This is the mail archive of the
gcc-bugs@gcc.gnu.org
mailing list for the GCC project.
[Bug tree-optimization/22548] New: Aliasing can not tell array members apart
- From: "rguenth at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 18 Jul 2005 14:49:20 -0000
- Subject: [Bug tree-optimization/22548] New: Aliasing can not tell array members apart
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
For the following testcase (s is global so SRA cannot decompose it), aliasing
can not tell that the store to s.i[1] does not alias s.i[0]. So instead of
optimizing this to return 3; at the tree-level, we do a load of s.i[0].
struct { int i[2]; } s;
int foo(void)
{
s.i[0] = 1;
s.i[1] = 2;
return s.i[0] + s.i[1];
}
Note that it cannot even do this if you remove the wrapping structure,
though you won't find many instances of such in C++ code. But at least
for this I'd have a patch, if not IVOPTs would suck so much wrt aliasing.
--
Summary: Aliasing can not tell array members apart
Product: gcc
Version: 4.1.0
Status: UNCONFIRMED
Keywords: missed-optimization
Severity: normal
Priority: P2
Component: tree-optimization
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: rguenth at gcc dot gnu dot org
CC: gcc-bugs at gcc dot gnu dot org
OtherBugsDependingO 22501
nThis:
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22548