llvm/lib/CodeGen/RegAllocEvictionAdvisor.cpp

   1 //===- RegAllocEvictionAdvisor.cpp - eviction advisor ---------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // Implementation of the default eviction advisor and of the Analysis pass.
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #include "RegAllocEvictionAdvisor.h"
  14 #include "RegAllocGreedy.h"
  15 #include "llvm/CodeGen/MachineFunction.h"
  16 #include "llvm/CodeGen/RegisterClassInfo.h"
  17 #include "llvm/CodeGen/VirtRegMap.h"
  18 #include "llvm/InitializePasses.h"
  19 #include "llvm/Pass.h"
  20 #include "llvm/PassRegistry.h"
  21 #include "llvm/Support/CommandLine.h"
  22 #include "llvm/Support/ErrorHandling.h"
  23 #include "llvm/Target/TargetMachine.h"
  24
  25 using namespace llvm;
  26
  27 static cl::opt<RegAllocEvictionAdvisorAnalysis::AdvisorMode> Mode(
  28     "regalloc-enable-advisor", cl::Hidden,
  29     cl::init(RegAllocEvictionAdvisorAnalysis::AdvisorMode::Default),
  30     cl::desc("Enable regalloc advisor mode"),
  31     cl::values(
  32         clEnumValN(RegAllocEvictionAdvisorAnalysis::AdvisorMode::Default,
  33                    "default", "Default"),
  34         clEnumValN(RegAllocEvictionAdvisorAnalysis::AdvisorMode::Release,
  35                    "release", "precompiled"),
  36         clEnumValN(RegAllocEvictionAdvisorAnalysis::AdvisorMode::Development,
  37                    "development", "for training")));
  38
  39 static cl::opt<bool> EnableLocalReassignment(
  40     "enable-local-reassign", cl::Hidden,
  41     cl::desc("Local reassignment can yield better allocation decisions, but "
  42              "may be compile time intensive"),
  43     cl::init(false));
  44
  45 #define DEBUG_TYPE "regalloc"
  46
  47 char RegAllocEvictionAdvisorAnalysis::ID = 0;
  48 INITIALIZE_PASS(RegAllocEvictionAdvisorAnalysis, "regalloc-evict",
  49                 "Regalloc eviction policy", false, true)
  50
  51 namespace {
  52 class DefaultEvictionAdvisorAnalysis final
  53     : public RegAllocEvictionAdvisorAnalysis {
  54 public:
  55   DefaultEvictionAdvisorAnalysis(bool NotAsRequested)
  56       : RegAllocEvictionAdvisorAnalysis(AdvisorMode::Default),
  57         NotAsRequested(NotAsRequested) {}
  58
  59   // support for isa<> and dyn_cast.
  60   static bool classof(const RegAllocEvictionAdvisorAnalysis *R) {
  61     return R->getAdvisorMode() == AdvisorMode::Default;
  62   }
  63
  64 private:
  65   std::unique_ptr<RegAllocEvictionAdvisor>
  66   getAdvisor(const MachineFunction &MF, const RAGreedy &RA) override {
  67     return std::make_unique<DefaultEvictionAdvisor>(MF, RA);
  68   }
  69   bool doInitialization(Module &M) override {
  70     if (NotAsRequested)
  71       M.getContext().emitError("Requested regalloc eviction advisor analysis "
  72                                "could be created. Using default");
  73     return RegAllocEvictionAdvisorAnalysis::doInitialization(M);
  74   }
  75   const bool NotAsRequested;
  76 };
  77 } // namespace
  78
  79 template <> Pass *llvm::callDefaultCtor<RegAllocEvictionAdvisorAnalysis>() {
  80   Pass *Ret = nullptr;
  81   switch (Mode) {
  82   case RegAllocEvictionAdvisorAnalysis::AdvisorMode::Default:
  83     Ret = new DefaultEvictionAdvisorAnalysis(/*NotAsRequested*/ false);
  84     break;
  85   case RegAllocEvictionAdvisorAnalysis::AdvisorMode::Development:
  86     // TODO(mtrofin): add implementation
  87     break;
  88   case RegAllocEvictionAdvisorAnalysis::AdvisorMode::Release:
  89     // TODO(mtrofin): add implementation
  90     break;
  91   }
  92   if (Ret)
  93     return Ret;
  94   return new DefaultEvictionAdvisorAnalysis(/*NotAsRequested*/ true);
  95 }
  96
  97 StringRef RegAllocEvictionAdvisorAnalysis::getPassName() const {
  98   switch (getAdvisorMode()) {
  99   case AdvisorMode::Default:
 100     return "Default Regalloc Eviction Advisor";
 101   case AdvisorMode::Release:
 102     return "Release mode Regalloc Eviction Advisor";
 103   case AdvisorMode::Development:
 104     return "Development mode Regalloc Eviction Advisor";
 105   }
 106   llvm_unreachable("Unknown advisor kind");
 107 }
 108
 109 RegAllocEvictionAdvisor::RegAllocEvictionAdvisor(const MachineFunction &MF,
 110                                                  const RAGreedy &RA)
 111     : MF(MF), RA(RA), Matrix(RA.getInterferenceMatrix()),
 112       LIS(RA.getLiveIntervals()), VRM(RA.getVirtRegMap()),
 113       MRI(&VRM->getRegInfo()), TRI(MF.getSubtarget().getRegisterInfo()),
 114       RegClassInfo(RA.getRegClassInfo()), RegCosts(TRI->getRegisterCosts(MF)),
 115       EnableLocalReassign(EnableLocalReassignment ||
 116                           MF.getSubtarget().enableRALocalReassignment(
 117                               MF.getTarget().getOptLevel())) {}