Changes between Version 3 and Version 4 of Commentary/Compiler/NewCodeGen

Timestamp:

11/02/07 04:38:55 (6 years ago)

Author:

simonpj

Comment:

--

Commentary/Compiler/NewCodeGen

@@ -2 +2 @@
 
 This page summarises work that Norman Ramsey, Simon M, and Simon PJ are doing on re-architecting GHC's back end.
+
+Status:
+ * Code generator: first draft done.
+ * Control-flow opt: simple ones done
+   * Common block elmination: to do
+   * Block concatenation: to do
+ * Adams optimisation: currently done somewhere but not modularly.  I think.
+ * Proc-point analysis and transformation: done?
+ * Add spill/reload: done?
+ * Stack slot alloction?
+ * Make stack explicit: to do
+ * Split into multiple !CmmProcs: to do
+
+
+!ToDo list
+ * Get rid of `CmmFormals` on `LastJump` and `LastCall` in `ZipCfgCmm` in favour of `CopyIn` and `CopyOut`.
+ * Change the C-- parser (which parses RTS .cmm files) to directly construct `CmmGraph`.  
+ * Was there something about sinking spills and hoisting reloads?
 
 == The new Cmm data type ==
@@ -14 +32 @@
  * '''`ZipCfgCmm`''' instantiates `ZipCfg` for Cmm, by defining types `Middle` and `Last` and using these to instantiate the polymorphic fields of `ZipCfg`.  It also defines a bunch of smart constructor (`mkJump`, `mkAssign`, mkCmmIfThenElse` etc) which make it easy to build `CmmGraph`.
 
-Todo list:
-  * Get rid of `CmmFormals` on `LastJump` and `LastCall` in `ZipCfgCmm` in favour of `CopyIn` and `CopyOut`.
-  * Change the C-- parser (which parses RTS .cmm files) to directly construct `CmmGraph`.  
 
+ 
 == The pipeline ==
 
- * Code generator converts STG to `CmmGraph`.
+ * '''Code generator''' converts STG to `CmmGraph`.  Implemented in `StgCmm*` modules (in directory `codeGen`).
 
  * '''Simple control flow optimisation''', implemented in `CmmContFlowOpt`:
@@ -27 +43 @@
    * TODO: block concatenation.  branch to K; and this is the only use of K.
    * Consider: block duplication.  branch to K; and K is a short block.  Branch chain elimination is just a special case of this.
+   * TODO: Common block elimination (like CSE). This makes something else significantly simpler.  ('''!ToDo''': what?).
 
  * '''The Adams optimisation'''.  Given:
@@ -46 +63 @@
  Invariant: (something like) all variables in a block are gotten from `CopyIn` or `Reload`. 
 
+ * '''Stack slot layout'''.  Build inteference graph for variables live across calls, and allocate a stack slot for such variables.  That is, stack slot allocation is very like register allocation.
+
+ * '''Make the stack explicit'''. 
+   * Convert `CopyIn`, `CopyOut`, `Spill`, `Reload` to hardware-register and stack traffic.
+   * Add stack-pointer adjustment instructions.
+   * Avoid memory traffic at joins. (What does this mean?)
+
+ * '''Split into multiple !CmmProcs'''.
+