MachineFunction.cpp revision 1318bed20c52792913405c0d41766f69829cf944 
1//===-- MachineCodeForMethod.cpp -------------------------------------------=//
2//
3// Purpose:
4//   Collect native machine code information for a function.
5//   This allows target-specific information about the generated code
6//   to be stored with each function.
7//===---------------------------------------------------------------------===//
8
9#include "llvm/CodeGen/MachineCodeForMethod.h"
10#include "llvm/CodeGen/MachineInstr.h"  // For debug output
11#include "llvm/CodeGen/MachineCodeForBasicBlock.h"
12#include "llvm/Target/TargetMachine.h"
13#include "llvm/Target/MachineFrameInfo.h"
14#include "llvm/Target/MachineCacheInfo.h"
15#include "llvm/Function.h"
16#include "llvm/BasicBlock.h"
17#include "llvm/iOther.h"
18#include <limits.h>
19#include <iostream>
20
21const int INVALID_FRAME_OFFSET = INT_MAX; // std::numeric_limits<int>::max();
22
23static AnnotationID MCFM_AID(
24                 AnnotationManager::getID("CodeGen::MachineCodeForFunction"));
25
26// The next two methods are used to construct and to retrieve
27// the MachineCodeForFunction object for the given function.
28// construct() -- Allocates and initializes for a given function and target
29// get()       -- Returns a handle to the object.
30//                This should not be called before "construct()"
31//                for a given Function.
32//
33MachineCodeForMethod&
34MachineCodeForMethod::construct(const Function *M, const TargetMachine &Tar)
35{
36  assert(M->getAnnotation(MCFM_AID) == 0 &&
37         "Object already exists for this function!");
38  MachineCodeForMethod* mcInfo = new MachineCodeForMethod(M, Tar);
39  M->addAnnotation(mcInfo);
40  return *mcInfo;
41}
42
43void
44MachineCodeForMethod::destruct(const Function *M)
45{
46  bool Deleted = M->deleteAnnotation(MCFM_AID);
47  assert(Deleted && "Machine code did not exist for function!");
48}
49
50MachineCodeForMethod&
51MachineCodeForMethod::get(const Function *F)
52{
53  MachineCodeForMethod *mc = (MachineCodeForMethod*)F->getAnnotation(MCFM_AID);
54  assert(mc && "Call construct() method first to allocate the object");
55  return *mc;
56}
57
58static unsigned
59ComputeMaxOptionalArgsSize(const TargetMachine& target, const Function *F,
60                           unsigned &maxOptionalNumArgs)
61{
62  const MachineFrameInfo& frameInfo = target.getFrameInfo();
63
64  unsigned maxSize = 0;
65
66  for (Function::const_iterator BB = F->begin(), BBE = F->end(); BB !=BBE; ++BB)
67    for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I != E; ++I)
68      if (const CallInst *callInst = dyn_cast<CallInst>(&*I))
69        {
70          unsigned numOperands = callInst->getNumOperands() - 1;
71          int numExtra = (int)numOperands-frameInfo.getNumFixedOutgoingArgs();
72          if (numExtra <= 0)
73            continue;
74
75          unsigned int sizeForThisCall;
76          if (frameInfo.argsOnStackHaveFixedSize())
77            {
78              int argSize = frameInfo.getSizeOfEachArgOnStack();
79              sizeForThisCall = numExtra * (unsigned) argSize;
80            }
81          else
82            {
83              assert(0 && "UNTESTED CODE: Size per stack argument is not "
84                     "fixed on this architecture: use actual arg sizes to "
85                     "compute MaxOptionalArgsSize");
86              sizeForThisCall = 0;
87              for (unsigned i = 0; i < numOperands; ++i)
88                sizeForThisCall += target.findOptimalStorageSize(callInst->
89                                              getOperand(i)->getType());
90            }
91
92          if (maxSize < sizeForThisCall)
93            maxSize = sizeForThisCall;
94
95          if ((int)maxOptionalNumArgs < numExtra)
96            maxOptionalNumArgs = (unsigned) numExtra;
97        }
98
99  return maxSize;
100}
101
102// Align data larger than one L1 cache line on L1 cache line boundaries.
103// Align all smaller data on the next higher 2^x boundary (4, 8, ...),
104// but not higher than the alignment of the largest type we support
105// (currently a double word). -- see class TargetData).
106//
107// This function is similar to the corresponding function in EmitAssembly.cpp
108// but they are unrelated.  This one does not align at more than a
109// double-word boundary whereas that one might.
110//
111inline unsigned int
112SizeToAlignment(unsigned int size, const TargetMachine& target)
113{
114  unsigned short cacheLineSize = target.getCacheInfo().getCacheLineSize(1);
115  if (size > (unsigned) cacheLineSize / 2)
116    return cacheLineSize;
117  else
118    for (unsigned sz=1; /*no condition*/; sz *= 2)
119      if (sz >= size || sz >= target.DataLayout.getDoubleAlignment())
120        return sz;
121}
122
123
124/*ctor*/
125MachineCodeForMethod::MachineCodeForMethod(const Function *F,
126                                           const TargetMachine& target)
127  : Annotation(MCFM_AID),
128    method(F), staticStackSize(0),
129    automaticVarsSize(0), regSpillsSize(0),
130    maxOptionalArgsSize(0), maxOptionalNumArgs(0),
131    currentTmpValuesSize(0), maxTmpValuesSize(0), compiledAsLeaf(false),
132    spillsAreaFrozen(false), automaticVarsAreaFrozen(false)
133{
134  maxOptionalArgsSize = ComputeMaxOptionalArgsSize(target, method,
135                                                   maxOptionalNumArgs);
136  staticStackSize = maxOptionalArgsSize
137                    + target.getFrameInfo().getMinStackFrameSize();
138}
139
140int
141MachineCodeForMethod::computeOffsetforLocalVar(const TargetMachine& target,
142                                               const Value* val,
143                                               unsigned int& getPaddedSize,
144                                               unsigned int  sizeToUse)
145{
146  if (sizeToUse == 0)
147    sizeToUse = target.findOptimalStorageSize(val->getType());
148  unsigned int align = SizeToAlignment(sizeToUse, target);
149
150  bool growUp;
151  int firstOffset = target.getFrameInfo().getFirstAutomaticVarOffset(*this,
152                                                                     growUp);
153  int offset = growUp? firstOffset + getAutomaticVarsSize()
154                     : firstOffset - (getAutomaticVarsSize() + sizeToUse);
155
156  int aligned = target.getFrameInfo().adjustAlignment(offset, growUp, align);
157  getPaddedSize = sizeToUse + abs(aligned - offset);
158
159  return aligned;
160}
161
162int
163MachineCodeForMethod::allocateLocalVar(const TargetMachine& target,
164                                       const Value* val,
165                                       unsigned int sizeToUse)
166{
167  assert(! automaticVarsAreaFrozen &&
168         "Size of auto vars area has been used to compute an offset so "
169         "no more automatic vars should be allocated!");
170
171  // Check if we've allocated a stack slot for this value already
172  //
173  int offset = getOffset(val);
174  if (offset == INVALID_FRAME_OFFSET)
175    {
176      unsigned int getPaddedSize;
177      offset = this->computeOffsetforLocalVar(target, val, getPaddedSize,
178                                              sizeToUse);
179      offsets[val] = offset;
180      incrementAutomaticVarsSize(getPaddedSize);
181    }
182  return offset;
183}
184
185int
186MachineCodeForMethod::allocateSpilledValue(const TargetMachine& target,
187                                           const Type* type)
188{
189  assert(! spillsAreaFrozen &&
190         "Size of reg spills area has been used to compute an offset so "
191         "no more register spill slots should be allocated!");
192
193  unsigned int size  = target.findOptimalStorageSize(type);
194  unsigned char align = target.DataLayout.getTypeAlignment(type);
195
196  bool growUp;
197  int firstOffset = target.getFrameInfo().getRegSpillAreaOffset(*this, growUp);
198
199  int offset = growUp? firstOffset + getRegSpillsSize()
200                     : firstOffset - (getRegSpillsSize() + size);
201
202  int aligned = target.getFrameInfo().adjustAlignment(offset, growUp, align);
203  size += abs(aligned - offset); // include alignment padding in size
204
205  incrementRegSpillsSize(size);  // update size of reg. spills area
206
207  return aligned;
208}
209
210int
211MachineCodeForMethod::pushTempValue(const TargetMachine& target,
212                                    unsigned int size)
213{
214  unsigned int align = SizeToAlignment(size, target);
215
216  bool growUp;
217  int firstOffset = target.getFrameInfo().getTmpAreaOffset(*this, growUp);
218
219  int offset = growUp? firstOffset + currentTmpValuesSize
220                     : firstOffset - (currentTmpValuesSize + size);
221
222  int aligned = target.getFrameInfo().adjustAlignment(offset, growUp, align);
223  size += abs(aligned - offset); // include alignment padding in size
224
225  incrementTmpAreaSize(size);    // update "current" size of tmp area
226
227  return aligned;
228}
229
230void
231MachineCodeForMethod::popAllTempValues(const TargetMachine& target)
232{
233  resetTmpAreaSize();            // clear tmp area to reuse
234}
235
236int
237MachineCodeForMethod::getOffset(const Value* val) const
238{
239  hash_map<const Value*, int>::const_iterator pair = offsets.find(val);
240  return (pair == offsets.end())? INVALID_FRAME_OFFSET : pair->second;
241}
242
243void
244MachineCodeForMethod::dump() const
245{
246  std::cerr << "\n" << method->getReturnType()
247            << " \"" << method->getName() << "\"\n";
248
249  for (Function::const_iterator BB = method->begin(); BB != method->end(); ++BB)
250    {
251      std::cerr << std::endl << (*BB).getName() << " (" << (const void*) BB << ")" << ":" << std::endl;
252      MachineCodeForBasicBlock& mvec = MachineCodeForBasicBlock::get(BB);
253      for (unsigned i=0; i < mvec.size(); i++)
254	std::cerr << "\t" << *mvec[i];
255    }
256  std::cerr << "\nEnd function \"" << method->getName() << "\"\n\n";
257}
258