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/ADT/STLExtras.h" 20 #include "llvm/Analysis/TargetTransformInfo.h" 21 #include "llvm/CodeGen/TargetPassConfig.h" 22 #include "llvm/IR/Instructions.h" 23 #include "llvm/IR/Module.h" 24 25 #define DEBUG_TYPE "ppc-lower-massv-entries" 26 27 using namespace llvm; 28 29 namespace { 30 31 static StringRef MASSVFuncs[] = { 32 #define TLI_DEFINE_MASSV_VECFUNCS 33 #define TLI_DEFINE_VECFUNC(SCAL, VEC, VF, VABI_PREFIX) VEC, 34 #include "llvm/Analysis/VecFuncs.def" 35 #undef TLI_DEFINE_MASSV_VECFUNCS 36 }; 37 38 class PPCLowerMASSVEntries : public ModulePass { 39 public: 40 static char ID; 41 42 PPCLowerMASSVEntries() : ModulePass(ID) {} 43 44 bool runOnModule(Module &M) override; 45 46 StringRef getPassName() const override { return "PPC Lower MASS Entries"; } 47 48 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 handlePowSpecialCases(CallInst *CI, Function &Func, Module &M); 58 bool lowerMASSVCall(CallInst *CI, Function &Func, Module &M, 59 const PPCSubtarget *Subtarget); 60 }; 61 62 } // namespace 63 64 /// Checks if the specified function name represents an entry in the MASSV 65 /// library. 66 bool PPCLowerMASSVEntries::isMASSVFunc(StringRef Name) { 67 return llvm::is_contained(MASSVFuncs, Name); 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 minimum subtarget Power8 for Linux and Power7 for AIX. 75 StringRef PPCLowerMASSVEntries::getCPUSuffix(const PPCSubtarget *Subtarget) { 76 // Assume generic when Subtarget is unavailable. 77 if (!Subtarget) 78 return ""; 79 // TODO: add _P10 enties to Linux MASS lib and remove the check for AIX 80 if (Subtarget->isAIXABI() && Subtarget->hasP10Vector()) 81 return "_P10"; 82 if (Subtarget->hasP9Vector()) 83 return "_P9"; 84 if (Subtarget->hasP8Vector()) 85 return "_P8"; 86 if (Subtarget->isAIXABI()) 87 return "_P7"; 88 89 report_fatal_error( 90 "Mininum subtarget for -vector-library=MASSV option is Power8 on Linux " 91 "and Power7 on AIX when vectorization is not disabled."); 92 } 93 94 /// Creates PowerPC subtarget-specific name corresponding to the specified 95 /// generic MASSV function, and the PowerPC subtarget. 96 std::string 97 PPCLowerMASSVEntries::createMASSVFuncName(Function &Func, 98 const PPCSubtarget *Subtarget) { 99 StringRef Suffix = getCPUSuffix(Subtarget); 100 auto GenericName = Func.getName().str(); 101 std::string MASSVEntryName = GenericName + Suffix.str(); 102 return MASSVEntryName; 103 } 104 105 /// If there are proper fast-math flags, this function creates llvm.pow 106 /// intrinsics when the exponent is 0.25 or 0.75. 107 bool PPCLowerMASSVEntries::handlePowSpecialCases(CallInst *CI, Function &Func, 108 Module &M) { 109 if (Func.getName() != "__powf4" && Func.getName() != "__powd2") 110 return false; 111 112 if (Constant *Exp = dyn_cast<Constant>(CI->getArgOperand(1))) 113 if (ConstantFP *CFP = dyn_cast_or_null<ConstantFP>(Exp->getSplatValue())) { 114 // If the argument is 0.75 or 0.25 it is cheaper to turn it into pow 115 // intrinsic so that it could be optimzed as sequence of sqrt's. 116 if (!CI->hasNoInfs() || !CI->hasApproxFunc()) 117 return false; 118 119 if (!CFP->isExactlyValue(0.75) && !CFP->isExactlyValue(0.25)) 120 return false; 121 122 if (CFP->isExactlyValue(0.25) && !CI->hasNoSignedZeros()) 123 return false; 124 125 CI->setCalledFunction( 126 Intrinsic::getDeclaration(&M, Intrinsic::pow, CI->getType())); 127 return true; 128 } 129 130 return false; 131 } 132 133 /// Lowers generic MASSV entries to PowerPC subtarget-specific MASSV entries. 134 /// e.g.: __sind2_massv --> __sind2_P9 for a Power9 subtarget. 135 /// Both function prototypes and their callsites are updated during lowering. 136 bool PPCLowerMASSVEntries::lowerMASSVCall(CallInst *CI, Function &Func, 137 Module &M, 138 const PPCSubtarget *Subtarget) { 139 if (CI->use_empty()) 140 return false; 141 142 // Handling pow(x, 0.25), pow(x, 0.75), powf(x, 0.25), powf(x, 0.75) 143 if (handlePowSpecialCases(CI, Func, M)) 144 return true; 145 146 std::string MASSVEntryName = createMASSVFuncName(Func, Subtarget); 147 FunctionCallee FCache = M.getOrInsertFunction( 148 MASSVEntryName, Func.getFunctionType(), Func.getAttributes()); 149 150 CI->setCalledFunction(FCache); 151 152 return true; 153 } 154 155 bool PPCLowerMASSVEntries::runOnModule(Module &M) { 156 bool Changed = false; 157 158 auto *TPC = getAnalysisIfAvailable<TargetPassConfig>(); 159 if (!TPC) 160 return Changed; 161 162 auto &TM = TPC->getTM<PPCTargetMachine>(); 163 const PPCSubtarget *Subtarget; 164 165 for (Function &Func : M) { 166 if (!Func.isDeclaration()) 167 continue; 168 169 if (!isMASSVFunc(Func.getName())) 170 continue; 171 172 // Call to lowerMASSVCall() invalidates the iterator over users upon 173 // replacing the users. Precomputing the current list of users allows us to 174 // replace all the call sites. 175 SmallVector<User *, 4> MASSVUsers(Func.users()); 176 177 for (auto *User : MASSVUsers) { 178 auto *CI = dyn_cast<CallInst>(User); 179 if (!CI) 180 continue; 181 182 Subtarget = &TM.getSubtarget<PPCSubtarget>(*CI->getParent()->getParent()); 183 Changed |= lowerMASSVCall(CI, Func, M, Subtarget); 184 } 185 } 186 187 return Changed; 188 } 189 190 char PPCLowerMASSVEntries::ID = 0; 191 192 char &llvm::PPCLowerMASSVEntriesID = PPCLowerMASSVEntries::ID; 193 194 INITIALIZE_PASS(PPCLowerMASSVEntries, DEBUG_TYPE, "Lower MASSV entries", false, 195 false) 196 197 ModulePass *llvm::createPPCLowerMASSVEntriesPass() { 198 return new PPCLowerMASSVEntries(); 199 } 200