147 lines · cpp
1//===-- PPCGenScalarMASSEntries.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 transformation converts standard math functions into their10// corresponding MASS (scalar) entries for PowerPC targets.11// Following are examples of such conversion:12// tanh ---> __xl_tanh_finite13// Such lowering is legal under the fast-math option.14//15//===----------------------------------------------------------------------===//16 17#include "PPC.h"18#include "PPCSubtarget.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-gen-scalar-mass"25 26using namespace llvm;27 28namespace {29 30class PPCGenScalarMASSEntries : public ModulePass {31public:32 static char ID;33 34 PPCGenScalarMASSEntries() : ModulePass(ID) {35 ScalarMASSFuncs = {36#define TLI_DEFINE_SCALAR_MASS_FUNCS37#include "llvm/Analysis/ScalarFuncs.def"38 };39 }40 41 bool runOnModule(Module &M) override;42 43 StringRef getPassName() const override {44 return "PPC Generate Scalar MASS Entries";45 }46 47 void getAnalysisUsage(AnalysisUsage &AU) const override {48 AU.addRequired<TargetTransformInfoWrapperPass>();49 }50 51private:52 std::map<StringRef, StringRef> ScalarMASSFuncs;53 bool isCandidateSafeToLower(const CallInst &CI) const;54 bool isFiniteCallSafe(const CallInst &CI) const;55 bool createScalarMASSCall(StringRef MASSEntry, CallInst &CI,56 Function &Func) const;57};58 59} // namespace60 61// Returns true if 'afn' flag exists on the call instruction with the math62// function63bool PPCGenScalarMASSEntries::isCandidateSafeToLower(const CallInst &CI) const {64 // skip functions with no scalar or vector FP type (like cosisin)65 if (!isa<FPMathOperator>(CI))66 return false;67 68 return CI.hasApproxFunc();69}70 71// Returns true if 'nnan', 'ninf' and 'nsz' flags exist on the call instruction72// with the math function73bool PPCGenScalarMASSEntries::isFiniteCallSafe(const CallInst &CI) const {74 // skip functions with no scalar or vector FP type (like cosisin)75 if (!isa<FPMathOperator>(CI))76 return false;77 78 // FIXME: no-errno and trapping-math need to be set for MASS converstion79 // but they don't have IR representation.80 return CI.hasNoNaNs() && CI.hasNoInfs() && CI.hasNoSignedZeros();81}82 83/// Lowers scalar math functions to scalar MASS functions.84/// e.g.: tanh --> __xl_tanh_finite or __xl_tanh85/// Both function prototype and its callsite is updated during lowering.86bool PPCGenScalarMASSEntries::createScalarMASSCall(StringRef MASSEntry,87 CallInst &CI,88 Function &Func) const {89 if (CI.use_empty())90 return false;91 92 Module *M = Func.getParent();93 assert(M && "Expecting a valid Module");94 95 std::string MASSEntryStr = MASSEntry.str();96 if (isFiniteCallSafe(CI))97 MASSEntryStr += "_finite";98 99 FunctionCallee FCache = M->getOrInsertFunction(100 MASSEntryStr, Func.getFunctionType(), Func.getAttributes());101 102 CI.setCalledFunction(FCache);103 104 return true;105}106 107bool PPCGenScalarMASSEntries::runOnModule(Module &M) {108 bool Changed = false;109 110 auto *TPC = getAnalysisIfAvailable<TargetPassConfig>();111 if (!TPC || skipModule(M))112 return false;113 114 for (Function &Func : M) {115 if (!Func.isDeclaration())116 continue;117 118 auto Iter = ScalarMASSFuncs.find(Func.getName());119 if (Iter == ScalarMASSFuncs.end())120 continue;121 122 // The call to createScalarMASSCall() invalidates the iterator over users123 // upon replacing the users. Precomputing the current list of users allows124 // us to replace all the call sites.125 SmallVector<User *, 4> TheUsers(Func.users());126 127 for (auto *User : TheUsers)128 if (auto *CI = dyn_cast_or_null<CallInst>(User)) {129 if (isCandidateSafeToLower(*CI))130 Changed |= createScalarMASSCall(Iter->second, *CI, Func);131 }132 }133 134 return Changed;135}136 137char PPCGenScalarMASSEntries::ID = 0;138 139char &llvm::PPCGenScalarMASSEntriesID = PPCGenScalarMASSEntries::ID;140 141INITIALIZE_PASS(PPCGenScalarMASSEntries, DEBUG_TYPE,142 "Generate Scalar MASS entries", false, false)143 144ModulePass *llvm::createPPCGenScalarMASSEntriesPass() {145 return new PPCGenScalarMASSEntries();146}147