Displaying 20 results from an estimated 2000 matches similar to: "[LLVMdev] register constraints"
2018 Dec 14
2
Dealing with information loss for widened integer operations at ISel time
On Thu, 13 Dec 2018 at 21:41, Friedman, Eli <efriedma at codeaurora.org> wrote:
>
> On 12/13/2018 6:25 AM, Alex Bradbury wrote:
> > There's also likely to be cases where you want to calculate the demanded bits
> > in order to determine if e.g. a W-suffixed instruction can be selected for
> > `(somoeop (zexti32 GPR:$rs1), (zexti32 GPR:$rs2))`. This is easy to match
2018 Dec 13
2
Dealing with information loss for widened integer operations at ISel time
As previously discussed in an RFC
<http://lists.llvm.org/pipermail/llvm-dev/2018-October/126690.html>, the
RISC-V backend has i64 as the only legal integer type for the RV64 target.
Thanks to variable-sized register class support, this means there is no need
for duplication of either patterns or instruction definitions for RV32 and
RV64. It's worth noting that RV64I is a different base
2009 Jul 23
1
[LLVMdev] Case where VSETCC DAGCombiner hack doesn't work
On Jul 21, 2009, at 11:14 PM, Eli Friedman wrote:
> Testcase (compile with clang >= r76726):
> #include <emmintrin.h>
> __m128i a(__m128 a, __m128 b) { return a==a & b==b; }
>
> CodeGen ends up scalarizing the comparison, which is really bad, and
> AFAIK different from what we did before vsetcc was removed. The ideal
> code is a single cmpordps, although I
2019 Nov 25
2
Tablegen PAT limitation?
You are welcome.
I changed the pattern, the same old error pop up again, crash in the same place.
Type set is empty for each HW mode:
possible type contradiction in the pattern below (use -print-records with llvm-tblgen to see all expanded records).
vtInt: (vt:{ *:[Other] })
UNREACHABLE executed at /home/nancy/work/rpp_clang/llvm/utils/TableGen/CodeGenDAGPatterns.cpp:824!
2017 Jul 18
2
get ty2
Hello,
in some operations there is a ty2 type, for example in truncate. What is
the most right way to get it ? I have seen some EVT types, but this is
connected to DAG... and I don't believe that there is no easy way to get
ty2 with one call function.
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2007 Mar 01
2
OpenSSH use of OpenSSL in FIPS Mode
Now that OpenSSL has received FIPS 140-2 certification, does anyone know
if the work started a couple of years ago to allow OpenSSH to use
OpenSSL in FIPS mode will be reactivated?
Bill
2001 Dec 07
7
win2k joining Samba 2.2.2 PDC problems.
I'm running FreeBSD 4.4, with Samba 2.2.2 freshly installed, with
the FreeBSD Ports package to install files in correct places.
I've a Win2k system tring to join the domain "FREESIDE"
It will authenticate ok from the win2k command line.
"net use x: \\crypton\homes /USER:FREESIDE\jerry"
It seems to work ok during the first part of joining a domain, i.e.
password
2016 Jun 17
2
Opus Raw Pakcets
Hi,
I have application, where I am reciving the RTP packets, which has OPUS
payload.
>From the RTP packets I got following information:
(12 byes Header) tells about the version, payload time, time stamp, srsc,
etc. The rest of the packet is OPUS payload (raw format), The TOC byte from
OPUS payload tells its 20ms frame, even the time stamp different of 960
means 20 msec frame.
Questions:
1)
2014 Mar 26
19
[LLVMdev] 3.4.1 Release Plans
Hi,
We are now about halfway between the 3.4 and 3.5 releases, and I would
like to start preparing for a 3.4.1 release. Here is my proposed release
schedule:
Mar 26 - April 9: Identify and backport additional bug fixes to the 3.4 branch.
April 9 - April 18: Testing Phase
April 18: 3.4.1 Release
How you can help:
- If you have any bug fixes you think should be included to 3.4.1, send
me an
2016 Nov 11
2
RFC: Killing undef and spreading poison
Hi John,
John McCall wrote:
>> On Nov 10, 2016, at 10:37 PM, Sanjoy Das<sanjoy at playingwithpointers.com> wrote:
>> As a concrete example, say we have:
>>
>> i32 sum = x *nsw y
>> i64 sum.sext = sext sum to i64
>> ...
>> some use of sum.sext
>>
>>
>> Pretending "x +nsw 1" does not sign-overflow, we can commute the sext
2017 Jun 02
5
RFC: Killing undef and spreading poison
Sanjoy,
My answer is that step 3, commuting the multiply with the sign-extends, is invalid,
As this is what causes the `udiv` to fault. I think it is invalid with or without the “freeze”,
why do you think step 3, the commute, without the “freeze" is valid ?
Also, do you think you can come up with an example that does not depend on signed
overflow being “undefined” ?
Peter
2008 Oct 06
3
[LLVMdev] sext..to instruction
Hi,
I have a question about the "sext..to" instruction. In the document, I found
two examples:
%x = sext i8 -1 to i16
It means:
i8 -1 = 1111 1111 --> 1111 1111 1111 1111 = i16
how can it determinate, that the i16 value %x positive is (65535)?
And the second example:
%y = sext i1 true to i32
1 --> 1111 1111 1111 1111 1111 1111 1111 1111
In this example, %y is -1
I'm not sure
2015 Apr 01
2
[LLVMdev] Cast to SCEVAddRecExpr
Thanks Sanjoy.
> To be pedantic, "var[i<<1]" is not an add recurrence, but "&var[i <<
> 1]" is an add recurrence. I'll assume that's that you meant.
Yes, I meant the same.
> I think that is because in C, multiplication is nsw but left shift is
> not and so "i << 1" can legitimately sign-overflow but i * 2 cannot
>
2013 Jun 20
2
[LLVMdev] Error in the example of sext instruction in reference manual
Hi all,
There might be a simple error in the LLVM reference manual. The example for
sext instruction:
%X = sext i8 -1 to i16 ; yields i16 :65535
%X should yield i16: -1, as opposed to 65535.
Here is the simple patch (also attached):
Index: docs/LangRef.rst
===================================================================
--- docs/LangRef.rst (revision 184496)
+++ docs/LangRef.rst
2016 Oct 20
2
RFC: Killing undef and spreading poison
Hi Alexandre,
On Wed, Oct 19, 2016 at 6:27 PM, Alexandre Isoard
<alexandre.isoard at gmail.com> wrote:
> Really interesting read. I am perplexed now, and am not even sure what is
> the meaning of undef anymore.
Welcome aboard. :)
> Example (unrelated to your blog post, but still weird):
> %x = sext i1 undef to i2
>
> I understand that I can replace it by either of:
>
2016 Apr 23
2
[IndVarSimplify] Narrow IV's are not eliminated resulting in inefficient code
Hi Sanjoy,
Thank you for looking into this!
Yes, your patch does fix my larger test case too. My algorithm gets double
performance improvement with the patch, as the loop now has a smaller
instruction set and succeeds to unroll w/o any extra #pragma's.
I also ran the LLVM tests against the patch. There are 6 new failures:
Analysis/LoopAccessAnalysis/number-of-memchecks.ll
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
2017 Jun 07
2
RFC: Killing undef and spreading poison
Since most add/sub operations compiled from C have the nsw attribute, we
cannot simply restrict movement of these instructions.
Sure, we could drop nsw when moving these instructions, but there are still
many other problems left. Please read more about the topic here:
https://blog.regehr.org/archives/1496
For example, doing loop unswitching, followed by inline (just to illustrate
that the
2015 Mar 19
2
[LLVMdev] Cast to SCEVAddRecExpr
Hi Nick,
Thanks for looking into it.
I have tried that as well but it didn't worked.
"AddExpr->getOperand(0))" node is:
" (4 * (sext i32 {2,+,2}<%for.body4> to i64))<nsw>"
When I cast this to "SCEVAddRecExpr" it returns NULL.
Regards,
Ashutosh
-----Original Message-----
From: Nick Lewycky [mailto:nicholas at mxc.ca]
Sent: Thursday, March 19,
2015 Mar 19
3
[LLVMdev] Cast to SCEVAddRecExpr
Yes, I can get "SCEVAddRecExpr" from operands of "(sext i32 {2,+,2}<%for.body4> to i64)".
So whenever SCEV cast to "SCEVAddRecExpr" fails, we have drill down for such patterns ?
Is that the right way ?
Regards,
Ashutosh
-----Original Message-----
From: Nick Lewycky [mailto:nicholas at mxc.ca]
Sent: Thursday, March 19, 2015 1:02 PM
To: Nema, Ashutosh
Cc: