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[Bug tree-optimization/21485] [4.2/4.3/4.4 Regression] missed load PRE, PRE makes i?86 suck
- 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: 4 Oct 2008 00:57:47 -0000
- Subject: [Bug tree-optimization/21485] [4.2/4.3/4.4 Regression] missed load PRE, PRE makes i?86 suck
- References: <bug-21485-10607@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #32 from rguenth at gcc dot gnu dot org 2008-10-04 00:57 -------
As we PHI-translate k_1 * 4 we are not able to find D.1237_7 * 4 in the
SCCVN tables. So we allocate a new value-id for it. Oops. This is because
once we say its type is unsigned int and once it's unsigned long. And
we require types to be pointer-equal in the hash comparison fn.
I have a patch to fix this which makes this run even more slow. -fno-tree-pre
fixes the speed regression.
--
rguenth at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Summary|[4.2/4.3/4.4 Regression] |[4.2/4.3/4.4 Regression]
|missed load PRE |missed load PRE, PRE makes
| |i?86 suck
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21485