search for: shifting

Displaying 20 results from an estimated 5358 matches for "shifting".

2005 Feb 01
4
Shorewall problem
I am getting the following message when Shorewall stops can anybody shed any light on this message and where I should be looking? Thanks root@bobshost:~# shorewall stop Loading /usr/share/shorewall/functions... Processing /etc/shorewall/params ... Processing /etc/shorewall/shorewall.conf... Loading Modules... Stopping Shorewall...Processing /etc/shorewall/stop ... IP Forwarding Enabled
2006 Sep 11
2
Translating R code + library into Fortran?
Hi all, I'm running a monte carlo test of a neural network tool I've developed, and it looks like it's going to take a very long time if I run it in R so I'm interested in translating my code (included below) into something faster like Fortran (which I'll have to learn from scratch). However, as you'll see my code loads the nnet library and uses it quite a bit, and I
2019 Oct 01
2
Shift-by-signext - sext is bad for analysis - ignore it's use count?
Thanks for taking a look! On Tue, Oct 1, 2019 at 9:09 PM Philip Reames <listmail at philipreames.com> wrote: > On 9/27/19 1:40 PM, Roman Lebedev via llvm-dev wrote: > > In https://reviews.llvm.org/D68103 the InstCombine learned that shift-by-sext > > is simply a shift-by-zext. > > Just to make sure I'm following, the reasoning here is that the shift > amount must
2019 Feb 25
3
funnel shift, select, and poison
We have these transforms from funnel shift to a simpler shift op: // fshl(X, 0, C) -> shl X, C // fshl(X, undef, C) -> shl X, C // fshl(0, X, C) -> lshr X, (BW-C) // fshl(undef, X, C) -> lshr X, (BW-C) These were part of: https://reviews.llvm.org/D54778 In all cases, one operand must be 0 or undef and the shift amount is a constant, so I think these are safe.
2019 Oct 01
2
Shift-by-signext - sext is bad for analysis - ignore it's use count?
The thing is, we *don't* "not demand" those high bits. We *don't* not care what's in those bits - IR shifts don't mask their shift amounts. I.e we can't replace `x >> (32-y)` with `x >> (-y)`, which would be legal transform should we not demand those bits. We very much demand them. We just know those bits to be zero. And i'm not sure how to convey
2009 Dec 01
0
[LLVMdev] Possible bug in ExpandShiftWithUnknownAmountBit
Hi, > I'm working in adding support for 64-bit integers to my target. I'm using > LLVM to decompose the 64-bit integer operations by using 32-bit registers > wherever possible and emulating support where not. When looking at the bit > shift decomposition I saw what seems to be a bug in the implementation. The > affected function is ExpandShiftWithUnknownAmountBit in >
2019 Sep 27
2
Shift-by-signext - sext is bad for analysis - ignore it's use count?
In https://reviews.llvm.org/D68103 the InstCombine learned that shift-by-sext is simply a shift-by-zext. But the transform is limited to single-use sext. We can quite trivially get a case where there are two shifts by the same sext: https://godbolt.org/z/j6mO3t <- We should handle those cases. In https://reviews.llvm.org/D68103#1686130 Sanjay Patel notes that this sext is intrusive for
2009 Dec 01
2
[LLVMdev] Possible bug in ExpandShiftWithUnknownAmountBit
Hi Duncan, The problem is the implementation of the expansion. Perhaps an example can help illustrate better. Take the case of a 64-bit integer shifted left by say 6 bits and is decomposed using 32-bit registers. Because 6 is less than the 32 (the register size) the resulting low part should be equal to the source low part shifted left by 6 bits. The current implementation places a zero
2019 Feb 25
2
funnel shift, select, and poison
Don't we need to distinguish funnel shift from the more specific rotate? I'm not seeing how rotate (a single input op shifted by some amount) gets into trouble like funnel shift (two variables concatenated and shifted by some amount). Eg, if in pseudo IR we have: %funnel_shift = fshl %x, %y, %sh ; this is problematic because either x or y can be poison, but we may not touch the poison when
2005 May 31
11
More Tests for 2.4.0-RC2 - strange behaviour
Hi all, I was trying to test ROUTE specific code with a multi-isp serviced box. There is a bug somewhere, but I''m not able to understand what the real problem is: when I issue a "shorewall show capabilities" I get: Loading /usr/share/shorewall/functions... Processing /etc/shorewall/params ... Processing /etc/shorewall/shorewall.conf... Loading Modules... Shorewall has
2019 Feb 26
2
funnel shift, select, and poison
If I got poison propagation right, it's probably only by luck! Hopefully, the funnel shift bug is fixed here: https://reviews.llvm.org/rL354905 Nuno, IIUC this means that you do *not* need to change the funnel shift semantics in Alive. So I think that means we're still on track to go with John's suggestion that only select and phi can block poison? (I don't know of any
2019 Oct 07
2
Shift-by-signext - sext is bad for analysis - ignore it's use count?
On Mon, Oct 7, 2019 at 11:32 AM Roman Lebedev <lebedev.ri at gmail.com> wrote: > > Bump. Any further thoughts here? > > To recap - i don't really see how this can be a demandedbits problem - we do > demand all those bits, we just know they must be zero. > (i would love to be proven wrong though!) > > Roman. > > On Tue, Oct 1, 2019 at 11:17 PM Roman Lebedev
2018 Jul 02
2
Rotates, once again
On 7/2/2018 3:16 PM, Sanjay Patel wrote: > I also agree that the per-element rotate for vectors is what we want for > this intrinsic. > > So I have this so far: > > declare i32 @llvm.catshift.i32(i32 %a, i32 %b, i32 %shift_amount) > declare <2 x i32> @llvm.catshift.v2i32(<2 x i32> %a, <2 x i32> %b, <2 x i32> %shift_amount) > > For
2019 Feb 25
4
funnel shift, select, and poison
There's a question about the behavior of funnel shift [1] + select and poison here that reminds me of previous discussions about select and poison [2]: https://github.com/AliveToolkit/alive2/pull/32#discussion_r257528880 Example: define i8 @fshl_zero_shift_guard(i8 %x, i8 %y, i8 %sh) { %c = icmp eq i8 %sh, 0 %f = fshl i8 %x, i8 %y, i8 %sh %s = select i1 %c, i8 %x, i8 %f ; shift amount is 0
2007 Jul 12
2
lead
Hi, is there any function in R that shifts elements of a vector to the opposite direction of what Lag() of the Hmisc package does? (something like, Lag(x, shift = -1) ) Thanks Zava -------------------------------------------------------- This is not an offer (or solicitation of an offer) to buy/se...{{dropped}}
2020 Jun 22
3
FLAC specification clarification
Yes, this is such a case. However, implementing this in a future encoder/decoder would break compatibility with most (likely all) existing decoders, and only in some very, very rare cases where the material is such that the encoder chooses to use negative shifts, which makes it even harder to troubleshoot. Furthermore, as this can only be used in very rare cases, there is no benefit from allowing
2013 Dec 10
2
[RFC][PATCH 3/3] timekeeping: Fix potential lost pv notification of time change
In 780427f0e11 (Indicate that clock was set in the pvclock gtod notifier), logic was added to pass a CLOCK_WAS_SET notification to the pvclock notifier chain. While that patch added a action flag returned from accumulate_nsecs_to_secs(), it only uses the returned value in one location, and not in the logarithmic accumulation. This means if a leap second triggered during the logarithmic
2008 Mar 25
11
Failure to instal S10U4 HVM at SNV85 Dom0
System config:- bash-3.2# ifconfig -a lo0: flags=2001000849<UP,LOOPBACK,RUNNING,MULTICAST,IPv4,VIRTUAL> mtu 8232 index 1 inet 127.0.0.1 netmask ff000000 rge0: flags=201004843<UP,BROADCAST,RUNNING,MULTICAST,DHCP,IPv4,CoS> mtu 1500 index 2 inet 192.168.1.53 netmask ffffff00 broadcast 192.168.1.255 ether 0:1e:8c:25:cc:a5 lo0:
2020 Jul 08
4
[RFC] Saturating left shift intrinsics
Hello, This is an RFC for adding intrinsics which perform saturating signed/unsigned left shift. There is currently a patch on Phabricator here: https://reviews.llvm.org/D83216 The intrinsics are of the form i32 @llvm.sshl.sat.i32(i32, i32) i32 @llvm.ushl.sat.i32(i32, i32) <4 x i32> @llvm.sshl.sat.v4i32(<4 x i32>, <4 x i32>) <4 x i32>
2010 Jun 15
4
shifted window of string
...o","p","q","r","s","t","u","v","w","x","y") > window <- 5 > shift <- 2 I want a matrix of characters with "window" columns filled with "v" by filling a row, then shifting over "shift" and continuing to the next row until "v" is exhausted. You can assume "v" will evenly fit "m" so the result needs to look like this matrix where each row is shifted 2 (in this case): > m [,1] [,2] [,3] [,4] [,5] [1,] "a" &...