[cfe-commits] r67752 - in /cfe/trunk: docs/AnalyzerRegions.txt lib/Analysis/Design.txt

[Ted Kremenek]

Author: kremenek
Date: Thu Mar 26 10:29:38 2009
New Revision: 67752

URL: http://llvm.org/viewvc/llvm-project?rev=67752&view=rev
Log:
Move "regions" analyzer design document to 'docs'.

Added:
    cfe/trunk/docs/AnalyzerRegions.txt
      - copied unchanged from r67749, cfe/trunk/lib/Analysis/Design.txt
Removed:
    cfe/trunk/lib/Analysis/Design.txt

Removed: cfe/trunk/lib/Analysis/Design.txt
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Analysis/Design.txt?rev=67751&view=auto

==============================================================================
--- cfe/trunk/lib/Analysis/Design.txt (original)
+++ cfe/trunk/lib/Analysis/Design.txt (removed)
@@ -1,53 +0,0 @@
-Symbolic Region
-
-A symbolic region is a map of the concept of symbolic values into the domain of
-regions. It is the way that we represent symbolic pointers. Whenever a symbolic
-pointer value is needed, a symbolic region is created to represent it.
-
-A symbolic region has no type. It wraps a SymbolData. But sometimes we have type
-information associated with a symbolic region. For this case, a TypedViewRegion
-is created to layer the type information on top of the symbolic region. The
-reason we do not carry type information with the symbolic region is that
-the symbolic regions can have no type. To be consistent, we don't let them to
-carry type information.
-
-Like a symbolic pointer, a symbolic region may be NULL, has unknown extent, and
-represents a generic chunk of memory.
-
-We plan not to use loc::SymbolVal in RegionStore and remove it gradually.
-
-Pointer Casts
-
-Pointer casts allow people to impose different 'views' onto a chunk of memory.
-
-Usually we have two kinds of casts. One kind of casts cast down with in the type
-hierarchy. It imposes more specific views onto more generic memory regions. The
-other kind of casts cast up with in the type hierarchy. It strips away more
-specific views on top of the more generic memory regions. 
-
-We simulate the down casts by layering another TypedViewRegion on top of the
-original region. We simulate the up casts by striping away the top
-TypedViewRegion. Down casts is usually simple. For up casts, if the there is no
-TypedViewRegion to be stripped, we return the original region. If the underlying
-region is of the different type than the cast-to type, we flag an error state.
-
-For toll-free bridging casts, we return the original region.
-
-Region Bindings
-
-The following region kinds are boundable: VarRegion, CompoundLiteralRegion,
-StringRegion, ElementRegion, FieldRegion, and ObjCIvarRegion.
-
-When binding regions, we perform canonicalization on element regions and field
-regions. This is because we can have different views on the same region, some of
-which are essentially the same view with different sugar type names.
-
-To canonicalize a region, we get the canonical types for all TypedViewRegions
-along the way up to the root region, and make new TypedViewRegions with those
-canonical types.
-
-All bindings and retrievings are done on the canonicalized regions.
-
-Canonicalization is transparent outside the region store manager, and more
-specifically, unaware outside the Bind() and Retrieve() method. We don't need to
-consider region canonicalization when doing pointer cast.