phi nodes, even
> +  // though we don't want to propagate it's bonuses. The idea is to disable
> +  // SROA if it *might* be used in an inappropriate manner.
> +
> +  // Phi nodes are always zero-cost.
> +  return true;
> +}
> +
> +bool CallAnalyzer::visitGetElementPtr(GetElementPtrInst &I) {
> +  Value *SROAArg;
> +  DenseMap<Value *, int>::iterator CostIt;
> +  bool SROACandidate = lookupSROAArgAndCost(I.getPointerOperand(),
> +                                            SROAArg, CostIt);
> +
> +  // Try to fold GEPs of constant-offset call site argument pointers. This
> +  // requires target data and inbounds GEPs.
> +  if (TD && I.isInBounds()) {
> +    // Check if we have a base + offset for the pointer.
> +    Value *Ptr = I.getPointerOperand();
> +    std::pair<Value *, APInt> BaseAndOffset = ConstantOffsetPtrs.lookup(Ptr);
> +    if (BaseAndOffset.first) {
> +      // Check if the offset of this GEP is constant, and if so accumulate it
> +      // into Offset.
> +      if (!accumulateGEPOffset(cast<GEPOperator>(I), BaseAndOffset.second)) {
> +        // Non-constant GEPs aren't folded, and disable SROA.
> +        if (SROACandidate)
> +          disableSROA(CostIt);
> +        return false;
>       }
> 
> -      // Figure out if this instruction will be removed due to simple constant
> -      // propagation.
> -      Instruction &Inst = cast<Instruction>(*U);
> -
> -      // We can't constant propagate instructions which have effects or
> -      // read memory.
> -      //
> -      // FIXME: It would be nice to capture the fact that a load from a
> -      // pointer-to-constant-global is actually a *really* good thing to zap.
> -      // Unfortunately, we don't know the pointer that may get propagated here,
> -      // so we can't make this decision.
> -      if (Inst.mayReadFromMemory() || Inst.mayHaveSideEffects() ||
> -          isa<AllocaInst>(Inst))
> -        continue;
> +      // Add the result as a new mapping to Base + Offset.
> +      ConstantOffsetPtrs[&I] = BaseAndOffset;
> 
> -      bool AllOperandsConstant = true;
> -      for (unsigned i = 0, e = Inst.getNumOperands(); i != e; ++i)
> -        if (!isa<Constant>(Inst.getOperand(i)) && Inst.getOperand(i) != V) {
> -          AllOperandsConstant = false;
> -          break;
> -        }
> -      if (!AllOperandsConstant)
> -        continue;
> +      // Also handle SROA candidates here, we already know that the GEP is
> +      // all-constant indexed.
> +      if (SROACandidate)
> +        SROAArgValues[&I] = SROAArg;
> 
> -      // We will get to remove this instruction...
> -      Reduction += InlineConstants::InstrCost;
> +      return true;
> +    }
> +  }
> +
> +  if (isGEPOffsetConstant(I)) {
> +    if (SROACandidate)
> +      SROAArgValues[&I] = SROAArg;
> +
> +    // Constant GEPs are modeled as free.
> +    return true;
> +  }
> +
> +  // Variable GEPs will require math and will disable SROA.
> +  if (SROACandidate)
> +    disableSROA(CostIt);
> +  return false;
> +}
> 
> -      // And any other instructions that use it which become constants
> -      // themselves.
> -      Worklist.push_back(&Inst);
> +bool CallAnalyzer::visitBitCast(BitCastInst &I) {
> +  // Propagate constants through bitcasts.
> +  if (Constant *COp = dyn_cast<Constant>(I.getOperand(0)))
> +    if (Constant *C = ConstantExpr::getBitCast(COp, I.getType())) {
> +      SimplifiedValues[&I] = C;
> +      return true;
> +    }
> +
> +  // Track base/offsets through casts
> +  std::pair<Value *, APInt> BaseAndOffset
> +    = ConstantOffsetPtrs.lookup(I.getOperand(0));
> +  // Casts don't change the offset, just wrap it up.
> +  if (BaseAndOffset.first)
> +    ConstantOffsetPtrs[&I] = BaseAndOffset;
> +
> +  // Also look for SROA candidates here.
> +  Value *SROAArg;
> +  DenseMap<Value *, int>::iterator CostIt;
> +  if (lookupSROAArgAndCost(I.getOperand(0), SROAArg, CostIt))
> +    SROAArgValues[&I] = SROAArg;
> +
> +  // Bitcasts are always zero cost.
> +  return true;
> +}
> +
> +bool CallAnalyzer::visitPtrToInt(PtrToIntInst &I) {
> +  // Propagate constants through ptrtoint.
> +  if (Constant *COp = dyn_cast<Constant>(I.getOperand(0)))
> +    if (Constant *C = ConstantExpr::getPtrToInt(COp, I.getType())) {
> +      SimplifiedValues[&I] = C;
> +      return true;
>     }
> -  } while (!Worklist.empty());
> -  return Reduction;
> +
> +  // Track base/offset pairs when converted to a plain integer provided the
> +  // integer is large enough to represent the pointer.
> +  unsigned IntegerSize = I.getType()->getScalarSizeInBits();
> +  if (TD && IntegerSize >= TD->getPointerSizeInBits()) {
> +    std::pair<Value *, APInt> BaseAndOffset
> +      = ConstantOffsetPtrs.lookup(I.getOperand(0));
> +    if (BaseAndOffset.first)
> +      ConstantOffsetPtrs[&I] = BaseAndOffset;
> +  }
> +
> +  // This is really weird. Technically, ptrtoint will disable SROA. However,
> +  // unless that ptrtoint is *used* somewhere in the live basic blocks after
> +  // inlining, it will be nuked, and SROA should proceed. All of the uses which
> +  // would block SROA would also block SROA if applied directly to a pointer,
> +  // and so we can just add the integer in here. The only places where SROA is
> +  // preserved either cannot fire on an integer, or won't in-and-of themselves
> +  // disable SROA (ext) w/o some later use that we would see and disable.
> +  Value *SROAArg;
> +  DenseMap<Value *, int>::iterator CostIt;
> +  if (lookupSROAArgAndCost(I.getOperand(0), SROAArg, CostIt))
> +    SROAArgValues[&I] = SROAArg;
> +
> +  // A ptrtoint cast is free so long as the result is large enough to store the
> +  // pointer, and a legal integer type.
> +  return TD && TD->isLegalInteger(IntegerSize) &&
> +         IntegerSize >= TD->getPointerSizeInBits();
> +}
> +
> +bool CallAnalyzer::visitIntToPtr(IntToPtrInst &I) {
> +  // Propagate constants through ptrtoint.
> +  if (Constant *COp = dyn_cast<Constant>(I.getOperand(0)))
> +    if (Constant *C = ConstantExpr::getIntToPtr(COp, I.getType())) {
> +      SimplifiedValues[&I] = C;
> +      return true;
> +    }
> +
> +  // Track base/offset pairs when round-tripped through a pointer without
> +  // modifications provided the integer is not too large.
> +  Value *Op = I.getOperand(0);
> +  unsigned IntegerSize = Op->getType()->getScalarSizeInBits();
> +  if (TD && IntegerSize <= TD->getPointerSizeInBits()) {
> +    std::pair<Value *, APInt> BaseAndOffset = ConstantOffsetPtrs.lookup(Op);
> +    if (BaseAndOffset.first)
> +      ConstantOffsetPtrs[&I] = BaseAndOffset;
> +  }
> +
> +  // "Propagate" SROA here in the same manner as we do for ptrtoint above.
> +  Value *SROAArg;
> +  DenseMap<Value *, int>::iterator CostIt;
> +  if (lookupSROAArgAndCost(Op, SROAArg, CostIt))
> +    SROAArgValues[&I] = SROAArg;
> +
> +  // An inttoptr cast is free so long as the input is a legal integer type
> +  // which doesn't contain values outside the range of a pointer.
> +  return TD && TD->isLegalInteger(IntegerSize) &&
> +         IntegerSize <= TD->getPointerSizeInBits();
> +}
> +
> +bool CallAnalyzer::visitCastInst(CastInst &I) {
> +  // Propagate constants through ptrtoint.
> +  if (Constant *COp = dyn_cast<Constant>(I.getOperand(0)))
> +    if (Constant *C = ConstantExpr::getCast(I.getOpcode(), COp, I.getType())) {
> +      SimplifiedValues[&I] = C;
> +      return true;
> +    }
> +
> +  // Disable SROA in the face of arbitrary casts we don't whitelist elsewhere.
> +  disableSROA(I.getOperand(0));
> +
> +  // No-op casts don't have any cost.
> +  if (I.isLosslessCast())
> +    return true;
> +
> +  // trunc to a native type is free (assuming the target has compare and
> +  // shift-right of the same width).
> +  if (TD && isa<TruncInst>(I) &&
> +      TD->isLegalInteger(TD->getTypeSizeInBits(I.getType())))
> +    return true;
> +
> +  // Result of a cmp instruction is often extended (to be used by other
> +  // cmp instructions, logical or return instructions). These are usually
> +  // no-ops on most sane targets.
> +  if (isa<CmpInst>(I.getOperand(0)))
> +    return true;
> +
> +  // Assume the rest of the casts require work.
> +  return false;
> }
> 
> -static unsigned countCodeReductionForAllocaICmp(const CodeMetrics &Metrics,
> -                                                ICmpInst *ICI) {
> -  unsigned Reduction = 0;
> +bool CallAnalyzer::visitUnaryInstruction(UnaryInstruction &I) {
> +  Value *Operand = I.getOperand(0);
> +  Constant *Ops[1] = { dyn_cast<Constant>(Operand) };
> +  if (Ops[0] || (Ops[0] = SimplifiedValues.lookup(Operand)))
> +    if (Constant *C = ConstantFoldInstOperands(I.getOpcode(), I.getType(),
> +                                               Ops, TD)) {
> +      SimplifiedValues[&I] = C;
> +      return true;
> +    }
> 
> -  // Bail if this is comparing against a non-constant; there is nothing we can
> -  // do there.
> -  if (!isa<Constant>(ICI->getOperand(1)))
> -    return Reduction;
> +  // Disable any SROA on the argument to arbitrary unary operators.
> +  disableSROA(Operand);
> 
> -  // An icmp pred (alloca, C) becomes true if the predicate is true when
> -  // equal and false otherwise.
> -  bool Result = ICI->isTrueWhenEqual();
> +  return false;
> +}
> 
> -  SmallVector<Instruction *, 4> Worklist;
> -  Worklist.push_back(ICI);
> -  do {
> -    Instruction *U = Worklist.pop_back_val();
> -    Reduction += InlineConstants::InstrCost;
> -    for (Value::use_iterator UI = U->use_begin(), UE = U->use_end();
> -         UI != UE; ++UI) {
> -      Instruction *I = dyn_cast<Instruction>(*UI);
> -      if (!I || I->mayHaveSideEffects()) continue;
> -      if (I->getNumOperands() == 1)
> -        Worklist.push_back(I);
> -      if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
> -        // If BO produces the same value as U, then the other operand is
> -        // irrelevant and we can put it into the Worklist to continue
> -        // deleting dead instructions. If BO produces the same value as the
> -        // other operand, we can delete BO but that's it.
> -        if (Result == true) {
> -          if (BO->getOpcode() == Instruction::Or)
> -            Worklist.push_back(I);
> -          if (BO->getOpcode() == Instruction::And)
> -            Reduction += InlineConstants::InstrCost;
> -        } else {
> -          if (BO->getOpcode() == Instruction::Or ||
> -              BO->getOpcode() == Instruction::Xor)
> -            Reduction += InlineConstants::InstrCost;
> -          if (BO->getOpcode() == Instruction::And)
> -            Worklist.push_back(I);
> -        }
> +bool CallAnalyzer::visitICmp(ICmpInst &I) {
> +  Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
> +  // First try to handle simplified comparisons.
> +  if (!isa<Constant>(LHS))
> +    if (Constant *SimpleLHS = SimplifiedValues.lookup(LHS))
> +      LHS = SimpleLHS;
> +  if (!isa<Constant>(RHS))
> +    if (Constant *SimpleRHS = SimplifiedValues.lookup(RHS))
> +      RHS = SimpleRHS;
> +  if (Constant *CLHS = dyn_cast<Constant>(LHS))
> +    if (Constant *CRHS = dyn_cast<Constant>(RHS))
> +      if (Constant *C = ConstantExpr::getICmp(I.getPredicate(), CLHS, CRHS)) {
> +        SimplifiedValues[&I] = C;
> +        return true;
>       }
> -      if (BranchInst *BI = dyn_cast<BranchInst>(I)) {
> -        BasicBlock *BB = BI->getSuccessor(Result ? 0 : 1);
> -        if (BB->getSinglePredecessor())
> -          Reduction
> -            += InlineConstants::InstrCost * Metrics.NumBBInsts.lookup(BB);
> +
> +  // Otherwise look for a comparison between constant offset pointers with
> +  // a common base.
> +  Value *LHSBase, *RHSBase;
> +  APInt LHSOffset, RHSOffset;
> +  llvm::tie(LHSBase, LHSOffset) = ConstantOffsetPtrs.lookup(LHS);
> +  if (LHSBase) {
> +    llvm::tie(RHSBase, RHSOffset) = ConstantOffsetPtrs.lookup(RHS);
> +    if (RHSBase && LHSBase == RHSBase) {
> +      // We have common bases, fold the icmp to a constant based on the
> +      // offsets.
> +      Constant *CLHS = ConstantInt::get(LHS->getContext(), LHSOffset);
> +      Constant *CRHS = ConstantInt::get(RHS->getContext(), RHSOffset);
> +      if (Constant *C = ConstantExpr::getICmp(I.getPredicate(), CLHS, CRHS)) {
> +        SimplifiedValues[&I] = C;
> +        ++NumConstantPtrCmps;
> +        return true;
>       }
>     }
> -  } while (!Worklist.empty());
> +  }
> 
> -  return Reduction;
> -}
> +  // If the comparison is an equality comparison with null, we can simplify it
> +  // for any alloca-derived argument.
> +  if (I.isEquality() && isa<ConstantPointerNull>(I.getOperand(1)))
> +    if (isAllocaDerivedArg(I.getOperand(0))) {
> +      // We can actually predict the result of comparisons between an
> +      // alloca-derived value and null. Note that this fires regardless of
> +      // SROA firing.
> +      bool IsNotEqual = I.getPredicate() == CmpInst::ICMP_NE;
> +      SimplifiedValues[&I] = IsNotEqual ? ConstantInt::getTrue(I.getType())
> +                                        : ConstantInt::getFalse(I.getType());
> +      return true;
> +    }
> 
> -/// \brief Compute the reduction possible for a given instruction if we are able
> -/// to SROA an alloca.
> -///
> -/// The reduction for this instruction is added to the SROAReduction output
> -/// parameter. Returns false if this instruction is expected to defeat SROA in
> -/// general.
> -static bool countCodeReductionForSROAInst(Instruction *I,
> -                                          SmallVectorImpl<Value *> &Worklist,
> -                                          unsigned &SROAReduction) {
> -  if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
> -    if (!LI->isSimple())
> -      return false;
> -    SROAReduction += InlineConstants::InstrCost;
> -    return true;
> +  // Finally check for SROA candidates in comparisons.
> +  Value *SROAArg;
> +  DenseMap<Value *, int>::iterator CostIt;
> +  if (lookupSROAArgAndCost(I.getOperand(0), SROAArg, CostIt)) {
> +    if (isa<ConstantPointerNull>(I.getOperand(1))) {
> +      accumulateSROACost(CostIt, InlineConstants::InstrCost);
> +      return true;
> +    }
> +
> +    disableSROA(CostIt);
>   }
> 
> -  if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
> -    if (!SI->isSimple())
> -      return false;
> -    SROAReduction += InlineConstants::InstrCost;
> -    return true;
> +  return false;
> +}
> +
> +bool CallAnalyzer::visitSub(BinaryOperator &I) {
> +  // Try to handle a special case: we can fold computing the difference of two
> +  // constant-related pointers.
> +  Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
> +  Value *LHSBase, *RHSBase;
> +  APInt LHSOffset, RHSOffset;
> +  llvm::tie(LHSBase, LHSOffset) = ConstantOffsetPtrs.lookup(LHS);
> +  if (LHSBase) {
> +    llvm::tie(RHSBase, RHSOffset) = ConstantOffsetPtrs.lookup(RHS);
> +    if (RHSBase && LHSBase == RHSBase) {
> +      // We have common bases, fold the subtract to a constant based on the
> +      // offsets.
> +      Constant *CLHS = ConstantInt::get(LHS->getContext(), LHSOffset);
> +      Constant *CRHS = ConstantInt::get(RHS->getContext(), RHSOffset);
> +      if (Constant *C = ConstantExpr::getSub(CLHS, CRHS)) {
> +        SimplifiedValues[&I] = C;
> +        ++NumConstantPtrDiffs;
> +        return true;
> +      }
> +    }
>   }
> 
> -  if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(I)) {
> -    // If the GEP has variable indices, we won't be able to do much with it.
> -    if (!GEP->hasAllConstantIndices())
> -      return false;
> -    // A non-zero GEP will likely become a mask operation after SROA.
> -    if (GEP->hasAllZeroIndices())
> -      SROAReduction += InlineConstants::InstrCost;
> -    Worklist.push_back(GEP);
> +  // Otherwise, fall back to the generic logic for simplifying and handling
> +  // instructions.
> +  return Base::visitSub(I);
> +}
> +
> +bool CallAnalyzer::visitBinaryOperator(BinaryOperator &I) {
> +  Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
> +  if (!isa<Constant>(LHS))
> +    if (Constant *SimpleLHS = SimplifiedValues.lookup(LHS))
> +      LHS = SimpleLHS;
> +  if (!isa<Constant>(RHS))
> +    if (Constant *SimpleRHS = SimplifiedValues.lookup(RHS))
> +      RHS = SimpleRHS;
> +  Value *SimpleV = SimplifyBinOp(I.getOpcode(), LHS, RHS, TD);
> +  if (Constant *C = dyn_cast_or_null<Constant>(SimpleV)) {
> +    SimplifiedValues[&I] = C;
>     return true;
>   }
> 
> -  if (BitCastInst *BCI = dyn_cast<BitCastInst>(I)) {
> -    // Track pointer through bitcasts.
> -    Worklist.push_back(BCI);
> -    SROAReduction += InlineConstants::InstrCost;
> -    return true;
> +  // Disable any SROA on arguments to arbitrary, unsimplified binary operators.
> +  disableSROA(LHS);
> +  disableSROA(RHS);
> +
> +  return false;
> +}
> +
> +bool CallAnalyzer::visitLoad(LoadInst &I) {
> +  Value *SROAArg;
> +  DenseMap<Value *, int>::iterator CostIt;
> +  if (lookupSROAArgAndCost(I.getOperand(0), SROAArg, CostIt)) {
> +    if (I.isSimple()) {
> +      accumulateSROACost(CostIt, InlineConstants::InstrCost);
> +      return true;
> +    }
> +
> +    disableSROA(CostIt);
>   }
> 
> -  // We just look for non-constant operands to ICmp instructions as those will
> -  // defeat SROA. The actual reduction for these happens even without SROA.
> -  if (ICmpInst *ICI = dyn_cast<ICmpInst>(I))
> -    return isa<Constant>(ICI->getOperand(1));
> -
> -  if (SelectInst *SI = dyn_cast<SelectInst>(I)) {
> -    // SROA can handle a select of alloca iff all uses of the alloca are
> -    // loads, and dereferenceable. We assume it's dereferenceable since
> -    // we're told the input is an alloca.
> -    for (Value::use_iterator UI = SI->use_begin(), UE = SI->use_end();
> -         UI != UE; ++UI) {
> -      LoadInst *LI = dyn_cast<LoadInst>(*UI);
> -      if (LI == 0 || !LI->isSimple())
> -        return false;
> +  return false;
> +}
> +
> +bool CallAnalyzer::visitStore(StoreInst &I) {
> +  Value *SROAArg;
> +  DenseMap<Value *, int>::iterator CostIt;
> +  if (lookupSROAArgAndCost(I.getOperand(0), SROAArg, CostIt)) {
> +    if (I.isSimple()) {
> +      accumulateSROACost(CostIt, InlineConstants::InstrCost);
> +      return true;
>     }
> -    // We don't know whether we'll be deleting the rest of the chain of
> -    // instructions from the SelectInst on, because we don't know whether
> -    // the other side of the select is also an alloca or not.
> -    return true;
> +
> +    disableSROA(CostIt);
> +  }
> +
> +  return false;
> +}
> +
> +bool CallAnalyzer::visitCallSite(CallSite CS) {
> +  if (CS.isCall() && cast<CallInst>(CS.getInstruction())->canReturnTwice() &&
> +      !F.hasFnAttr(Attribute::ReturnsTwice)) {
> +    // This aborts the entire analysis.
> +    ExposesReturnsTwice = true;
> +    return false;
>   }
> 
> -  if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) {
> +  if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(CS.getInstruction())) {
>     switch (II->getIntrinsicID()) {
>     default:
> -      return false;
> +      return Base::visitCallSite(CS);
> +
> +    case Intrinsic::dbg_declare:
> +    case Intrinsic::dbg_value:
> +    case Intrinsic::invariant_start:
> +    case Intrinsic::invariant_end:
> +    case Intrinsic::lifetime_start:
> +    case Intrinsic::lifetime_end:
>     case Intrinsic::memset:
>     case Intrinsic::memcpy:
>     case Intrinsic::memmove:
> -    case Intrinsic::lifetime_start:
> -    case Intrinsic::lifetime_end:
> -      // SROA can usually chew through these intrinsics.
> -      SROAReduction += InlineConstants::InstrCost;
> +    case Intrinsic::objectsize:
> +    case Intrinsic::ptr_annotation:
> +    case Intrinsic::var_annotation:
> +      // SROA can usually chew through these intrinsics and they have no cost
> +      // so don't pay the price of analyzing them in detail.
>       return true;
>     }
>   }
> 
> -  // If there is some other strange instruction, we're not going to be
> -  // able to do much if we inline this.
> +  if (Function *F = CS.getCalledFunction()) {
> +    if (F == CS.getInstruction()->getParent()->getParent()) {
> +      // This flag will fully abort the analysis, so don't bother with anything
> +      // else.
> +      IsRecursive = true;
> +      return false;
> +    }
> +
> +    if (!callIsSmall(F)) {
> +      // We account for the average 1 instruction per call argument setup
> +      // here.
> +      Cost += CS.arg_size() * InlineConstants::InstrCost;
> +
> +      // Everything other than inline ASM will also have a significant cost
> +      // merely from making the call.
> +      if (!isa<InlineAsm>(CS.getCalledValue()))
> +        Cost += InlineConstants::CallPenalty;
> +    }
> +
> +    return Base::visitCallSite(CS);
> +  }
> +
> +  // Otherwise we're in a very special case -- an indirect function call. See
> +  // if we can be particularly clever about this.
> +  Value *Callee = CS.getCalledValue();
> +
> +  // First, pay the price of the argument setup. We account for the average
> +  // 1 instruction per call argument setup here.
> +  Cost += CS.arg_size() * InlineConstants::InstrCost;
> +
> +  // Next, check if this happens to be an indirect function call to a known
> +  // function in this inline context. If not, we've done all we can.
> +  Function *F = dyn_cast_or_null<Function>(SimplifiedValues.lookup(Callee));
> +  if (!F)
> +    return Base::visitCallSite(CS);
> +
> +  // If we have a constant that we are calling as a function, we can peer
> +  // through it and see the function target. This happens not infrequently
> +  // during devirtualization and so we want to give it a hefty bonus for
> +  // inlining, but cap that bonus in the event that inlining wouldn't pan
> +  // out. Pretend to inline the function, with a custom threshold.
> +  CallAnalyzer CA(TD, *F, InlineConstants::IndirectCallThreshold);
> +  if (CA.analyzeCall(CS)) {
> +    // We were able to inline the indirect call! Subtract the cost from the
> +    // bonus we want to apply, but don't go below zero.
> +    Cost -= std::max(0, InlineConstants::IndirectCallThreshold - CA.getCost());
> +  }
> +
> +  return Base::visitCallSite(CS);
> +}
> +
> +bool CallAnalyzer::visitInstruction(Instruction &I) {
> +  // We found something we don't understand or can't handle. Mark any SROA-able
> +  // values in the operand list as no longer viable.
> +  for (User::op_iterator OI = I.op_begin(), OE = I.op_end(); OI != OE; ++OI)
> +    disableSROA(*OI);
> +
>   return false;
> }
> 
> -unsigned InlineCostAnalyzer::FunctionInfo::countCodeReductionForAlloca(
> -    const CodeMetrics &Metrics, Value *V) {
> -  if (!V->getType()->isPointerTy()) return 0;  // Not a pointer
> -  unsigned Reduction = 0;
> -  unsigned SROAReduction = 0;
> -  bool CanSROAAlloca = true;
> 
> -  SmallVector<Value *, 4> Worklist;
> -  Worklist.push_back(V);
> -  do {
> -    Value *V = Worklist.pop_back_val();
> -    for (Value::use_iterator UI = V->use_begin(), E = V->use_end();
> -         UI != E; ++UI){
> -      Instruction *I = cast<Instruction>(*UI);
> +/// \brief Analyze a basic block for its contribution to the inline cost.
> +///
> +/// This method walks the analyzer over every instruction in the given basic
> +/// block and accounts for their cost during inlining at this callsite. It
> +/// aborts early if the threshold has been exceeded or an impossible to inline
> +/// construct has been detected. It returns false if inlining is no longer
> +/// viable, and true if inlining remains viable.
> +bool CallAnalyzer::analyzeBlock(BasicBlock *BB) {
> +  for (BasicBlock::iterator I = BB->begin(), E = llvm::prior(BB->end());
> +       I != E; ++I) {
> +    ++NumInstructions;
> +    if (isa<ExtractElementInst>(I) || I->getType()->isVectorTy())
> +      ++NumVectorInstructions;
> +
> +    // If the instruction simplified to a constant, there is no cost to this
> +    // instruction. Visit the instructions using our InstVisitor to account for
> +    // all of the per-instruction logic. The visit tree returns true if we
> +    // consumed the instruction in any way, and false if the instruction's base
> +    // cost should count against inlining.
> +    if (Base::visit(I))
> +      ++NumInstructionsSimplified;
> +    else
> +      Cost += InlineConstants::InstrCost;
> 
> -      if (ICmpInst *ICI = dyn_cast<ICmpInst>(I))
> -        Reduction += countCodeReductionForAllocaICmp(Metrics, ICI);
> +    // If the visit this instruction detected an uninlinable pattern, abort.
> +    if (IsRecursive || ExposesReturnsTwice || HasDynamicAlloca)
> +      return false;
> 
> -      if (CanSROAAlloca)
> -        CanSROAAlloca = countCodeReductionForSROAInst(I, Worklist,
> -                                                      SROAReduction);
> -    }
> -  } while (!Worklist.empty());
> +    if (NumVectorInstructions > NumInstructions/2)
> +      VectorBonus = FiftyPercentVectorBonus;
> +    else if (NumVectorInstructions > NumInstructions/10)
> +      VectorBonus = TenPercentVectorBonus;
> +    else
> +      VectorBonus = 0;
> +
> +    // Check if we've past the threshold so we don't spin in huge basic
> +    // blocks that will never inline.
> +    if (!AlwaysInline && Cost > (Threshold + VectorBonus))
> +      return false;
> +  }
> 
> -  return Reduction + (CanSROAAlloca ? SROAReduction : 0);
> +  return true;
> }
> 
> -void InlineCostAnalyzer::FunctionInfo::countCodeReductionForPointerPair(
> -    const CodeMetrics &Metrics, DenseMap<Value *, unsigned> &PointerArgs,
> -    Value *V, unsigned ArgIdx) {
> -  SmallVector<Value *, 4> Worklist;
> -  Worklist.push_back(V);
> +/// \brief Compute the base pointer and cumulative constant offsets for V.
> +///
> +/// This strips all constant offsets off of V, leaving it the base pointer, and
> +/// accumulates the total constant offset applied in the returned constant. It
> +/// returns 0 if V is not a pointer, and returns the constant '0' if there are
> +/// no constant offsets applied.
> +ConstantInt *CallAnalyzer::stripAndComputeInBoundsConstantOffsets(Value *&V) {
> +  if (!TD || !V->getType()->isPointerTy())
> +    return 0;
> +
> +  unsigned IntPtrWidth = TD->getPointerSizeInBits();
> +  APInt Offset = APInt::getNullValue(IntPtrWidth);
> +
> +  // Even though we don't look through PHI nodes, we could be called on an
> +  // instruction in an unreachable block, which may be on a cycle.
> +  SmallPtrSet<Value *, 4> Visited;
> +  Visited.insert(V);
>   do {
> -    Value *V = Worklist.pop_back_val();
> -    for (Value::use_iterator UI = V->use_begin(), E = V->use_end();
> -         UI != E; ++UI){
> -      Instruction *I = cast<Instruction>(*UI);
> -
> -      if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(I)) {
> -        // If the GEP has variable indices, we won't be able to do much with it.
> -        if (!GEP->hasAllConstantIndices())
> -          continue;
> -        // Unless the GEP is in-bounds, some comparisons will be non-constant.
> -        // Fortunately, the real-world cases where this occurs uses in-bounds
> -        // GEPs, and so we restrict the optimization to them here.
> -        if (!GEP->isInBounds())
> -          continue;
> +    if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
> +      if (!GEP->isInBounds() || !accumulateGEPOffset(*GEP, Offset))
> +        return 0;
> +      V = GEP->getPointerOperand();
> +    } else if (Operator::getOpcode(V) == Instruction::BitCast) {
> +      V = cast<Operator>(V)->getOperand(0);
> +    } else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) {
> +      if (GA->mayBeOverridden())
> +        break;
> +      V = GA->getAliasee();
> +    } else {
> +      break;
> +    }
> +    assert(V->getType()->isPointerTy() && "Unexpected operand type!");
> +  } while (Visited.insert(V));
> 
> -        // Constant indices just change the constant offset. Add the resulting
> -        // value both to our worklist for this argument, and to the set of
> -        // viable paired values with future arguments.
> -        PointerArgs[GEP] = ArgIdx;
> -        Worklist.push_back(GEP);
> -        continue;
> -      }
> +  Type *IntPtrTy = TD->getIntPtrType(V->getContext());
> +  return cast<ConstantInt>(ConstantInt::get(IntPtrTy, Offset));
> +}
> 
> -      // Track pointer through casts. Even when the result is not a pointer, it
> -      // remains a constant relative to constants derived from other constant
> -      // pointers.
> -      if (CastInst *CI = dyn_cast<CastInst>(I)) {
> -        PointerArgs[CI] = ArgIdx;
> -        Worklist.push_back(CI);
> -        continue;
> -      }
> +/// \brief Analyze a call site for potential inlining.
> +///
> +/// Returns true if inlining this call is viable, and false if it is not
> +/// viable. It computes the cost and adjusts the threshold based on numerous
> +/// factors and heuristics. If this method returns false but the computed cost
> +/// is below the computed threshold, then inlining was forcibly disabled by
> +/// some artifact of the rountine.
> +bool CallAnalyzer::analyzeCall(CallSite CS) {
> +  // Track whether the post-inlining function would have more than one basic
> +  // block. A single basic block is often intended for inlining. Balloon the
> +  // threshold by 50% until we pass the single-BB phase.
> +  bool SingleBB = true;
> +  int SingleBBBonus = Threshold / 2;
> +  Threshold += SingleBBBonus;
> +
> +  // Unless we are always-inlining, perform some tweaks to the cost and
> +  // threshold based on the direct callsite information.
> +  if (!AlwaysInline) {
> +    // We want to more aggressively inline vector-dense kernels, so up the
> +    // threshold, and we'll lower it if the % of vector instructions gets too
> +    // low.
> +    assert(NumInstructions == 0);
> +    assert(NumVectorInstructions == 0);
> +    FiftyPercentVectorBonus = Threshold;
> +    TenPercentVectorBonus = Threshold / 2;
> +
> +    // Subtract off one instruction per call argument as those will be free after
> +    // inlining.
> +    Cost -= CS.arg_size() * InlineConstants::InstrCost;
> +
> +    // If there is only one call of the function, and it has internal linkage,
> +    // the cost of inlining it drops dramatically.
> +    if (F.hasLocalLinkage() && F.hasOneUse() && &F == CS.getCalledFunction())
> +      Cost += InlineConstants::LastCallToStaticBonus;
> +
> +    // If the instruction after the call, or if the normal destination of the
> +    // invoke is an unreachable instruction, the function is noreturn.  As such,
> +    // there is little point in inlining this unless there is literally zero cost.
> +    if (InvokeInst *II = dyn_cast<InvokeInst>(CS.getInstruction())) {
> +      if (isa<UnreachableInst>(II->getNormalDest()->begin()))
> +        Threshold = 1;
> +    } else if (isa<UnreachableInst>(++BasicBlock::iterator(CS.getInstruction())))
> +      Threshold = 1;
> +
> +    // If this function uses the coldcc calling convention, prefer not to inline
> +    // it.
> +    if (F.getCallingConv() == CallingConv::Cold)
> +      Cost += InlineConstants::ColdccPenalty;
> 
> -      // There are two instructions which produce a strict constant value when
> -      // applied to two related pointer values. Ignore everything else.
> -      if (!isa<ICmpInst>(I) && I->getOpcode() != Instruction::Sub)
> -        continue;
> -      assert(I->getNumOperands() == 2);
> +    // Check if we're done. This can happen due to bonuses and penalties.
> +    if (Cost > Threshold)
> +      return false;
> +  }
> 
> -      // Ensure that the two operands are in our set of potentially paired
> -      // pointers (or are derived from them).
> -      Value *OtherArg = I->getOperand(0);
> -      if (OtherArg == V)
> -        OtherArg = I->getOperand(1);
> -      DenseMap<Value *, unsigned>::const_iterator ArgIt
> -        = PointerArgs.find(OtherArg);
> -      if (ArgIt == PointerArgs.end())
> -        continue;
> -      std::pair<unsigned, unsigned> ArgPair(ArgIt->second, ArgIdx);
> -      if (ArgPair.first > ArgPair.second)
> -        std::swap(ArgPair.first, ArgPair.second);
> -
> -      PointerArgPairWeights[ArgPair]
> -        += countCodeReductionForConstant(Metrics, I);
> -    }
> -  } while (!Worklist.empty());
> -}
> -
> -/// analyzeFunction - Fill in the current structure with information gleaned
> -/// from the specified function.
> -void InlineCostAnalyzer::FunctionInfo::analyzeFunction(Function *F,
> -                                                       const TargetData *TD) {
> -  Metrics.analyzeFunction(F, TD);
> -
> -  // A function with exactly one return has it removed during the inlining
> -  // process (see InlineFunction), so don't count it.
> -  // FIXME: This knowledge should really be encoded outside of FunctionInfo.
> -  if (Metrics.NumRets==1)
> -    --Metrics.NumInsts;
> -
> -  ArgumentWeights.reserve(F->arg_size());
> -  DenseMap<Value *, unsigned> PointerArgs;
> -  unsigned ArgIdx = 0;
> -  for (Function::arg_iterator I = F->arg_begin(), E = F->arg_end(); I != E;
> -       ++I, ++ArgIdx) {
> -    // Count how much code can be eliminated if one of the arguments is
> -    // a constant or an alloca.
> -    ArgumentWeights.push_back(ArgInfo(countCodeReductionForConstant(Metrics, I),
> -                                      countCodeReductionForAlloca(Metrics, I)));
> -
> -    // If the argument is a pointer, also check for pairs of pointers where
> -    // knowing a fixed offset between them allows simplification. This pattern
> -    // arises mostly due to STL algorithm patterns where pointers are used as
> -    // random access iterators.
> -    if (!I->getType()->isPointerTy())
> -      continue;
> -    PointerArgs[I] = ArgIdx;
> -    countCodeReductionForPointerPair(Metrics, PointerArgs, I, ArgIdx);
> +  if (F.empty())
> +    return true;
> +
> +  // Track whether we've seen a return instruction. The first return
> +  // instruction is free, as at least one will usually disappear in inlining.
> +  bool HasReturn = false;
> +
> +  // Populate our simplified values by mapping from function arguments to call
> +  // arguments with known important simplifications.
> +  CallSite::arg_iterator CAI = CS.arg_begin();
> +  for (Function::arg_iterator FAI = F.arg_begin(), FAE = F.arg_end();
> +       FAI != FAE; ++FAI, ++CAI) {
> +    assert(CAI != CS.arg_end());
> +    if (Constant *C = dyn_cast<Constant>(CAI))
> +      SimplifiedValues[FAI] = C;
> +
> +    Value *PtrArg = *CAI;
> +    if (ConstantInt *C = stripAndComputeInBoundsConstantOffsets(PtrArg)) {
> +      ConstantOffsetPtrs[FAI] = std::make_pair(PtrArg, C->getValue());
> +
> +      // We can SROA any pointer arguments derived from alloca instructions.
> +      if (isa<AllocaInst>(PtrArg)) {
> +        SROAArgValues[FAI] = PtrArg;
> +        SROAArgCosts[PtrArg] = 0;
> +      }
> +    }
>   }
> -}
> +  NumConstantArgs = SimplifiedValues.size();
> +  NumConstantOffsetPtrArgs = ConstantOffsetPtrs.size();
> +  NumAllocaArgs = SROAArgValues.size();
> +
> +  // The worklist of live basic blocks in the callee *after* inlining. We avoid
> +  // adding basic blocks of the callee which can be proven to be dead for this
> +  // particular call site in order to get more accurate cost estimates. This
> +  // requires a somewhat heavyweight iteration pattern: we need to walk the
> +  // basic blocks in a breadth-first order as we insert live successors. To
> +  // accomplish this, prioritizing for small iterations because we exit after
> +  // crossing our threshold, we use a small-size optimized SetVector.
> +  typedef SetVector<BasicBlock *, SmallVector<BasicBlock *, 16>,
> +                                  SmallPtrSet<BasicBlock *, 16> > BBSetVector;
> +  BBSetVector BBWorklist;
> +  BBWorklist.insert(&F.getEntryBlock());
> +  // Note that we *must not* cache the size, this loop grows the worklist.
> +  for (unsigned Idx = 0; Idx != BBWorklist.size(); ++Idx) {
> +    // Bail out the moment we cross the threshold. This means we'll under-count
> +    // the cost, but only when undercounting doesn't matter.
> +    if (!AlwaysInline && Cost > (Threshold + VectorBonus))
> +      break;
> 
> -/// NeverInline - returns true if the function should never be inlined into
> -/// any caller
> -bool InlineCostAnalyzer::FunctionInfo::NeverInline() {
> -  return (Metrics.exposesReturnsTwice || Metrics.isRecursive ||
> -          Metrics.containsIndirectBr);
> -}
> -
> -// ConstantFunctionBonus - Figure out how much of a bonus we can get for
> -// possibly devirtualizing a function. We'll subtract the size of the function
> -// we may wish to inline from the indirect call bonus providing a limit on
> -// growth. Leave an upper limit of 0 for the bonus - we don't want to penalize
> -// inlining because we decide we don't want to give a bonus for
> -// devirtualizing.
> -int InlineCostAnalyzer::ConstantFunctionBonus(CallSite CS, Constant *C) {
> -
> -  // This could just be NULL.
> -  if (!C) return 0;
> -
> -  Function *F = dyn_cast<Function>(C);
> -  if (!F) return 0;
> -
> -  int Bonus = InlineConstants::IndirectCallBonus + getInlineSize(CS, F);
> -  return (Bonus > 0) ? 0 : Bonus;
> -}
> -
> -// CountBonusForConstant - Figure out an approximation for how much per-call
> -// performance boost we can expect if the specified value is constant.
> -int InlineCostAnalyzer::CountBonusForConstant(Value *V, Constant *C) {
> -  unsigned Bonus = 0;
> -  for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI != E;++UI){
> -    User *U = *UI;
> -    if (CallInst *CI = dyn_cast<CallInst>(U)) {
> -      // Turning an indirect call into a direct call is a BIG win
> -      if (CI->getCalledValue() == V)
> -        Bonus += ConstantFunctionBonus(CallSite(CI), C);
> -    } else if (InvokeInst *II = dyn_cast<InvokeInst>(U)) {
> -      // Turning an indirect call into a direct call is a BIG win
> -      if (II->getCalledValue() == V)
> -        Bonus += ConstantFunctionBonus(CallSite(II), C);
> -    }
> -    // FIXME: Eliminating conditional branches and switches should
> -    // also yield a per-call performance boost.
> -    else {
> -      // Figure out the bonuses that wll accrue due to simple constant
> -      // propagation.
> -      Instruction &Inst = cast<Instruction>(*U);
> -
> -      // We can't constant propagate instructions which have effects or
> -      // read memory.
> -      //
> -      // FIXME: It would be nice to capture the fact that a load from a
> -      // pointer-to-constant-global is actually a *really* good thing to zap.
> -      // Unfortunately, we don't know the pointer that may get propagated here,
> -      // so we can't make this decision.
> -      if (Inst.mayReadFromMemory() || Inst.mayHaveSideEffects() ||
> -          isa<AllocaInst>(Inst))
> -        continue;
> +    BasicBlock *BB = BBWorklist[Idx];
> +    if (BB->empty())
> +      continue;
> 
> -      bool AllOperandsConstant = true;
> -      for (unsigned i = 0, e = Inst.getNumOperands(); i != e; ++i)
> -        if (!isa<Constant>(Inst.getOperand(i)) && Inst.getOperand(i) != V) {
> -          AllOperandsConstant = false;
> -          break;
> +    // Handle the terminator cost here where we can track returns and other
> +    // function-wide constructs.
> +    TerminatorInst *TI = BB->getTerminator();
> +
> +    // We never want to inline functions that contain an indirectbr.  This is
> +    // incorrect because all the blockaddress's (in static global initializers
> +    // for example) would be referring to the original function, and this indirect
> +    // jump would jump from the inlined copy of the function into the original
> +    // function which is extremely undefined behavior.
> +    // FIXME: This logic isn't really right; we can safely inline functions
> +    // with indirectbr's as long as no other function or global references the
> +    // blockaddress of a block within the current function.  And as a QOI issue,
> +    // if someone is using a blockaddress without an indirectbr, and that
> +    // reference somehow ends up in another function or global, we probably
> +    // don't want to inline this function.
> +    if (isa<IndirectBrInst>(TI))
> +      return false;
> +
> +    if (!HasReturn && isa<ReturnInst>(TI))
> +      HasReturn = true;
> +    else
> +      Cost += InlineConstants::InstrCost;
> +
> +    // Analyze the cost of this block. If we blow through the threshold, this
> +    // returns false, and we can bail on out.
> +    if (!analyzeBlock(BB)) {
> +      if (IsRecursive || ExposesReturnsTwice || HasDynamicAlloca)
> +        return false;
> +      break;
> +    }
> +
> +    // Add in the live successors by first checking whether we have terminator
> +    // that may be simplified based on the values simplified by this call.
> +    if (BranchInst *BI = dyn_cast<BranchInst>(TI)) {
> +      if (BI->isConditional()) {
> +        Value *Cond = BI->getCondition();
> +        if (ConstantInt *SimpleCond
> +              = dyn_cast_or_null<ConstantInt>(SimplifiedValues.lookup(Cond))) {
> +          BBWorklist.insert(BI->getSuccessor(SimpleCond->isZero() ? 1 : 0));
> +          continue;
>         }
> +      }
> +    } else if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) {
> +      Value *Cond = SI->getCondition();
> +      if (ConstantInt *SimpleCond
> +            = dyn_cast_or_null<ConstantInt>(SimplifiedValues.lookup(Cond))) {
> +        BBWorklist.insert(SI->findCaseValue(SimpleCond).getCaseSuccessor());
> +        continue;
> +      }
> +    }
> 
> -      if (AllOperandsConstant)
> -        Bonus += CountBonusForConstant(&Inst);
> +    // If we're unable to select a particular successor, just count all of
> +    // them.
> +    for (unsigned TIdx = 0, TSize = TI->getNumSuccessors(); TIdx != TSize; ++TIdx)
> +      BBWorklist.insert(TI->getSuccessor(TIdx));
> +
> +    // If we had any successors at this point, than post-inlining is likely to
> +    // have them as well. Note that we assume any basic blocks which existed
> +    // due to branches or switches which folded above will also fold after
> +    // inlining.
> +    if (SingleBB && TI->getNumSuccessors() > 1) {
> +      // Take off the bonus we applied to the threshold.
> +      Threshold -= SingleBBBonus;
> +      SingleBB = false;
>     }
>   }
> 
> -  return Bonus;
> -}
> +  Threshold += VectorBonus;
> 
> -int InlineCostAnalyzer::getInlineSize(CallSite CS, Function *Callee) {
> -  // Get information about the callee.
> -  FunctionInfo *CalleeFI = &CachedFunctionInfo[Callee];
> -
> -  // If we haven't calculated this information yet, do so now.
> -  if (CalleeFI->Metrics.NumBlocks == 0)
> -    CalleeFI->analyzeFunction(Callee, TD);
> -
> -  // InlineCost - This value measures how good of an inline candidate this call
> -  // site is to inline.  A lower inline cost make is more likely for the call to
> -  // be inlined.  This value may go negative.
> -  //
> -  int InlineCost = 0;
> -
> -  // Compute any size reductions we can expect due to arguments being passed into
> -  // the function.
> -  //
> -  unsigned ArgNo = 0;
> -  CallSite::arg_iterator I = CS.arg_begin();
> -  for (Function::arg_iterator FI = Callee->arg_begin(), FE = Callee->arg_end();
> -       FI != FE; ++I, ++FI, ++ArgNo) {
> -
> -    // If an alloca is passed in, inlining this function is likely to allow
> -    // significant future optimization possibilities (like scalar promotion, and
> -    // scalarization), so encourage the inlining of the function.
> -    //
> -    if (isa<AllocaInst>(I))
> -      InlineCost -= CalleeFI->ArgumentWeights[ArgNo].AllocaWeight;
> -
> -    // If this is a constant being passed into the function, use the argument
> -    // weights calculated for the callee to determine how much will be folded
> -    // away with this information.
> -    else if (isa<Constant>(I))
> -      InlineCost -= CalleeFI->ArgumentWeights[ArgNo].ConstantWeight;
> -  }
> -
> -  const DenseMap<std::pair<unsigned, unsigned>, unsigned> &ArgPairWeights
> -    = CalleeFI->PointerArgPairWeights;
> -  for (DenseMap<std::pair<unsigned, unsigned>, unsigned>::const_iterator I
> -         = ArgPairWeights.begin(), E = ArgPairWeights.end();
> -       I != E; ++I)
> -    if (CS.getArgument(I->first.first)->stripInBoundsConstantOffsets() ==
> -        CS.getArgument(I->first.second)->stripInBoundsConstantOffsets())
> -      InlineCost -= I->second;
> -
> -  // Each argument passed in has a cost at both the caller and the callee
> -  // sides.  Measurements show that each argument costs about the same as an
> -  // instruction.
> -  InlineCost -= (CS.arg_size() * InlineConstants::InstrCost);
> -
> -  // Now that we have considered all of the factors that make the call site more
> -  // likely to be inlined, look at factors that make us not want to inline it.
> -
> -  // Calls usually take a long time, so they make the inlining gain smaller.
> -  InlineCost += CalleeFI->Metrics.NumCalls * InlineConstants::CallPenalty;
> -
> -  // Look at the size of the callee. Each instruction counts as 5.
> -  InlineCost += CalleeFI->Metrics.NumInsts * InlineConstants::InstrCost;
> -
> -  return InlineCost;
> -}
> -
> -int InlineCostAnalyzer::getInlineBonuses(CallSite CS, Function *Callee) {
> -  // Get information about the callee.
> -  FunctionInfo *CalleeFI = &CachedFunctionInfo[Callee];
> -
> -  // If we haven't calculated this information yet, do so now.
> -  if (CalleeFI->Metrics.NumBlocks == 0)
> -    CalleeFI->analyzeFunction(Callee, TD);
> -
> -  bool isDirectCall = CS.getCalledFunction() == Callee;
> -  Instruction *TheCall = CS.getInstruction();
> -  int Bonus = 0;
> -
> -  // If there is only one call of the function, and it has internal linkage,
> -  // make it almost guaranteed to be inlined.
> -  //
> -  if (Callee->hasLocalLinkage() && Callee->hasOneUse() && isDirectCall)
> -    Bonus += InlineConstants::LastCallToStaticBonus;
> -
> -  // If the instruction after the call, or if the normal destination of the
> -  // invoke is an unreachable instruction, the function is noreturn.  As such,
> -  // there is little point in inlining this.
> -  if (InvokeInst *II = dyn_cast<InvokeInst>(TheCall)) {
> -    if (isa<UnreachableInst>(II->getNormalDest()->begin()))
> -      Bonus += InlineConstants::NoreturnPenalty;
> -  } else if (isa<UnreachableInst>(++BasicBlock::iterator(TheCall)))
> -    Bonus += InlineConstants::NoreturnPenalty;
> -
> -  // If this function uses the coldcc calling convention, prefer not to inline
> -  // it.
> -  if (Callee->getCallingConv() == CallingConv::Cold)
> -    Bonus += InlineConstants::ColdccPenalty;
> -
> -  // Add to the inline quality for properties that make the call valuable to
> -  // inline.  This includes factors that indicate that the result of inlining
> -  // the function will be optimizable.  Currently this just looks at arguments
> -  // passed into the function.
> -  //
> -  CallSite::arg_iterator I = CS.arg_begin();
> -  for (Function::arg_iterator FI = Callee->arg_begin(), FE = Callee->arg_end();
> -       FI != FE; ++I, ++FI)
> -    // Compute any constant bonus due to inlining we want to give here.
> -    if (isa<Constant>(I))
> -      Bonus += CountBonusForConstant(FI, cast<Constant>(I));
> -
> -  return Bonus;
> +  return AlwaysInline || Cost < Threshold;
> }
> 
> -// getInlineCost - The heuristic used to determine if we should inline the
> -// function call or not.
> -//
> -InlineCost InlineCostAnalyzer::getInlineCost(CallSite CS) {
> -  return getInlineCost(CS, CS.getCalledFunction());
> +/// \brief Dump stats about this call's analysis.
> +void CallAnalyzer::dump() {
> +#define DEBUG_PRINT_STAT(x) llvm::dbgs() << "      " #x ": " << x << "\n"
> +  DEBUG_PRINT_STAT(NumConstantArgs);
> +  DEBUG_PRINT_STAT(NumConstantOffsetPtrArgs);
> +  DEBUG_PRINT_STAT(NumAllocaArgs);
> +  DEBUG_PRINT_STAT(NumConstantPtrCmps);
> +  DEBUG_PRINT_STAT(NumConstantPtrDiffs);
> +  DEBUG_PRINT_STAT(NumInstructionsSimplified);
> +  DEBUG_PRINT_STAT(SROACostSavings);
> +  DEBUG_PRINT_STAT(SROACostSavingsLost);
> +#undef DEBUG_PRINT_STAT
> }
> 
> -InlineCost InlineCostAnalyzer::getInlineCost(CallSite CS, Function *Callee) {
> -  Instruction *TheCall = CS.getInstruction();
> -  Function *Caller = TheCall->getParent()->getParent();
> +InlineCost InlineCostAnalyzer::getInlineCost(CallSite CS, int Threshold) {
> +  Function *Callee = CS.getCalledFunction();
> 
>   // Don't inline functions which can be redefined at link-time to mean
>   // something else.  Don't inline functions marked noinline or call sites
>   // marked noinline.
> -  if (Callee->mayBeOverridden() || Callee->hasFnAttr(Attribute::NoInline) ||
> -      CS.isNoInline())
> +  if (!Callee || Callee->mayBeOverridden() ||
> +      Callee->hasFnAttr(Attribute::NoInline) || CS.isNoInline())
>     return llvm::InlineCost::getNever();
> 
> -  // Get information about the callee.
> -  FunctionInfo *CalleeFI = &CachedFunctionInfo[Callee];
> +  DEBUG(llvm::dbgs() << "      Analyzing call of " << Callee->getName() << "...\n");
> 
> -  // If we haven't calculated this information yet, do so now.
> -  if (CalleeFI->Metrics.NumBlocks == 0)
> -    CalleeFI->analyzeFunction(Callee, TD);
> +  CallAnalyzer CA(TD, *Callee, Threshold);
> +  bool ShouldInline = CA.analyzeCall(CS);
> 
> -  // If we should never inline this, return a huge cost.
> -  if (CalleeFI->NeverInline())
> -    return InlineCost::getNever();
> +  DEBUG(CA.dump());
> 
> -  // FIXME: It would be nice to kill off CalleeFI->NeverInline. Then we
> -  // could move this up and avoid computing the FunctionInfo for
> -  // things we are going to just return always inline for. This
> -  // requires handling setjmp somewhere else, however.
> -  if (!Callee->isDeclaration() && Callee->hasFnAttr(Attribute::AlwaysInline))
> +  // Check if there was a reason to force inlining or no inlining.
> +  if (!ShouldInline && CA.getCost() < CA.getThreshold())
> +    return InlineCost::getNever();
> +  if (ShouldInline && CA.getCost() >= CA.getThreshold())
>     return InlineCost::getAlways();
> 
> -  if (CalleeFI->Metrics.usesDynamicAlloca) {
> -    // Get information about the caller.
> -    FunctionInfo &CallerFI = CachedFunctionInfo[Caller];
> -
> -    // If we haven't calculated this information yet, do so now.
> -    if (CallerFI.Metrics.NumBlocks == 0) {
> -      CallerFI.analyzeFunction(Caller, TD);
> -
> -      // Recompute the CalleeFI pointer, getting Caller could have invalidated
> -      // it.
> -      CalleeFI = &CachedFunctionInfo[Callee];
> -    }
> -
> -    // Don't inline a callee with dynamic alloca into a caller without them.
> -    // Functions containing dynamic alloca's are inefficient in various ways;
> -    // don't create more inefficiency.
> -    if (!CallerFI.Metrics.usesDynamicAlloca)
> -      return InlineCost::getNever();
> -  }
> -
> -  // InlineCost - This value measures how good of an inline candidate this call
> -  // site is to inline.  A lower inline cost make is more likely for the call to
> -  // be inlined.  This value may go negative due to the fact that bonuses
> -  // are negative numbers.
> -  //
> -  int InlineCost = getInlineSize(CS, Callee) + getInlineBonuses(CS, Callee);
> -  return llvm::InlineCost::get(InlineCost);
> -}
> -
> -// getInlineFudgeFactor - Return a > 1.0 factor if the inliner should use a
> -// higher threshold to determine if the function call should be inlined.
> -float InlineCostAnalyzer::getInlineFudgeFactor(CallSite CS) {
> -  Function *Callee = CS.getCalledFunction();
> -
> -  // Get information about the callee.
> -  FunctionInfo &CalleeFI = CachedFunctionInfo[Callee];
> -
> -  // If we haven't calculated this information yet, do so now.
> -  if (CalleeFI.Metrics.NumBlocks == 0)
> -    CalleeFI.analyzeFunction(Callee, TD);
> -
> -  float Factor = 1.0f;
> -  // Single BB functions are often written to be inlined.
> -  if (CalleeFI.Metrics.NumBlocks == 1)
> -    Factor += 0.5f;
> -
> -  // Be more aggressive if the function contains a good chunk (if it mades up
> -  // at least 10% of the instructions) of vector instructions.
> -  if (CalleeFI.Metrics.NumVectorInsts > CalleeFI.Metrics.NumInsts/2)
> -    Factor += 2.0f;
> -  else if (CalleeFI.Metrics.NumVectorInsts > CalleeFI.Metrics.NumInsts/10)
> -    Factor += 1.5f;
> -  return Factor;
> +  return llvm::InlineCost::get(CA.getCost(), CA.getThreshold());
> }
> 
> /// growCachedCostInfo - update the cached cost info for Caller after Callee has
> /// been inlined.
> void
> InlineCostAnalyzer::growCachedCostInfo(Function *Caller, Function *Callee) {
> -  CodeMetrics &CallerMetrics = CachedFunctionInfo[Caller].Metrics;
> -
> -  // For small functions we prefer to recalculate the cost for better accuracy.
> -  if (CallerMetrics.NumBlocks < 10 && CallerMetrics.NumInsts < 1000) {
> -    resetCachedCostInfo(Caller);
> -    return;
> -  }
> -
> -  // For large functions, we can save a lot of computation time by skipping
> -  // recalculations.
> -  if (CallerMetrics.NumCalls > 0)
> -    --CallerMetrics.NumCalls;
> -
> -  if (Callee == 0) return;
> -
> -  CodeMetrics &CalleeMetrics = CachedFunctionInfo[Callee].Metrics;
> -
> -  // If we don't have metrics for the callee, don't recalculate them just to
> -  // update an approximation in the caller.  Instead, just recalculate the
> -  // caller info from scratch.
> -  if (CalleeMetrics.NumBlocks == 0) {
> -    resetCachedCostInfo(Caller);
> -    return;
> -  }
> -
> -  // Since CalleeMetrics were already calculated, we know that the CallerMetrics
> -  // reference isn't invalidated: both were in the DenseMap.
> -  CallerMetrics.usesDynamicAlloca |= CalleeMetrics.usesDynamicAlloca;
> -
> -  // FIXME: If any of these three are true for the callee, the callee was
> -  // not inlined into the caller, so I think they're redundant here.
> -  CallerMetrics.exposesReturnsTwice |= CalleeMetrics.exposesReturnsTwice;
> -  CallerMetrics.isRecursive |= CalleeMetrics.isRecursive;
> -  CallerMetrics.containsIndirectBr |= CalleeMetrics.containsIndirectBr;
> -
> -  CallerMetrics.NumInsts += CalleeMetrics.NumInsts;
> -  CallerMetrics.NumBlocks += CalleeMetrics.NumBlocks;
> -  CallerMetrics.NumCalls += CalleeMetrics.NumCalls;
> -  CallerMetrics.NumVectorInsts += CalleeMetrics.NumVectorInsts;
> -  CallerMetrics.NumRets += CalleeMetrics.NumRets;
> -
> -  // analyzeBasicBlock counts each function argument as an inst.
> -  if (CallerMetrics.NumInsts >= Callee->arg_size())
> -    CallerMetrics.NumInsts -= Callee->arg_size();
> -  else
> -    CallerMetrics.NumInsts = 0;
> -
> -  // We are not updating the argument weights. We have already determined that
> -  // Caller is a fairly large function, so we accept the loss of precision.
> }
> 
> /// clear - empty the cache of inline costs
> void InlineCostAnalyzer::clear() {
> -  CachedFunctionInfo.clear();
> }
> 
> Modified: llvm/trunk/lib/Transforms/IPO/InlineAlways.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/IPO/InlineAlways.cpp?rev=153812&r1=153811&r2=153812&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Transforms/IPO/InlineAlways.cpp (original)
> +++ llvm/trunk/lib/Transforms/IPO/InlineAlways.cpp Sat Mar 31 07:42:41 2012
> @@ -59,10 +59,7 @@
>       // We still have to check the inline cost in case there are reasons to
>       // not inline which trump the always-inline attribute such as setjmp and
>       // indirectbr.
> -      return CA.getInlineCost(CS);
> -    }
> -    float getInlineFudgeFactor(CallSite CS) {
> -      return CA.getInlineFudgeFactor(CS);
> +      return CA.getInlineCost(CS, getInlineThreshold(CS));
>     }
>     void resetCachedCostInfo(Function *Caller) {
>       CA.resetCachedCostInfo(Caller);
> 
> Modified: llvm/trunk/lib/Transforms/IPO/InlineSimple.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/IPO/InlineSimple.cpp?rev=153812&r1=153811&r2=153812&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Transforms/IPO/InlineSimple.cpp (original)
> +++ llvm/trunk/lib/Transforms/IPO/InlineSimple.cpp Sat Mar 31 07:42:41 2012
> @@ -40,10 +40,7 @@
>     }
>     static char ID; // Pass identification, replacement for typeid
>     InlineCost getInlineCost(CallSite CS) {
> -      return CA.getInlineCost(CS);
> -    }
> -    float getInlineFudgeFactor(CallSite CS) {
> -      return CA.getInlineFudgeFactor(CS);
> +      return CA.getInlineCost(CS, getInlineThreshold(CS));
>     }
>     void resetCachedCostInfo(Function *Caller) {
>       CA.resetCachedCostInfo(Caller);
> 
> Modified: llvm/trunk/lib/Transforms/IPO/Inliner.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/IPO/Inliner.cpp?rev=153812&r1=153811&r2=153812&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Transforms/IPO/Inliner.cpp (original)
> +++ llvm/trunk/lib/Transforms/IPO/Inliner.cpp Sat Mar 31 07:42:41 2012
> @@ -231,14 +231,10 @@
>     return false;
>   }
> 
> -  int Cost = IC.getValue();
>   Function *Caller = CS.getCaller();
> -  int CurrentThreshold = getInlineThreshold(CS);
> -  float FudgeFactor = getInlineFudgeFactor(CS);
> -  int AdjThreshold = (int)(CurrentThreshold * FudgeFactor);
> -  if (Cost >= AdjThreshold) {
> -    DEBUG(dbgs() << "    NOT Inlining: cost=" << Cost
> -          << ", thres=" << AdjThreshold
> +  if (!IC) {
> +    DEBUG(dbgs() << "    NOT Inlining: cost=" << IC.getCost()
> +          << ", thres=" << (IC.getCostDelta() + IC.getCost())
>           << ", Call: " << *CS.getInstruction() << "\n");
>     return false;
>   }
> @@ -255,10 +251,15 @@
>   // are used. Thus we will always have the opportunity to make local inlining
>   // decisions. Importantly the linkonce-ODR linkage covers inline functions
>   // and templates in C++.
> +  //
> +  // FIXME: All of this logic should be sunk into getInlineCost. It relies on
> +  // the internal implementation of the inline cost metrics rather than
> +  // treating them as truly abstract units etc.
>   if (Caller->hasLocalLinkage() ||
>       Caller->getLinkage() == GlobalValue::LinkOnceODRLinkage) {
>     int TotalSecondaryCost = 0;
> -    bool outerCallsFound = false;
> +    // The candidate cost to be imposed upon the current function.
> +    int CandidateCost = IC.getCost() - (InlineConstants::CallPenalty + 1);
>     // This bool tracks what happens if we do NOT inline C into B.
>     bool callerWillBeRemoved = Caller->hasLocalLinkage();
>     // This bool tracks what happens if we DO inline C into B.
> @@ -276,26 +277,19 @@
>       }
> 
>       InlineCost IC2 = getInlineCost(CS2);
> -      if (IC2.isNever())
> +      if (!IC2) {
>         callerWillBeRemoved = false;
> -      if (IC2.isAlways() || IC2.isNever())
> +        continue;
> +      }
> +      if (IC2.isAlways())
>         continue;
> 
> -      outerCallsFound = true;
> -      int Cost2 = IC2.getValue();
> -      int CurrentThreshold2 = getInlineThreshold(CS2);
> -      float FudgeFactor2 = getInlineFudgeFactor(CS2);
> -
> -      if (Cost2 >= (int)(CurrentThreshold2 * FudgeFactor2))
> -        callerWillBeRemoved = false;
> -
> -      // See if we have this case.  We subtract off the penalty
> -      // for the call instruction, which we would be deleting.
> -      if (Cost2 < (int)(CurrentThreshold2 * FudgeFactor2) &&
> -          Cost2 + Cost - (InlineConstants::CallPenalty + 1) >= 
> -                (int)(CurrentThreshold2 * FudgeFactor2)) {
> +      // See if inlining or original callsite would erase the cost delta of
> +      // this callsite. We subtract off the penalty for the call instruction,
> +      // which we would be deleting.
> +      if (IC2.getCostDelta() <= CandidateCost) {
>         inliningPreventsSomeOuterInline = true;
> -        TotalSecondaryCost += Cost2;
> +        TotalSecondaryCost += IC2.getCost();
>       }
>     }
>     // If all outer calls to Caller would get inlined, the cost for the last
> @@ -305,17 +299,16 @@
>     if (callerWillBeRemoved && Caller->use_begin() != Caller->use_end())
>       TotalSecondaryCost += InlineConstants::LastCallToStaticBonus;
> 
> -    if (outerCallsFound && inliningPreventsSomeOuterInline &&
> -        TotalSecondaryCost < Cost) {
> -      DEBUG(dbgs() << "    NOT Inlining: " << *CS.getInstruction() << 
> -           " Cost = " << Cost << 
> +    if (inliningPreventsSomeOuterInline && TotalSecondaryCost < IC.getCost()) {
> +      DEBUG(dbgs() << "    NOT Inlining: " << *CS.getInstruction() <<
> +           " Cost = " << IC.getCost() <<
>            ", outer Cost = " << TotalSecondaryCost << '\n');
>       return false;
>     }
>   }
> 
> -  DEBUG(dbgs() << "    Inlining: cost=" << Cost
> -        << ", thres=" << AdjThreshold
> +  DEBUG(dbgs() << "    Inlining: cost=" << IC.getCost()
> +        << ", thres=" << (IC.getCostDelta() + IC.getCost())
>         << ", Call: " << *CS.getInstruction() << '\n');
>   return true;
> }
> 
> Modified: llvm/trunk/test/Transforms/Inline/alloca-bonus.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/Inline/alloca-bonus.ll?rev=153812&r1=153811&r2=153812&view=diff
> ==============================================================================
> --- llvm/trunk/test/Transforms/Inline/alloca-bonus.ll (original)
> +++ llvm/trunk/test/Transforms/Inline/alloca-bonus.ll Sat Mar 31 07:42:41 2012
> @@ -1,5 +1,7 @@
> ; RUN: opt -inline < %s -S -o - -inline-threshold=8 | FileCheck %s
> 
> +target datalayout = "p:32:32"
> +
> declare void @llvm.lifetime.start(i64 %size, i8* nocapture %ptr)
> 
> @glbl = external global i32
> @@ -15,8 +17,8 @@
> define void @inner1(i32 *%ptr) {
>   %A = load i32* %ptr
>   store i32 0, i32* %ptr
> -  %C = getelementptr i32* %ptr, i32 0
> -  %D = getelementptr i32* %ptr, i32 1
> +  %C = getelementptr inbounds i32* %ptr, i32 0
> +  %D = getelementptr inbounds i32* %ptr, i32 1
>   %E = bitcast i32* %ptr to i8*
>   %F = select i1 false, i32* %ptr, i32* @glbl
>   call void @llvm.lifetime.start(i64 0, i8* %E)
> @@ -35,8 +37,8 @@
> define void @inner2(i32 *%ptr) {
>   %A = load i32* %ptr
>   store i32 0, i32* %ptr
> -  %C = getelementptr i32* %ptr, i32 0
> -  %D = getelementptr i32* %ptr, i32 %A
> +  %C = getelementptr inbounds i32* %ptr, i32 0
> +  %D = getelementptr inbounds i32* %ptr, i32 %A
>   %E = bitcast i32* %ptr to i8*
>   %F = select i1 false, i32* %ptr, i32* @glbl
>   call void @llvm.lifetime.start(i64 0, i8* %E)
> @@ -93,7 +95,7 @@
> ; %B poisons this call, scalar-repl can't handle that instruction. However, we
> ; still want to detect that the icmp and branch *can* be handled.
> define void @inner4(i32 *%ptr, i32 %A) {
> -  %B = getelementptr i32* %ptr, i32 %A
> +  %B = getelementptr inbounds i32* %ptr, i32 %A
>   %C = icmp eq i32* %ptr, null
>   br i1 %C, label %bb.true, label %bb.false
> bb.true:
> @@ -122,3 +124,32 @@
> bb.false:
>   ret void
> }
> +
> +define void @outer5() {
> +; CHECK: @outer5
> +; CHECK-NOT: call void @inner5
> +  %ptr = alloca i32
> +  call void @inner5(i1 false, i32* %ptr)
> +  ret void
> +}
> +
> +; %D poisons this call, scalar-repl can't handle that instruction. However, if
> +; the flag is set appropriately, the poisoning instruction is inside of dead
> +; code, and so shouldn't be counted.
> +define void @inner5(i1 %flag, i32 *%ptr) {
> +  %A = load i32* %ptr
> +  store i32 0, i32* %ptr
> +  %C = getelementptr inbounds i32* %ptr, i32 0
> +  br i1 %flag, label %if.then, label %exit
> +
> +if.then:
> +  %D = getelementptr inbounds i32* %ptr, i32 %A
> +  %E = bitcast i32* %ptr to i8*
> +  %F = select i1 false, i32* %ptr, i32* @glbl
> +  call void @llvm.lifetime.start(i64 0, i8* %E)
> +  ret void
> +
> +exit:
> +  ret void
> +}
> +
> 
> Modified: llvm/trunk/test/Transforms/Inline/dynamic_alloca_test.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/Inline/dynamic_alloca_test.ll?rev=153812&r1=153811&r2=153812&view=diff
> ==============================================================================
> --- llvm/trunk/test/Transforms/Inline/dynamic_alloca_test.ll (original)
> +++ llvm/trunk/test/Transforms/Inline/dynamic_alloca_test.ll Sat Mar 31 07:42:41 2012
> @@ -4,6 +4,11 @@
> ; already have dynamic allocas.
> 
> ; RUN: opt < %s -inline -S | FileCheck %s
> +;
> +; FIXME: This test is xfailed because the inline cost rewrite disabled *all*
> +; inlining of functions which contain a dynamic alloca. It should be re-enabled
> +; once that functionality is restored.
> +; XFAIL: *
> 
> declare void @ext(i32*)
> 
> 
> Modified: llvm/trunk/test/Transforms/Inline/inline_constprop.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/Inline/inline_constprop.ll?rev=153812&r1=153811&r2=153812&view=diff
> ==============================================================================
> --- llvm/trunk/test/Transforms/Inline/inline_constprop.ll (original)
> +++ llvm/trunk/test/Transforms/Inline/inline_constprop.ll Sat Mar 31 07:42:41 2012
> @@ -1,4 +1,4 @@
> -; RUN: opt < %s -inline -S | FileCheck %s
> +; RUN: opt < %s -inline -inline-threshold=20 -S | FileCheck %s
> 
> define internal i32 @callee1(i32 %A, i32 %B) {
>   %C = sdiv i32 %A, %B
> @@ -14,17 +14,18 @@
> }
> 
> define i32 @caller2() {
> +; Check that we can constant-prop through instructions after inlining callee21
> +; to get constants in the inlined callsite to callee22.
> +; FIXME: Currently, the threshold is fixed at 20 because we don't perform
> +; *recursive* cost analysis to realize that the nested call site will definitely
> +; inline and be cheap. We should eventually do that and lower the threshold here
> +; to 1.
> +;
> ; CHECK: @caller2
> ; CHECK-NOT: call void @callee2
> ; CHECK: ret
> 
> -; We contrive to make this hard for *just* the inline pass to do in order to
> -; simulate what can actually happen with large, complex functions getting
> -; inlined.
> -  %a = add i32 42, 0
> -  %b = add i32 48, 0
> -
> -  %x = call i32 @callee21(i32 %a, i32 %b)
> +  %x = call i32 @callee21(i32 42, i32 48)
>   ret i32 %x
> }
> 
> @@ -41,49 +42,71 @@
>   br i1 %icmp, label %bb.true, label %bb.false
> bb.true:
>   ; This block musn't be counted in the inline cost.
> -  %ptr = call i8* @getptr()
> -  load volatile i8* %ptr
> -  load volatile i8* %ptr
> -  load volatile i8* %ptr
> -  load volatile i8* %ptr
> -  load volatile i8* %ptr
> -  load volatile i8* %ptr
> -  load volatile i8* %ptr
> -  load volatile i8* %ptr
> -  load volatile i8* %ptr
> -  load volatile i8* %ptr
> -  load volatile i8* %ptr
> -  load volatile i8* %ptr
> -  load volatile i8* %ptr
> -  load volatile i8* %ptr
> -  load volatile i8* %ptr
> -  load volatile i8* %ptr
> -  load volatile i8* %ptr
> -  load volatile i8* %ptr
> -  load volatile i8* %ptr
> -  load volatile i8* %ptr
> -  load volatile i8* %ptr
> -  load volatile i8* %ptr
> -  load volatile i8* %ptr
> -  load volatile i8* %ptr
> -  load volatile i8* %ptr
> -  load volatile i8* %ptr
> -  load volatile i8* %ptr
> -  load volatile i8* %ptr
> -  load volatile i8* %ptr
> -  load volatile i8* %ptr
> -  load volatile i8* %ptr
> -  load volatile i8* %ptr
> -  load volatile i8* %ptr
> -  load volatile i8* %ptr
> -  load volatile i8* %ptr
> -  load volatile i8* %ptr
> -  load volatile i8* %ptr
> -  load volatile i8* %ptr
> -  load volatile i8* %ptr
> -  load volatile i8* %ptr
> +  %x1 = add i32 %x, 1
> +  %x2 = add i32 %x1, 1
> +  %x3 = add i32 %x2, 1
> +  %x4 = add i32 %x3, 1
> +  %x5 = add i32 %x4, 1
> +  %x6 = add i32 %x5, 1
> +  %x7 = add i32 %x6, 1
> +  %x8 = add i32 %x7, 1
> 
> -  ret i32 %x
> +  ret i32 %x8
> bb.false:
>   ret i32 %x
> }
> +
> +define i32 @caller3() {
> +; Check that even if the expensive path is hidden behind several basic blocks,
> +; it doesn't count toward the inline cost when constant-prop proves those paths
> +; dead.
> +;
> +; CHECK: @caller3
> +; CHECK-NOT: call
> +; CHECK: ret i32 6
> +
> +entry:
> +  %x = call i32 @callee3(i32 42, i32 48)
> +  ret i32 %x
> +}
> +
> +define i32 @callee3(i32 %x, i32 %y) {
> +  %sub = sub i32 %y, %x
> +  %icmp = icmp ugt i32 %sub, 42
> +  br i1 %icmp, label %bb.true, label %bb.false
> +
> +bb.true:
> +  %icmp2 = icmp ult i32 %sub, 64
> +  br i1 %icmp2, label %bb.true.true, label %bb.true.false
> +
> +bb.true.true:
> +  ; This block musn't be counted in the inline cost.
> +  %x1 = add i32 %x, 1
> +  %x2 = add i32 %x1, 1
> +  %x3 = add i32 %x2, 1
> +  %x4 = add i32 %x3, 1
> +  %x5 = add i32 %x4, 1
> +  %x6 = add i32 %x5, 1
> +  %x7 = add i32 %x6, 1
> +  %x8 = add i32 %x7, 1
> +  br label %bb.merge
> +
> +bb.true.false:
> +  ; This block musn't be counted in the inline cost.
> +  %y1 = add i32 %y, 1
> +  %y2 = add i32 %y1, 1
> +  %y3 = add i32 %y2, 1
> +  %y4 = add i32 %y3, 1
> +  %y5 = add i32 %y4, 1
> +  %y6 = add i32 %y5, 1
> +  %y7 = add i32 %y6, 1
> +  %y8 = add i32 %y7, 1
> +  br label %bb.merge
> +
> +bb.merge:
> +  %result = phi i32 [ %x8, %bb.true.true ], [ %y8, %bb.true.false ]
> +  ret i32 %result
> +
> +bb.false:
> +  ret i32 %sub
> +}
> 
> Modified: llvm/trunk/test/Transforms/Inline/noinline-recursive-fn.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/Inline/noinline-recursive-fn.ll?rev=153812&r1=153811&r2=153812&view=diff
> ==============================================================================
> --- llvm/trunk/test/Transforms/Inline/noinline-recursive-fn.ll (original)
> +++ llvm/trunk/test/Transforms/Inline/noinline-recursive-fn.ll Sat Mar 31 07:42:41 2012
> @@ -71,3 +71,40 @@
>   call void @f2(i32 123, i8* bitcast (void (i32, i8*, i8*)* @f1 to i8*), i8* bitcast (void (i32, i8*, i8*)* @f2 to i8*)) nounwind ssp
>   ret void
> }
> +
> +
> +; Check that a recursive function, when called with a constant that makes the
> +; recursive path dead code can actually be inlined.
> +define i32 @fib(i32 %i) {
> +entry:
> +  %is.zero = icmp eq i32 %i, 0
> +  br i1 %is.zero, label %zero.then, label %zero.else
> +
> +zero.then:
> +  ret i32 0
> +
> +zero.else:
> +  %is.one = icmp eq i32 %i, 1
> +  br i1 %is.one, label %one.then, label %one.else
> +
> +one.then:
> +  ret i32 1
> +
> +one.else:
> +  %i1 = sub i32 %i, 1
> +  %f1 = call i32 @fib(i32 %i1)
> +  %i2 = sub i32 %i, 2
> +  %f2 = call i32 @fib(i32 %i2)
> +  %f = add i32 %f1, %f2
> +  ret i32 %f
> +}
> +
> +define i32 @fib_caller() {
> +; CHECK: @fib_caller
> +; CHECK-NOT: call
> +; CHECK: ret
> +  %f1 = call i32 @fib(i32 0)
> +  %f2 = call i32 @fib(i32 1)
> +  %result = add i32 %f1, %f2
> +  ret i32 %result
> +}
> 
> Modified: llvm/trunk/test/Transforms/Inline/ptr-diff.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/Inline/ptr-diff.ll?rev=153812&r1=153811&r2=153812&view=diff
> ==============================================================================
> --- llvm/trunk/test/Transforms/Inline/ptr-diff.ll (original)
> +++ llvm/trunk/test/Transforms/Inline/ptr-diff.ll Sat Mar 31 07:42:41 2012
> @@ -1,5 +1,7 @@
> ; RUN: opt -inline < %s -S -o - -inline-threshold=10 | FileCheck %s
> 
> +target datalayout = "p:32:32"
> +
> define i32 @outer1() {
> ; CHECK: @outer1
> ; CHECK-NOT: call
> 
> 
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-David





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