Changes between Version 22 and Version 23 of Commentary/Compiler/StackAreas

Timestamp:

06/06/08 08:38:16 (5 years ago)

Author:

dias

Comment:

--

Commentary/Compiler/StackAreas

@@ -78 +78 @@
 }}}
 
-An {{{Area}}} represents space on the stack; it may contain either a single stack slot for a register or a number of parameters passed to/from a function call/return. The {{{BlockId}}} is the label of the function call's continuation, and the two integers are the sizes of the outgoing and incoming parameter-passing areas.
+An {{{Area}}} represents space on the stack; it may use either the {{{RegSlot}}} constructor to represent a single stack slot for a register or the {{{CallArea}}} constructor to represent parameters passed to/from a function call/return. In a {{{CallArea}}}, the {{{BlockId}}} is the label of the function call's continuation, and the two integers are the sizes of the outgoing and incoming parameter-passing areas.
 
-To name a specific location on the stack, we represent its address with a new kind of {{{CmmExpr}}}: the {{{CmmStackSlot}}}. A {{{CmmStackSlot}}} is just an integer offset into an {{{Area}}}.
+To name a specific location on the stack, we represent its address with a new kind of {{{CmmExpr}}}: the {{{CmmStackSlot}}}. A {{{CmmStackSlot}}} is just an integer offset into an {{{Area}}}. If the {{{Area}}} is a {{{RegSlot}}}, it is a dynamic invariant that the offset must be {{{0}}}.
 
 Note: We don't have a virtual frame pointer in this story, but do we really need it? Here's a minor argument against: it requires special treatment by some analyses in Quick C--, although it might just fold away into the large set of global registers in GHC.