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 MF_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 //===---------------------------------------------------------------------===//
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 //
86 MachineFunction&
87 MachineFunction::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 
96 void
97 MachineFunction::destruct(const Function *Fn)
98 {
99   bool Deleted = Fn->deleteAnnotation(MF_AID);
100   assert(Deleted && "Machine code did not exist for function!");
101 }
102 
103 MachineFunction& 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 
110 static unsigned
111 ComputeMaxOptionalArgsSize(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 //
163 inline unsigned int
164 SizeToAlignment(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 
176 /*ctor*/
177 MachineFunction::MachineFunction(const Function *F,
178                                  const TargetMachine& target)
179   : Annotation(MF_AID),
180     Fn(F), Target(target), staticStackSize(0),
181     automaticVarsSize(0), regSpillsSize(0),
182     maxOptionalArgsSize(0), maxOptionalNumArgs(0),
183     currentTmpValuesSize(0), maxTmpValuesSize(0), compiledAsLeaf(false),
184     spillsAreaFrozen(false), automaticVarsAreaFrozen(false)
185 {
186   maxOptionalArgsSize = ComputeMaxOptionalArgsSize(target, Fn,
187                                                    maxOptionalNumArgs);
188   staticStackSize = maxOptionalArgsSize
189                     + target.getFrameInfo().getMinStackFrameSize();
190 }
191 
192 int
193 MachineFunction::computeOffsetforLocalVar(const TargetMachine& target,
194                                                const Value* val,
195                                                unsigned int& getPaddedSize,
196                                                unsigned int  sizeToUse)
197 {
198   if (sizeToUse == 0)
199     sizeToUse = target.findOptimalStorageSize(val->getType());
200   unsigned int align = SizeToAlignment(sizeToUse, target);
201 
202   bool growUp;
203   int firstOffset = target.getFrameInfo().getFirstAutomaticVarOffset(*this,
204                                                                      growUp);
205   int offset = growUp? firstOffset + getAutomaticVarsSize()
206                      : firstOffset - (getAutomaticVarsSize() + sizeToUse);
207 
208   int aligned = target.getFrameInfo().adjustAlignment(offset, growUp, align);
209   getPaddedSize = sizeToUse + abs(aligned - offset);
210 
211   return aligned;
212 }
213 
214 int
215 MachineFunction::allocateLocalVar(const TargetMachine& target,
216                                        const Value* val,
217                                        unsigned int sizeToUse)
218 {
219   assert(! automaticVarsAreaFrozen &&
220          "Size of auto vars area has been used to compute an offset so "
221          "no more automatic vars should be allocated!");
222 
223   // Check if we've allocated a stack slot for this value already
224   //
225   int offset = getOffset(val);
226   if (offset == INVALID_FRAME_OFFSET)
227     {
228       unsigned int getPaddedSize;
229       offset = computeOffsetforLocalVar(target, val, getPaddedSize, sizeToUse);
230       offsets[val] = offset;
231       incrementAutomaticVarsSize(getPaddedSize);
232     }
233   return offset;
234 }
235 
236 int
237 MachineFunction::allocateSpilledValue(const TargetMachine& target,
238                                            const Type* type)
239 {
240   assert(! spillsAreaFrozen &&
241          "Size of reg spills area has been used to compute an offset so "
242          "no more register spill slots should be allocated!");
243 
244   unsigned int size  = target.DataLayout.getTypeSize(type);
245   unsigned char align = target.DataLayout.getTypeAlignment(type);
246 
247   bool growUp;
248   int firstOffset = target.getFrameInfo().getRegSpillAreaOffset(*this, growUp);
249 
250   int offset = growUp? firstOffset + getRegSpillsSize()
251                      : firstOffset - (getRegSpillsSize() + size);
252 
253   int aligned = target.getFrameInfo().adjustAlignment(offset, growUp, align);
254   size += abs(aligned - offset); // include alignment padding in size
255 
256   incrementRegSpillsSize(size);  // update size of reg. spills area
257 
258   return aligned;
259 }
260 
261 int
262 MachineFunction::pushTempValue(const TargetMachine& target,
263                                     unsigned int size)
264 {
265   unsigned int align = SizeToAlignment(size, target);
266 
267   bool growUp;
268   int firstOffset = target.getFrameInfo().getTmpAreaOffset(*this, growUp);
269 
270   int offset = growUp? firstOffset + currentTmpValuesSize
271                      : firstOffset - (currentTmpValuesSize + size);
272 
273   int aligned = target.getFrameInfo().adjustAlignment(offset, growUp, align);
274   size += abs(aligned - offset); // include alignment padding in size
275 
276   incrementTmpAreaSize(size);    // update "current" size of tmp area
277 
278   return aligned;
279 }
280 
281 void
282 MachineFunction::popAllTempValues(const TargetMachine& target)
283 {
284   resetTmpAreaSize();            // clear tmp area to reuse
285 }
286 
287 int
288 MachineFunction::getOffset(const Value* val) const
289 {
290   hash_map<const Value*, int>::const_iterator pair = offsets.find(val);
291   return (pair == offsets.end()) ? INVALID_FRAME_OFFSET : pair->second;
292 }
293 
294 void
295 MachineFunction::dump() const
296 {
297   std::cerr << "\n" << Fn->getReturnType()
298             << " \"" << Fn->getName() << "\"\n";
299 
300   for (const_iterator BB = begin(); BB != end(); ++BB) {
301     std::cerr << "\n" << BB->getBasicBlock()->getName() << " ("
302               << (const void*)BB->getBasicBlock() << ")" << ":" << "\n";
303     for (MachineBasicBlock::const_iterator I = BB->begin(); I != BB->end(); ++I)
304       std::cerr << "\t" << *I;
305   }
306   std::cerr << "\nEnd function \"" << Fn->getName() << "\"\n\n";
307 }
308