[PATCH] D18092: Swift Calling Convention: add swifterror attribute

[John McCall via llvm-commits]

rjmccall added inline comments.

================
Comment at: docs/LangRef.rst:1082
@@ +1081,3 @@
+    that error objects do not alias with other objects, and two error objects
+    do not alias.
+
----------------
joker.eph wrote:
> rjmccall wrote:
> > I would say:
> > 
> > These constraints also allow LLVM to assume that a swifterror argument
> > does not alias any other memory visible within a function and that a swifterror
> > alloca passed as an argument does not escape.
> It seems to me that this address the swift-error "fake pointer", but not the error itself. Can we (Do we want) to provide guarantee on the error object as well?
No.  To the extent that it's even true that the error object doesn't alias anything, it would be better to express that with other IR tools.


http://reviews.llvm.org/D18092