<div dir="ltr">You'd think isBarrier might work but this is a sync mechanism and doesn't prevent instructions from crossing the barrier that aren't use dependent. </div><div class="gmail_extra"><br><div class="gmail_quote">On Tue, Nov 15, 2016 at 11:12 PM, Madhur Amilkanthwar <span dir="ltr"><<a href="mailto:madhur13490@gmail.com" target="_blank">madhur13490@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><p dir="ltr">Just a thought. What about putting a dummy barrier between the instructions during selectionDAG creation? </p>
<div class="gmail_extra"><br><div class="gmail_quote">On Nov 16, 2016 4:00 AM, "Ryan Taylor via llvm-dev" <<a href="mailto:llvm-dev@lists.llvm.org" target="_blank">llvm-dev@lists.llvm.org</a>> wrote:<br type="attribution"><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;padding-left:1ex;border-left-color:rgb(204,204,204);border-left-width:1px;border-left-style:solid"><div dir="ltr"><div>Setting the MI as isTerminator should have the same impact, yes? I'm not sure of the other consequences of this though, if any, have to look into it.</div><div><br></div><div>Thanks.</div><div><br></div><div>-Ryan</div></div><div class="gmail_extra"><br><div class="gmail_quote">On Tue, Nov 15, 2016 at 5:18 PM, Krzysztof Parzyszek <span dir="ltr"><<a href="mailto:kparzysz@codeaurora.org" target="_blank">kparzysz@codeaurora.org</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;padding-left:1ex;border-left-color:rgb(204,204,204);border-left-width:1px;border-left-style:solid">You can override TargetInstrInfo::isSchedulingB<wbr>oundary for that.<br>
<br>
-Krzysztof<span><br>
<br>
On 11/15/2016 4:13 PM, Ryan Taylor wrote:<br>
</span><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;padding-left:1ex;border-left-color:rgb(204,204,204);border-left-width:1px;border-left-style:solid"><span>
I have the same issue, would it be easier and more useful to attach a<br>
flag to the instruction to tell the scheduler not to move instructions<br>
across this boundary?<br>
<br>
-Ryan<br>
<br>
On Tue, Nov 15, 2016 at 5:11 PM, Krzysztof Parzyszek via llvm-dev<br></span><div><div class="m_1809479387803108079m_-7312215327072905670h5">
<<a href="mailto:llvm-dev@lists.llvm.org" target="_blank">llvm-dev@lists.llvm.org</a> <mailto:<a href="mailto:llvm-dev@lists.llvm.org" target="_blank">llvm-dev@lists.llvm.or<wbr>g</a>>> wrote:<br>
<br>
You can create a DAG mutation that adds artificial dependencies<br>
between A, B and Z.<br>
<br>
-Krzysztof<br>
<br>
<br>
On 11/15/2016 3:26 PM, Wei Ding via llvm-dev wrote:<br>
<br>
Hello,<br>
<br>
I have a LLVM backend question regarding how to prevent compiler<br>
from<br>
reordering instructions. For example, I have the following<br>
instructions.<br>
Z_instruction is the one which I want to insert.<br>
<br>
<br>
// instruction order which I am looking for<br>
//////////////////////////////<wbr>///////////<br>
A_instruction<br>
B_instruction<br>
<br>
*Z_instruction*<br>
<br>
C_instruction<br>
D_instruction<br>
E_instruction<br>
F_instruction<br>
<br>
*Z_instruction*<br>
<br>
G_instruction<br>
F_instruction<br>
<br>
<br>
==============================<wbr>====================<br>
<br>
But I found compiler reordered those instructions like the<br>
following.<br>
How could I prevent compiler from moving *A_instruction* and<br>
*B_instruction* after the first *Z_instruction*? Any<br>
recommendations and<br>
suggestion are greatly appreciated here!!!<br>
<br>
*Z_instruction*<br>
*<br>
*<br>
A_instruction<br>
B_instruction<br>
<br>
C_instruction<br>
D_instruction<br>
E_instruction<br>
F_instruction<br>
<br>
*Z_instruction*<br>
<br>
G_instruction<br>
F_instruction<br>
<br>
BTW, I have define input/output chain for : *C_instruction,<br>
D_instruction, E_instruction, F_instruction and Z_instruction*<br>
*<br>
*<br>
Thank you so much!<br>
<br>
--<br>
Wei Ding<br>
<br>
<br>
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