1 //===-- MachineFunctionPass.cpp -------------------------------------------===//
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 // This file contains the definitions of the MachineFunctionPass members.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #include "llvm/CodeGen/MachineFunctionPass.h"
14 #include "llvm/Analysis/BasicAliasAnalysis.h"
15 #include "llvm/Analysis/DominanceFrontier.h"
16 #include "llvm/Analysis/GlobalsModRef.h"
17 #include "llvm/Analysis/IVUsers.h"
18 #include "llvm/Analysis/LoopInfo.h"
19 #include "llvm/Analysis/MemoryDependenceAnalysis.h"
20 #include "llvm/Analysis/OptimizationRemarkEmitter.h"
21 #include "llvm/Analysis/ScalarEvolution.h"
22 #include "llvm/Analysis/ScalarEvolutionAliasAnalysis.h"
23 #include "llvm/CodeGen/MachineFunction.h"
24 #include "llvm/CodeGen/MachineModuleInfo.h"
25 #include "llvm/CodeGen/MachineOptimizationRemarkEmitter.h"
26 #include "llvm/CodeGen/Passes.h"
27 #include "llvm/IR/Dominators.h"
28 #include "llvm/IR/Function.h"
29 #include "llvm/IR/PrintPasses.h"
30 
31 using namespace llvm;
32 using namespace ore;
33 
34 Pass *MachineFunctionPass::createPrinterPass(raw_ostream &O,
35                                              const std::string &Banner) const {
36   return createMachineFunctionPrinterPass(O, Banner);
37 }
38 
39 bool MachineFunctionPass::runOnFunction(Function &F) {
40   // Do not codegen any 'available_externally' functions at all, they have
41   // definitions outside the translation unit.
42   if (F.hasAvailableExternallyLinkage())
43     return false;
44 
45   MachineModuleInfo &MMI = getAnalysis<MachineModuleInfoWrapperPass>().getMMI();
46   MachineFunction &MF = MMI.getOrCreateMachineFunction(F);
47 
48   MachineFunctionProperties &MFProps = MF.getProperties();
49 
50 #ifndef NDEBUG
51   if (!MFProps.verifyRequiredProperties(RequiredProperties)) {
52     errs() << "MachineFunctionProperties required by " << getPassName()
53            << " pass are not met by function " << F.getName() << ".\n"
54            << "Required properties: ";
55     RequiredProperties.print(errs());
56     errs() << "\nCurrent properties: ";
57     MFProps.print(errs());
58     errs() << "\n";
59     llvm_unreachable("MachineFunctionProperties check failed");
60   }
61 #endif
62   // Collect the MI count of the function before the pass.
63   unsigned CountBefore, CountAfter;
64 
65   // Check if the user asked for size remarks.
66   bool ShouldEmitSizeRemarks =
67       F.getParent()->shouldEmitInstrCountChangedRemark();
68 
69   // If we want size remarks, collect the number of MachineInstrs in our
70   // MachineFunction before the pass runs.
71   if (ShouldEmitSizeRemarks)
72     CountBefore = MF.getInstructionCount();
73 
74   // For --print-changed, if the function name is a candidate, save the
75   // serialized MF to be compared later.
76   // TODO Implement --filter-passes.
77   SmallString<0> BeforeStr, AfterStr;
78   bool ShouldPrintChanged = PrintChanged != ChangePrinter::None &&
79                             isFunctionInPrintList(MF.getName());
80   if (ShouldPrintChanged) {
81     raw_svector_ostream OS(BeforeStr);
82     MF.print(OS);
83   }
84 
85   bool RV = runOnMachineFunction(MF);
86 
87   if (ShouldEmitSizeRemarks) {
88     // We wanted size remarks. Check if there was a change to the number of
89     // MachineInstrs in the module. Emit a remark if there was a change.
90     CountAfter = MF.getInstructionCount();
91     if (CountBefore != CountAfter) {
92       MachineOptimizationRemarkEmitter MORE(MF, nullptr);
93       MORE.emit([&]() {
94         int64_t Delta = static_cast<int64_t>(CountAfter) -
95                         static_cast<int64_t>(CountBefore);
96         MachineOptimizationRemarkAnalysis R("size-info", "FunctionMISizeChange",
97                                             MF.getFunction().getSubprogram(),
98                                             &MF.front());
99         R << NV("Pass", getPassName())
100           << ": Function: " << NV("Function", F.getName()) << ": "
101           << "MI Instruction count changed from "
102           << NV("MIInstrsBefore", CountBefore) << " to "
103           << NV("MIInstrsAfter", CountAfter)
104           << "; Delta: " << NV("Delta", Delta);
105         return R;
106       });
107     }
108   }
109 
110   MFProps.set(SetProperties);
111   MFProps.reset(ClearedProperties);
112 
113   // For --print-changed, print if the serialized MF has changed. Modes other
114   // than quiet/verbose are unimplemented and treated the same as 'quiet'.
115   if (ShouldPrintChanged) {
116     raw_svector_ostream OS(AfterStr);
117     MF.print(OS);
118     if (BeforeStr != AfterStr) {
119       StringRef Arg;
120       if (const PassInfo *PI = Pass::lookupPassInfo(getPassID()))
121         Arg = PI->getPassArgument();
122       errs() << ("*** IR Dump After " + getPassName() + " (" + Arg + ") on " +
123                  MF.getName() + " ***\n" + AfterStr);
124     } else if (PrintChanged == ChangePrinter::Verbose) {
125       errs() << ("*** IR Dump After " + getPassName() + " on " + MF.getName() +
126                  " omitted because no change ***\n");
127     }
128   }
129   return RV;
130 }
131 
132 void MachineFunctionPass::getAnalysisUsage(AnalysisUsage &AU) const {
133   AU.addRequired<MachineModuleInfoWrapperPass>();
134   AU.addPreserved<MachineModuleInfoWrapperPass>();
135 
136   // MachineFunctionPass preserves all LLVM IR passes, but there's no
137   // high-level way to express this. Instead, just list a bunch of
138   // passes explicitly. This does not include setPreservesCFG,
139   // because CodeGen overloads that to mean preserving the MachineBasicBlock
140   // CFG in addition to the LLVM IR CFG.
141   AU.addPreserved<BasicAAWrapperPass>();
142   AU.addPreserved<DominanceFrontierWrapperPass>();
143   AU.addPreserved<DominatorTreeWrapperPass>();
144   AU.addPreserved<AAResultsWrapperPass>();
145   AU.addPreserved<GlobalsAAWrapperPass>();
146   AU.addPreserved<IVUsersWrapperPass>();
147   AU.addPreserved<LoopInfoWrapperPass>();
148   AU.addPreserved<MemoryDependenceWrapperPass>();
149   AU.addPreserved<ScalarEvolutionWrapperPass>();
150   AU.addPreserved<SCEVAAWrapperPass>();
151 
152   FunctionPass::getAnalysisUsage(AU);
153 }
154