From: Chris Lattner
This really makes your programming go faster. Think about compiling code
for the following C/C++ expression: (a|b)*((x+1)/(y+1))
. Assuming
the values are on the stack in the order a, b, x, y, this could be
expressed in stacker as: 1 + SWAP 1 + / ROT2 OR *
.
-You could write a function using LLVM that computes this expression like this:
+You could write a function using LLVM that computes this expression like
+this:
+
+
Value*
expression(BasicBlock* bb, Value* a, Value* b, Value* x, Value* y )
{
- Instruction* tail = bb->getTerminator();
- ConstantSInt* one = ConstantSInt::get( Type::IntTy, 1);
- BinaryOperator* or1 =
- BinaryOperator::create( Instruction::Or, a, b, "", tail );
- BinaryOperator* add1 =
- BinaryOperator::create( Instruction::Add, x, one, "", tail );
- BinaryOperator* add2 =
- BinaryOperator::create( Instruction::Add, y, one, "", tail );
- BinaryOperator* div1 =
- BinaryOperator::create( Instruction::Div, add1, add2, "", tail);
- BinaryOperator* mult1 =
- BinaryOperator::create( Instruction::Mul, or1, div1, "", tail );
-
+ ConstantSInt* one = ConstantSInt::get(Type::IntTy, 1);
+ BinaryOperator* or1 = BinaryOperator::createOr(a, b, "", bb);
+ BinaryOperator* add1 = BinaryOperator::createAdd(x, one, "", bb);
+ BinaryOperator* add2 = BinaryOperator::createAdd(y, one, "", bb);
+ BinaryOperator* div1 = BinaryOperator::createDiv(add1, add2, "", bb);
+ BinaryOperator* mult1 = BinaryOperator::createMul(or1, div1, "", bb);
return mult1;
}
-
+
+
"Okay, big deal," you say? It is a big deal. Here's why. Note that I didn't
have to tell this function which kinds of Values are being passed in. They could be
Instruction
s, Constant
s, GlobalVariable
s, or