LLVM  3.7.0
SystemZTargetMachine.cpp
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1 //===-- SystemZTargetMachine.cpp - Define TargetMachine for SystemZ -------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 
10 #include "SystemZTargetMachine.h"
12 #include "llvm/CodeGen/Passes.h"
14 #include "llvm/Transforms/Scalar.h"
16 
17 using namespace llvm;
18 
19 extern "C" void LLVMInitializeSystemZTarget() {
20  // Register the target.
22 }
23 
24 // Determine whether we use the vector ABI.
25 static bool UsesVectorABI(StringRef CPU, StringRef FS) {
26  // We use the vector ABI whenever the vector facility is avaiable.
27  // This is the case by default if CPU is z13 or later, and can be
28  // overridden via "[+-]vector" feature string elements.
29  bool VectorABI = true;
30  if (CPU.empty() || CPU == "generic" ||
31  CPU == "z10" || CPU == "z196" || CPU == "zEC12")
32  VectorABI = false;
33 
35  FS.split(Features, ",", -1, false /* KeepEmpty */);
36  for (auto &Feature : Features) {
37  if (Feature == "vector" || Feature == "+vector")
38  VectorABI = true;
39  if (Feature == "-vector")
40  VectorABI = false;
41  }
42 
43  return VectorABI;
44 }
45 
46 static std::string computeDataLayout(const Triple &TT, StringRef CPU,
47  StringRef FS) {
48  bool VectorABI = UsesVectorABI(CPU, FS);
49  std::string Ret = "";
50 
51  // Big endian.
52  Ret += "E";
53 
54  // Data mangling.
56 
57  // Make sure that global data has at least 16 bits of alignment by
58  // default, so that we can refer to it using LARL. We don't have any
59  // special requirements for stack variables though.
60  Ret += "-i1:8:16-i8:8:16";
61 
62  // 64-bit integers are naturally aligned.
63  Ret += "-i64:64";
64 
65  // 128-bit floats are aligned only to 64 bits.
66  Ret += "-f128:64";
67 
68  // When using the vector ABI, 128-bit vectors are also aligned to 64 bits.
69  if (VectorABI)
70  Ret += "-v128:64";
71 
72  // We prefer 16 bits of aligned for all globals; see above.
73  Ret += "-a:8:16";
74 
75  // Integer registers are 32 or 64 bits.
76  Ret += "-n32:64";
77 
78  return Ret;
79 }
80 
82  StringRef CPU, StringRef FS,
83  const TargetOptions &Options,
86  : LLVMTargetMachine(T, computeDataLayout(TT, CPU, FS), TT, CPU, FS, Options,
87  RM, CM, OL),
89  Subtarget(TT, CPU, FS, *this) {
90  initAsmInfo();
91 }
92 
94 
95 namespace {
96 /// SystemZ Code Generator Pass Configuration Options.
97 class SystemZPassConfig : public TargetPassConfig {
98 public:
99  SystemZPassConfig(SystemZTargetMachine *TM, PassManagerBase &PM)
100  : TargetPassConfig(TM, PM) {}
101 
102  SystemZTargetMachine &getSystemZTargetMachine() const {
103  return getTM<SystemZTargetMachine>();
104  }
105 
106  void addIRPasses() override;
107  bool addInstSelector() override;
108  void addPreSched2() override;
109  void addPreEmitPass() override;
110 };
111 } // end anonymous namespace
112 
113 void SystemZPassConfig::addIRPasses() {
115 }
116 
117 bool SystemZPassConfig::addInstSelector() {
118  addPass(createSystemZISelDag(getSystemZTargetMachine(), getOptLevel()));
119 
120  if (getOptLevel() != CodeGenOpt::None)
121  addPass(createSystemZLDCleanupPass(getSystemZTargetMachine()));
122 
123  return false;
124 }
125 
126 void SystemZPassConfig::addPreSched2() {
127  if (getOptLevel() != CodeGenOpt::None &&
128  getSystemZTargetMachine().getSubtargetImpl()->hasLoadStoreOnCond())
129  addPass(&IfConverterID);
130 }
131 
132 void SystemZPassConfig::addPreEmitPass() {
133  // We eliminate comparisons here rather than earlier because some
134  // transformations can change the set of available CC values and we
135  // generally want those transformations to have priority. This is
136  // especially true in the commonest case where the result of the comparison
137  // is used by a single in-range branch instruction, since we will then
138  // be able to fuse the compare and the branch instead.
139  //
140  // For example, two-address NILF can sometimes be converted into
141  // three-address RISBLG. NILF produces a CC value that indicates whether
142  // the low word is zero, but RISBLG does not modify CC at all. On the
143  // other hand, 64-bit ANDs like NILL can sometimes be converted to RISBG.
144  // The CC value produced by NILL isn't useful for our purposes, but the
145  // value produced by RISBG can be used for any comparison with zero
146  // (not just equality). So there are some transformations that lose
147  // CC values (while still being worthwhile) and others that happen to make
148  // the CC result more useful than it was originally.
149  //
150  // Another reason is that we only want to use BRANCH ON COUNT in cases
151  // where we know that the count register is not going to be spilled.
152  //
153  // Doing it so late makes it more likely that a register will be reused
154  // between the comparison and the branch, but it isn't clear whether
155  // preventing that would be a win or not.
156  if (getOptLevel() != CodeGenOpt::None)
157  addPass(createSystemZElimComparePass(getSystemZTargetMachine()), false);
158  if (getOptLevel() != CodeGenOpt::None)
159  addPass(createSystemZShortenInstPass(getSystemZTargetMachine()), false);
160  addPass(createSystemZLongBranchPass(getSystemZTargetMachine()));
161 }
162 
164  return new SystemZPassConfig(this, PM);
165 }
166 
168  return TargetIRAnalysis([this](Function &F) {
169  return TargetTransformInfo(SystemZTTIImpl(this, F));
170  });
171 }
virtual void addIRPasses()
Add common target configurable passes that perform LLVM IR to IR transforms following machine indepen...
Definition: Passes.cpp:377
std::pair< StringRef, StringRef > split(char Separator) const
Split into two substrings around the first occurrence of a separator character.
Definition: StringRef.h:450
const FeatureBitset Features
Analysis pass providing the TargetTransformInfo.
F(f)
Target TheSystemZTarget
static const char * getManglingComponent(const Triple &T)
Definition: DataLayout.cpp:150
TargetIRAnalysis getTargetIRAnalysis() override
Get a TargetIRAnalysis implementation for the target.
FunctionPass * createSystemZISelDag(SystemZTargetMachine &TM, CodeGenOpt::Level OptLevel)
static std::string computeDataLayout(const Triple &TT, StringRef CPU, StringRef FS)
Target-Independent Code Generator Pass Configuration Options.
FunctionPass * createSystemZShortenInstPass(SystemZTargetMachine &TM)
std::enable_if<!std::is_array< T >::value, std::unique_ptr< T > >::type make_unique(Args &&...args)
Constructs a new T() with the given args and returns a unique_ptr<T> which owns the object...
Definition: STLExtras.h:354
static bool UsesVectorABI(StringRef CPU, StringRef FS)
TargetPassConfig * createPassConfig(PassManagerBase &PM) override
Create a pass configuration object to be used by addPassToEmitX methods for generating a pipeline of ...
static GCMetadataPrinterRegistry::Add< ErlangGCPrinter > X("erlang","erlang-compatible garbage collector")
This class describes a target machine that is implemented with the LLVM target-independent code gener...
Triple - Helper class for working with autoconf configuration names.
Definition: Triple.h:44
This pass provides access to the codegen interfaces that are needed for IR-level transformations.
This is a 'vector' (really, a variable-sized array), optimized for the case when the array is small...
Definition: SmallVector.h:861
FunctionPass * createSystemZLongBranchPass(SystemZTargetMachine &TM)
void LLVMInitializeSystemZTarget()
Target - Wrapper for Target specific information.
SystemZTargetMachine(const Target &T, const Triple &TT, StringRef CPU, StringRef FS, const TargetOptions &Options, Reloc::Model RM, CodeModel::Model CM, CodeGenOpt::Level OL)
FunctionPass * createSystemZLDCleanupPass(SystemZTargetMachine &TM)
char & IfConverterID
IfConverter - This pass performs machine code if conversion.
FunctionPass * createSystemZElimComparePass(SystemZTargetMachine &TM)
RegisterTargetMachine - Helper template for registering a target machine implementation, for use in the target machine initialization function.
StringRef - Represent a constant reference to a string, i.e.
Definition: StringRef.h:40
bool empty() const
empty - Check if the string is empty.
Definition: StringRef.h:110