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[Bug tree-optimization/37101] [4.2/4.3 Regression] wrong code: tree vectorizer omits bogus movq/movlps construct
- From: "christophe at saout dot de" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 13 Aug 2008 16:14:15 -0000
- Subject: [Bug tree-optimization/37101] [4.2/4.3 Regression] wrong code: tree vectorizer omits bogus movq/movlps construct
- References: <bug-37101-10561@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #3 from christophe at saout dot de 2008-08-13 16:14 -------
Ok, tried that...
Now xorg-server doesn't segfault, but hang in an infinite loop.
Adding printouts after the loop shows that the upper and lower parts of the
register are inverted:
(contents of the "tails" array):
0 0x28e1c98
1 0x28e1c90
2 0x28e1ca8
3 0x28e1ca0
4 0x28e1cb8
...
So, the movlps is correct to fill the lower half of the register without
touching the upper half, but the "movd %rax, %xmm1" should fill the upper half
instead. I tried changing it into a movhps, but that won't take the %rax as
source register.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37101