1 //===-- MachineCodeForMethod.cpp -------------------------------------------=//
2 //
3 // Purpose:
4 //   Collect native machine code information for a function.
5 //   This allows target-specific information about the generated code
6 //   to be stored with each function.
7 //===---------------------------------------------------------------------===//
8 
9 #include "llvm/CodeGen/MachineFunction.h"
10 #include "llvm/CodeGen/MachineInstr.h"  // For debug output
11 #include "llvm/CodeGen/MachineCodeForBasicBlock.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 <limits.h>
18 
19 const int INVALID_FRAME_OFFSET = INT_MAX; // std::numeric_limits<int>::max();
20 
21 static AnnotationID MCFM_AID(
22                  AnnotationManager::getID("CodeGen::MachineCodeForFunction"));
23 
24 // The next two methods are used to construct and to retrieve
25 // the MachineCodeForFunction object for the given function.
26 // construct() -- Allocates and initializes for a given function and target
27 // get()       -- Returns a handle to the object.
28 //                This should not be called before "construct()"
29 //                for a given Function.
30 //
31 MachineFunction&
32 MachineFunction::construct(const Function *M, const TargetMachine &Tar)
33 {
34   assert(M->getAnnotation(MCFM_AID) == 0 &&
35          "Object already exists for this function!");
36   MachineFunction* mcInfo = new MachineFunction(M, Tar);
37   M->addAnnotation(mcInfo);
38   return *mcInfo;
39 }
40 
41 void
42 MachineFunction::destruct(const Function *M)
43 {
44   bool Deleted = M->deleteAnnotation(MCFM_AID);
45   assert(Deleted && "Machine code did not exist for function!");
46 }
47 
48 MachineFunction&
49 MachineFunction::get(const Function *F)
50 {
51   MachineFunction *mc = (MachineFunction*)F->getAnnotation(MCFM_AID);
52   assert(mc && "Call construct() method first to allocate the object");
53   return *mc;
54 }
55 
56 static unsigned
57 ComputeMaxOptionalArgsSize(const TargetMachine& target, const Function *F,
58                            unsigned &maxOptionalNumArgs)
59 {
60   const MachineFrameInfo& frameInfo = target.getFrameInfo();
61 
62   unsigned maxSize = 0;
63 
64   for (Function::const_iterator BB = F->begin(), BBE = F->end(); BB !=BBE; ++BB)
65     for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I != E; ++I)
66       if (const CallInst *callInst = dyn_cast<CallInst>(&*I))
67         {
68           unsigned numOperands = callInst->getNumOperands() - 1;
69           int numExtra = (int)numOperands-frameInfo.getNumFixedOutgoingArgs();
70           if (numExtra <= 0)
71             continue;
72 
73           unsigned int sizeForThisCall;
74           if (frameInfo.argsOnStackHaveFixedSize())
75             {
76               int argSize = frameInfo.getSizeOfEachArgOnStack();
77               sizeForThisCall = numExtra * (unsigned) argSize;
78             }
79           else
80             {
81               assert(0 && "UNTESTED CODE: Size per stack argument is not "
82                      "fixed on this architecture: use actual arg sizes to "
83                      "compute MaxOptionalArgsSize");
84               sizeForThisCall = 0;
85               for (unsigned i = 0; i < numOperands; ++i)
86                 sizeForThisCall += target.DataLayout.getTypeSize(callInst->
87                                               getOperand(i)->getType());
88             }
89 
90           if (maxSize < sizeForThisCall)
91             maxSize = sizeForThisCall;
92 
93           if ((int)maxOptionalNumArgs < numExtra)
94             maxOptionalNumArgs = (unsigned) numExtra;
95         }
96 
97   return maxSize;
98 }
99 
100 // Align data larger than one L1 cache line on L1 cache line boundaries.
101 // Align all smaller data on the next higher 2^x boundary (4, 8, ...),
102 // but not higher than the alignment of the largest type we support
103 // (currently a double word). -- see class TargetData).
104 //
105 // This function is similar to the corresponding function in EmitAssembly.cpp
106 // but they are unrelated.  This one does not align at more than a
107 // double-word boundary whereas that one might.
108 //
109 inline unsigned int
110 SizeToAlignment(unsigned int size, const TargetMachine& target)
111 {
112   unsigned short cacheLineSize = target.getCacheInfo().getCacheLineSize(1);
113   if (size > (unsigned) cacheLineSize / 2)
114     return cacheLineSize;
115   else
116     for (unsigned sz=1; /*no condition*/; sz *= 2)
117       if (sz >= size || sz >= target.DataLayout.getDoubleAlignment())
118         return sz;
119 }
120 
121 
122 /*ctor*/
123 MachineFunction::MachineFunction(const Function *F,
124                                            const TargetMachine& target)
125   : Annotation(MCFM_AID),
126     method(F), staticStackSize(0),
127     automaticVarsSize(0), regSpillsSize(0),
128     maxOptionalArgsSize(0), maxOptionalNumArgs(0),
129     currentTmpValuesSize(0), maxTmpValuesSize(0), compiledAsLeaf(false),
130     spillsAreaFrozen(false), automaticVarsAreaFrozen(false)
131 {
132   maxOptionalArgsSize = ComputeMaxOptionalArgsSize(target, method,
133                                                    maxOptionalNumArgs);
134   staticStackSize = maxOptionalArgsSize
135                     + target.getFrameInfo().getMinStackFrameSize();
136 }
137 
138 int
139 MachineFunction::computeOffsetforLocalVar(const TargetMachine& target,
140                                                const Value* val,
141                                                unsigned int& getPaddedSize,
142                                                unsigned int  sizeToUse)
143 {
144   if (sizeToUse == 0)
145     sizeToUse = target.findOptimalStorageSize(val->getType());
146   unsigned int align = SizeToAlignment(sizeToUse, target);
147 
148   bool growUp;
149   int firstOffset = target.getFrameInfo().getFirstAutomaticVarOffset(*this,
150                                                                      growUp);
151   int offset = growUp? firstOffset + getAutomaticVarsSize()
152                      : firstOffset - (getAutomaticVarsSize() + sizeToUse);
153 
154   int aligned = target.getFrameInfo().adjustAlignment(offset, growUp, align);
155   getPaddedSize = sizeToUse + abs(aligned - offset);
156 
157   return aligned;
158 }
159 
160 int
161 MachineFunction::allocateLocalVar(const TargetMachine& target,
162                                        const Value* val,
163                                        unsigned int sizeToUse)
164 {
165   assert(! automaticVarsAreaFrozen &&
166          "Size of auto vars area has been used to compute an offset so "
167          "no more automatic vars should be allocated!");
168 
169   // Check if we've allocated a stack slot for this value already
170   //
171   int offset = getOffset(val);
172   if (offset == INVALID_FRAME_OFFSET)
173     {
174       unsigned int getPaddedSize;
175       offset = this->computeOffsetforLocalVar(target, val, getPaddedSize,
176                                               sizeToUse);
177       offsets[val] = offset;
178       incrementAutomaticVarsSize(getPaddedSize);
179     }
180   return offset;
181 }
182 
183 int
184 MachineFunction::allocateSpilledValue(const TargetMachine& target,
185                                            const Type* type)
186 {
187   assert(! spillsAreaFrozen &&
188          "Size of reg spills area has been used to compute an offset so "
189          "no more register spill slots should be allocated!");
190 
191   unsigned int size  = target.DataLayout.getTypeSize(type);
192   unsigned char align = target.DataLayout.getTypeAlignment(type);
193 
194   bool growUp;
195   int firstOffset = target.getFrameInfo().getRegSpillAreaOffset(*this, growUp);
196 
197   int offset = growUp? firstOffset + getRegSpillsSize()
198                      : firstOffset - (getRegSpillsSize() + size);
199 
200   int aligned = target.getFrameInfo().adjustAlignment(offset, growUp, align);
201   size += abs(aligned - offset); // include alignment padding in size
202 
203   incrementRegSpillsSize(size);  // update size of reg. spills area
204 
205   return aligned;
206 }
207 
208 int
209 MachineFunction::pushTempValue(const TargetMachine& target,
210                                     unsigned int size)
211 {
212   unsigned int align = SizeToAlignment(size, target);
213 
214   bool growUp;
215   int firstOffset = target.getFrameInfo().getTmpAreaOffset(*this, growUp);
216 
217   int offset = growUp? firstOffset + currentTmpValuesSize
218                      : firstOffset - (currentTmpValuesSize + size);
219 
220   int aligned = target.getFrameInfo().adjustAlignment(offset, growUp, align);
221   size += abs(aligned - offset); // include alignment padding in size
222 
223   incrementTmpAreaSize(size);    // update "current" size of tmp area
224 
225   return aligned;
226 }
227 
228 void
229 MachineFunction::popAllTempValues(const TargetMachine& target)
230 {
231   resetTmpAreaSize();            // clear tmp area to reuse
232 }
233 
234 int
235 MachineFunction::getOffset(const Value* val) const
236 {
237   hash_map<const Value*, int>::const_iterator pair = offsets.find(val);
238   return (pair == offsets.end())? INVALID_FRAME_OFFSET : pair->second;
239 }
240 
241 void
242 MachineFunction::dump() const
243 {
244   std::cerr << "\n" << method->getReturnType()
245             << " \"" << method->getName() << "\"\n";
246 
247   for (Function::const_iterator BB = method->begin(); BB != method->end(); ++BB)
248     {
249       std::cerr << std::endl << (*BB).getName() << " (" << (const void*) BB << ")" << ":" << std::endl;
250       MachineCodeForBasicBlock& mvec = MachineCodeForBasicBlock::get(BB);
251       for (unsigned i=0; i < mvec.size(); i++)
252 	std::cerr << "\t" << *mvec[i];
253     }
254   std::cerr << "\nEnd function \"" << method->getName() << "\"\n\n";
255 }
256