MachineFunction.cpp revision 88726188fe9a3e30ec9bdd9f2449905c0d8cedcf 
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 MF_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).CalculateArgSize();
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//===---------------------------------------------------------------------===//
76// MachineFunction implementation
77//===---------------------------------------------------------------------===//
78
79// The next two methods are used to construct and to retrieve
80// the MachineCodeForFunction object for the given function.
81// construct() -- Allocates and initializes for a given function and target
82// get()       -- Returns a handle to the object.
83//                This should not be called before "construct()"
84//                for a given Function.
85//
86MachineFunction&
87MachineFunction::construct(const Function *Fn, const TargetMachine &Tar)
88{
89  assert(Fn->getAnnotation(MF_AID) == 0 &&
90         "Object already exists for this function!");
91  MachineFunction* mcInfo = new MachineFunction(Fn, Tar);
92  Fn->addAnnotation(mcInfo);
93  return *mcInfo;
94}
95
96void
97MachineFunction::destruct(const Function *Fn)
98{
99  bool Deleted = Fn->deleteAnnotation(MF_AID);
100  assert(Deleted && "Machine code did not exist for function!");
101}
102
103MachineFunction& MachineFunction::get(const Function *F)
104{
105  MachineFunction *mc = (MachineFunction*)F->getAnnotation(MF_AID);
106  assert(mc && "Call construct() method first to allocate the object");
107  return *mc;
108}
109
110static unsigned
111ComputeMaxOptionalArgsSize(const TargetMachine& target, const Function *F,
112                           unsigned &maxOptionalNumArgs)
113{
114  const MachineFrameInfo& frameInfo = target.getFrameInfo();
115
116  unsigned maxSize = 0;
117
118  for (Function::const_iterator BB = F->begin(), BBE = F->end(); BB !=BBE; ++BB)
119    for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I != E; ++I)
120      if (const CallInst *callInst = dyn_cast<CallInst>(&*I))
121        {
122          unsigned numOperands = callInst->getNumOperands() - 1;
123          int numExtra = (int)numOperands-frameInfo.getNumFixedOutgoingArgs();
124          if (numExtra <= 0)
125            continue;
126
127          unsigned int sizeForThisCall;
128          if (frameInfo.argsOnStackHaveFixedSize())
129            {
130              int argSize = frameInfo.getSizeOfEachArgOnStack();
131              sizeForThisCall = numExtra * (unsigned) argSize;
132            }
133          else
134            {
135              assert(0 && "UNTESTED CODE: Size per stack argument is not "
136                     "fixed on this architecture: use actual arg sizes to "
137                     "compute MaxOptionalArgsSize");
138              sizeForThisCall = 0;
139              for (unsigned i = 0; i < numOperands; ++i)
140                sizeForThisCall += target.DataLayout.getTypeSize(callInst->
141                                              getOperand(i)->getType());
142            }
143
144          if (maxSize < sizeForThisCall)
145            maxSize = sizeForThisCall;
146
147          if ((int)maxOptionalNumArgs < numExtra)
148            maxOptionalNumArgs = (unsigned) numExtra;
149        }
150
151  return maxSize;
152}
153
154// Align data larger than one L1 cache line on L1 cache line boundaries.
155// Align all smaller data on the next higher 2^x boundary (4, 8, ...),
156// but not higher than the alignment of the largest type we support
157// (currently a double word). -- see class TargetData).
158//
159// This function is similar to the corresponding function in EmitAssembly.cpp
160// but they are unrelated.  This one does not align at more than a
161// double-word boundary whereas that one might.
162//
163inline unsigned int
164SizeToAlignment(unsigned int size, const TargetMachine& target)
165{
166  unsigned short cacheLineSize = target.getCacheInfo().getCacheLineSize(1);
167  if (size > (unsigned) cacheLineSize / 2)
168    return cacheLineSize;
169  else
170    for (unsigned sz=1; /*no condition*/; sz *= 2)
171      if (sz >= size || sz >= target.DataLayout.getDoubleAlignment())
172        return sz;
173}
174
175
176MachineFunction::MachineFunction(const Function *F,
177                                 const TargetMachine& target)
178  : Annotation(MF_AID),
179    Fn(F), Target(target), staticStackSize(0),
180    automaticVarsSize(0), regSpillsSize(0),
181    maxOptionalArgsSize(0), maxOptionalNumArgs(0),
182    currentTmpValuesSize(0), maxTmpValuesSize(0), compiledAsLeaf(false),
183    spillsAreaFrozen(false), automaticVarsAreaFrozen(false)
184{
185}
186
187void MachineFunction::CalculateArgSize() {
188  maxOptionalArgsSize = ComputeMaxOptionalArgsSize(Target, Fn,
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" << Fn->getReturnType()
300            << " \"" << Fn->getName() << "\"\n";
301
302  for (const_iterator BB = begin(); BB != end(); ++BB) {
303    std::cerr << "\n" << BB->getBasicBlock()->getName() << " ("
304              << (const void*)BB->getBasicBlock() << ")" << ":" << "\n";
305    for (MachineBasicBlock::const_iterator I = BB->begin(); I != BB->end(); ++I)
306      std::cerr << "\t" << *I;
307  }
308  std::cerr << "\nEnd function \"" << Fn->getName() << "\"\n\n";
309}
310