1 //===-- StackMapLivenessAnalysis.cpp - StackMap live Out Analysis ----------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements the StackMap Liveness analysis pass. The pass calculates
11 // the liveness for each basic block in a function and attaches the register
12 // live-out information to a stackmap or patchpoint intrinsic if present.
14 //===----------------------------------------------------------------------===//
16 #include "llvm/ADT/Statistic.h"
17 #include "llvm/CodeGen/LivePhysRegs.h"
18 #include "llvm/CodeGen/MachineFrameInfo.h"
19 #include "llvm/CodeGen/MachineFunction.h"
20 #include "llvm/CodeGen/MachineFunctionPass.h"
21 #include "llvm/CodeGen/Passes.h"
22 #include "llvm/Support/CommandLine.h"
23 #include "llvm/Support/Debug.h"
24 #include "llvm/Support/raw_ostream.h"
25 #include "llvm/Target/TargetSubtargetInfo.h"
29 #define DEBUG_TYPE "stackmaps"
31 static cl::opt<bool> EnablePatchPointLiveness(
32 "enable-patchpoint-liveness", cl::Hidden, cl::init(true),
33 cl::desc("Enable PatchPoint Liveness Analysis Pass"));
35 STATISTIC(NumStackMapFuncVisited, "Number of functions visited");
36 STATISTIC(NumStackMapFuncSkipped, "Number of functions skipped");
37 STATISTIC(NumBBsVisited, "Number of basic blocks visited");
38 STATISTIC(NumBBsHaveNoStackmap, "Number of basic blocks with no stackmap");
39 STATISTIC(NumStackMaps, "Number of StackMaps visited");
42 /// \brief This pass calculates the liveness information for each basic block in
43 /// a function and attaches the register live-out information to a patchpoint
44 /// intrinsic if present.
46 /// This pass can be disabled via the -enable-patchpoint-liveness=false flag.
47 /// The pass skips functions that don't have any patchpoint intrinsics. The
48 /// information provided by this pass is optional and not required by the
49 /// aformentioned intrinsic to function.
50 class StackMapLiveness : public MachineFunctionPass {
51 const TargetRegisterInfo *TRI;
52 LivePhysRegs LiveRegs;
57 /// \brief Default construct and initialize the pass.
60 /// \brief Tell the pass manager which passes we depend on and what
61 /// information we preserve.
62 void getAnalysisUsage(AnalysisUsage &AU) const override;
64 MachineFunctionProperties getRequiredProperties() const override {
65 return MachineFunctionProperties().set(
66 MachineFunctionProperties::Property::NoVRegs);
69 /// \brief Calculate the liveness information for the given machine function.
70 bool runOnMachineFunction(MachineFunction &MF) override;
73 /// \brief Performs the actual liveness calculation for the function.
74 bool calculateLiveness(MachineFunction &MF);
76 /// \brief Add the current register live set to the instruction.
77 void addLiveOutSetToMI(MachineFunction &MF, MachineInstr &MI);
79 /// \brief Create a register mask and initialize it with the registers from
80 /// the register live set.
81 uint32_t *createRegisterMask(MachineFunction &MF) const;
85 char StackMapLiveness::ID = 0;
86 char &llvm::StackMapLivenessID = StackMapLiveness::ID;
87 INITIALIZE_PASS(StackMapLiveness, "stackmap-liveness",
88 "StackMap Liveness Analysis", false, false)
90 /// Default construct and initialize the pass.
91 StackMapLiveness::StackMapLiveness() : MachineFunctionPass(ID) {
92 initializeStackMapLivenessPass(*PassRegistry::getPassRegistry());
95 /// Tell the pass manager which passes we depend on and what information we
97 void StackMapLiveness::getAnalysisUsage(AnalysisUsage &AU) const {
98 // We preserve all information.
100 AU.setPreservesCFG();
101 MachineFunctionPass::getAnalysisUsage(AU);
104 /// Calculate the liveness information for the given machine function.
105 bool StackMapLiveness::runOnMachineFunction(MachineFunction &MF) {
106 if (!EnablePatchPointLiveness)
109 DEBUG(dbgs() << "********** COMPUTING STACKMAP LIVENESS: " << MF.getName()
111 TRI = MF.getSubtarget().getRegisterInfo();
112 ++NumStackMapFuncVisited;
114 // Skip this function if there are no patchpoints to process.
115 if (!MF.getFrameInfo().hasPatchPoint()) {
116 ++NumStackMapFuncSkipped;
119 return calculateLiveness(MF);
122 /// Performs the actual liveness calculation for the function.
123 bool StackMapLiveness::calculateLiveness(MachineFunction &MF) {
124 bool HasChanged = false;
125 // For all basic blocks in the function.
126 for (auto &MBB : MF) {
127 DEBUG(dbgs() << "****** BB " << MBB.getName() << " ******\n");
129 // FIXME: This should probably be addLiveOuts().
130 LiveRegs.addLiveOutsNoPristines(MBB);
131 bool HasStackMap = false;
132 // Reverse iterate over all instructions and add the current live register
133 // set to an instruction if we encounter a patchpoint instruction.
134 for (auto I = MBB.rbegin(), E = MBB.rend(); I != E; ++I) {
135 if (I->getOpcode() == TargetOpcode::PATCHPOINT) {
136 addLiveOutSetToMI(MF, *I);
141 DEBUG(dbgs() << " " << LiveRegs << " " << *I);
142 LiveRegs.stepBackward(*I);
146 ++NumBBsHaveNoStackmap;
151 /// Add the current register live set to the instruction.
152 void StackMapLiveness::addLiveOutSetToMI(MachineFunction &MF,
154 uint32_t *Mask = createRegisterMask(MF);
155 MachineOperand MO = MachineOperand::CreateRegLiveOut(Mask);
156 MI.addOperand(MF, MO);
159 /// Create a register mask and initialize it with the registers from the
160 /// register live set.
161 uint32_t *StackMapLiveness::createRegisterMask(MachineFunction &MF) const {
162 // The mask is owned and cleaned up by the Machine Function.
163 uint32_t *Mask = MF.allocateRegisterMask(TRI->getNumRegs());
164 for (auto Reg : LiveRegs)
165 Mask[Reg / 32] |= 1U << (Reg % 32);
167 // Give the target a chance to adjust the mask.
168 TRI->adjustStackMapLiveOutMask(Mask);