MachineFunction.cpp revision 6b9445389a226b4ac97ceb89a34ee1a5bf921714 
1//===-- MachineFunction.cpp -----------------------------------------------===//
2//
3// Collect native machine code information for a function.  This allows
4// target-specific information about the generated code to be stored with each
5// function.
6//
7//===----------------------------------------------------------------------===//
8
9#include "llvm/CodeGen/MachineInstr.h"  // For debug output
10#include "llvm/CodeGen/MachineFunction.h"
11#include "llvm/CodeGen/MachineCodeForBasicBlock.h"
12#include "llvm/CodeGen/MachineCodeForInstruction.h"
13#include "llvm/Target/TargetMachine.h"
14#include "llvm/Target/MachineFrameInfo.h"
15#include "llvm/Target/MachineCacheInfo.h"
16#include "llvm/Function.h"
17#include "llvm/iOther.h"
18#include "llvm/Pass.h"
19#include <limits.h>
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
27//===---------------------------------------------------------------------===//
28// Code generation/destruction passes
29//===---------------------------------------------------------------------===//
30
31namespace {
32  class ConstructMachineFunction : public FunctionPass {
33    TargetMachine &Target;
34  public:
35    ConstructMachineFunction(TargetMachine &T) : Target(T) {}
36
37    const char *getPassName() const {
38      return "ConstructMachineFunction";
39    }
40
41    bool runOnFunction(Function &F) {
42      MachineFunction::construct(&F, Target);
43      return false;
44    }
45  };
46
47  struct DestroyMachineFunction : public FunctionPass {
48    const char *getPassName() const { return "FreeMachineFunction"; }
49
50    static void freeMachineCode(Instruction &I) {
51      MachineCodeForInstruction::destroy(&I);
52    }
53
54    bool runOnFunction(Function &F) {
55      for (Function::iterator FI = F.begin(), FE = F.end(); FI != FE; ++FI)
56        for (BasicBlock::iterator I = FI->begin(), E = FI->end(); I != E; ++I)
57          MachineCodeForInstruction::get(I).dropAllReferences();
58
59      for (Function::iterator FI = F.begin(), FE = F.end(); FI != FE; ++FI)
60        for_each(FI->begin(), FI->end(), freeMachineCode);
61
62      return false;
63    }
64  };
65}
66
67Pass *createMachineCodeConstructionPass(TargetMachine &Target) {
68  return new ConstructMachineFunction(Target);
69}
70
71Pass *createMachineCodeDestructionPass() {
72  return new DestroyMachineFunction();
73}
74
75
76//===---------------------------------------------------------------------===//
77// MachineFunction implementation
78//===---------------------------------------------------------------------===//
79
80// The next two methods are used to construct and to retrieve
81// the MachineCodeForFunction object for the given function.
82// construct() -- Allocates and initializes for a given function and target
83// get()       -- Returns a handle to the object.
84//                This should not be called before "construct()"
85//                for a given Function.
86//
87MachineFunction&
88MachineFunction::construct(const Function *M, const TargetMachine &Tar)
89{
90  assert(M->getAnnotation(MCFM_AID) == 0 &&
91         "Object already exists for this function!");
92  MachineFunction* mcInfo = new MachineFunction(M, Tar);
93  M->addAnnotation(mcInfo);
94  return *mcInfo;
95}
96
97void
98MachineFunction::destruct(const Function *M)
99{
100  bool Deleted = M->deleteAnnotation(MCFM_AID);
101  assert(Deleted && "Machine code did not exist for function!");
102}
103
104MachineFunction&
105MachineFunction::get(const Function *F)
106{
107  MachineFunction *mc = (MachineFunction*)F->getAnnotation(MCFM_AID);
108  assert(mc && "Call construct() method first to allocate the object");
109  return *mc;
110}
111
112static unsigned
113ComputeMaxOptionalArgsSize(const TargetMachine& target, const Function *F,
114                           unsigned &maxOptionalNumArgs)
115{
116  const MachineFrameInfo& frameInfo = target.getFrameInfo();
117
118  unsigned maxSize = 0;
119
120  for (Function::const_iterator BB = F->begin(), BBE = F->end(); BB !=BBE; ++BB)
121    for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I != E; ++I)
122      if (const CallInst *callInst = dyn_cast<CallInst>(&*I))
123        {
124          unsigned numOperands = callInst->getNumOperands() - 1;
125          int numExtra = (int)numOperands-frameInfo.getNumFixedOutgoingArgs();
126          if (numExtra <= 0)
127            continue;
128
129          unsigned int sizeForThisCall;
130          if (frameInfo.argsOnStackHaveFixedSize())
131            {
132              int argSize = frameInfo.getSizeOfEachArgOnStack();
133              sizeForThisCall = numExtra * (unsigned) argSize;
134            }
135          else
136            {
137              assert(0 && "UNTESTED CODE: Size per stack argument is not "
138                     "fixed on this architecture: use actual arg sizes to "
139                     "compute MaxOptionalArgsSize");
140              sizeForThisCall = 0;
141              for (unsigned i = 0; i < numOperands; ++i)
142                sizeForThisCall += target.DataLayout.getTypeSize(callInst->
143                                              getOperand(i)->getType());
144            }
145
146          if (maxSize < sizeForThisCall)
147            maxSize = sizeForThisCall;
148
149          if ((int)maxOptionalNumArgs < numExtra)
150            maxOptionalNumArgs = (unsigned) numExtra;
151        }
152
153  return maxSize;
154}
155
156// Align data larger than one L1 cache line on L1 cache line boundaries.
157// Align all smaller data on the next higher 2^x boundary (4, 8, ...),
158// but not higher than the alignment of the largest type we support
159// (currently a double word). -- see class TargetData).
160//
161// This function is similar to the corresponding function in EmitAssembly.cpp
162// but they are unrelated.  This one does not align at more than a
163// double-word boundary whereas that one might.
164//
165inline unsigned int
166SizeToAlignment(unsigned int size, const TargetMachine& target)
167{
168  unsigned short cacheLineSize = target.getCacheInfo().getCacheLineSize(1);
169  if (size > (unsigned) cacheLineSize / 2)
170    return cacheLineSize;
171  else
172    for (unsigned sz=1; /*no condition*/; sz *= 2)
173      if (sz >= size || sz >= target.DataLayout.getDoubleAlignment())
174        return sz;
175}
176
177
178/*ctor*/
179MachineFunction::MachineFunction(const Function *F,
180                                           const TargetMachine& target)
181  : Annotation(MCFM_AID),
182    method(F), staticStackSize(0),
183    automaticVarsSize(0), regSpillsSize(0),
184    maxOptionalArgsSize(0), maxOptionalNumArgs(0),
185    currentTmpValuesSize(0), maxTmpValuesSize(0), compiledAsLeaf(false),
186    spillsAreaFrozen(false), automaticVarsAreaFrozen(false)
187{
188  maxOptionalArgsSize = ComputeMaxOptionalArgsSize(target, method,
189                                                   maxOptionalNumArgs);
190  staticStackSize = maxOptionalArgsSize
191                    + target.getFrameInfo().getMinStackFrameSize();
192}
193
194int
195MachineFunction::computeOffsetforLocalVar(const TargetMachine& target,
196                                               const Value* val,
197                                               unsigned int& getPaddedSize,
198                                               unsigned int  sizeToUse)
199{
200  if (sizeToUse == 0)
201    sizeToUse = target.findOptimalStorageSize(val->getType());
202  unsigned int align = SizeToAlignment(sizeToUse, target);
203
204  bool growUp;
205  int firstOffset = target.getFrameInfo().getFirstAutomaticVarOffset(*this,
206                                                                     growUp);
207  int offset = growUp? firstOffset + getAutomaticVarsSize()
208                     : firstOffset - (getAutomaticVarsSize() + sizeToUse);
209
210  int aligned = target.getFrameInfo().adjustAlignment(offset, growUp, align);
211  getPaddedSize = sizeToUse + abs(aligned - offset);
212
213  return aligned;
214}
215
216int
217MachineFunction::allocateLocalVar(const TargetMachine& target,
218                                       const Value* val,
219                                       unsigned int sizeToUse)
220{
221  assert(! automaticVarsAreaFrozen &&
222         "Size of auto vars area has been used to compute an offset so "
223         "no more automatic vars should be allocated!");
224
225  // Check if we've allocated a stack slot for this value already
226  //
227  int offset = getOffset(val);
228  if (offset == INVALID_FRAME_OFFSET)
229    {
230      unsigned int getPaddedSize;
231      offset = computeOffsetforLocalVar(target, val, getPaddedSize, sizeToUse);
232      offsets[val] = offset;
233      incrementAutomaticVarsSize(getPaddedSize);
234    }
235  return offset;
236}
237
238int
239MachineFunction::allocateSpilledValue(const TargetMachine& target,
240                                           const Type* type)
241{
242  assert(! spillsAreaFrozen &&
243         "Size of reg spills area has been used to compute an offset so "
244         "no more register spill slots should be allocated!");
245
246  unsigned int size  = target.DataLayout.getTypeSize(type);
247  unsigned char align = target.DataLayout.getTypeAlignment(type);
248
249  bool growUp;
250  int firstOffset = target.getFrameInfo().getRegSpillAreaOffset(*this, growUp);
251
252  int offset = growUp? firstOffset + getRegSpillsSize()
253                     : firstOffset - (getRegSpillsSize() + size);
254
255  int aligned = target.getFrameInfo().adjustAlignment(offset, growUp, align);
256  size += abs(aligned - offset); // include alignment padding in size
257
258  incrementRegSpillsSize(size);  // update size of reg. spills area
259
260  return aligned;
261}
262
263int
264MachineFunction::pushTempValue(const TargetMachine& target,
265                                    unsigned int size)
266{
267  unsigned int align = SizeToAlignment(size, target);
268
269  bool growUp;
270  int firstOffset = target.getFrameInfo().getTmpAreaOffset(*this, growUp);
271
272  int offset = growUp? firstOffset + currentTmpValuesSize
273                     : firstOffset - (currentTmpValuesSize + size);
274
275  int aligned = target.getFrameInfo().adjustAlignment(offset, growUp, align);
276  size += abs(aligned - offset); // include alignment padding in size
277
278  incrementTmpAreaSize(size);    // update "current" size of tmp area
279
280  return aligned;
281}
282
283void
284MachineFunction::popAllTempValues(const TargetMachine& target)
285{
286  resetTmpAreaSize();            // clear tmp area to reuse
287}
288
289int
290MachineFunction::getOffset(const Value* val) const
291{
292  hash_map<const Value*, int>::const_iterator pair = offsets.find(val);
293  return (pair == offsets.end()) ? INVALID_FRAME_OFFSET : pair->second;
294}
295
296void
297MachineFunction::dump() const
298{
299  std::cerr << "\n" << method->getReturnType()
300            << " \"" << method->getName() << "\"\n";
301
302  for (Function::const_iterator BB = method->begin(); BB != method->end(); ++BB)
303    {
304      std::cerr << "\n" << BB->getName() << " (" << (const void*)BB
305                << ")" << ":" << "\n";
306      MachineCodeForBasicBlock& mvec = MachineCodeForBasicBlock::get(BB);
307      for (unsigned i=0; i < mvec.size(); i++)
308	std::cerr << "\t" << *mvec[i];
309    }
310  std::cerr << "\nEnd function \"" << method->getName() << "\"\n\n";
311}
312