MachineBranchProbabilityInfo.h revision 25101bb2a799a36be9f077ee2fc2dcf0df2b6efb
17cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak 27cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak//==- MachineBranchProbabilityInfo.h - Machine Branch Probability Analysis -==// 37cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak// 47cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak// The LLVM Compiler Infrastructure 57cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak// 67cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak// This file is distributed under the University of Illinois Open Source 77cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak// License. See LICENSE.TXT for details. 87cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak// 97cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak//===----------------------------------------------------------------------===// 107cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak// 117cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak// This pass is used to evaluate branch probabilties on machine basic blocks. 127cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak// 137cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak//===----------------------------------------------------------------------===// 147cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak 157cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak#ifndef LLVM_CODEGEN_MACHINEBRANCHPROBABILITYINFO_H 167cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak#define LLVM_CODEGEN_MACHINEBRANCHPROBABILITYINFO_H 177cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak 187cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak#include "llvm/Pass.h" 197cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak#include "llvm/Support/BranchProbability.h" 207cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak#include <climits> 217cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak 227cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszaknamespace llvm { 237cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak 247cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszakclass raw_ostream; 25687dc24e1d17d3d8bb4f4f095929db16f65f3067Jakub Staszakclass MachineBasicBlock; 267cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak 277cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszakclass MachineBranchProbabilityInfo : public ImmutablePass { 282d24e2a396a1d211baaeedf32148a3b657240170David Blaikie virtual void anchor(); 297cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak 307cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak // Default weight value. Used when we don't have information about the edge. 317cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak // TODO: DEFAULT_WEIGHT makes sense during static predication, when none of 327cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak // the successors have a weight yet. But it doesn't make sense when providing 337cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak // weight to an edge that may have siblings with non-zero weights. This can 347cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak // be handled various ways, but it's probably fine for an edge with unknown 357cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak // weight to just "inherit" the non-zero weight of an adjacent successor. 367cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak static const uint32_t DEFAULT_WEIGHT = 16; 377cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak 387cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszakpublic: 397cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak static char ID; 407cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak 417cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak MachineBranchProbabilityInfo() : ImmutablePass(ID) { 427cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak PassRegistry &Registry = *PassRegistry::getPassRegistry(); 437cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak initializeMachineBranchProbabilityInfoPass(Registry); 447cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak } 457cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak 467cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak void getAnalysisUsage(AnalysisUsage &AU) const { 477cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak AU.setPreservesAll(); 487cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak } 497cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak 507cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak // Return edge weight. If we don't have any informations about it - return 517cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak // DEFAULT_WEIGHT. 5225101bb2a799a36be9f077ee2fc2dcf0df2b6efbJakub Staszak uint32_t getEdgeWeight(const MachineBasicBlock *Src, 5325101bb2a799a36be9f077ee2fc2dcf0df2b6efbJakub Staszak const MachineBasicBlock *Dst) const; 547cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak 55340d596509129de8c3fa9dbe4184a2b148b78757Chandler Carruth // Get sum of the block successors' weights, potentially scaling them to fit 56340d596509129de8c3fa9dbe4184a2b148b78757Chandler Carruth // within 32-bits. If scaling is required, sets Scale based on the necessary 57340d596509129de8c3fa9dbe4184a2b148b78757Chandler Carruth // adjustment. Any edge weights used with the sum should be divided by Scale. 5825101bb2a799a36be9f077ee2fc2dcf0df2b6efbJakub Staszak uint32_t getSumForBlock(const MachineBasicBlock *MBB, uint32_t &Scale) const; 59340d596509129de8c3fa9dbe4184a2b148b78757Chandler Carruth 607cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak // A 'Hot' edge is an edge which probability is >= 80%. 617cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak bool isEdgeHot(MachineBasicBlock *Src, MachineBasicBlock *Dst) const; 627cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak 637cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak // Return a hot successor for the block BB or null if there isn't one. 64c4e15628255b24cb17138404abe3d94bde811e25Chandler Carruth // NB: This routine's complexity is linear on the number of successors. 657cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak MachineBasicBlock *getHotSucc(MachineBasicBlock *MBB) const; 667cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak 677cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak // Return a probability as a fraction between 0 (0% probability) and 687cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak // 1 (100% probability), however the value is never equal to 0, and can be 1 697cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak // only iff SRC block has only one successor. 70883f2fab47ca2f7f6efebb10a5e859f5804bed07Chandler Carruth // NB: This routine's complexity is linear on the number of successors of 71883f2fab47ca2f7f6efebb10a5e859f5804bed07Chandler Carruth // Src. Querying sequentially for each successor's probability is a quadratic 72883f2fab47ca2f7f6efebb10a5e859f5804bed07Chandler Carruth // query pattern. 737cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak BranchProbability getEdgeProbability(MachineBasicBlock *Src, 747cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak MachineBasicBlock *Dst) const; 757cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak 767cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak // Print value between 0 (0% probability) and 1 (100% probability), 777cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak // however the value is never equal to 0, and can be 1 only iff SRC block 787cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak // has only one successor. 797cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak raw_ostream &printEdgeProbability(raw_ostream &OS, MachineBasicBlock *Src, 807cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak MachineBasicBlock *Dst) const; 817cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak}; 827cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak 837cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak} 847cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak 857cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak 867cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak#endif 87