llvm dev - Sep 2009 - [LLVMdev] tblgen bug in handling case , switch_on

Hi Mikhail,

What is mentioned in the reference manual is this:

    // Evaluates to "cmdline1" if the option "-A" is
provided on the
    // command line; to "cmdline2" if "-B" is provided;
    // otherwise to "cmdline3".
  
   (case
        (switch_on "A"), "cmdline1",
        (switch_on "B"), "cmdline2",
        (default), "cmdline3")
 

What is generated is this:

     if (A) {
       ...
     }
   
     if (B) {
       ....
     } else {
       ....
     }

   
IMO, What should be generated is below:

     if (A) {
       ...
     } else if (B) {
       ....
     } else {
       ....
     }

BTW, to give you more details, I am using append_cmd on each switch_on.


- Sanjiv

Sanjiv Gupta wrote:
> Hi Mikhail,
>
> What is mentioned in the reference manual is this:
>
>     // Evaluates to "cmdline1" if the option "-A" is
provided on the
>     // command line; to "cmdline2" if "-B" is provided;
>     // otherwise to "cmdline3".
>   
>    (case
>         (switch_on "A"), "cmdline1",
>         (switch_on "B"), "cmdline2",
>         (default), "cmdline3")
>  
>
> What is generated is this:
>
>      if (A) {
>        ...
>      }
>    
>      if (B) {
>        ....
>      } else {
>        ....
>      }
>
>    
> IMO, What should be generated is below:
>
>      if (A) {
>        ...
>      } else if (B) {
>        ....
>      } else {
>        ....
>      }
>
> BTW, to give you more details, I am using append_cmd on each switch_on.
>
>
> - Sanjiv
>
> _______________________________________________
>   
Is the patch below ok?

Index: LLVMCConfigurationEmitter.cpp
==================================================================---
LLVMCConfigurationEmitter.cpp    (revision 80668)
+++ LLVMCConfigurationEmitter.cpp    (working copy)
@@ -1141,6 +1141,7 @@
                                Callback, EmitElseIf, OptDescs, O);
     }
     else {
+      EmitElseIf = true;
       Callback(arg, (std::string(IndentLevel) + Indent1).c_str(), O);
     }
     O << IndentLevel << "}\n";

- Sanjiv
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>

Hi,

On Sat, Sep 5, 2009 at 9:12 PM, Sanjiv Gupta<sanjiv.gupta at
microchip.com> wrote:
> Is the patch below ok?
>
> Index: LLVMCConfigurationEmitter.cpp
> ==================================================================> ---
LLVMCConfigurationEmitter.cpp    (revision 80668)
> +++ LLVMCConfigurationEmitter.cpp    (working copy)
> @@ -1141,6 +1141,7 @@
>                               Callback, EmitElseIf, OptDescs, O);
>    }
>    else {
> +      EmitElseIf = true;
>      Callback(arg, (std::string(IndentLevel) + Indent1).c_str(), O);
>    }
>    O << IndentLevel << "}\n";
No, this is not OK - EmitCaseConstructHandler is supposed to be able
to generate both 'if (...) ... if (...) ... if (...) ...' and 'if
(...) ... else if (...) ... else ...' forms. That's what the
EmitElseIf argument controls.

BTW, the example in the documentation generates the 'if (...) ... else
if (...) ... else ...'  form since the 'case' there is assumed to be
inside the 'cmd_line' property.

Can you provide a small TableGen code example of what you're trying to
do which is not working?

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