MachineFunction.cpp revision 335d5c399b52c2507ad11048310edc51462f4811 
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/MachineCodeForInstruction.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/iOther.h"
17#include "llvm/Pass.h"
18#include <limits.h>
19
20const int INVALID_FRAME_OFFSET = INT_MAX; // std::numeric_limits<int>::max();
21
22static AnnotationID MCFM_AID(
23                 AnnotationManager::getID("CodeGen::MachineCodeForFunction"));
24
25
26//===---------------------------------------------------------------------===//
27// Code generation/destruction passes
28//===---------------------------------------------------------------------===//
29
30namespace {
31  class ConstructMachineFunction : public FunctionPass {
32    TargetMachine &Target;
33  public:
34    ConstructMachineFunction(TargetMachine &T) : Target(T) {}
35
36    const char *getPassName() const {
37      return "ConstructMachineFunction";
38    }
39
40    bool runOnFunction(Function &F) {
41      MachineFunction::construct(&F, Target);
42      return false;
43    }
44  };
45
46  struct DestroyMachineFunction : public FunctionPass {
47    const char *getPassName() const { return "FreeMachineFunction"; }
48
49    static void freeMachineCode(Instruction &I) {
50      MachineCodeForInstruction::destroy(&I);
51    }
52
53    bool runOnFunction(Function &F) {
54      for (Function::iterator FI = F.begin(), FE = F.end(); FI != FE; ++FI)
55        for (BasicBlock::iterator I = FI->begin(), E = FI->end(); I != E; ++I)
56          MachineCodeForInstruction::get(I).dropAllReferences();
57
58      for (Function::iterator FI = F.begin(), FE = F.end(); FI != FE; ++FI)
59        for_each(FI->begin(), FI->end(), freeMachineCode);
60
61      return false;
62    }
63  };
64}
65
66Pass *createMachineCodeConstructionPass(TargetMachine &Target) {
67  return new ConstructMachineFunction(Target);
68}
69
70Pass *createMachineCodeDestructionPass() {
71  return new DestroyMachineFunction();
72}
73
74
75// get - This deprecated static method returns the MachineBasicBlock object
76// for the specified BasicBlock.
77//
78MachineBasicBlock& MachineBasicBlock::get(const BasicBlock *BB) {
79  const Function *F = BB->getParent();
80  MachineFunction &MF = MachineFunction::get(F);
81
82  for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E; ++I)
83    if (I->getBasicBlock() == BB)
84      return *I;
85  assert(0 && "MachineBasicBlock object not found for specified block!");
86  return get(BB);
87}
88
89
90//===---------------------------------------------------------------------===//
91// MachineFunction implementation
92//===---------------------------------------------------------------------===//
93
94// The next two methods are used to construct and to retrieve
95// the MachineCodeForFunction object for the given function.
96// construct() -- Allocates and initializes for a given function and target
97// get()       -- Returns a handle to the object.
98//                This should not be called before "construct()"
99//                for a given Function.
100//
101MachineFunction&
102MachineFunction::construct(const Function *Fn, const TargetMachine &Tar)
103{
104  assert(Fn->getAnnotation(MCFM_AID) == 0 &&
105         "Object already exists for this function!");
106  MachineFunction* mcInfo = new MachineFunction(Fn, Tar);
107  Fn->addAnnotation(mcInfo);
108  return *mcInfo;
109}
110
111void
112MachineFunction::destruct(const Function *Fn)
113{
114  bool Deleted = Fn->deleteAnnotation(MCFM_AID);
115  assert(Deleted && "Machine code did not exist for function!");
116}
117
118MachineFunction& MachineFunction::get(const Function *F)
119{
120  MachineFunction *mc = (MachineFunction*)F->getAnnotation(MCFM_AID);
121  assert(mc && "Call construct() method first to allocate the object");
122  return *mc;
123}
124
125static unsigned
126ComputeMaxOptionalArgsSize(const TargetMachine& target, const Function *F,
127                           unsigned &maxOptionalNumArgs)
128{
129  const MachineFrameInfo& frameInfo = target.getFrameInfo();
130
131  unsigned maxSize = 0;
132
133  for (Function::const_iterator BB = F->begin(), BBE = F->end(); BB !=BBE; ++BB)
134    for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I != E; ++I)
135      if (const CallInst *callInst = dyn_cast<CallInst>(&*I))
136        {
137          unsigned numOperands = callInst->getNumOperands() - 1;
138          int numExtra = (int)numOperands-frameInfo.getNumFixedOutgoingArgs();
139          if (numExtra <= 0)
140            continue;
141
142          unsigned int sizeForThisCall;
143          if (frameInfo.argsOnStackHaveFixedSize())
144            {
145              int argSize = frameInfo.getSizeOfEachArgOnStack();
146              sizeForThisCall = numExtra * (unsigned) argSize;
147            }
148          else
149            {
150              assert(0 && "UNTESTED CODE: Size per stack argument is not "
151                     "fixed on this architecture: use actual arg sizes to "
152                     "compute MaxOptionalArgsSize");
153              sizeForThisCall = 0;
154              for (unsigned i = 0; i < numOperands; ++i)
155                sizeForThisCall += target.DataLayout.getTypeSize(callInst->
156                                              getOperand(i)->getType());
157            }
158
159          if (maxSize < sizeForThisCall)
160            maxSize = sizeForThisCall;
161
162          if ((int)maxOptionalNumArgs < numExtra)
163            maxOptionalNumArgs = (unsigned) numExtra;
164        }
165
166  return maxSize;
167}
168
169// Align data larger than one L1 cache line on L1 cache line boundaries.
170// Align all smaller data on the next higher 2^x boundary (4, 8, ...),
171// but not higher than the alignment of the largest type we support
172// (currently a double word). -- see class TargetData).
173//
174// This function is similar to the corresponding function in EmitAssembly.cpp
175// but they are unrelated.  This one does not align at more than a
176// double-word boundary whereas that one might.
177//
178inline unsigned int
179SizeToAlignment(unsigned int size, const TargetMachine& target)
180{
181  unsigned short cacheLineSize = target.getCacheInfo().getCacheLineSize(1);
182  if (size > (unsigned) cacheLineSize / 2)
183    return cacheLineSize;
184  else
185    for (unsigned sz=1; /*no condition*/; sz *= 2)
186      if (sz >= size || sz >= target.DataLayout.getDoubleAlignment())
187        return sz;
188}
189
190
191/*ctor*/
192MachineFunction::MachineFunction(const Function *F,
193                                 const TargetMachine& target)
194  : Annotation(MCFM_AID),
195    Fn(F), Target(target), staticStackSize(0),
196    automaticVarsSize(0), regSpillsSize(0),
197    maxOptionalArgsSize(0), maxOptionalNumArgs(0),
198    currentTmpValuesSize(0), maxTmpValuesSize(0), compiledAsLeaf(false),
199    spillsAreaFrozen(false), automaticVarsAreaFrozen(false)
200{
201  maxOptionalArgsSize = ComputeMaxOptionalArgsSize(target, Fn,
202                                                   maxOptionalNumArgs);
203  staticStackSize = maxOptionalArgsSize
204                    + target.getFrameInfo().getMinStackFrameSize();
205}
206
207int
208MachineFunction::computeOffsetforLocalVar(const TargetMachine& target,
209                                               const Value* val,
210                                               unsigned int& getPaddedSize,
211                                               unsigned int  sizeToUse)
212{
213  if (sizeToUse == 0)
214    sizeToUse = target.findOptimalStorageSize(val->getType());
215  unsigned int align = SizeToAlignment(sizeToUse, target);
216
217  bool growUp;
218  int firstOffset = target.getFrameInfo().getFirstAutomaticVarOffset(*this,
219                                                                     growUp);
220  int offset = growUp? firstOffset + getAutomaticVarsSize()
221                     : firstOffset - (getAutomaticVarsSize() + sizeToUse);
222
223  int aligned = target.getFrameInfo().adjustAlignment(offset, growUp, align);
224  getPaddedSize = sizeToUse + abs(aligned - offset);
225
226  return aligned;
227}
228
229int
230MachineFunction::allocateLocalVar(const TargetMachine& target,
231                                       const Value* val,
232                                       unsigned int sizeToUse)
233{
234  assert(! automaticVarsAreaFrozen &&
235         "Size of auto vars area has been used to compute an offset so "
236         "no more automatic vars should be allocated!");
237
238  // Check if we've allocated a stack slot for this value already
239  //
240  int offset = getOffset(val);
241  if (offset == INVALID_FRAME_OFFSET)
242    {
243      unsigned int getPaddedSize;
244      offset = computeOffsetforLocalVar(target, val, getPaddedSize, sizeToUse);
245      offsets[val] = offset;
246      incrementAutomaticVarsSize(getPaddedSize);
247    }
248  return offset;
249}
250
251int
252MachineFunction::allocateSpilledValue(const TargetMachine& target,
253                                           const Type* type)
254{
255  assert(! spillsAreaFrozen &&
256         "Size of reg spills area has been used to compute an offset so "
257         "no more register spill slots should be allocated!");
258
259  unsigned int size  = target.DataLayout.getTypeSize(type);
260  unsigned char align = target.DataLayout.getTypeAlignment(type);
261
262  bool growUp;
263  int firstOffset = target.getFrameInfo().getRegSpillAreaOffset(*this, growUp);
264
265  int offset = growUp? firstOffset + getRegSpillsSize()
266                     : firstOffset - (getRegSpillsSize() + size);
267
268  int aligned = target.getFrameInfo().adjustAlignment(offset, growUp, align);
269  size += abs(aligned - offset); // include alignment padding in size
270
271  incrementRegSpillsSize(size);  // update size of reg. spills area
272
273  return aligned;
274}
275
276int
277MachineFunction::pushTempValue(const TargetMachine& target,
278                                    unsigned int size)
279{
280  unsigned int align = SizeToAlignment(size, target);
281
282  bool growUp;
283  int firstOffset = target.getFrameInfo().getTmpAreaOffset(*this, growUp);
284
285  int offset = growUp? firstOffset + currentTmpValuesSize
286                     : firstOffset - (currentTmpValuesSize + size);
287
288  int aligned = target.getFrameInfo().adjustAlignment(offset, growUp, align);
289  size += abs(aligned - offset); // include alignment padding in size
290
291  incrementTmpAreaSize(size);    // update "current" size of tmp area
292
293  return aligned;
294}
295
296void
297MachineFunction::popAllTempValues(const TargetMachine& target)
298{
299  resetTmpAreaSize();            // clear tmp area to reuse
300}
301
302int
303MachineFunction::getOffset(const Value* val) const
304{
305  hash_map<const Value*, int>::const_iterator pair = offsets.find(val);
306  return (pair == offsets.end()) ? INVALID_FRAME_OFFSET : pair->second;
307}
308
309void
310MachineFunction::dump() const
311{
312  std::cerr << "\n" << Fn->getReturnType()
313            << " \"" << Fn->getName() << "\"\n";
314
315  for (Function::const_iterator BB = Fn->begin(); BB != Fn->end(); ++BB)
316    {
317      std::cerr << "\n" << BB->getName() << " (" << (const void*)BB
318                << ")" << ":" << "\n";
319      MachineBasicBlock& mvec = MachineBasicBlock::get(BB);
320      for (unsigned i=0; i < mvec.size(); i++)
321	std::cerr << "\t" << *mvec[i];
322    }
323  std::cerr << "\nEnd function \"" << Fn->getName() << "\"\n\n";
324}
325