InlineCost.h revision caa2c40a57040dc3e1a5e40401cd1e4ede845451
15faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org//===- InlineCost.h - Cost analysis for inliner -----------------*- C++ -*-===// 25faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org// 35faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org// The LLVM Compiler Infrastructure 45faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org// 55faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org// This file is distributed under the University of Illinois Open Source 65faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org// License. See LICENSE.TXT for details. 75faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org// 85faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org//===----------------------------------------------------------------------===// 95faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org// 105faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org// This file implements heuristics for inlining decisions. 115faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org// 125faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org//===----------------------------------------------------------------------===// 138640d5024d57da5508bdf7585849e3b1f1cb365bsenorblanco@chromium.org 145faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org#ifndef LLVM_ANALYSIS_INLINECOST_H 153bc16c8bc1ecb9ac4450f58093cc9e3edb8a50b8senorblanco@chromium.org#define LLVM_ANALYSIS_INLINECOST_H 16d698f77c13d97c61109b861eac4d25b14a5de935bsalomon@google.com 17dbe49f735484f8862e378b63d0a074a301093dd0bsalomon@google.com#include "llvm/Function.h" 182eaaefd7e6a58339b3f93333f1e9cc92252cc303bsalomon@google.com#include "llvm/ADT/DenseMap.h" 1917fc651dbe2e0624f6c85fb6e081d28a87d5a08bbsalomon@google.com#include "llvm/ADT/SmallPtrSet.h" 2017fc651dbe2e0624f6c85fb6e081d28a87d5a08bbsalomon@google.com#include "llvm/ADT/ValueMap.h" 213bc16c8bc1ecb9ac4450f58093cc9e3edb8a50b8senorblanco@chromium.org#include "llvm/Analysis/CodeMetrics.h" 223bc16c8bc1ecb9ac4450f58093cc9e3edb8a50b8senorblanco@chromium.org#include <cassert> 237938bae14af94c1d48d122a2d686e123b66411a7senorblanco@chromium.org#include <climits> 247938bae14af94c1d48d122a2d686e123b66411a7senorblanco@chromium.org#include <vector> 257938bae14af94c1d48d122a2d686e123b66411a7senorblanco@chromium.org 267938bae14af94c1d48d122a2d686e123b66411a7senorblanco@chromium.orgnamespace llvm { 277938bae14af94c1d48d122a2d686e123b66411a7senorblanco@chromium.org 287938bae14af94c1d48d122a2d686e123b66411a7senorblanco@chromium.org class CallSite; 297938bae14af94c1d48d122a2d686e123b66411a7senorblanco@chromium.org class TargetData; 307938bae14af94c1d48d122a2d686e123b66411a7senorblanco@chromium.org 317938bae14af94c1d48d122a2d686e123b66411a7senorblanco@chromium.org namespace InlineConstants { 327938bae14af94c1d48d122a2d686e123b66411a7senorblanco@chromium.org // Various magic constants used to adjust heuristics. 337938bae14af94c1d48d122a2d686e123b66411a7senorblanco@chromium.org const int InstrCost = 5; 345faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org const int IndirectCallThreshold = 100; 355faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org const int CallPenalty = 25; 365faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org const int LastCallToStaticBonus = -15000; 375faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org const int ColdccPenalty = 2000; 388640d5024d57da5508bdf7585849e3b1f1cb365bsenorblanco@chromium.org const int NoreturnPenalty = 10000; 398640d5024d57da5508bdf7585849e3b1f1cb365bsenorblanco@chromium.org } 405faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org 415faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org /// \brief Represents the cost of inlining a function. 425faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org /// 433bc16c8bc1ecb9ac4450f58093cc9e3edb8a50b8senorblanco@chromium.org /// This supports special values for functions which should "always" or 445faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org /// "never" be inlined. Otherwise, the cost represents a unitless amount; 455faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org /// smaller values increase the likelihood of the function being inlined. 465faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org /// 475faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org /// Objects of this type also provide the adjusted threshold for inlining 487938bae14af94c1d48d122a2d686e123b66411a7senorblanco@chromium.org /// based on the information available for a particular callsite. They can be 497938bae14af94c1d48d122a2d686e123b66411a7senorblanco@chromium.org /// directly tested to determine if inlining should occur given the cost and 505faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org /// threshold for this cost metric. 515faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org class InlineCost { 525faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org enum SentinelValues { 535faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org AlwaysInlineCost = INT_MIN, 540e51577a14f903ffeafa117a75954baeb173ffb9humper@google.com NeverInlineCost = INT_MAX 555faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org }; 565faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org 575faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org /// \brief The estimated cost of inlining this callsite. 58528952b5afea0e82bf6db9ef22128533d50ef9e3senorblanco@chromium.org const int Cost; 59528952b5afea0e82bf6db9ef22128533d50ef9e3senorblanco@chromium.org 605faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org /// \brief The adjusted threshold against which this cost was computed. 618640d5024d57da5508bdf7585849e3b1f1cb365bsenorblanco@chromium.org const int Threshold; 625faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org 635faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org // Trivial constructor, interesting logic in the factory functions below. 645faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org InlineCost(int Cost, int Threshold) 655faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org : Cost(Cost), Threshold(Threshold) {} 665faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org 675faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org public: 685faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org static InlineCost get(int Cost, int Threshold) { 695faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org assert(Cost > AlwaysInlineCost && "Cost crosses sentinel value"); 705faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org assert(Cost < NeverInlineCost && "Cost crosses sentinel value"); 71528952b5afea0e82bf6db9ef22128533d50ef9e3senorblanco@chromium.org return InlineCost(Cost, Threshold); 72528952b5afea0e82bf6db9ef22128533d50ef9e3senorblanco@chromium.org } 735faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org static InlineCost getAlways() { 748640d5024d57da5508bdf7585849e3b1f1cb365bsenorblanco@chromium.org return InlineCost(AlwaysInlineCost, 0); 755faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org } 765faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org static InlineCost getNever() { 775faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org return InlineCost(NeverInlineCost, 0); 785faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org } 795faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org 805faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org /// \brief Test whether the inline cost is low enough for inlining. 815faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org operator bool() const { 825faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org return Cost < Threshold; 837938bae14af94c1d48d122a2d686e123b66411a7senorblanco@chromium.org } 845faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org 855faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org bool isAlways() const { return Cost == AlwaysInlineCost; } 865faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org bool isNever() const { return Cost == NeverInlineCost; } 875faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org bool isVariable() const { return !isAlways() && !isNever(); } 885faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org 895faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org /// \brief Get the inline cost estimate. 907938bae14af94c1d48d122a2d686e123b66411a7senorblanco@chromium.org /// It is an error to call this on an "always" or "never" InlineCost. 917938bae14af94c1d48d122a2d686e123b66411a7senorblanco@chromium.org int getCost() const { 927938bae14af94c1d48d122a2d686e123b66411a7senorblanco@chromium.org assert(isVariable() && "Invalid access of InlineCost"); 935faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org return Cost; 945faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org } 955faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org 965faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org /// \brief Get the cost delta from the threshold for inlining. 975faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org /// Only valid if the cost is of the variable kind. Returns a negative 985faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org /// value if the cost is too high to inline. 997938bae14af94c1d48d122a2d686e123b66411a7senorblanco@chromium.org int getCostDelta() const { return Threshold - getCost(); } 1007938bae14af94c1d48d122a2d686e123b66411a7senorblanco@chromium.org }; 1017938bae14af94c1d48d122a2d686e123b66411a7senorblanco@chromium.org 1027938bae14af94c1d48d122a2d686e123b66411a7senorblanco@chromium.org /// InlineCostAnalyzer - Cost analyzer used by inliner. 1037938bae14af94c1d48d122a2d686e123b66411a7senorblanco@chromium.org class InlineCostAnalyzer { 1045faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org // TargetData if available, or null. 1057938bae14af94c1d48d122a2d686e123b66411a7senorblanco@chromium.org const TargetData *TD; 1067938bae14af94c1d48d122a2d686e123b66411a7senorblanco@chromium.org 1075faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org public: 1085faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org InlineCostAnalyzer(): TD(0) {} 1095faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org 1105faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org void setTargetData(const TargetData *TData) { TD = TData; } 1115faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org 1125faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org /// \brief Get an InlineCost object representing the cost of inlining this 1135faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org /// callsite. 1147938bae14af94c1d48d122a2d686e123b66411a7senorblanco@chromium.org /// 1157938bae14af94c1d48d122a2d686e123b66411a7senorblanco@chromium.org /// Note that threshold is passed into this function. Only costs below the 1165faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org /// threshold are computed with any accuracy. The threshold can be used to 1175faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org /// bound the computation necessary to determine whether the cost is 1185faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org /// sufficiently low to warrant inlining. 1195faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org InlineCost getInlineCost(CallSite CS, int Threshold); 1205faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org }; 1215faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org 1225faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org /// callIsSmall - If a call is likely to lower to a single target instruction, 1238640d5024d57da5508bdf7585849e3b1f1cb365bsenorblanco@chromium.org /// or is otherwise deemed small return true. 1247938bae14af94c1d48d122a2d686e123b66411a7senorblanco@chromium.org bool callIsSmall(const Function *Callee); 1257938bae14af94c1d48d122a2d686e123b66411a7senorblanco@chromium.org} 1267938bae14af94c1d48d122a2d686e123b66411a7senorblanco@chromium.org 1277938bae14af94c1d48d122a2d686e123b66411a7senorblanco@chromium.org#endif 1285faa2dc266ec933b3961f985e5718236f1ecbe47senorblanco@chromium.org