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depend on and use other analyses (as long as they're either immutable passes or CGSCC passes of course -- nothing in the pass manager has been fixed here). Leverage this to thread TargetTransformInfo down through the inline cost analysis. No functionality changed here, this just threads things through. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@173031 91177308-0d34-0410-b5e6-96231b3b80d8
144 lines
4.8 KiB
C++
144 lines
4.8 KiB
C++
//===- InlineCost.h - Cost analysis for inliner -----------------*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements heuristics for inlining decisions.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_ANALYSIS_INLINECOST_H
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#define LLVM_ANALYSIS_INLINECOST_H
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#include "llvm/Analysis/CodeMetrics.h"
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#include "llvm/Analysis/CallGraphSCCPass.h"
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#include <cassert>
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#include <climits>
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namespace llvm {
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class CallSite;
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class DataLayout;
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class Function;
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class TargetTransformInfo;
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namespace InlineConstants {
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// Various magic constants used to adjust heuristics.
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const int InstrCost = 5;
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const int IndirectCallThreshold = 100;
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const int CallPenalty = 25;
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const int LastCallToStaticBonus = -15000;
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const int ColdccPenalty = 2000;
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const int NoreturnPenalty = 10000;
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/// Do not inline functions which allocate this many bytes on the stack
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/// when the caller is recursive.
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const unsigned TotalAllocaSizeRecursiveCaller = 1024;
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}
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/// \brief Represents the cost of inlining a function.
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///
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/// This supports special values for functions which should "always" or
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/// "never" be inlined. Otherwise, the cost represents a unitless amount;
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/// smaller values increase the likelihood of the function being inlined.
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///
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/// Objects of this type also provide the adjusted threshold for inlining
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/// based on the information available for a particular callsite. They can be
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/// directly tested to determine if inlining should occur given the cost and
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/// threshold for this cost metric.
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class InlineCost {
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enum SentinelValues {
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AlwaysInlineCost = INT_MIN,
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NeverInlineCost = INT_MAX
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};
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/// \brief The estimated cost of inlining this callsite.
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const int Cost;
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/// \brief The adjusted threshold against which this cost was computed.
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const int Threshold;
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// Trivial constructor, interesting logic in the factory functions below.
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InlineCost(int Cost, int Threshold) : Cost(Cost), Threshold(Threshold) {}
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public:
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static InlineCost get(int Cost, int Threshold) {
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assert(Cost > AlwaysInlineCost && "Cost crosses sentinel value");
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assert(Cost < NeverInlineCost && "Cost crosses sentinel value");
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return InlineCost(Cost, Threshold);
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}
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static InlineCost getAlways() {
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return InlineCost(AlwaysInlineCost, 0);
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}
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static InlineCost getNever() {
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return InlineCost(NeverInlineCost, 0);
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}
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/// \brief Test whether the inline cost is low enough for inlining.
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operator bool() const {
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return Cost < Threshold;
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}
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bool isAlways() const { return Cost == AlwaysInlineCost; }
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bool isNever() const { return Cost == NeverInlineCost; }
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bool isVariable() const { return !isAlways() && !isNever(); }
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/// \brief Get the inline cost estimate.
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/// It is an error to call this on an "always" or "never" InlineCost.
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int getCost() const {
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assert(isVariable() && "Invalid access of InlineCost");
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return Cost;
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}
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/// \brief Get the cost delta from the threshold for inlining.
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/// Only valid if the cost is of the variable kind. Returns a negative
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/// value if the cost is too high to inline.
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int getCostDelta() const { return Threshold - getCost(); }
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};
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/// \brief Cost analyzer used by inliner.
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class InlineCostAnalysis : public CallGraphSCCPass {
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const DataLayout *TD;
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const TargetTransformInfo *TTI;
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public:
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static char ID;
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InlineCostAnalysis();
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~InlineCostAnalysis();
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// Pass interface implementation.
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void getAnalysisUsage(AnalysisUsage &AU) const;
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bool runOnSCC(CallGraphSCC &SCC);
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/// \brief Get an InlineCost object representing the cost of inlining this
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/// callsite.
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///
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/// Note that threshold is passed into this function. Only costs below the
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/// threshold are computed with any accuracy. The threshold can be used to
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/// bound the computation necessary to determine whether the cost is
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/// sufficiently low to warrant inlining.
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///
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/// Also note that calling this function *dynamically* computes the cost of
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/// inlining the callsite. It is an expensive, heavyweight call.
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InlineCost getInlineCost(CallSite CS, int Threshold);
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/// \brief Get an InlineCost with the callee explicitly specified.
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/// This allows you to calculate the cost of inlining a function via a
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/// pointer. This behaves exactly as the version with no explicit callee
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/// parameter in all other respects.
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//
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// Note: This is used by out-of-tree passes, please do not remove without
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// adding a replacement API.
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InlineCost getInlineCost(CallSite CS, Function *Callee, int Threshold);
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/// \brief Minimal filter to detect invalid constructs for inlining.
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bool isInlineViable(Function &Callee);
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};
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}
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#endif
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