/* 折半查找 */
static void TranslateSwitchBuckets (SwitchBucket *bucketArray, int left, int right, Symbol choice, BBlock currBB, BBlock defBB)
{
int mid, len, i;
AstCaseStatement p;
BBlock lhalfBB, rhalfBB;
BBlock *dstBBs;
Symbol index;
if (left > right)
return;
mid = (left + right) / 2;
lhalfBB = (left > mid - 1) ? defBB : CreateBBlock();
rhalfBB = (mid + 1 > right) ? defBB : CreateBBlock();
len = bucketArray[mid]->maxVal - bucketArray[mid]->minVal + 1;
dstBBs = HeapAllocate (CurrentHeap, (len + 1)* sizeof(BBlock));
for (i = 0; i < len; ++i)
dstBBs[i] = defBB;
dstBBs[len] = NULL;
for (p = bucketArray[mid]->cases; p; p = p->nextCase) {
i = p->expr->val.i[0] - bucketArray[mid]->minVal;
dstBBs[i] = p->respBB;
}
if (currBB != NULL) {
StartBBlock (currBB);
}
GenerateBranch (choice->ty, lhalfBB, JL, choice, IntConstant (bucketArray[mid]->minVal));
StartBBlock (CreateBBlock());
GenerateBranch (choice->ty, rhalfBB, JG, choice, IntConstant (bucketArray[mid]->maxVal));
StartBBlock (CreateBBlock());
if (len != 1) {
index = CreateTemp (choice->ty);
GenerateAssign (choice->ty, index, SUB, choice, IntConstant (bucketArray[mid]->minVal));
GenerateIndirectJump (dstBBs, len, index);
} else {
GenerateJump (dstBBs[0]);
}
StartBBlock (CreateBBlock ());
/* 二分递归 */
TranslateSwitchBuckets (bucketArray, left, mid - 1, choice, lhalfBB, defBB);
TranslateSwitchBuckets (bucketArray, mid + 1, right, choice, rhalfBB, defBB);
}
void Compiler::EmitCall(IRInst inst)
{
ParameterList argslist = (ParameterList)SRC2;
Symbol arg;
int i, stksize = 0;
for (i = argslist->npara - 1; i >= 0; i--)
{
arg = argslist->args[i];
PushArgument(arg);
stksize += sizeof(int) * 1;
}
// call func
PutASMCode(X86_CALL, inst->opds);
// 如果参数不为0, 则返回时需要复原栈顶
if (stksize != 0) {
Symbol p;
p = IntConstant(stksize);
PutASMCode(X86_REDUCEF, &p);
}
if (DST) DST->ref--;
// 这里DST 不会 DST == NULL，因为根据要求为ID = call ID.
//函数返回值放在EAX
//AllocateReg(inst, 0);
//if (DST->reg != Regs[EAX])
//{
// Move(DST, Regs[EAX]);
//}
DST->reg = Regs[EAX];
}
void Compiler::EmitPrologue(int varsize)
{
PutASMCode(PROLOGUE, NULL);
if (varsize != 0) {
Symbol sym = IntConstant(varsize*sizeof(int));
PutASMCode(EXPANDF, &sym);
}
}
/*
* ClearInst -> Clear VarName, constant
* */
void GenerateClear (Symbol dst, int size)
{
IRInst inst;
CALLOC (inst);
dst->ref++;
inst->ty = T(UCHAR);
inst->opcode = CLR;
inst->opds[0] = dst;
inst->opds[1] = IntConstant (size);
inst->opds[1]->ref++;
inst->opds[2] = NULL;
AppendInst (inst);
}
/**
* Perform algebraic simplification and strenth reduction
*/
Symbol Simplify(Type ty, int opcode, Symbol src1, Symbol src2)
{
VariableSymbol t;
Symbol p1, p2;
int c1, c2;
if (IsRealType(ty))
goto add_value;
if (src2 == NULL || (src2->kind != SK_Constant && opcode != SUB))
goto add_value;
switch (opcode)
{
case ADD:
// a + 0 = a
if (src2->val.i[0] == 0)
return src1;
// a + c1 + c2 = a + (c1 + c2)
// a - c1 + c2 = a + (-c1 + c2)
p1 = src1; c1 = 0;
if (src1->kind == SK_Temp)
{
t = AsVar(src1);
if (t->def->src2 && t->def->src2->kind == SK_Constant &&
(t->def->op == ADD || t->def->op == SUB))
{
p1 = t->def->src1;
c1 = (t->def->op == ADD ? 1 : -1) * t->def->src2->val.i[0];
}
}
if (c1 != 0)
{
src1 = p1;
src2 = IntConstant(c1 + src2->val.i[0]);
}
break;
case SUB:
// a - 0 = a
if (src2->kind == SK_Constant && src2->val.i[0] == 0)
return src1;
// put source operand into v + c format (v maybe NULL, c maybe 0)
p1 = src1; c1 = 0;
if (src1->kind == SK_Temp)
{
t = AsVar(src1);
if (t->def->src2 && t->def->src2->kind == SK_Constant &&
(t->def->op == ADD || t->def->op == SUB))
{
p1 = t->def->src1;
c1 = (t->def->op == ADD ? 1 : -1) * t->def->src2->val.i[0];
}
}
else if (src1->kind == SK_Constant)
{
p1 = NULL;
c1 = src1->val.i[0];
}
p2 = src2; c2 = 0;
if (src2->kind == SK_Temp)
{
t = AsVar(src2);
if (t->def->src2 && t->def->src2->kind == SK_Constant &&
(t->def->op == ADD || t->def->op == SUB))
{
p2 = t->def->src1;
c2 = (t->def->op == ADD ? 1 : -1) * t->def->src2->val.i[0];
}
}
else if (src2->kind == SK_Constant)
{
p2 = NULL;
c2 = src2->val.i[0];
}
if (p1 == p2)
{
// (a + c1) - (a + c2) = c1 - c2
return IntConstant(c1 - c2);
}
else if (p1 == NULL)
{
// c1 - (a + c2) = (c1 - c2) - a
src1 = IntConstant(c1 - c2);
src2 = p2;
}
else if (p2 == NULL)
{
// (a + c1) - c2 = a + (c1 - c2)
src1 = p1;
opcode = ADD;
src2 = IntConstant(c1 - c2);
}
break;
case MUL:
case DIV:
// a * 1 = a; a / 1 = a;
if (src2->val.i[0] == 1)
return src1;
// a * 2 power of n = a >> n
c1 = Power2(src2->val.i[0]);
if (c1 != 0)
{
src2 = IntConstant(c1);
opcode = opcode == MUL ? LSH : RSH;
}
break;
case MOD:
// a % 1 = 0
if (src2->val.i[0] == 1)
return IntConstant(0);
// a % 2 power of n = a & (2 power of n - 1)
c1 = Power2(src2->val.i[0]);
if (c1 != 0)
{
src2 = IntConstant(src2->val.i[0] - 1);
opcode = BAND;
}
break;
case LSH:
case RSH:
// a >> 0 = a << 0 = a
if (src2->val.i[0] == 0)
return src1;
break;
case BOR:
// a | 0 = a; a | -1 = -1
if (src2->val.i[0] == 0)
return src1;
if (src2->val.i[0] == -1)
return src2;
break;
case BXOR:
// a ^ 0 = a
if (src2->val.i[0] == 0)
return src1;
break;
case BAND:
// a & 0 = 0, a & -1 = a
if (src2->val.i[0] == 0)
return IntConstant(0);
if (src2->val.i[0] == -1)
return src1;
break;
default:
break;
}
add_value:
return TryAddValue(ty, opcode, src1, src2);
}
/* 算数优化 */
Symbol Simplify (Type ty, int opcode, Symbol src1, Symbol src2)
{
VariableSymbol t;
Symbol p1, p2;
int c1, c2;
/* 浮点 */
if (IsRealType (ty))
goto add_value;
if (src2 == NULL || (src2->kind != SK_Constant && opcode != SUB))
goto add_value;
/* 以下是 加, 减, 乘, 除, 取余, 左移, 右移, 按位操作的优化 */
switch (opcode) {
case ADD: {
/* a + 0 = a */
if (src2->val.i[0] == 0)
return src1;
/* a + c1 + c2 = a + (c1 + c2) */
/* a - c1 + c2 = a + (-c1 + c2) */
p1 = src1; c1 = 0;
if (src1->kind == SK_Temp) {
t = AsVar(src1);
if (t->def->src2 && t->def->src2->kind == SK_Constant &&
(t->def->op == ADD || t->def->op == SUB)) {
p1 = t->def->src1;
c1 = (t->def->op == ADD ? 1 : -1) * t->def->src2->val.i[0];
}
}
if (c1 != 0) {
src1 = p1;
/* 合并c1, c2 */
src2 = IntConstant (c1 + src2->val.i[0]);
}
}break;
case SUB: {
/* a - 0 = a */
if (src2->kind == SK_Constant && src2->val.i[0] == 0)
return src1;
// put source operand into v + c format (v maybe NULL, c maybe 0)
p1 = src1; c1 = 0;
if (src1->kind == SK_Temp) {
t = AsVar(src1);
if (t->def->src2 && t->def->src2->kind == SK_Constant &&
(t->def->op == ADD || t->def->op == SUB)) {
p1 = t->def->src1;
c1 = (t->def->op == ADD ? 1 : -1) * t->def->src2->val.i[0];
}
} else if (src1->kind == SK_Constant) {
p1 = NULL;
c1 = src1->val.i[0];
}
p2 = src2; c2 = 0;
if (src2->kind == SK_Temp) {
t = AsVar(src2);
if (t->def->src2 && t->def->src2->kind == SK_Constant &&
(t->def->op == ADD || t->def->op == SUB)) {
p2 = t->def->src1;
c2 = (t->def->op == ADD ? 1 : -1) * t->def->src2->val.i[0];
}
} else if (src2->kind == SK_Constant) {
p2 = NULL;
c2 = src2->val.i[0];
}
if (p1 == p2) {
/* (a + c1) - (a + c2) = c1 - c2 */
return IntConstant (c1 - c2);
} else if (p1 == NULL) {
/* c1 - (a + c2) = (c1 - c2) - a */
src1 = IntConstant (c1 - c2);
src2 = p2;
} else if (p2 == NULL) {
/* (a + c1) - c2 = a + (c1 - c2) */
src1 = p1;
opcode = ADD;
src2 = IntConstant(c1 - c2);
}
}break;
case MUL: case DIV: {
/* a * 1 = a; a / 1 = a; */
if (src2->val.i[0] == 1)
return src1;
/* a * 2 power of n = a >> n */
c1 = Power2 (src2->val.i[0]);
if (c1 != 0) {
/* 转换乘除为位移操作 */
src2 = IntConstant (c1);
opcode = opcode == MUL ? LSH : RSH;
}
}break;
case MOD: {
/* a % 1 = 0 */
if (src2->val.i[0] == 1)
return IntConstant (0);
/* a % 2 power of n = a & (2 power of n - 1) */
c1 = Power2 (src2->val.i[0]);
if (c1 != 0) {
src2 = IntConstant (src2->val.i[0] - 1);
opcode = BAND;
}
}break;
case LSH: case RSH: {
/* a >> 0 = a << 0 = a */
if (src2->val.i[0] == 0)
return src1;
}break;
case BOR: {
/* a | 0 = a; a | -1 = -1 */
if (src2->val.i[0] == 0)
return src1;
if (src2->val.i[0] == -1)
return src2;
}break;
case BXOR: {
/* a ^ 0 = a */
if (src2->val.i[0] == 0)
return src1;
}break;
case BAND: {
/* a & 0 = 0, a & -1 = a */
if (src2->val.i[0] == 0)
return IntConstant(0);
if (src2->val.i[0] == -1)
return src1;
}break;
default: break;
}
add_value:
/* 构造值添加到符号表中,并返回 */
return TryAddValue (ty, opcode, src1, src2);
}