Rebuilding the cfg

[Richard Guenther]

On Fri, Sep 10, 2010 at 5:51 PM, Ian Lance Taylor <iant@google.com> wrote:
> Richard Guenther <richard.guenther@gmail.com> writes:
>
>> On Fri, Sep 10, 2010 at 5:39 PM, Paulo J. Matos <pocmatos@gmail.com> wrote:
>>> Hello,
>>>
>>> On my frontend pass, I am dealing with basic blocks and I am for:
>>> ,----
>>> | int f(int n)
>>> | {
>>> |   switch(n)
>>> |   {
>>> |     case 0: f1("0"); break;
>>> |     case 500: f2("500"); break;
>>> |     case 1000: f3("1000"); break;
>>> |     default: d(); break;
>>> |   }
>>> | }
>>> `----
>>>
>>> transforming it into:
>>> ,----
>>> | int f(int n)
>>> | {
>>> |   if(n < 500)
>>> |     if(n == 0)
>>> |       f1("0");
>>> |     else
>>> |       goto def;
>>> |   else
>>> |     if(n == 500)
>>> |       f2("500");
>>> |     else
>>> |       if(n == 1000)
>>> |         f3("1000");
>>> |       else
>>> |         goto def;
>>> |
>>> |   return;
>>> |
>>> | def:
>>> |   d();
>>> |   return;
>>> | }
>>> `----
>>>
>>> The problem with this is that it contains nested ifs.
>>> Is there a way for me to insert this tree and ask GCC to rebuild the CFG
>>> or I need to build the correct CFG manually?
>>
>> You need to build it manually.
>
> Can't he just call find_many_sub_basic_blocks?

I doubt that anbody tested this on the tree-level, so I doubt it'll work
correctly.

Richard.

> Ian
>