From: Duncan Sands <baldrick@free.fr>
Date: Mon, 28 Jan 2008 19:25:47 +0000 (+0000)
Subject: Pure/const functions with ByVal parameters cannot
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=07d403e222931ff20fdfecca1e1702b2cec2891c;p=oota-llvm.git

Pure/const functions with ByVal parameters cannot
be marked readonly either.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@46456 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/test/CFrontend/2008-01-25-ByValReadNone.c b/test/CFrontend/2008-01-25-ByValReadNone.c
index afbf97066c7..8ec60525af8 100644
--- a/test/CFrontend/2008-01-25-ByValReadNone.c
+++ b/test/CFrontend/2008-01-25-ByValReadNone.c
@@ -1,10 +1,15 @@
-// RUN: %llvmgcc -O3 -S -o - -emit-llvm %s | grep readonly
+// RUN: %llvmgcc -O3 -S -o - -emit-llvm %s | not grep readonly
 // RUN: %llvmgcc -O3 -S -o - -emit-llvm %s | not grep readnone
 
 
-// The struct being passed byval means that we need to mark the 
-// function readonly instead of readnone.  Readnone would allow
-// stores to the arg to be deleted in the caller.
+// The struct being passed byval means that we cannot mark the
+// function readnone.  Readnone would allow stores to the arg to
+// be deleted in the caller.  We also don't allow readonly since
+// the callee might write to the byval parameter.  The inliner
+// would have to assume the worse and introduce an explicit
+// temporary when inlining such a function, which is costly for
+// the common case in which the byval argument is not written.
 struct S { int A[1000]; };
 int __attribute__ ((const)) f(struct S x) { return x.A[0]; }
-
+int g(struct S x) __attribute__ ((pure));
+int h(struct S x) { return g(x); }