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).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 
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 MachineFunction::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 
187 void MachineFunction::CalculateArgSize() {
188   maxOptionalArgsSize = ComputeMaxOptionalArgsSize(Target, Fn,
189                                                    maxOptionalNumArgs);
190   staticStackSize = maxOptionalArgsSize
191     + Target.getFrameInfo().getMinStackFrameSize();
192 }
193 
194 int
195 MachineFunction::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 
216 int
217 MachineFunction::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 
238 int
239 MachineFunction::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 
263 int
264 MachineFunction::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 
283 void
284 MachineFunction::popAllTempValues(const TargetMachine& target)
285 {
286   resetTmpAreaSize();            // clear tmp area to reuse
287 }
288 
289 int
290 MachineFunction::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 
296 void
297 MachineFunction::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