Displaying 20 results from an estimated 2000 matches similar to: "[LLVMdev] Tail Duplication Questions"
2012 Oct 31
0
[LLVMdev] Tail Duplication Questions
We used to have an LLVM-IR pass did tail duplication
(http://llvm.org/viewvc/llvm-project/llvm/tags/RELEASE_29/final/lib/Transforms/Scalar/TailDuplication.cpp)
It was not used and went away with 3.0. The documentation is out of
date.
commit f940a1a869b4fe6f857e7fd8aeb97e7b7e9b390e
Author: Rafael Espindola <rafael.espindola at gmail.com>
Date: Tue Aug 30 23:03:45 2011 +0000
Remove the
2012 Oct 31
2
[LLVMdev] Tail Duplication Questions
Arnold Schwaighofer <arnold.schwaighofer at gmail.com> writes:
> We used to have an LLVM-IR pass did tail duplication
> (http://llvm.org/viewvc/llvm-project/llvm/tags/RELEASE_29/final/lib/Transforms/Scalar/TailDuplication.cpp)
> It was not used and went away with 3.0. The documentation is out of
> date.
Ah. So is the MachineFunction version expected to work correctly?
2014 Jun 17
2
[LLVMdev] Question about 'DuplicateInstruction' function of TailDuplicatePass in CodeGen
Hi all,
I have faced a little bit of a strange transformation from the
TailDuplicatePass In CodeGen. When the pass clones the contents of
TailBB into PredBB, the bundled instructions in TailBB are not bundled
in PredBB. I think the reason why it is not bundled is that the
'DuplicateInstruction' function does not set up the flag of the first
instruction of the bundle in PredBB when it
2012 Nov 01
0
[LLVMdev] Tail Duplication Questions
http://llvm.org/viewvc/llvm-project/llvm/tags/RELEASE_31/final/lib/CodeGen/Passes.cpp?revision=156747&view=markup
void TargetPassConfig::addMachineSSAOptimization() {
// Pre-ra tail duplication.
if (addPass(EarlyTailDuplicateID) != &NoPassID)
printAndVerify("After Pre-RegAlloc TailDuplicate");
/// Add passes that optimize machine instructions after register allocation.
2008 Jul 24
0
[LLVMdev] Irreducible CFG from tail duplication
On Thu, Jul 24, 2008 at 2:00 PM, Mark Leone <markleone at gmail.com> wrote:
> Is irreducibility a problem for existing LLVM passes?
There aren't any LLVM passes that expect a reducible CFG at the
moment; of course, some passes are more effective with reducible CFGs.
> It looks like
> there was once an open project for a pass to make irreducible graphs
> reducible. Was that
2012 Nov 01
2
[LLVMdev] Tail Duplication Questions
Eli Friedman <eli.friedman at gmail.com> writes:
>> Ah. So is the MachineFunction version expected to work correctly?
>
> It's part of the default set of CodeGen passes.
It is? Was that true in 3.1? I can't see where it is initialized in
llc. I probably missed something important. :)
Thanks!
-David
2008 Jul 24
3
[LLVMdev] Irreducible CFG from tail duplication
It seems that tail duplication can make a reducible CFG irreducible
(example below). Is that intentional? Are there other optimizations
that have that property?
Is irreducibility a problem for existing LLVM passes? It looks like
there was once an open project for a pass to make irreducible graphs
reducible. Was that ever implemented?
- Mark
; "opt -inline -tailduplicate" makes an
2008 Jul 24
1
[LLVMdev] Irreducible CFG from tail duplication
Thanks Eli. It's not introducing loops, just unstructured
conditionals (e.g. X's in the control-flow graph, rather than
diamonds). You can see it using "opt -view-cfg" on the code below.
Sounds like it's not a bug. Thanks for the info.
- Mark
; Tail duplication yielded this code, which has non-structured control flow.
; Note that "then.i2" and
2016 Mar 04
2
PHI node to different register class vs TailDuplication
Hi,
We're having an issue with TailDuplication in our out-of-tree target and
it's this PHI-node that seems to be the cause of the trouble:
%vreg2<def> = PHI %vreg0, <BB#2>, %vreg1, <BB#3>; rN:%vreg2
aNlh_0_7:%vreg0 aNlh_rN:%vreg1
Note that the defined %vreg2 has register class "rN" while the read
%vreg0 has register class "aNlh_0_7".
2014 Oct 14
2
[LLVMdev] Thoughts on maintaining liveness information for stackmaps
I think what's happening is BranchFolder::MaintainLiveIns is using a
forward analysis on top of these missing kill flags, and updating the
BB-live-ins/live-outs with an incorrect set of registers. Then when the
stackmaps liveness analysis happens, it's not doing anything wrong, but it
starts with the wrong set of live registers and will propagate those to the
point of the
2012 Oct 31
0
[LLVMdev] Tail Duplication Questions
On Wed, Oct 31, 2012 at 11:19 AM, <dag at cray.com> wrote:
> Arnold Schwaighofer <arnold.schwaighofer at gmail.com> writes:
>
>> We used to have an LLVM-IR pass did tail duplication
>> (http://llvm.org/viewvc/llvm-project/llvm/tags/RELEASE_29/final/lib/Transforms/Scalar/TailDuplication.cpp)
>> It was not used and went away with 3.0. The documentation is out of
2008 Jun 11
1
[LLVMdev] Unnatural loops with O0
On Thursday 08 May 2008 18:33:48 Adrian Prantl wrote:
> we noticed that llvmgcc4.2-2.2 sometimes generates non-natural loops
> when compiling to bytecode without any optimizations. Apparently what
> happens is that the loop header is duplicated, which results in two
> entry points for the loop.
this is actually a problem with the tailduplication pass of llvm. it does not
consider
2008 May 14
1
[LLVMdev] Useless check in TailDuplication
Hi,
while reading the TailDuplication pass, I found a check that looks rather
pointless.
TailDuplication looks at an unconditional branch instruction, BI. It performs
a number of checks on the successor of this branch instruction, Dest. One of
this checks is counting the number of predecessor. If this count is zero, Dest
is regarded as dead and no tail duplication happens.
However, as far as I
2008 Jun 21
0
[LLVMdev] Unnatural loops with O0
On Jun 11, 2008, at 6:27 AM, Florian Brandner wrote:
> On Thursday 08 May 2008 18:33:48 Adrian Prantl wrote:
>> we noticed that llvmgcc4.2-2.2 sometimes generates non-natural loops
>> when compiling to bytecode without any optimizations. Apparently what
>> happens is that the loop header is duplicated, which results in two
>> entry points for the loop.
>
> this is
2009 Nov 26
1
[LLVMdev] Problemo: createTailDuplicationPass
Good morning!
After updating and recompiling my copy of the LLVM trunk I noticed
that the line "_passManager.add(llvm::createTailDuplicationPass());"
in my code fails with the following assertion:
Assertion failed: NormalCtor && "Cannot call createPass on PassInfo
without default ctor!", file
D:\Workspace\llvmtrunk\include\llvm/PassSupport.h, line 111
This behavior
2012 Jun 12
2
[LLVMdev] How to use LLVM optimizations with clang
Thanks again.
I executed the following command line
llc -O3 comb.ll.bc -debug-pass=Arguments
and got
Pass Arguments: -targetdata -targetpassconfig -no-aa -tbaa
-targetlibinfo -basicaa -collector-metadata -machinemoduleinfo
-machine-branch-prob -preverify -domtree -verify -loops -loop-simplify
-scalar-evolution -loop-simplify -iv-users -loop-reduce -gc-lowering
-unreachableblockelim
2012 Jun 12
0
[LLVMdev] How to use LLVM optimizations with clang
Hi,
> I executed the following command line
>
> llc -O3 comb.ll.bc -debug-pass=Arguments
>
> and got
>
> Pass Arguments: -targetdata -targetpassconfig -no-aa -tbaa
> -targetlibinfo -basicaa -collector-metadata -machinemoduleinfo
> -machine-branch-prob -preverify -domtree -verify -loops -loop-simplify
> -scalar-evolution -loop-simplify -iv-users -loop-reduce
2015 Jan 17
3
[LLVMdev] loop multiversioning
Does LLVM have loop multiversioning ? it seems it does not with clang++ -O3
-mllvm -debug-pass=Arguments program.c -c
bash-4.1$ clang++ -O3 -mllvm -debug-pass=Arguments fast_algorithms.c -c
clang-3.6: warning: treating 'c' input as 'c++' when in C++ mode, this
behavior is deprecated
Pass Arguments: -datalayout -notti -basictti -x86tti -targetlibinfo -no-aa
-tbaa -scoped-noalias
2020 Jul 02
2
flags to reproduce clang -O3 with opt -O3
Hello,
I've been trying to figure out how to reproduce the results of a single
clang -O3 compilation to a binary with a multi-step process using opt.
Specifically I have:
clang -O3 foo.c -o foo.exe
which I want to replicate with:
clang -O0 -c -emit-llvm foo.c
opt -O3 foo.bc -o foo_o.bc
clang foo_o.bc -o foo.exe
Any hints / suggestions on what additional flags I need to produce the same
2020 Jul 03
2
flags to reproduce clang -O3 with opt -O3
Awesome, thanks!
I'd like to have the last step (llc in your example) not perform
additional optimization passes, such as O3, and simply use the O3 pass from
opt in the previous line.
Do you happen to know if I should use 'llc -O0 foo_o.bc -o foo.exe' instead
to achieve this?
On Thu, Jul 2, 2020 at 6:35 PM Mehdi AMINI <joker.eph at gmail.com> wrote:
>
>
> On Thu,