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   struct Printer : public FunctionPass {
66     const char *getPassName() const { return "MachineFunction Printer"; }
67 
68     virtual void getAnalysisUsage(AnalysisUsage &AU) const {
69       AU.setPreservesAll();
70     }
71 
72     bool runOnFunction(Function &F) {
73       MachineFunction::get(&F).dump();
74       return false;
75     }
76   };
77 }
78 
79 Pass *createMachineCodeConstructionPass(TargetMachine &Target) {
80   return new ConstructMachineFunction(Target);
81 }
82 
83 Pass *createMachineCodeDestructionPass() {
84   return new DestroyMachineFunction();
85 }
86 
87 Pass *createMachineFunctionPrinterPass() {
88   return new Printer();
89 }
90 
91 
92 //===---------------------------------------------------------------------===//
93 // MachineFunction implementation
94 //===---------------------------------------------------------------------===//
95 
96 MachineFunction::MachineFunction(const Function *F,
97                                  const TargetMachine& target)
98   : Annotation(MF_AID),
99     Fn(F), Target(target), staticStackSize(0),
100     automaticVarsSize(0), regSpillsSize(0),
101     maxOptionalArgsSize(0), maxOptionalNumArgs(0),
102     currentTmpValuesSize(0), maxTmpValuesSize(0), compiledAsLeaf(false),
103     spillsAreaFrozen(false), automaticVarsAreaFrozen(false)
104 {
105   SSARegMapping = new SSARegMap();
106 }
107 
108 void MachineFunction::dump() const { print(std::cerr); }
109 
110 void MachineFunction::print(std::ostream &OS) const {
111   OS << "\n" << *(Value*)Fn->getReturnType() << " \"" << Fn->getName()<< "\"\n";
112 
113   for (const_iterator BB = begin(); BB != end(); ++BB) {
114     BasicBlock *LBB = BB->getBasicBlock();
115     OS << "\n" << LBB->getName() << " ("
116        << (const void*)BB->getBasicBlock() << "):\n";
117     for (MachineBasicBlock::const_iterator I = BB->begin(); I != BB->end();++I){
118       OS << "\t";
119       (*I)->print(OS, Target);
120     }
121   }
122   OS << "\nEnd function \"" << Fn->getName() << "\"\n\n";
123 }
124 
125 
126 // The next two methods are used to construct and to retrieve
127 // the MachineCodeForFunction object for the given function.
128 // construct() -- Allocates and initializes for a given function and target
129 // get()       -- Returns a handle to the object.
130 //                This should not be called before "construct()"
131 //                for a given Function.
132 //
133 MachineFunction&
134 MachineFunction::construct(const Function *Fn, const TargetMachine &Tar)
135 {
136   assert(Fn->getAnnotation(MF_AID) == 0 &&
137          "Object already exists for this function!");
138   MachineFunction* mcInfo = new MachineFunction(Fn, Tar);
139   Fn->addAnnotation(mcInfo);
140   return *mcInfo;
141 }
142 
143 void
144 MachineFunction::destruct(const Function *Fn)
145 {
146   bool Deleted = Fn->deleteAnnotation(MF_AID);
147   assert(Deleted && "Machine code did not exist for function!");
148 }
149 
150 MachineFunction& MachineFunction::get(const Function *F)
151 {
152   MachineFunction *mc = (MachineFunction*)F->getAnnotation(MF_AID);
153   assert(mc && "Call construct() method first to allocate the object");
154   return *mc;
155 }
156 
157 static unsigned
158 ComputeMaxOptionalArgsSize(const TargetMachine& target, const Function *F,
159                            unsigned &maxOptionalNumArgs)
160 {
161   const MachineFrameInfo& frameInfo = target.getFrameInfo();
162 
163   unsigned maxSize = 0;
164 
165   for (Function::const_iterator BB = F->begin(), BBE = F->end(); BB !=BBE; ++BB)
166     for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I != E; ++I)
167       if (const CallInst *callInst = dyn_cast<CallInst>(&*I))
168         {
169           unsigned numOperands = callInst->getNumOperands() - 1;
170           int numExtra = (int)numOperands-frameInfo.getNumFixedOutgoingArgs();
171           if (numExtra <= 0)
172             continue;
173 
174           unsigned int sizeForThisCall;
175           if (frameInfo.argsOnStackHaveFixedSize())
176             {
177               int argSize = frameInfo.getSizeOfEachArgOnStack();
178               sizeForThisCall = numExtra * (unsigned) argSize;
179             }
180           else
181             {
182               assert(0 && "UNTESTED CODE: Size per stack argument is not "
183                      "fixed on this architecture: use actual arg sizes to "
184                      "compute MaxOptionalArgsSize");
185               sizeForThisCall = 0;
186               for (unsigned i = 0; i < numOperands; ++i)
187                 sizeForThisCall += target.DataLayout.getTypeSize(callInst->
188                                               getOperand(i)->getType());
189             }
190 
191           if (maxSize < sizeForThisCall)
192             maxSize = sizeForThisCall;
193 
194           if ((int)maxOptionalNumArgs < numExtra)
195             maxOptionalNumArgs = (unsigned) numExtra;
196         }
197 
198   return maxSize;
199 }
200 
201 // Align data larger than one L1 cache line on L1 cache line boundaries.
202 // Align all smaller data on the next higher 2^x boundary (4, 8, ...),
203 // but not higher than the alignment of the largest type we support
204 // (currently a double word). -- see class TargetData).
205 //
206 // This function is similar to the corresponding function in EmitAssembly.cpp
207 // but they are unrelated.  This one does not align at more than a
208 // double-word boundary whereas that one might.
209 //
210 inline unsigned int
211 SizeToAlignment(unsigned int size, const TargetMachine& target)
212 {
213   unsigned short cacheLineSize = target.getCacheInfo().getCacheLineSize(1);
214   if (size > (unsigned) cacheLineSize / 2)
215     return cacheLineSize;
216   else
217     for (unsigned sz=1; /*no condition*/; sz *= 2)
218       if (sz >= size || sz >= target.DataLayout.getDoubleAlignment())
219         return sz;
220 }
221 
222 
223 void MachineFunction::CalculateArgSize() {
224   maxOptionalArgsSize = ComputeMaxOptionalArgsSize(Target, Fn,
225                                                    maxOptionalNumArgs);
226   staticStackSize = maxOptionalArgsSize
227     + Target.getFrameInfo().getMinStackFrameSize();
228 }
229 
230 int
231 MachineFunction::computeOffsetforLocalVar(const TargetMachine& target,
232                                                const Value* val,
233                                                unsigned int& getPaddedSize,
234                                                unsigned int  sizeToUse)
235 {
236   if (sizeToUse == 0)
237     sizeToUse = target.findOptimalStorageSize(val->getType());
238   unsigned int align = SizeToAlignment(sizeToUse, target);
239 
240   bool growUp;
241   int firstOffset = target.getFrameInfo().getFirstAutomaticVarOffset(*this,
242                                                                      growUp);
243   int offset = growUp? firstOffset + getAutomaticVarsSize()
244                      : firstOffset - (getAutomaticVarsSize() + sizeToUse);
245 
246   int aligned = target.getFrameInfo().adjustAlignment(offset, growUp, align);
247   getPaddedSize = sizeToUse + abs(aligned - offset);
248 
249   return aligned;
250 }
251 
252 int
253 MachineFunction::allocateLocalVar(const TargetMachine& target,
254                                        const Value* val,
255                                        unsigned int sizeToUse)
256 {
257   assert(! automaticVarsAreaFrozen &&
258          "Size of auto vars area has been used to compute an offset so "
259          "no more automatic vars should be allocated!");
260 
261   // Check if we've allocated a stack slot for this value already
262   //
263   int offset = getOffset(val);
264   if (offset == INVALID_FRAME_OFFSET)
265     {
266       unsigned int getPaddedSize;
267       offset = computeOffsetforLocalVar(target, val, getPaddedSize, sizeToUse);
268       offsets[val] = offset;
269       incrementAutomaticVarsSize(getPaddedSize);
270     }
271   return offset;
272 }
273 
274 int
275 MachineFunction::allocateSpilledValue(const TargetMachine& target,
276                                            const Type* type)
277 {
278   assert(! spillsAreaFrozen &&
279          "Size of reg spills area has been used to compute an offset so "
280          "no more register spill slots should be allocated!");
281 
282   unsigned int size  = target.DataLayout.getTypeSize(type);
283   unsigned char align = target.DataLayout.getTypeAlignment(type);
284 
285   bool growUp;
286   int firstOffset = target.getFrameInfo().getRegSpillAreaOffset(*this, growUp);
287 
288   int offset = growUp? firstOffset + getRegSpillsSize()
289                      : firstOffset - (getRegSpillsSize() + size);
290 
291   int aligned = target.getFrameInfo().adjustAlignment(offset, growUp, align);
292   size += abs(aligned - offset); // include alignment padding in size
293 
294   incrementRegSpillsSize(size);  // update size of reg. spills area
295 
296   return aligned;
297 }
298 
299 int
300 MachineFunction::pushTempValue(const TargetMachine& target,
301                                     unsigned int size)
302 {
303   unsigned int align = SizeToAlignment(size, target);
304 
305   bool growUp;
306   int firstOffset = target.getFrameInfo().getTmpAreaOffset(*this, growUp);
307 
308   int offset = growUp? firstOffset + currentTmpValuesSize
309                      : firstOffset - (currentTmpValuesSize + size);
310 
311   int aligned = target.getFrameInfo().adjustAlignment(offset, growUp, align);
312   size += abs(aligned - offset); // include alignment padding in size
313 
314   incrementTmpAreaSize(size);    // update "current" size of tmp area
315 
316   return aligned;
317 }
318 
319 void
320 MachineFunction::popAllTempValues(const TargetMachine& target)
321 {
322   resetTmpAreaSize();            // clear tmp area to reuse
323 }
324 
325 int
326 MachineFunction::getOffset(const Value* val) const
327 {
328   hash_map<const Value*, int>::const_iterator pair = offsets.find(val);
329   return (pair == offsets.end()) ? INVALID_FRAME_OFFSET : pair->second;
330 }
331