GHC.CmmToAsm.Monad

Given a jump destination, if it refers to a block, return the block id of the destination.

Does this jump always jump to a single destination and is shortcutable?

We use this to determine whether the given instruction is a shortcutable jump to some destination - See Note [supporting shortcutting] Note that if we return a destination here we *most* support the relevant shortcutting in shortcutStatics for jump tables and shortcutJump for the instructions itself.

Replace references to blockIds with other destinations - used to update jump tables.

Change the jump destination(s) of an instruction.

Rewrites the destination of a jump instruction to another destination, if the given function returns a new jump destination for the BlockId of the original destination.

For instance, for a mapping block_a -> dest_b and a instruction goto block_a we would rewrite the instruction to goto dest_b

Module is only for printing internal labels. See Note [Internal proc labels] in CLabel.

The list of block ids records the redirected jumps to allow us to update the CFG.

given the instruction sequence of a block, produce a list of the block's UnwindPoints See Note [What is this unwinding business?] in GHC.Cmm.DebugBlock and Note [Unwinding information in the NCG] in this module.

Turn the sequence of jcc l1; jmp l2 into jncc l2; <block_l1> when possible.

Stack offset for unwinding information

Having a CFG with additional information is essential for some operations. However we can't reconstruct all information once we generated instructions. So instead we update the CFG as we go.