A note on this – we’re using this internally for Hexagon, and it works – at 
least for the fairly simple calls I’ve tried :).

 

From: lldb-dev-boun...@cs.uiuc.edu [mailto:lldb-dev-boun...@cs.uiuc.edu] On 
Behalf Of Colin Riley
Sent: Tuesday, March 31, 2015 10:46 AM
To: Sean Callanan
Cc: lldb-dev@cs.uiuc.edu
Subject: Re: [lldb-dev] Expressions on baremetal target

 

Hey Sean,

Yeah, it's a nice feature - even if it only works with basic types as you 
noticed. I'll look to fix up the concerns you've identified. We're working on a 
few other hexagon-related patches to put into review, so I'll add this one to 
the list. We'll add you as a reviewer when it happens - thanks!

Colin

On 31/03/2015 16:02, Sean Callanan wrote:

Colin,

 

looking at that patch, it looks like it has some great ideas!

 

I have a few concerns:

 

  (a) it looks like it is not 64-bit clean, it assumes that everything it works 
with is 4 bytes wide;

  (b) it's got some assertions where I'd prefer proper error handling;

  (c) it relies on the PrepareTrivialCall infrastructure which only handles 
simple argument types; and

  (d) while it tries hard to ensure that strings are exported into the target's 
memory, it doesn't have any provisions for moving other data that the 
expression allocated.

 

While I'd defer to Jim Ingham for comment on the thread plan aspect, I think 
the interpreter side looks like it has potential.  Also that part might still 
apply.  I'm fine with ironing out (c) and (d) in tree, working with the LLVM 
folks to get better solutions, but (a) and (b) and a style nit here and there 
would currently block integration from my point of view.  Hopefully you agree 
that those are the easy bits to fix.

 

If you can resurrect this patch against recent ToT, I'm happy to be a reviewer.

 

Sean


Sent from my iPad


On Mar 31, 2015, at 4:41 AM, Colin Riley <co...@codeplay.com 
<mailto:co...@codeplay.com> > wrote:

Hi Bhushan

We ran into this problem whilst doing the Hexagon DSP support in LLDB. 

This review was up (http://reviews.llvm.org/D4672) but is now stale without 
reviewers. Basically we added the ability to the IR interpreter to call 
functions on the target using a threadplan which manipulated the stack and 
registers to call functions and capture any return values, which works well on 
bare metal without ability to jit.

Maybe the patches can be of help to you. I doubt they would apply cleanly now 
given the length of time since it was uploaded. It's a valuable feature, but 
priorities on the list were elsewhere :)

Colin



On 31/03/2015 12:30, Bhushan Attarde wrote:

Hi,

 

We are debugging a baremetal application using LLDB which is connected to a 
remote target (supporting GDB remote protocol). 

We are able to execute expressions involving global and frame variables such as:

 

(lldb) expr var+4

 

However, LLDB is unable to execute expressions involving function calls.

 

(lldb) expr (int) bar(1,2)

error: Can't run the expression locally: Interpreter doesn't handle one of the 
expression's opcodes

 

Function bar is defined as int bar(int, int).

 

The expression execution_policy is set to eExecutionPolicyNever as CanJIT() 
returns false for baremetal applications.

This is because JIT is disabled for static dynamic loader targets.

The IRInterpreter::CanInterpret returns false as it fails to interpret call 
instruction (call to 'bar' is not an intrinsic).  

 

Could you please help us on this?

 

-Regards

Bhushan






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-- 
- Colin Riley
Games Technology Director
 
Codeplay Software Ltd
45 York Place, Edinburgh, EH1 3HP
Tel: 0131 466 0503
Fax: 0131 557 6600
Website: http://www.codeplay.com
Twitter: https://twitter.com/codeplaysoft
 
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its contents to any other person. Any views or other information in this 
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