[llvm-commits] [llvm] r46456 - /llvm/trunk/test/CFrontend/2008-01-25-ByValReadNone.c

[Duncan Sands]

Author: baldrick
Date: Mon Jan 28 13:25:47 2008
New Revision: 46456

URL: http://llvm.org/viewvc/llvm-project?rev=46456&view=rev
Log:
Pure/const functions with ByVal parameters cannot
be marked readonly either.

Modified:
    llvm/trunk/test/CFrontend/2008-01-25-ByValReadNone.c

Modified: llvm/trunk/test/CFrontend/2008-01-25-ByValReadNone.c
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CFrontend/2008-01-25-ByValReadNone.c?rev=46456&r1=46455&r2=46456&view=diff

==============================================================================
--- llvm/trunk/test/CFrontend/2008-01-25-ByValReadNone.c (original)
+++ llvm/trunk/test/CFrontend/2008-01-25-ByValReadNone.c Mon Jan 28 13:25:47 2008
@@ -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); }