1 //===-- PPCLowerMASSVEntries.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 implements lowering of MASSV (SIMD) entries for specific PowerPC
10 // subtargets.
11 // Following is an example of a conversion specific to Power9 subtarget:
12 // __sind2_massv ---> __sind2_P9
13 //
14 //===----------------------------------------------------------------------===//
15
16 #include "PPC.h"
17 #include "PPCSubtarget.h"
18 #include "PPCTargetMachine.h"
19 #include "llvm/Analysis/TargetTransformInfo.h"
20 #include "llvm/CodeGen/TargetPassConfig.h"
21 #include "llvm/IR/Instructions.h"
22 #include "llvm/IR/Module.h"
23
24 #define DEBUG_TYPE "ppc-lower-massv-entries"
25
26 using namespace llvm;
27
28 namespace {
29
30 // Length of the suffix "massv", which is specific to IBM MASSV library entries.
31 const unsigned MASSVSuffixLength = 5;
32
33 static StringRef MASSVFuncs[] = {
34 #define TLI_DEFINE_MASSV_VECFUNCS_NAMES
35 #include "llvm/Analysis/VecFuncs.def"
36 };
37
38 class PPCLowerMASSVEntries : public ModulePass {
39 public:
40 static char ID;
41
PPCLowerMASSVEntries()42 PPCLowerMASSVEntries() : ModulePass(ID) {}
43
44 bool runOnModule(Module &M) override;
45
getPassName() const46 StringRef getPassName() const override { return "PPC Lower MASS Entries"; }
47
getAnalysisUsage(AnalysisUsage & AU) const48 void getAnalysisUsage(AnalysisUsage &AU) const override {
49 AU.addRequired<TargetTransformInfoWrapperPass>();
50 }
51
52 private:
53 static bool isMASSVFunc(StringRef Name);
54 static StringRef getCPUSuffix(const PPCSubtarget *Subtarget);
55 static std::string createMASSVFuncName(Function &Func,
56 const PPCSubtarget *Subtarget);
57 bool lowerMASSVCall(CallInst *CI, Function &Func, Module &M,
58 const PPCSubtarget *Subtarget);
59 };
60
61 } // namespace
62
63 /// Checks if the specified function name represents an entry in the MASSV
64 /// library.
isMASSVFunc(StringRef Name)65 bool PPCLowerMASSVEntries::isMASSVFunc(StringRef Name) {
66 auto Iter = std::find(std::begin(MASSVFuncs), std::end(MASSVFuncs), Name);
67 return Iter != std::end(MASSVFuncs);
68 }
69
70 // FIXME:
71 /// Returns a string corresponding to the specified PowerPC subtarget. e.g.:
72 /// "P8" for Power8, "P9" for Power9. The string is used as a suffix while
73 /// generating subtarget-specific MASSV library functions. Current support
74 /// includes Power8 and Power9 subtargets.
getCPUSuffix(const PPCSubtarget * Subtarget)75 StringRef PPCLowerMASSVEntries::getCPUSuffix(const PPCSubtarget *Subtarget) {
76 // Assume Power8 when Subtarget is unavailable.
77 if (!Subtarget)
78 return "P8";
79 if (Subtarget->hasP9Vector())
80 return "P9";
81 if (Subtarget->hasP8Vector())
82 return "P8";
83
84 report_fatal_error("Unsupported Subtarget: MASSV is supported only on "
85 "Power8 and Power9 subtargets.");
86 }
87
88 /// Creates PowerPC subtarget-specific name corresponding to the specified
89 /// generic MASSV function, and the PowerPC subtarget.
90 std::string
createMASSVFuncName(Function & Func,const PPCSubtarget * Subtarget)91 PPCLowerMASSVEntries::createMASSVFuncName(Function &Func,
92 const PPCSubtarget *Subtarget) {
93 StringRef Suffix = getCPUSuffix(Subtarget);
94 auto GenericName = Func.getName().drop_back(MASSVSuffixLength).str();
95 std::string MASSVEntryName = GenericName + Suffix.str();
96 return MASSVEntryName;
97 }
98
99 /// Lowers generic MASSV entries to PowerPC subtarget-specific MASSV entries.
100 /// e.g.: __sind2_massv --> __sind2_P9 for a Power9 subtarget.
101 /// Both function prototypes and their callsites are updated during lowering.
lowerMASSVCall(CallInst * CI,Function & Func,Module & M,const PPCSubtarget * Subtarget)102 bool PPCLowerMASSVEntries::lowerMASSVCall(CallInst *CI, Function &Func,
103 Module &M,
104 const PPCSubtarget *Subtarget) {
105 if (CI->use_empty())
106 return false;
107
108 std::string MASSVEntryName = createMASSVFuncName(Func, Subtarget);
109 FunctionCallee FCache = M.getOrInsertFunction(
110 MASSVEntryName, Func.getFunctionType(), Func.getAttributes());
111
112 CallSite CS(CI);
113 CI->setCalledFunction(FCache);
114
115 return true;
116 }
117
runOnModule(Module & M)118 bool PPCLowerMASSVEntries::runOnModule(Module &M) {
119 bool Changed = false;
120
121 auto *TPC = getAnalysisIfAvailable<TargetPassConfig>();
122 if (!TPC)
123 return Changed;
124
125 auto &TM = TPC->getTM<PPCTargetMachine>();
126 const PPCSubtarget *Subtarget;
127
128 for (Function &Func : M) {
129 if (!Func.isDeclaration())
130 continue;
131
132 if (!isMASSVFunc(Func.getName()))
133 continue;
134
135 // Call to lowerMASSVCall() invalidates the iterator over users upon
136 // replacing the users. Precomputing the current list of users allows us to
137 // replace all the call sites.
138 SmallVector<User *, 4> MASSVUsers;
139 for (auto *User: Func.users())
140 MASSVUsers.push_back(User);
141
142 for (auto *User : MASSVUsers) {
143 auto *CI = dyn_cast<CallInst>(User);
144 if (!CI)
145 continue;
146
147 Subtarget = &TM.getSubtarget<PPCSubtarget>(*CI->getParent()->getParent());
148 Changed |= lowerMASSVCall(CI, Func, M, Subtarget);
149 }
150 }
151
152 return Changed;
153 }
154
155 char PPCLowerMASSVEntries::ID = 0;
156
157 char &llvm::PPCLowerMASSVEntriesID = PPCLowerMASSVEntries::ID;
158
159 INITIALIZE_PASS(PPCLowerMASSVEntries, DEBUG_TYPE, "Lower MASSV entries", false,
160 false)
161
createPPCLowerMASSVEntriesPass()162 ModulePass *llvm::createPPCLowerMASSVEntriesPass() {
163 return new PPCLowerMASSVEntries();
164 }
165