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/AliasAnalysis.h"
15 #include "llvm/Analysis/BasicAliasAnalysis.h"
16 #include "llvm/Analysis/DominanceFrontier.h"
17 #include "llvm/Analysis/GlobalsModRef.h"
18 #include "llvm/Analysis/IVUsers.h"
19 #include "llvm/Analysis/LoopInfo.h"
20 #include "llvm/Analysis/MemoryDependenceAnalysis.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 
30 using namespace llvm;
31 using namespace ore;
32 
createPrinterPass(raw_ostream & O,const std::string & Banner) const33 Pass *MachineFunctionPass::createPrinterPass(raw_ostream &O,
34                                              const std::string &Banner) const {
35   return createMachineFunctionPrinterPass(O, Banner);
36 }
37 
runOnFunction(Function & F)38 bool MachineFunctionPass::runOnFunction(Function &F) {
39   // Do not codegen any 'available_externally' functions at all, they have
40   // definitions outside the translation unit.
41   if (F.hasAvailableExternallyLinkage())
42     return false;
43 
44   MachineModuleInfo &MMI = getAnalysis<MachineModuleInfoWrapperPass>().getMMI();
45   MachineFunction &MF = MMI.getOrCreateMachineFunction(F);
46 
47   MachineFunctionProperties &MFProps = MF.getProperties();
48 
49 #ifndef NDEBUG
50   if (!MFProps.verifyRequiredProperties(RequiredProperties)) {
51     errs() << "MachineFunctionProperties required by " << getPassName()
52            << " pass are not met by function " << F.getName() << ".\n"
53            << "Required properties: ";
54     RequiredProperties.print(errs());
55     errs() << "\nCurrent properties: ";
56     MFProps.print(errs());
57     errs() << "\n";
58     llvm_unreachable("MachineFunctionProperties check failed");
59   }
60 #endif
61   // Collect the MI count of the function before the pass.
62   unsigned CountBefore, CountAfter;
63 
64   // Check if the user asked for size remarks.
65   bool ShouldEmitSizeRemarks =
66       F.getParent()->shouldEmitInstrCountChangedRemark();
67 
68   // If we want size remarks, collect the number of MachineInstrs in our
69   // MachineFunction before the pass runs.
70   if (ShouldEmitSizeRemarks)
71     CountBefore = MF.getInstructionCount();
72 
73   bool RV = runOnMachineFunction(MF);
74 
75   if (ShouldEmitSizeRemarks) {
76     // We wanted size remarks. Check if there was a change to the number of
77     // MachineInstrs in the module. Emit a remark if there was a change.
78     CountAfter = MF.getInstructionCount();
79     if (CountBefore != CountAfter) {
80       MachineOptimizationRemarkEmitter MORE(MF, nullptr);
81       MORE.emit([&]() {
82         int64_t Delta = static_cast<int64_t>(CountAfter) -
83                         static_cast<int64_t>(CountBefore);
84         MachineOptimizationRemarkAnalysis R("size-info", "FunctionMISizeChange",
85                                             MF.getFunction().getSubprogram(),
86                                             &MF.front());
87         R << NV("Pass", getPassName())
88           << ": Function: " << NV("Function", F.getName()) << ": "
89           << "MI Instruction count changed from "
90           << NV("MIInstrsBefore", CountBefore) << " to "
91           << NV("MIInstrsAfter", CountAfter)
92           << "; Delta: " << NV("Delta", Delta);
93         return R;
94       });
95     }
96   }
97 
98   MFProps.set(SetProperties);
99   MFProps.reset(ClearedProperties);
100   return RV;
101 }
102 
getAnalysisUsage(AnalysisUsage & AU) const103 void MachineFunctionPass::getAnalysisUsage(AnalysisUsage &AU) const {
104   AU.addRequired<MachineModuleInfoWrapperPass>();
105   AU.addPreserved<MachineModuleInfoWrapperPass>();
106 
107   // MachineFunctionPass preserves all LLVM IR passes, but there's no
108   // high-level way to express this. Instead, just list a bunch of
109   // passes explicitly. This does not include setPreservesCFG,
110   // because CodeGen overloads that to mean preserving the MachineBasicBlock
111   // CFG in addition to the LLVM IR CFG.
112   AU.addPreserved<BasicAAWrapperPass>();
113   AU.addPreserved<DominanceFrontierWrapperPass>();
114   AU.addPreserved<DominatorTreeWrapperPass>();
115   AU.addPreserved<AAResultsWrapperPass>();
116   AU.addPreserved<GlobalsAAWrapperPass>();
117   AU.addPreserved<IVUsersWrapperPass>();
118   AU.addPreserved<LoopInfoWrapperPass>();
119   AU.addPreserved<MemoryDependenceWrapperPass>();
120   AU.addPreserved<ScalarEvolutionWrapperPass>();
121   AU.addPreserved<SCEVAAWrapperPass>();
122 
123   FunctionPass::getAnalysisUsage(AU);
124 }
125