Author: lattner
Date: Fri Jan 11 00:17:47 2008
New Revision: 45854
URL: http://llvm.org/viewvc/llvm-project?rev=45854&view=rev
Log:
add some notes.
Modified:
llvm/trunk/lib/Target/README.txt
Modified: llvm/trunk/lib/Target/README.txt
URL:
http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/README.txt?rev=45854&r1=45853&r2=45854&view=diff
==============================================================================
--- llvm/trunk/lib/Target/README.txt (original)
+++ llvm/trunk/lib/Target/README.txt Fri Jan 11 00:17:47 2008
@@ -595,3 +595,21 @@
once.
//===---------------------------------------------------------------------===//
+
+We should extend parameter attributes to capture more information about
+pointer parameters for alias analysis. Some ideas:
+
+1. Add a "nocapture" attribute, which indicates that the callee does not store
+ the address of the parameter into a global or any other memory location
+ visible to the callee. This can be used to make basicaa and other analyses
+ more powerful. It is true for things like memcpy, strcat, and many other
+ things, including structs passed by value, most C++ references, etc.
+2. Generalize readonly to be set on parameters. This is important mod/ref
+ info for the function, which is important for basicaa and others. It can
+ also be used by the inliner to avoid inserting a memcpy for byval
+ arguments when the function is inlined.
+
+These functions can be inferred by various analysis passes such as the
+globalsmodrefaa pass.
+
+//===---------------------------------------------------------------------===//
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