qzdoom-gpl/src/zscript/vmbuilder.cpp
Randy Heit 3001708d16 - Added some code for generating VM code from FxExpressions. This is completely untested, since
it isn't even used anywhere yet. In retrospect, I probably should have targeted an intermediate
  representation and done codegen with that instead, since that would be something I can reuse.

SVN r1908 (scripting)
2009-10-11 00:02:14 +00:00

513 lines
14 KiB
C++

#include "vmbuilder.h"
//==========================================================================
//
// VMFunctionBuilder - Constructor
//
//==========================================================================
VMFunctionBuilder::VMFunctionBuilder()
{
NumIntConstants = 0;
NumFloatConstants = 0;
NumAddressConstants = 0;
NumStringConstants = 0;
MaxParam = 0;
ActiveParam = 0;
}
//==========================================================================
//
// VMFunctionBuilder - Destructor
//
//==========================================================================
VMFunctionBuilder::~VMFunctionBuilder()
{
}
//==========================================================================
//
// VMFunctionBuilder :: MakeFunction
//
// Creates a new VMScriptFunction out of the data passed to this class.
//
//==========================================================================
VMScriptFunction *VMFunctionBuilder::MakeFunction()
{
VMScriptFunction *func = new VMScriptFunction;
// Copy code block.
memcpy(func->AllocCode(Code.Size()), &Code[0], Code.Size());
// Create constant tables.
if (NumIntConstants > 0)
{
FillIntConstants(func->AllocKonstD(NumIntConstants));
}
if (NumFloatConstants > 0)
{
FillFloatConstants(func->AllocKonstF(NumFloatConstants));
}
if (NumAddressConstants > 0)
{
func->AllocKonstA(NumAddressConstants);
FillAddressConstants(func->KonstA, func->KonstATags());
}
if (NumStringConstants > 0)
{
FillStringConstants(func->AllocKonstS(NumStringConstants));
}
// Assign required register space.
func->NumRegD = Registers[REGT_INT].MostUsed;
func->NumRegF = Registers[REGT_FLOAT].MostUsed;
func->NumRegA = Registers[REGT_POINTER].MostUsed;
func->NumRegS = Registers[REGT_STRING].MostUsed;
func->MaxParam = MaxParam;
// Technically, there's no reason why we can't end the function with
// entries on the parameter stack, but it means the caller probably
// did something wrong.
assert(ActiveParam == 0);
return func;
}
//==========================================================================
//
// VMFunctionBuilder :: FillIntConstants
//
//==========================================================================
void VMFunctionBuilder::FillIntConstants(int *konst)
{
TMapIterator<int, int> it(IntConstants);
TMap<int, int>::Pair *pair;
while (it.NextPair(pair))
{
konst[pair->Value] = pair->Key;
}
}
//==========================================================================
//
// VMFunctionBuilder :: FillFloatConstants
//
//==========================================================================
void VMFunctionBuilder::FillFloatConstants(double *konst)
{
TMapIterator<double, int> it(FloatConstants);
TMap<double, int>::Pair *pair;
while (it.NextPair(pair))
{
konst[pair->Value] = pair->Key;
}
}
//==========================================================================
//
// VMFunctionBuilder :: FillAddressConstants
//
//==========================================================================
void VMFunctionBuilder::FillAddressConstants(FVoidObj *konst, VM_ATAG *tags)
{
TMapIterator<void *, AddrKonst> it(AddressConstants);
TMap<void *, AddrKonst>::Pair *pair;
while (it.NextPair(pair))
{
konst[pair->Value.KonstNum].v = pair->Key;
tags[pair->Value.KonstNum] = pair->Value.Tag;
}
}
//==========================================================================
//
// VMFunctionBuilder :: FillStringConstants
//
//==========================================================================
void VMFunctionBuilder::FillStringConstants(FString *konst)
{
TMapIterator<FString, int> it(StringConstants);
TMap<FString, int>::Pair *pair;
while (it.NextPair(pair))
{
konst[pair->Value] = pair->Key;
}
}
//==========================================================================
//
// VMFunctionBuilder :: GetConstantInt
//
// Returns a constant register initialized with the given value, or -1 if
// there were no more constants free.
//
//==========================================================================
int VMFunctionBuilder::GetConstantInt(int val)
{
int *locp = IntConstants.CheckKey(val);
if (locp != NULL)
{
return *locp;
}
else
{
int loc = NumIntConstants++;
IntConstants.Insert(val, loc);
return loc;
}
}
//==========================================================================
//
// VMFunctionBuilder :: GetConstantFloat
//
// Returns a constant register initialized with the given value, or -1 if
// there were no more constants free.
//
//==========================================================================
int VMFunctionBuilder::GetConstantFloat(double val)
{
int *locp = FloatConstants.CheckKey(val);
if (locp != NULL)
{
return *locp;
}
else
{
int loc = NumFloatConstants++;
FloatConstants.Insert(val, loc);
return loc;
}
}
//==========================================================================
//
// VMFunctionBuilder :: GetConstantString
//
// Returns a constant register initialized with the given value, or -1 if
// there were no more constants free.
//
//==========================================================================
int VMFunctionBuilder::GetConstantString(FString val)
{
int *locp = StringConstants.CheckKey(val);
if (locp != NULL)
{
return *locp;
}
else
{
int loc = NumStringConstants++;
StringConstants.Insert(val, loc);
return loc;
}
}
//==========================================================================
//
// VMFunctionBuilder :: GetConstantAddress
//
// Returns a constant register initialized with the given value, or -1 if
// there were no more constants free.
//
//==========================================================================
int VMFunctionBuilder::GetConstantAddress(void *ptr, VM_ATAG tag)
{
AddrKonst *locp = AddressConstants.CheckKey(ptr);
if (locp != NULL)
{
// There should only be one tag associated with a memory location.
assert(locp->Tag == tag);
return locp->KonstNum;
}
else
{
AddrKonst loc = { NumAddressConstants++, tag };
AddressConstants.Insert(ptr, loc);
return loc.KonstNum;
}
}
//==========================================================================
//
// VMFunctionBuilder :: ParamChange
//
// Adds delta to ActiveParam and keeps track of MaxParam.
//
//==========================================================================
void VMFunctionBuilder::ParamChange(int delta)
{
assert(delta > 0 || -delta <= ActiveParam);
ActiveParam += delta;
if (ActiveParam > MaxParam)
{
MaxParam = ActiveParam;
}
}
//==========================================================================
//
// VMFunctionBuilder :: RegAvailability - Constructor
//
//==========================================================================
VMFunctionBuilder::RegAvailability::RegAvailability()
{
memset(Used, 0, sizeof(Used));
MostUsed = 0;
}
//==========================================================================
//
// VMFunctionBuilder :: RegAvailibity :: Get
//
// Gets one or more unused registers. If getting multiple registers, they
// will all be consecutive. Returns -1 if there were not enough consecutive
// registers to satisfy the request.
//
// Preference is given to low-numbered registers in an attempt to keep
// the maximum register count low so as to preserve VM stack space when this
// function is executed.
//
//==========================================================================
int VMFunctionBuilder::RegAvailability::Get(int count)
{
VM_UWORD mask;
int i, firstbit;
// Getting fewer than one register makes no sense, and
// the algorithm used here can only obtain ranges of up to 32 bits.
if (count < 1 || count > 32)
{
return -1;
}
mask = count == 32 ? ~0u : (1 << count) - 1;
for (i = 0; i < 256/32; ++i)
{
// Find the first word with free registers
VM_UWORD bits = Used[i];
if (bits != ~0u)
{
// Are there enough consecutive bits to satisfy the request?
// Search by 16, then 8, then 1 bit at a time for the first
// free register.
if ((bits & 0xFFFF) == 0xFFFF)
{
firstbit = ((bits & 0xFF0000) == 0xFF0000) ? 24 : 16;
}
else
{
firstbit = ((bits & 0xFF) == 0xFF) ? 8 : 0;
}
for (; firstbit < 32; ++firstbit)
{
if (((bits >> firstbit) & mask) == 0)
{
if (firstbit + count <= 32)
{ // Needed bits all fit in one word, so we got it.
if (firstbit + count > MostUsed)
{
MostUsed = firstbit + count;
}
Used[i] |= mask << firstbit;
return i * 32 + firstbit;
}
// Needed bits span two words, so check the next word.
else if (i < 256/32 - 1)
{ // There is a next word.
if (((Used[i + 1]) & (mask >> (32 - firstbit))) == 0)
{ // The next word has the needed open space, too.
if (firstbit + count > MostUsed)
{
MostUsed = firstbit + count;
}
Used[i] |= mask << firstbit;
Used[i + 1] |= mask >> (32 - firstbit);
return i * 32 + firstbit;
}
else
{ // Skip to the next word, because we know we won't find
// what we need if we stay inside this one. All bits
// from firstbit to the end of the word are 0. If the
// next word does not start with the x amount of 0's, we
// need to satisfy the request, then it certainly won't
// have the x+1 0's we would need if we started at
// firstbit+1 in this one.
firstbit = 32;
}
}
else
{ // Out of words.
break;
}
}
}
}
}
// No room!
return -1;
}
//==========================================================================
//
// VMFunctionBuilder :: RegAvailibity :: Return
//
// Marks a range of registers as free again.
//
//==========================================================================
void VMFunctionBuilder::RegAvailability::Return(int reg, int count)
{
assert(count >= 1 && count <= 32);
assert(reg >= 0 && reg + count <= 256);
VM_UWORD mask, partialmask;
int firstword, firstbit;
mask = count == 32 ? ~0u : (1 << count) - 1;
firstword = reg / 32;
firstbit = reg & 31;
if (firstbit + count <= 32)
{ // Range is all in one word.
mask <<= firstbit;
// If we are trying to return registers that are already free,
// it probably means that the caller messed up somewhere.
assert((Used[firstword] & mask) == mask);
Used[firstword] &= ~mask;
}
else
{ // Range is in two words.
partialmask = mask << firstbit;
assert((Used[firstword] & partialmask) == partialmask);
Used[firstword] &= ~partialmask;
partialmask = mask >> (32 - firstbit);
assert((Used[firstword + 1] & partialmask) == partialmask);
Used[firstword + 1] &= ~partialmask;
}
}
//==========================================================================
//
// VMFunctionBuilder :: Emit
//
// Just dumbly output an instruction. Returns instruction position, not
// byte position. (Because all instructions are exactly four bytes long.)
//
//==========================================================================
size_t VMFunctionBuilder::Emit(int opcode, int opa, int opb, int opc)
{
assert(opcode >= 0 && opcode < NUM_OPS);
assert(opa >= 0 && opa <= 255);
assert(opb >= 0 && opb <= 255);
assert(opc >= 0 && opc <= 255);
size_t loc = Code.Reserve(4);
VM_UBYTE *code = &Code[loc];
code[0] = opcode;
code[1] = opa;
code[2] = opb;
code[3] = opc;
return loc / 4;
}
size_t VMFunctionBuilder::Emit(int opcode, int opa, VM_SHALF opbc)
{
assert(opcode >= 0 && opcode < NUM_OPS);
assert(opa >= 0 && opa <= 255);
assert(opbc >= -32768 && opbc <= 32767);
size_t loc = Code.Reserve(4);
VM_UBYTE *code = &Code[loc];
code[0] = opcode;
code[1] = opa;
*(VM_SHALF *)&code[2] = opbc;
return loc / 4;
}
size_t VMFunctionBuilder::Emit(int opcode, int opabc)
{
assert(opcode >= 0 && opcode < NUM_OPS);
assert(opabc >= -(1 << 23) && opabc <= (1 << 24) - 1);
size_t loc = Code.Reserve(4);
#ifdef __BIG_ENDIAN__
*(VM_UWORD *)&Code[loc] = (opabc & 0xFFFFFF) | (opcode << 24);
#else
*(VM_UWORD *)&Code[loc] = opcode | (opabc << 8);
#endif
return loc / 4;
}
//==========================================================================
//
// VMFunctionBuilder :: EmitLoadInt
//
// Loads an integer constant into a register, using either an immediate
// value or a constant register, as appropriate.
//
//==========================================================================
size_t VMFunctionBuilder::EmitLoadInt(int regnum, int value)
{
assert(regnum >= 0 && regnum < Registers[REGT_INT].MostUsed);
if (value >= -32768 && value <= 32767)
{
return Emit(OP_LI, regnum, value);
}
else
{
return Emit(OP_LK, regnum, GetConstantInt(value));
}
}
//==========================================================================
//
// VMFunctionBuilder :: Backpatch
//
// Store a JMP instruction at <loc> that points at <target>.
//
//==========================================================================
void VMFunctionBuilder::Backpatch(size_t loc, size_t target)
{
assert(loc < Code.Size() / 4);
int offset = int(target - loc - 1);
assert(offset >= -(1 << 24) && offset <= (1 << 24) - 1);
#ifdef __BIG_ENDIAN__
*(VM_UWORD *)&Code[loc * 4] = (offset & 0xFFFFFF) | (OP_JMP << 24);
#else
*(VM_UWORD *)&Code[loc * 4] = OP_JMP | (offset << 8);
#endif
}
//==========================================================================
//
// VMFunctionBuilder :: BackpatchToHere
//
// Store a JMP instruction at <loc> that points to the current code gen
// location.
//
//==========================================================================
void VMFunctionBuilder::BackpatchToHere(size_t loc)
{
Backpatch(loc, Code.Size() / 4);
}