LLVM Essentials

Implementing frame lowering

Frame lowering involves emitting function prologue and epilogue. The prologue happens at the beginning of a function. It sets up the stack frame of the called function. The epilogue happens last in a function, it restores the stack frame of the calling (parent) function.

The "stack" serves several purposes in the execution of a program, as follows:

• Keeping track of return address, when calling a function
• Storage of local variables in the context of a function call
• Passing arguments from the caller to the callee.

Thus there are 2 main functions that need to be defined when implementing frame lowering – emitPrologue() and emitEpilogue().

The emitPrologue() function can be defined as follows:

void TOYFrameLowering::emitPrologue(MachineFunction ...