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[Bug ada/35194] floating point truncation error on intel platform
- From: "k-tsubota at ap dot jp dot nec dot com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 19 Oct 2009 06:35:14 -0000
- Subject: [Bug ada/35194] floating point truncation error on intel platform
- References: <bug-35194-15778@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #11 from k-tsubota at ap dot jp dot nec dot com 2009-10-19 06:35 -------
I wonder if the bug is caused by errata of core2duo processor
because the bug was only reproduced on core2duo and pentium D.
(- not on UltraSPARC III)
Intel Core2duo processor has errata in its FPU
- Errata AI20, AI38 (*1).
And, the processor has workarounds of the errata.
If these workaround was not implemented in the GCC version,
the bug might be caused by these errata.
And, Intel Celeron M processor also has similar errata
- Errata W34, W56 (*2).
---------------------------------------------------------
(*1)
Core2duo processor Specification Update
-> http://download.intel.com/design/processor/specupdt/313279.pdf
-> Errata AI20,AI38
---------------------------------------------------------
(*2)
Celeron M processor Specification Update
-> http://download.intel.com/design/mobile/SPECUPDT/300303.pdf
-> Errata W34,W56
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35194