mirror of
https://github.com/c64scene-ar/llvm-6502.git
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bd199fb114
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@5126 91177308-0d34-0410-b5e6-96231b3b80d8
108 lines
3.3 KiB
C++
108 lines
3.3 KiB
C++
//===-- Emitter.cpp - Write machine code to executable memory -------------===//
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//
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// This file defines a MachineCodeEmitter object that is used by Jello to write
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// machine code to memory and remember where relocatable values lie.
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//
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//===----------------------------------------------------------------------===//
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#include "VM.h"
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#include "llvm/CodeGen/MachineCodeEmitter.h"
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#include "llvm/CodeGen/MachineFunction.h"
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#include "llvm/Function.h"
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#include "Support/Statistic.h"
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namespace {
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Statistic<> NumBytes("jello", "Number of bytes of machine code compiled");
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class Emitter : public MachineCodeEmitter {
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VM &TheVM;
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unsigned char *CurBlock;
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unsigned char *CurByte;
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std::vector<std::pair<BasicBlock*, unsigned *> > BBRefs;
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std::map<BasicBlock*, unsigned> BBLocations;
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public:
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Emitter(VM &vm) : TheVM(vm) {}
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virtual void startFunction(MachineFunction &F);
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virtual void finishFunction(MachineFunction &F);
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virtual void startBasicBlock(MachineBasicBlock &BB);
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virtual void emitByte(unsigned char B);
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virtual void emitPCRelativeDisp(Value *V);
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virtual void emitGlobalAddress(GlobalValue *V);
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};
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}
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MachineCodeEmitter *VM::createEmitter(VM &V) {
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return new Emitter(V);
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}
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#define _POSIX_MAPPED_FILES
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#include <unistd.h>
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#include <sys/mman.h>
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static void *getMemory() {
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return mmap(0, 4096*2, PROT_READ|PROT_WRITE|PROT_EXEC,
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MAP_PRIVATE|MAP_ANONYMOUS, 0, 0);
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}
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void Emitter::startFunction(MachineFunction &F) {
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CurBlock = (unsigned char *)getMemory();
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CurByte = CurBlock; // Start writing at the beginning of the fn.
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TheVM.addGlobalMapping(F.getFunction(), CurBlock);
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}
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void Emitter::finishFunction(MachineFunction &F) {
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for (unsigned i = 0, e = BBRefs.size(); i != e; ++i) {
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unsigned Location = BBLocations[BBRefs[i].first];
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unsigned *Ref = BBRefs[i].second;
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*Ref = Location-(unsigned)Ref-4;
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}
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BBRefs.clear();
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BBLocations.clear();
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NumBytes += CurByte-CurBlock;
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DEBUG(std::cerr << "Finished CodeGen of [" << std::hex << (unsigned)CurBlock
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<< std::dec << "] Function: " << F.getFunction()->getName()
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<< ": " << CurByte-CurBlock << " bytes of text\n");
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}
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void Emitter::startBasicBlock(MachineBasicBlock &BB) {
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BBLocations[BB.getBasicBlock()] = (unsigned)CurByte;
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}
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void Emitter::emitByte(unsigned char B) {
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*CurByte++ = B; // Write the byte to memory
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}
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// emitPCRelativeDisp - For functions, just output a displacement that will
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// cause a reference to the zero page, which will cause a seg-fault, causing
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// things to get resolved on demand. Keep track of these markers.
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//
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// For basic block references, keep track of where the references are so they
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// may be patched up when the basic block is defined.
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//
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void Emitter::emitPCRelativeDisp(Value *V) {
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if (Function *F = dyn_cast<Function>(V)) {
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TheVM.addFunctionRef(CurByte, F);
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unsigned ZeroAddr = -(unsigned)CurByte-4; // Calculate displacement to null
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*(unsigned*)CurByte = ZeroAddr; // 4 byte offset
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CurByte += 4;
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} else {
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BasicBlock *BB = cast<BasicBlock>(V); // Keep track of reference...
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BBRefs.push_back(std::make_pair(BB, (unsigned*)CurByte));
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CurByte += 4;
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}
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}
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void Emitter::emitGlobalAddress(GlobalValue *V) {
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*(void**)CurByte = TheVM.getPointerToGlobal(V);
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CurByte += 4;
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}
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