-//===- InlineCost.cpp - Cost analysis for inliner ---------------*- C++ -*-===//
+//===- InlineCost.h - Cost analysis for inliner -----------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
#ifndef LLVM_ANALYSIS_INLINECOST_H
#define LLVM_ANALYSIS_INLINECOST_H
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/ValueMap.h"
+#include "llvm/Analysis/CodeMetrics.h"
+#include "llvm/Function.h"
#include <cassert>
#include <climits>
-#include <map>
#include <vector>
-#include "llvm/ADT/DenseMap.h"
namespace llvm {
- class Value;
- class Function;
- class BasicBlock;
class CallSite;
- template<class PtrType, unsigned SmallSize>
- class SmallPtrSet;
-
- // CodeMetrics - Calculate size and a few similar metrics for a set of
- // basic blocks.
- struct CodeMetrics {
- /// NeverInline - True if this callee should never be inlined into a
- /// caller.
- bool NeverInline;
-
- /// usesDynamicAlloca - True if this function calls alloca (in the C sense).
- bool usesDynamicAlloca;
-
- /// NumInsts, NumBlocks - Keep track of how large each function is, which
- /// is used to estimate the code size cost of inlining it.
- unsigned NumInsts, NumBlocks;
-
- /// NumBBInsts - Keeps track of basic block code size estimates.
- DenseMap<const BasicBlock *, unsigned> NumBBInsts;
-
- /// NumCalls - Keep track of the number of calls to 'big' functions.
- unsigned NumCalls;
-
- /// NumVectorInsts - Keep track of how many instructions produce vector
- /// values. The inliner is being more aggressive with inlining vector
- /// kernels.
- unsigned NumVectorInsts;
-
- /// NumRets - Keep track of how many Ret instructions the block contains.
- unsigned NumRets;
-
- CodeMetrics() : NeverInline(false), usesDynamicAlloca(false), NumInsts(0),
- NumBlocks(0), NumCalls(0), NumVectorInsts(0), NumRets(0) {}
-
- /// analyzeBasicBlock - Add information about the specified basic block
- /// to the current structure.
- void analyzeBasicBlock(const BasicBlock *BB);
-
- /// analyzeFunction - Add information about the specified function
- /// to the current structure.
- void analyzeFunction(Function *F);
- };
+ class DataLayout;
namespace InlineConstants {
// Various magic constants used to adjust heuristics.
const int InstrCost = 5;
- const int IndirectCallBonus = 500;
+ const int IndirectCallThreshold = 100;
const int CallPenalty = 25;
const int LastCallToStaticBonus = -15000;
const int ColdccPenalty = 2000;
const int NoreturnPenalty = 10000;
+ /// Do not inline functions which allocate this many bytes on the stack
+ /// when the caller is recursive.
+ const unsigned TotalAllocaSizeRecursiveCaller = 1024;
}
- /// 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 likelyhood 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 SentinelValues {
+ AlwaysInlineCost = INT_MIN,
+ NeverInlineCost = INT_MAX
};
- // 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;
+ /// \brief The estimated cost of inlining this callsite.
+ const int Cost;
- Kind getType() const {
- return Kind(TypedCost >> COST_BITS);
- }
+ /// \brief The adjusted threshold against which this cost was computed.
+ 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, int Threshold)
+ : Cost(Cost), Threshold(Threshold) {}
+
+ public:
+ static InlineCost get(int Cost, int Threshold) {
+ assert(Cost > AlwaysInlineCost && "Cost crosses sentinel value");
+ assert(Cost < NeverInlineCost && "Cost crosses sentinel value");
+ return InlineCost(Cost, Threshold);
+ }
+ static InlineCost getAlways() {
+ return InlineCost(AlwaysInlineCost, 0);
+ }
+ static InlineCost getNever() {
+ return InlineCost(NeverInlineCost, 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 {
+ 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
- /// an error to call this on an "always" or "never" InlineCost.
- int getValue() const {
- assert(getType() == Value && "Invalid access of InlineCost");
- return getCost();
+
+ bool isAlways() const { return Cost == AlwaysInlineCost; }
+ bool isNever() const { return Cost == NeverInlineCost; }
+ bool isVariable() const { return !isAlways() && !isNever(); }
+
+ /// \brief Get the inline cost estimate.
+ /// It is an error to call this on an "always" or "never" InlineCost.
+ int getCost() const {
+ assert(isVariable() && "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;
-
- /// CountCodeReductionForConstant - Figure out an approximation for how
- /// many instructions will be constant folded if the specified value is
- /// constant.
- unsigned CountCodeReductionForConstant(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(Value *V);
-
- /// analyzeFunction - Add information about the specified function
- /// to the current structure.
- void analyzeFunction(Function *F);
- };
-
- std::map<const Function *, FunctionInfo> CachedFunctionInfo;
+ // DataLayout if available, or null.
+ const DataLayout *TD;
public:
+ InlineCostAnalyzer(): TD(0) {}
- /// getInlineCost - The heuristic used to determine if we should inline the
- /// function call or not.
- ///
- InlineCost getInlineCost(CallSite CS,
- SmallPtrSet<const Function *, 16> &NeverInline);
-
- /// 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);
+ void setDataLayout(const DataLayout *TData) { TD = TData; }
- /// 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
- /// has been inlined. If Callee is NULL it means a dead call has been
- /// eliminated.
- void growCachedCostInfo(Function* Caller, Function* Callee);
+ /// \brief Get an InlineCost object representing the cost of inlining this
+ /// callsite.
+ ///
+ /// 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);
+
+ /// \brief Get an InlineCost with the callee explicitly specified.
+ /// This allows you to calculate the cost of inlining a function via a
+ /// pointer. This behaves exactly as the version with no explicit callee
+ /// parameter in all other respects.
+ //
+ // Note: This is used by out-of-tree passes, please do not remove without
+ // adding a replacement API.
+ InlineCost getInlineCost(CallSite CS, Function *Callee, int Threshold);
+
+ /// \brief Minimal filter to detect invalid constructs for inlining.
+ bool isInlineViable(Function &Callee);
};
-
- /// callIsSmall - If a call is likely to lower to a single target instruction,
- /// or is otherwise deemed small return true.
- bool callIsSmall(const Function *Callee);
}
#endif
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