From 65844fbd8496cc7981758f61a6699cd07bfe32c7 Mon Sep 17 00:00:00 2001 From: Chris Lattner Date: Sat, 12 Jan 2008 18:58:46 +0000 Subject: [PATCH] clarify a note git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@45914 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Target/README.txt | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/lib/Target/README.txt b/lib/Target/README.txt index f39d8b2a244..623c86f3555 100644 --- a/lib/Target/README.txt +++ b/lib/Target/README.txt @@ -610,6 +610,14 @@ pointer parameters for alias analysis. Some ideas: arguments when the function is inlined. These functions can be inferred by various analysis passes such as the -globalsmodrefaa pass. +globalsmodrefaa pass. Note that getting #2 right is actually really tricky. +Consider this code: + +struct S; S G; +void caller(S byvalarg) { G.field = 1; ... } +void callee() { caller(G); } + +The fact that the caller does not modify byval arg is not enough, we need +to know that it doesn't modify G either. This is very tricky. //===---------------------------------------------------------------------===// -- 2.34.1