IR-code ======= The purpose of an intermediate representation (IR) of a program is to decouple the implementation of a front-end from the implementation of a back-end. That is, front ends generate IR-code, optimizers optimize this code and lastly backends transform it into machine code or something else. A good IR has several characteristics: - It should be simple enough for front-ends to generate code. - It should be rich enough to exploit the target instructions best. The IR in the ppci.ir module has the following properties: - It is `static single assignment form `_. Meaning a value can only be assigned once, and is then never changed. This has several advantages. - It contains only basic types. Structures, arrays and void types are not represented. Top level structure ------------------- The IR-code is implemented in the ir package. .. autoclass:: ppci.ir.Module :members: variables, functions, add_variable .. autoclass:: ppci.ir.Variable .. autoclass:: ppci.ir.SubRoutine :members: add_block, remove_block .. autoclass:: ppci.ir.Procedure .. autoclass:: ppci.ir.Function .. autoclass:: ppci.ir.Block :members: add_instruction, remove_instruction, is_empty, is_closed, predecessors, successors Types ----- Only simple types are available. .. autodata:: ppci.ir.ptr :annotation: .. autodata:: ppci.ir.i64 :annotation: .. autodata:: ppci.ir.i32 :annotation: .. autodata:: ppci.ir.i16 :annotation: .. autodata:: ppci.ir.i8 :annotation: .. autodata:: ppci.ir.u64 :annotation: .. autodata:: ppci.ir.u32 :annotation: .. autodata:: ppci.ir.u16 :annotation: .. autodata:: ppci.ir.u8 .. autodata:: ppci.ir.f64 :annotation: .. autodata:: ppci.ir.f32 :annotation: Instructions ------------ The following instructions are available. **Memory instructions** .. autoclass:: ppci.ir.Load .. autoclass:: ppci.ir.Store .. autoclass:: ppci.ir.Alloc **Data instructions** .. autoclass:: ppci.ir.Const .. autoclass:: ppci.ir.Binop .. autoclass:: ppci.ir.Cast **Control flow instructions** .. autoclass:: ppci.ir.ProcedureCall .. autoclass:: ppci.ir.FunctionCall .. autoclass:: ppci.ir.Jump .. autoclass:: ppci.ir.CJump .. autoclass:: ppci.ir.Return .. autoclass:: ppci.ir.Exit **Other** .. autoclass:: ppci.ir.Phi .. autoclass:: ppci.ir.Undefined Abstract instruction classes ---------------------------- There are some abstract instructions, which cannot be used directly but serve as base classes for other instructions. .. autoclass:: ppci.ir.Instruction :members: function .. autoclass:: ppci.ir.Value :members: is_used .. autoclass:: ppci.ir.FinalInstruction Uml --- .. uml:: ppci.ir