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 *M, const TargetMachine &Tar)
103 {
104   assert(M->getAnnotation(MCFM_AID) == 0 &&
105          "Object already exists for this function!");
106   MachineFunction* mcInfo = new MachineFunction(M, Tar);
107   M->addAnnotation(mcInfo);
108   return *mcInfo;
109 }
110 
111 void
112 MachineFunction::destruct(const Function *M)
113 {
114   bool Deleted = M->deleteAnnotation(MCFM_AID);
115   assert(Deleted && "Machine code did not exist for function!");
116 }
117 
118 MachineFunction&
119 MachineFunction::get(const Function *F)
120 {
121   MachineFunction *mc = (MachineFunction*)F->getAnnotation(MCFM_AID);
122   assert(mc && "Call construct() method first to allocate the object");
123   return *mc;
124 }
125 
126 static unsigned
127 ComputeMaxOptionalArgsSize(const TargetMachine& target, const Function *F,
128                            unsigned &maxOptionalNumArgs)
129 {
130   const MachineFrameInfo& frameInfo = target.getFrameInfo();
131 
132   unsigned maxSize = 0;
133 
134   for (Function::const_iterator BB = F->begin(), BBE = F->end(); BB !=BBE; ++BB)
135     for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I != E; ++I)
136       if (const CallInst *callInst = dyn_cast<CallInst>(&*I))
137         {
138           unsigned numOperands = callInst->getNumOperands() - 1;
139           int numExtra = (int)numOperands-frameInfo.getNumFixedOutgoingArgs();
140           if (numExtra <= 0)
141             continue;
142 
143           unsigned int sizeForThisCall;
144           if (frameInfo.argsOnStackHaveFixedSize())
145             {
146               int argSize = frameInfo.getSizeOfEachArgOnStack();
147               sizeForThisCall = numExtra * (unsigned) argSize;
148             }
149           else
150             {
151               assert(0 && "UNTESTED CODE: Size per stack argument is not "
152                      "fixed on this architecture: use actual arg sizes to "
153                      "compute MaxOptionalArgsSize");
154               sizeForThisCall = 0;
155               for (unsigned i = 0; i < numOperands; ++i)
156                 sizeForThisCall += target.DataLayout.getTypeSize(callInst->
157                                               getOperand(i)->getType());
158             }
159 
160           if (maxSize < sizeForThisCall)
161             maxSize = sizeForThisCall;
162 
163           if ((int)maxOptionalNumArgs < numExtra)
164             maxOptionalNumArgs = (unsigned) numExtra;
165         }
166 
167   return maxSize;
168 }
169 
170 // Align data larger than one L1 cache line on L1 cache line boundaries.
171 // Align all smaller data on the next higher 2^x boundary (4, 8, ...),
172 // but not higher than the alignment of the largest type we support
173 // (currently a double word). -- see class TargetData).
174 //
175 // This function is similar to the corresponding function in EmitAssembly.cpp
176 // but they are unrelated.  This one does not align at more than a
177 // double-word boundary whereas that one might.
178 //
179 inline unsigned int
180 SizeToAlignment(unsigned int size, const TargetMachine& target)
181 {
182   unsigned short cacheLineSize = target.getCacheInfo().getCacheLineSize(1);
183   if (size > (unsigned) cacheLineSize / 2)
184     return cacheLineSize;
185   else
186     for (unsigned sz=1; /*no condition*/; sz *= 2)
187       if (sz >= size || sz >= target.DataLayout.getDoubleAlignment())
188         return sz;
189 }
190 
191 
192 /*ctor*/
193 MachineFunction::MachineFunction(const Function *F,
194                                            const TargetMachine& target)
195   : Annotation(MCFM_AID),
196     method(F), staticStackSize(0),
197     automaticVarsSize(0), regSpillsSize(0),
198     maxOptionalArgsSize(0), maxOptionalNumArgs(0),
199     currentTmpValuesSize(0), maxTmpValuesSize(0), compiledAsLeaf(false),
200     spillsAreaFrozen(false), automaticVarsAreaFrozen(false)
201 {
202   maxOptionalArgsSize = ComputeMaxOptionalArgsSize(target, method,
203                                                    maxOptionalNumArgs);
204   staticStackSize = maxOptionalArgsSize
205                     + target.getFrameInfo().getMinStackFrameSize();
206 }
207 
208 int
209 MachineFunction::computeOffsetforLocalVar(const TargetMachine& target,
210                                                const Value* val,
211                                                unsigned int& getPaddedSize,
212                                                unsigned int  sizeToUse)
213 {
214   if (sizeToUse == 0)
215     sizeToUse = target.findOptimalStorageSize(val->getType());
216   unsigned int align = SizeToAlignment(sizeToUse, target);
217 
218   bool growUp;
219   int firstOffset = target.getFrameInfo().getFirstAutomaticVarOffset(*this,
220                                                                      growUp);
221   int offset = growUp? firstOffset + getAutomaticVarsSize()
222                      : firstOffset - (getAutomaticVarsSize() + sizeToUse);
223 
224   int aligned = target.getFrameInfo().adjustAlignment(offset, growUp, align);
225   getPaddedSize = sizeToUse + abs(aligned - offset);
226 
227   return aligned;
228 }
229 
230 int
231 MachineFunction::allocateLocalVar(const TargetMachine& target,
232                                        const Value* val,
233                                        unsigned int sizeToUse)
234 {
235   assert(! automaticVarsAreaFrozen &&
236          "Size of auto vars area has been used to compute an offset so "
237          "no more automatic vars should be allocated!");
238 
239   // Check if we've allocated a stack slot for this value already
240   //
241   int offset = getOffset(val);
242   if (offset == INVALID_FRAME_OFFSET)
243     {
244       unsigned int getPaddedSize;
245       offset = computeOffsetforLocalVar(target, val, getPaddedSize, sizeToUse);
246       offsets[val] = offset;
247       incrementAutomaticVarsSize(getPaddedSize);
248     }
249   return offset;
250 }
251 
252 int
253 MachineFunction::allocateSpilledValue(const TargetMachine& target,
254                                            const Type* type)
255 {
256   assert(! spillsAreaFrozen &&
257          "Size of reg spills area has been used to compute an offset so "
258          "no more register spill slots should be allocated!");
259 
260   unsigned int size  = target.DataLayout.getTypeSize(type);
261   unsigned char align = target.DataLayout.getTypeAlignment(type);
262 
263   bool growUp;
264   int firstOffset = target.getFrameInfo().getRegSpillAreaOffset(*this, growUp);
265 
266   int offset = growUp? firstOffset + getRegSpillsSize()
267                      : firstOffset - (getRegSpillsSize() + size);
268 
269   int aligned = target.getFrameInfo().adjustAlignment(offset, growUp, align);
270   size += abs(aligned - offset); // include alignment padding in size
271 
272   incrementRegSpillsSize(size);  // update size of reg. spills area
273 
274   return aligned;
275 }
276 
277 int
278 MachineFunction::pushTempValue(const TargetMachine& target,
279                                     unsigned int size)
280 {
281   unsigned int align = SizeToAlignment(size, target);
282 
283   bool growUp;
284   int firstOffset = target.getFrameInfo().getTmpAreaOffset(*this, growUp);
285 
286   int offset = growUp? firstOffset + currentTmpValuesSize
287                      : firstOffset - (currentTmpValuesSize + size);
288 
289   int aligned = target.getFrameInfo().adjustAlignment(offset, growUp, align);
290   size += abs(aligned - offset); // include alignment padding in size
291 
292   incrementTmpAreaSize(size);    // update "current" size of tmp area
293 
294   return aligned;
295 }
296 
297 void
298 MachineFunction::popAllTempValues(const TargetMachine& target)
299 {
300   resetTmpAreaSize();            // clear tmp area to reuse
301 }
302 
303 int
304 MachineFunction::getOffset(const Value* val) const
305 {
306   hash_map<const Value*, int>::const_iterator pair = offsets.find(val);
307   return (pair == offsets.end()) ? INVALID_FRAME_OFFSET : pair->second;
308 }
309 
310 void
311 MachineFunction::dump() const
312 {
313   std::cerr << "\n" << method->getReturnType()
314             << " \"" << method->getName() << "\"\n";
315 
316   for (Function::const_iterator BB = method->begin(); BB != method->end(); ++BB)
317     {
318       std::cerr << "\n" << BB->getName() << " (" << (const void*)BB
319                 << ")" << ":" << "\n";
320       MachineBasicBlock& mvec = MachineBasicBlock::get(BB);
321       for (unsigned i=0; i < mvec.size(); i++)
322 	std::cerr << "\t" << *mvec[i];
323     }
324   std::cerr << "\nEnd function \"" << method->getName() << "\"\n\n";
325 }
326