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Re: [GSoC] writing test-case


On Sun, May 11, 2014 at 5:00 PM, Prathamesh Kulkarni
<bilbotheelffriend@gmail.com> wrote:
> On Sun, May 11, 2014 at 8:10 PM, Andreas Schwab <schwab@linux-m68k.org> wrote:
>> Prathamesh Kulkarni <bilbotheelffriend@gmail.com> writes:
>>
>>> a) I am not able to follow why 3 slashes are required here
>>> in x_.\\\(D\\\) ? Why does x_.\(D\) not work ?
>>
>> Two of the three backslashes are eaten by the tcl parser.  But actually
>> only two backslashes are needed, since the parens are not special to tcl
>> (but are special to the regexp engine, so you want a single backslash
>> surviving the tcl parser).
>>
>>> b) The expression after folding would be of the form:
>>> t2_<digit> = x_<digit>(D) - y_<digit>(D)
>>> I have used the operator "." in the pattern to match digit.
>>> While that works in the above case, I think a better
>>> idea would be to match using [0-9].
>>> I tried the following but it does not work:
>>> t_[0-9] = x_[0-9]\\\(D\\\) - y_[0-9]\\\(D\\\)
>>> Neither does \\\[ and \\\] work.
>>
>> Brackets are special in tcl (including inside double quotes), so they
>> need to be quoted.  But you want the brackets to appear unquoted to the
>> regexp engine, so a single backslash will do the Right Thing.
>>
>> See tcl(n) for the tcl parsing rules.
>>
> Thanks. Now I get it, the double backslash \\ is an escape sequence
> for \, and special characters like (, [
> retain their meaning in quotes, so to match input text: (D), the
> pattern has to be written as: "\\(D\\)".
> I believe "\(D\)" would only match D in the input ?
> I have modified the test-case. Is this version correct ?

I usually verify that by running the testcase in isolation on a GCC version
that should FAIL it and on one that should PASS it (tcl quoting is also
try-and-error for me most of the time...).

Thus I do

gcc/> make check-gcc RUNTESTFLAGS="tree-ssa.exp=match-2.c"
<test should FAIL>
<patch source tree>
gcc/> make cc1
... compiles cc1 ...
gcc/> make check-gcc RUNTESTFLAGS="tree-ssa.exp=match-2.c"
<test should PASS>

A more complete matching for an SSA name would be (allowing
for SSA name versions > 9) _\\d\+ with \\(D\\) appended if
suitable (that's usually known from the testcase).  \\d\+ should match
at least one decimal digit.

Richard.

> Thanks and Regards,
> Prathamesh
>
>
>> Andreas.
>>
>> --
>> Andreas Schwab, schwab@linux-m68k.org
>> GPG Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
>> "And now for something completely different."


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