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Re: [RFA][PATCH] Isolate erroneous paths optimization


On Wed, Nov 6, 2013 at 4:20 PM, Ian Lance Taylor <iant@google.com> wrote:
> On Wed, Nov 6, 2013 at 7:15 AM, Richard Biener
> <richard.guenther@gmail.com> wrote:
>>
>> But I think that you cannot transform
>>
>> foo ()
>> {
>>   *0 = 1;
>> }
>>
>> to __builtin_trap as you can catch the trap via an exception handler
>> in a caller of foo, no?
>
> That is true.  OK, I can see an argument that when using
> -fnon-call-exceptions that kind of code should not be changed to call
> __builtin_trap.
>
> In that case I think it would be fine to run the isolate paths
> optimization, but to not omit the actual dereference of the NULL
> pointer (possibly the dereference could be followed by a trap).

Yeah, we need the trap to properly end the BB (even if that is a
waste instruction generated).

Richard.

> Ian


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