llvm dev - Dec 2012 - [LLVMdev] Getting rid of tabs in LLVM's assembly output?

Scenario: sometimes when creating tests for MC, I run llc, take its
assembly (.s) output and copy-paste parts of it into a test.

Problem: I then get tabs in my tests, which are discouraged by LLVM's
own code standards, because assembly output uses tabs extensively.

Proposal: get rid of tabs by just replacing them with two spaces everywhere.

I had an informal chat about this with Jim on the IRC channel and he
tends to agree, but I just wanted to make sure it makes sense for the
community before starting this. The change mostly involves lib/MC and
the target-specific TableGen files defining instructions.

Eli

> From: llvmdev-bounces at cs.uiuc.edu [mailto:llvmdev-bounces at
cs.uiuc.edu]
> On Behalf Of Eli Bendersky
> Subject: [LLVMdev] Getting rid of tabs in LLVM's assembly output?
> Problem: I then get tabs in my tests, which are discouraged by LLVM's
> own code standards, because assembly output uses tabs extensively.
> Proposal: get rid of tabs by just replacing them with two spaces
everywhere.
That will cause some really ugly output; can a somewhat more intelligent
formatter be used to keep columns aligned?

 - Chuck


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On Dec 18, 2012, at 11:36 AM, "Caldarale, Charles R"
<Chuck.Caldarale at unisys.com> wrote:
>> From: llvmdev-bounces at cs.uiuc.edu [mailto:llvmdev-bounces at
cs.uiuc.edu]
>> On Behalf Of Eli Bendersky
>> Subject: [LLVMdev] Getting rid of tabs in LLVM's assembly output?
> 
>> Problem: I then get tabs in my tests, which are discouraged by
LLVM's
>> own code standards, because assembly output uses tabs extensively.
> 
>> Proposal: get rid of tabs by just replacing them with two spaces
everywhere.
> 
> That will cause some really ugly output; can a somewhat more intelligent
formatter be used to keep columns aligned?
> 
I don't mind getting rid of tabs as a general thing, but it is a rather
large undertaking. I concur with Chuck that we'd want to replace them with
some intelligent column-aware formatting rather than a straight "two spaces
per tab."

FWIW, partly for this exact reason, there's effectively a local exception
that tabs are OK in .s file assembler test cases. If that's the main
motivation, I wouldn't worry about it.

-Jim

> - Chuck
> 
> 
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On Tue, Dec 18, 2012 at 11:36 AM, Caldarale, Charles R
<Chuck.Caldarale at unisys.com> wrote:
>> From: llvmdev-bounces at cs.uiuc.edu [mailto:llvmdev-bounces at
cs.uiuc.edu]
>> On Behalf Of Eli Bendersky
>> Subject: [LLVMdev] Getting rid of tabs in LLVM's assembly output?
>
>> Problem: I then get tabs in my tests, which are discouraged by
LLVM's
>> own code standards, because assembly output uses tabs extensively.
>
>> Proposal: get rid of tabs by just replacing them with two spaces
everywhere.
>
> That will cause some really ugly output; can a somewhat more intelligent
formatter be used to keep columns aligned?
>
Here's how some random output currently looks in a 2-space-per-tab editor:

  cmpl  $0, -28(%rbp)
  je  .LBB2_9
  movsbl  -81(%rbp), %eax
  movq  -16(%rbp), %rcx
  movb  56(%rcx), %dl
  andb  $1, %dl
  movzbl  %dl, %esi

So if you're worried about ugliness, it's already there :-)

Eli