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
27using namespace llvm;
28
29namespace {
30
31static 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
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} // namespace
63
64/// Checks if the specified function name represents an entry in the MASSV
65/// library.
66bool PPCLowerMASSVEntries::isMASSVFunc(StringRef Name) {
67 return llvm::is_contained(Range&: MASSVFuncs, Element: 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.
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 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 reason: "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.
96std::string
97PPCLowerMASSVEntries::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.
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>(Val: CI->getArgOperand(i: 1)))
113 if (ConstantFP *CFP = dyn_cast_or_null<ConstantFP>(Val: 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(V: 0.75) && !CFP->isExactlyValue(V: 0.25))
120 return false;
121
122 if (CFP->isExactlyValue(V: 0.25) && !CI->hasNoSignedZeros())
123 return false;
124
125 CI->setCalledFunction(
126 Intrinsic::getOrInsertDeclaration(M: &M, id: Intrinsic::pow, Tys: 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 Name: MASSVEntryName, T: Func.getFunctionType(), AttributeList: 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(Name: 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>(Val: User);
179 if (!CI)
180 continue;
181
182 Subtarget = &TM.getSubtarget<PPCSubtarget>(F: *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