--- /dev/null
+Sketch of the new arrivals:
+
+ MkZipCfg Constructor functions for control-flow graphs.
+ Not understandable in its entirety without reference
+ to ZipCfg, but nevertheless a worthy starting point,
+ as it is a good deal simpler than full ZipCfg.
+ MkZipCfg is polymorphic in the types of middle and last
+ nodes.
+
+ ZipCfg Describes a zipper-like representation for true basic-block
+ control-flow graphs. A block has a single entry point,
+ which is a always a label, followed by zero or mode 'middle
+ nodes', each of which represents an uninterruptible
+ single-entry, single-exit computation, then finally a 'last
+ node', which may have zero or more successors. A special
+ 'exit node' is used for splicing together graphs.
+
+ In addition to three representations of flow graphs, the
+ module provides a surfeit of functions for observing and
+ modifying graphs and related data:
+ - Block IDs, sets and environments thereof
+ - supply of fresh block IDS (as String -> UniqSM BlockId)
+ - myriad functions for splicing graphs
+ - postorder_dfs layout of blocks
+ - folding, mapping, and translation functions
+
+ ZipCFG is polymorphic in the type of middle and last nodes.
+
+ CmmExpr Code for C-- expressions, which is shared among old and new
+ representations of flow graphs. Of primary interest is the
+ type class UserOfLocalRegs and its method foldRegsUsed,
+ which is sufficiently overloaded to be used against
+ expressions, statements, formals, hinted formals, and so
+ on. This overloading greatly clarifies the computation of
+ liveness as well as some other analyses.
+
+ ZipCfgCmm Types to instantiate ZipCfg for C--: middle and last nodes,
+ and a bunch of abbreviations of types in ZipCfg and Cmm.
+ Also provides suitable constructor functions for building
+ graphs from Cmm statements.
+
+ CmmLiveZ A good example of a very simple dataflow analysis. It
+ computes the set of live local registers at each point.
+
+ DFMonad Support for dataflow analysis and dataflow-based
+ transformation. This module needs work. Includes
+ DataflowLattice - for tracking dataflow facts (good)
+ DFA - monad for iterative dataflow analysis (OK)
+ DFM - monad for iterative dataflow analysis and rewriting (OK)
+ DFTx - monad to track Whalley/Davidson transactions (ugly)
+ type class DataflowAnalysis - operations common to DFA, DFM
+ Some dodgy bits are
+ subAnalysis, which may not be right
+
+ ZipDataflow Iteratively solve forward and backward dataflow problems over
+ flow graphs. Polymorphic in the type of graph and in the
+ lattice of dataflow facts. Supports the incremental
+ rewriting technique described by Lerner, Grove, and Chambers
+ in POPL 2002. The code is a mess and is still being
+ sorted out.
+
+
+ CmmTx A simple monad for tracking when a transformation has
+ occurred (something has changed).
+
+ CmmCvt Converts between Cmm and ZipCfgCmm representations.
+
+ CmmProcPointZ One module that performs three analyses and
+ transformations:
+
+ 1. Using Michael Adams's iterative algorithm, computes a
+ minimal set of proc points that enable code to be
+ generated without copying any basic blocks.
+
+ 2. Assigns a protocol to each proc point. The assigner
+ is rigged to enable the 'Adams optimization' whereby
+ we attempt to eliminate return continuations by
+ making procedures return directly to join points.
+ Arguably this could be done by a separate rewriting
+ pass to perform earlier.
+
+ 3. Insert CopyIn and CopyOut nodes where needed
+ according to the protocols.
+
+ CmmSpillReload Inserts spills and reloads to establish the invariant that
+ at a safe call, there are no live variables in registers.
+
+ CmmCPSZ The CPS transformation so far.
+
+ CmmContFlowOpt Branch-chain elimination and elimination of unreachable code.
+
+ CmmCvt Conversion to and from the new format.
+
+ CmmOpt Changed optimization to use 'foldRegsUsed'; eliminated
+ significant duplication of code.
+
+ PprCmmZ Prettyprinting functions related to ZipCfg and ZipCfgCmm
projects / ghc-hetmet.git / blobdiff