200 lines · cpp
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-exception6//7//===----------------------------------------------------------------------===//8//9// This file implements lowering of MASSV (SIMD) entries for specific PowerPC10// subtargets.11// Following is an example of a conversion specific to Power9 subtarget:12// __sind2_massv ---> __sind2_P913//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 27using namespace llvm;28 29namespace {30 31static StringRef MASSVFuncs[] = {32#define TLI_DEFINE_MASSV_VECFUNCS33#define TLI_DEFINE_VECFUNC(SCAL, VEC, VF, VABI_PREFIX) VEC,34#include "llvm/Analysis/VecFuncs.def"35#undef TLI_DEFINE_MASSV_VECFUNCS36};37 38class PPCLowerMASSVEntries : public ModulePass {39public: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 52private: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} // namespace63 64/// Checks if the specified function name represents an entry in the MASSV65/// library.66bool 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 while73/// generating subtarget-specific MASSV library functions. Current support74/// includes minimum subtarget Power8 for Linux and Power7 for AIX.75StringRef 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 AIX80 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 specified95/// generic MASSV function, and the PowerPC subtarget.96std::string97PPCLowerMASSVEntries::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.pow106/// intrinsics when the exponent is 0.25 or 0.75.107bool 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 pow115 // 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::getOrInsertDeclaration(&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.136bool 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 155bool 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 upon173 // replacing the users. Precomputing the current list of users allows us to174 // 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 190char PPCLowerMASSVEntries::ID = 0;191 192char &llvm::PPCLowerMASSVEntriesID = PPCLowerMASSVEntries::ID;193 194INITIALIZE_PASS(PPCLowerMASSVEntries, DEBUG_TYPE, "Lower MASSV entries", false,195 false)196 197ModulePass *llvm::createPPCLowerMASSVEntriesPass() {198 return new PPCLowerMASSVEntries();199}200