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 
20 const int INVALID_FRAME_OFFSET = INT_MAX; // std::numeric_limits<int>::max();
21 
22 static AnnotationID MCFM_AID(
23                  AnnotationManager::getID("CodeGen::MachineCodeForFunction"));
24 
25 
26 //===---------------------------------------------------------------------===//
27 // Code generation/destruction passes
28 //===---------------------------------------------------------------------===//
29 
30 namespace {
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 
66 Pass *createMachineCodeConstructionPass(TargetMachine &Target) {
67   return new ConstructMachineFunction(Target);
68 }
69 
70 Pass *createMachineCodeDestructionPass() {
71   return new DestroyMachineFunction();
72 }
73 
74 
75 // get - This deprecated static method returns the MachineBasicBlock object
76 // for the specified BasicBlock.
77 //
78 MachineBasicBlock& 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 //
101 MachineFunction&
102 MachineFunction::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 
111 void
112 MachineFunction::destruct(const Function *Fn)
113 {
114   bool Deleted = Fn->deleteAnnotation(MCFM_AID);
115   assert(Deleted && "Machine code did not exist for function!");
116 }
117 
118 MachineFunction& 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 
125 static unsigned
126 ComputeMaxOptionalArgsSize(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 //
178 inline unsigned int
179 SizeToAlignment(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*/
192 MachineFunction::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 
207 int
208 MachineFunction::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 
229 int
230 MachineFunction::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 
251 int
252 MachineFunction::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 
276 int
277 MachineFunction::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 
296 void
297 MachineFunction::popAllTempValues(const TargetMachine& target)
298 {
299   resetTmpAreaSize();            // clear tmp area to reuse
300 }
301 
302 int
303 MachineFunction::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 
309 void
310 MachineFunction::dump() const
311 {
312   std::cerr << "\n" << Fn->getReturnType()
313             << " \"" << Fn->getName() << "\"\n";
314 
315   for (const_iterator BB = begin(); BB != end(); ++BB) {
316     std::cerr << "\n" << BB->getBasicBlock()->getName() << " ("
317               << (const void*)BB->getBasicBlock() << ")" << ":" << "\n";
318     for (MachineBasicBlock::const_iterator I = BB->begin(); I != BB->end(); ++I)
319       std::cerr << "\t" << *I;
320   }
321   std::cerr << "\nEnd function \"" << Fn->getName() << "\"\n\n";
322 }
323