1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
|
//===-- PPCLowerMASSVEntries.cpp ------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file implements lowering of MASSV (SIMD) entries for specific PowerPC
// subtargets.
// Following is an example of a conversion specific to Power9 subtarget:
// __sind2_massv ---> __sind2_P9
//
//===----------------------------------------------------------------------===//
#include "PPC.h"
#include "PPCSubtarget.h"
#include "PPCTargetMachine.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/Analysis/TargetTransformInfo.h"
#include "llvm/CodeGen/TargetPassConfig.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/Module.h"
#define DEBUG_TYPE "ppc-lower-massv-entries"
using namespace llvm;
namespace {
// Length of the suffix "massv", which is specific to IBM MASSV library entries.
const unsigned MASSVSuffixLength = 5;
static StringRef MASSVFuncs[] = {
#define TLI_DEFINE_MASSV_VECFUNCS_NAMES
#include "llvm/Analysis/VecFuncs.def"
};
class PPCLowerMASSVEntries : public ModulePass {
public:
static char ID;
PPCLowerMASSVEntries() : ModulePass(ID) {}
bool runOnModule(Module &M) override;
StringRef getPassName() const override { return "PPC Lower MASS Entries"; }
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.addRequired<TargetTransformInfoWrapperPass>();
}
private:
static bool isMASSVFunc(StringRef Name);
static StringRef getCPUSuffix(const PPCSubtarget *Subtarget);
static std::string createMASSVFuncName(Function &Func,
const PPCSubtarget *Subtarget);
bool handlePowSpecialCases(CallInst *CI, Function &Func, Module &M);
bool lowerMASSVCall(CallInst *CI, Function &Func, Module &M,
const PPCSubtarget *Subtarget);
};
} // namespace
/// Checks if the specified function name represents an entry in the MASSV
/// library.
bool PPCLowerMASSVEntries::isMASSVFunc(StringRef Name) {
return llvm::is_contained(MASSVFuncs, Name);
}
// FIXME:
/// Returns a string corresponding to the specified PowerPC subtarget. e.g.:
/// "P8" for Power8, "P9" for Power9. The string is used as a suffix while
/// generating subtarget-specific MASSV library functions. Current support
/// includes Power8 and Power9 subtargets.
StringRef PPCLowerMASSVEntries::getCPUSuffix(const PPCSubtarget *Subtarget) {
// Assume Power8 when Subtarget is unavailable.
if (!Subtarget)
return "P8";
if (Subtarget->hasP9Vector())
return "P9";
if (Subtarget->hasP8Vector())
return "P8";
report_fatal_error("Unsupported Subtarget: MASSV is supported only on "
"Power8 and Power9 subtargets.");
}
/// Creates PowerPC subtarget-specific name corresponding to the specified
/// generic MASSV function, and the PowerPC subtarget.
std::string
PPCLowerMASSVEntries::createMASSVFuncName(Function &Func,
const PPCSubtarget *Subtarget) {
StringRef Suffix = getCPUSuffix(Subtarget);
auto GenericName = Func.getName().drop_back(MASSVSuffixLength).str();
std::string MASSVEntryName = GenericName + Suffix.str();
return MASSVEntryName;
}
/// If there are proper fast-math flags, this function creates llvm.pow
/// intrinsics when the exponent is 0.25 or 0.75.
bool PPCLowerMASSVEntries::handlePowSpecialCases(CallInst *CI, Function &Func,
Module &M) {
if (Func.getName() != "__powf4_massv" && Func.getName() != "__powd2_massv")
return false;
if (Constant *Exp = dyn_cast<Constant>(CI->getArgOperand(1)))
if (ConstantFP *CFP = dyn_cast_or_null<ConstantFP>(Exp->getSplatValue())) {
// If the argument is 0.75 or 0.25 it is cheaper to turn it into pow
// intrinsic so that it could be optimzed as sequence of sqrt's.
if (!CI->hasNoInfs() || !CI->hasApproxFunc())
return false;
if (!CFP->isExactlyValue(0.75) && !CFP->isExactlyValue(0.25))
return false;
if (CFP->isExactlyValue(0.25) && !CI->hasNoSignedZeros())
return false;
CI->setCalledFunction(
Intrinsic::getDeclaration(&M, Intrinsic::pow, CI->getType()));
return true;
}
return false;
}
/// Lowers generic MASSV entries to PowerPC subtarget-specific MASSV entries.
/// e.g.: __sind2_massv --> __sind2_P9 for a Power9 subtarget.
/// Both function prototypes and their callsites are updated during lowering.
bool PPCLowerMASSVEntries::lowerMASSVCall(CallInst *CI, Function &Func,
Module &M,
const PPCSubtarget *Subtarget) {
if (CI->use_empty())
return false;
// Handling pow(x, 0.25), pow(x, 0.75), powf(x, 0.25), powf(x, 0.75)
if (handlePowSpecialCases(CI, Func, M))
return true;
std::string MASSVEntryName = createMASSVFuncName(Func, Subtarget);
FunctionCallee FCache = M.getOrInsertFunction(
MASSVEntryName, Func.getFunctionType(), Func.getAttributes());
CI->setCalledFunction(FCache);
return true;
}
bool PPCLowerMASSVEntries::runOnModule(Module &M) {
bool Changed = false;
auto *TPC = getAnalysisIfAvailable<TargetPassConfig>();
if (!TPC)
return Changed;
auto &TM = TPC->getTM<PPCTargetMachine>();
const PPCSubtarget *Subtarget;
for (Function &Func : M) {
if (!Func.isDeclaration())
continue;
if (!isMASSVFunc(Func.getName()))
continue;
// Call to lowerMASSVCall() invalidates the iterator over users upon
// replacing the users. Precomputing the current list of users allows us to
// replace all the call sites.
SmallVector<User *, 4> MASSVUsers;
for (auto *User: Func.users())
MASSVUsers.push_back(User);
for (auto *User : MASSVUsers) {
auto *CI = dyn_cast<CallInst>(User);
if (!CI)
continue;
Subtarget = &TM.getSubtarget<PPCSubtarget>(*CI->getParent()->getParent());
Changed |= lowerMASSVCall(CI, Func, M, Subtarget);
}
}
return Changed;
}
char PPCLowerMASSVEntries::ID = 0;
char &llvm::PPCLowerMASSVEntriesID = PPCLowerMASSVEntries::ID;
INITIALIZE_PASS(PPCLowerMASSVEntries, DEBUG_TYPE, "Lower MASSV entries", false,
false)
ModulePass *llvm::createPPCLowerMASSVEntriesPass() {
return new PPCLowerMASSVEntries();
}
|
