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[Bug tree-optimization/50413] Incorrect instruction is used to shift value of 128 bit xmm0 registrer
- From: "aries.nah at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Thu, 15 Sep 2011 13:42:05 +0000
- Subject: [Bug tree-optimization/50413] Incorrect instruction is used to shift value of 128 bit xmm0 registrer
- Auto-submitted: auto-generated
- References: <bug-50413-4@http.gcc.gnu.org/bugzilla/>
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50413
Anatoly <aries.nah at gmail dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|RESOLVED |UNCONFIRMED
Resolution|INVALID |
--- Comment #4 from Anatoly <aries.nah at gmail dot com> 2011-09-15 13:42:05 UTC ---
It's not serious.
Yes, I'm not an expert in SSE instructions (and in ASM at all), and it seems
you're right about shifting.
But, the bug is a real. GCC losts lower bit of upper quadword during shifting
by psrlq.
Try to compile my code and check it out.
We have V.bitmap.b63 = V.bitmap.b64; to shift a lower bit of the upper quadword
but GCC has decided not to do this.