This is a bare-bones outline of the SSA coloring pass. Many features are
missing, including:
- Handling instruction operand constraints beyond simple register
classes.
- Handling ABI requirements for function arguments and return values.
- Generating shuffle code for EBB arguments.
This is a bare-bones outline of the SSA coloring pass. Many features are
missing, including:
- Handling instruction operand constraints beyond simple register
classes.
- Handling ABI requirements for function arguments and return values.
- Generating shuffle code for EBB arguments.
Some polymorphic instructions don't return the controlling type
variable, so it has to be computed from the designated operand instead.
- Add a requires_typevar_operand() method to the operand constraints
which indicates that.
- Add a ctrl_typevar(dfg) method to InstructionData which computes the
controlling type variable correctly, and returns VOID for monomorphic
instructions.
- Use ctrl_typevar(dfg) to drive the level-1 encoding table lookups.
Some polymorphic instructions don't return the controlling type
variable, so it has to be computed from the designated operand instead.
- Add a requires_typevar_operand() method to the operand constraints
which indicates that.
- Add a ctrl_typevar(dfg) method to InstructionData which computes the
controlling type variable correctly, and returns VOID for monomorphic
instructions.
- Use ctrl_typevar(dfg) to drive the level-1 encoding table lookups.
When the liveness pass implements dead code elimination, missing live
ranges can be used to indicate unused values that it may be possible to
remove. But even then, we may have to keep dead defs around if the
instruction has side effects or other live defs.
When the liveness pass implements dead code elimination, missing live
ranges can be used to indicate unused values that it may be possible to
remove. But even then, we may have to keep dead defs around if the
instruction has side effects or other live defs.
Move the flow graph computation into a compute method which can be
called with multiple functions.
This allows us to reuse the ControlFlowGraph memory and keep an instance
in the Context.
Move the flow graph computation into a compute method which can be
called with multiple functions.
This allows us to reuse the ControlFlowGraph memory and keep an instance
in the Context.
This will provide main entry points for compiling functions, and it
serves as a place for keeping data structures that should be preserved
between function compilations to reduce allocator thrashing.
So far, Context is just basic scaffolding. More to be added.
This will provide main entry points for compiling functions, and it
serves as a place for keeping data structures that should be preserved
between function compilations to reduce allocator thrashing.
So far, Context is just basic scaffolding. More to be added.
Most of the register allocator algorithms will only have to look at the
currently live values as presented by LiveValueTracker. Many also need
the value's affinity which is stored in the LiveRange associated with
the value.
Save the extra table lookup by caching the affinity value inside
LiveValue.
Most of the register allocator algorithms will only have to look at the
currently live values as presented by LiveValueTracker. Many also need
the value's affinity which is stored in the LiveRange associated with
the value.
Save the extra table lookup by caching the affinity value inside
LiveValue.
LiveRanges represent the live-in range of a value as a sorted
list of intervals. Each interval starts at an EBB and continues
to an instruction. Before this commit, the LiveRange would store
an interval for each EBB. This commit changes the representation
such that intervals continuing from one EBB to another are coalesced
into one.
Fixes#37.
LiveRanges represent the live-in range of a value as a sorted
list of intervals. Each interval starts at an EBB and continues
to an instruction. Before this commit, the LiveRange would store
an interval for each EBB. This commit changes the representation
such that intervals continuing from one EBB to another are coalesced
into one.
Fixes#37.
Each live range has an affinity hint containing the preferred register
class (or stack slot). Compute the affinity by merging the constraints
of the def and all uses.
Each live range has an affinity hint containing the preferred register
class (or stack slot). Compute the affinity by merging the constraints
of the def and all uses.
