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 //===---------------------------------------------------------------------===//
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 *M, const TargetMachine &Tar)
88 {
89   assert(M->getAnnotation(MCFM_AID) == 0 &&
90          "Object already exists for this function!");
91   MachineFunction* mcInfo = new MachineFunction(M, Tar);
92   M->addAnnotation(mcInfo);
93   return *mcInfo;
94 }
95 
96 void
97 MachineFunction::destruct(const Function *M)
98 {
99   bool Deleted = M->deleteAnnotation(MCFM_AID);
100   assert(Deleted && "Machine code did not exist for function!");
101 }
102 
103 MachineFunction&
104 MachineFunction::get(const Function *F)
105 {
106   MachineFunction *mc = (MachineFunction*)F->getAnnotation(MCFM_AID);
107   assert(mc && "Call construct() method first to allocate the object");
108   return *mc;
109 }
110 
111 static unsigned
112 ComputeMaxOptionalArgsSize(const TargetMachine& target, const Function *F,
113                            unsigned &maxOptionalNumArgs)
114 {
115   const MachineFrameInfo& frameInfo = target.getFrameInfo();
116 
117   unsigned maxSize = 0;
118 
119   for (Function::const_iterator BB = F->begin(), BBE = F->end(); BB !=BBE; ++BB)
120     for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I != E; ++I)
121       if (const CallInst *callInst = dyn_cast<CallInst>(&*I))
122         {
123           unsigned numOperands = callInst->getNumOperands() - 1;
124           int numExtra = (int)numOperands-frameInfo.getNumFixedOutgoingArgs();
125           if (numExtra <= 0)
126             continue;
127 
128           unsigned int sizeForThisCall;
129           if (frameInfo.argsOnStackHaveFixedSize())
130             {
131               int argSize = frameInfo.getSizeOfEachArgOnStack();
132               sizeForThisCall = numExtra * (unsigned) argSize;
133             }
134           else
135             {
136               assert(0 && "UNTESTED CODE: Size per stack argument is not "
137                      "fixed on this architecture: use actual arg sizes to "
138                      "compute MaxOptionalArgsSize");
139               sizeForThisCall = 0;
140               for (unsigned i = 0; i < numOperands; ++i)
141                 sizeForThisCall += target.DataLayout.getTypeSize(callInst->
142                                               getOperand(i)->getType());
143             }
144 
145           if (maxSize < sizeForThisCall)
146             maxSize = sizeForThisCall;
147 
148           if ((int)maxOptionalNumArgs < numExtra)
149             maxOptionalNumArgs = (unsigned) numExtra;
150         }
151 
152   return maxSize;
153 }
154 
155 // Align data larger than one L1 cache line on L1 cache line boundaries.
156 // Align all smaller data on the next higher 2^x boundary (4, 8, ...),
157 // but not higher than the alignment of the largest type we support
158 // (currently a double word). -- see class TargetData).
159 //
160 // This function is similar to the corresponding function in EmitAssembly.cpp
161 // but they are unrelated.  This one does not align at more than a
162 // double-word boundary whereas that one might.
163 //
164 inline unsigned int
165 SizeToAlignment(unsigned int size, const TargetMachine& target)
166 {
167   unsigned short cacheLineSize = target.getCacheInfo().getCacheLineSize(1);
168   if (size > (unsigned) cacheLineSize / 2)
169     return cacheLineSize;
170   else
171     for (unsigned sz=1; /*no condition*/; sz *= 2)
172       if (sz >= size || sz >= target.DataLayout.getDoubleAlignment())
173         return sz;
174 }
175 
176 
177 /*ctor*/
178 MachineFunction::MachineFunction(const Function *F,
179                                            const TargetMachine& target)
180   : Annotation(MCFM_AID),
181     method(F), staticStackSize(0),
182     automaticVarsSize(0), regSpillsSize(0),
183     maxOptionalArgsSize(0), maxOptionalNumArgs(0),
184     currentTmpValuesSize(0), maxTmpValuesSize(0), compiledAsLeaf(false),
185     spillsAreaFrozen(false), automaticVarsAreaFrozen(false)
186 {
187   maxOptionalArgsSize = ComputeMaxOptionalArgsSize(target, method,
188                                                    maxOptionalNumArgs);
189   staticStackSize = maxOptionalArgsSize
190                     + target.getFrameInfo().getMinStackFrameSize();
191 }
192 
193 int
194 MachineFunction::computeOffsetforLocalVar(const TargetMachine& target,
195                                                const Value* val,
196                                                unsigned int& getPaddedSize,
197                                                unsigned int  sizeToUse)
198 {
199   if (sizeToUse == 0)
200     sizeToUse = target.findOptimalStorageSize(val->getType());
201   unsigned int align = SizeToAlignment(sizeToUse, target);
202 
203   bool growUp;
204   int firstOffset = target.getFrameInfo().getFirstAutomaticVarOffset(*this,
205                                                                      growUp);
206   int offset = growUp? firstOffset + getAutomaticVarsSize()
207                      : firstOffset - (getAutomaticVarsSize() + sizeToUse);
208 
209   int aligned = target.getFrameInfo().adjustAlignment(offset, growUp, align);
210   getPaddedSize = sizeToUse + abs(aligned - offset);
211 
212   return aligned;
213 }
214 
215 int
216 MachineFunction::allocateLocalVar(const TargetMachine& target,
217                                        const Value* val,
218                                        unsigned int sizeToUse)
219 {
220   assert(! automaticVarsAreaFrozen &&
221          "Size of auto vars area has been used to compute an offset so "
222          "no more automatic vars should be allocated!");
223 
224   // Check if we've allocated a stack slot for this value already
225   //
226   int offset = getOffset(val);
227   if (offset == INVALID_FRAME_OFFSET)
228     {
229       unsigned int getPaddedSize;
230       offset = computeOffsetforLocalVar(target, val, getPaddedSize, sizeToUse);
231       offsets[val] = offset;
232       incrementAutomaticVarsSize(getPaddedSize);
233     }
234   return offset;
235 }
236 
237 int
238 MachineFunction::allocateSpilledValue(const TargetMachine& target,
239                                            const Type* type)
240 {
241   assert(! spillsAreaFrozen &&
242          "Size of reg spills area has been used to compute an offset so "
243          "no more register spill slots should be allocated!");
244 
245   unsigned int size  = target.DataLayout.getTypeSize(type);
246   unsigned char align = target.DataLayout.getTypeAlignment(type);
247 
248   bool growUp;
249   int firstOffset = target.getFrameInfo().getRegSpillAreaOffset(*this, growUp);
250 
251   int offset = growUp? firstOffset + getRegSpillsSize()
252                      : firstOffset - (getRegSpillsSize() + size);
253 
254   int aligned = target.getFrameInfo().adjustAlignment(offset, growUp, align);
255   size += abs(aligned - offset); // include alignment padding in size
256 
257   incrementRegSpillsSize(size);  // update size of reg. spills area
258 
259   return aligned;
260 }
261 
262 int
263 MachineFunction::pushTempValue(const TargetMachine& target,
264                                     unsigned int size)
265 {
266   unsigned int align = SizeToAlignment(size, target);
267 
268   bool growUp;
269   int firstOffset = target.getFrameInfo().getTmpAreaOffset(*this, growUp);
270 
271   int offset = growUp? firstOffset + currentTmpValuesSize
272                      : firstOffset - (currentTmpValuesSize + size);
273 
274   int aligned = target.getFrameInfo().adjustAlignment(offset, growUp, align);
275   size += abs(aligned - offset); // include alignment padding in size
276 
277   incrementTmpAreaSize(size);    // update "current" size of tmp area
278 
279   return aligned;
280 }
281 
282 void
283 MachineFunction::popAllTempValues(const TargetMachine& target)
284 {
285   resetTmpAreaSize();            // clear tmp area to reuse
286 }
287 
288 int
289 MachineFunction::getOffset(const Value* val) const
290 {
291   hash_map<const Value*, int>::const_iterator pair = offsets.find(val);
292   return (pair == offsets.end()) ? INVALID_FRAME_OFFSET : pair->second;
293 }
294 
295 void
296 MachineFunction::dump() const
297 {
298   std::cerr << "\n" << method->getReturnType()
299             << " \"" << method->getName() << "\"\n";
300 
301   for (Function::const_iterator BB = method->begin(); BB != method->end(); ++BB)
302     {
303       std::cerr << "\n" << BB->getName() << " (" << (const void*)BB
304                 << ")" << ":" << "\n";
305       MachineBasicBlock& mvec = MachineBasicBlock::get(BB);
306       for (unsigned i=0; i < mvec.size(); i++)
307 	std::cerr << "\t" << *mvec[i];
308     }
309   std::cerr << "\nEnd function \"" << method->getName() << "\"\n\n";
310 }
311