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Re: [PR70920] transform (intptr_t) x eq/ne CST to x eq/ne (typeof x) cst
On 28 July 2016 at 15:58, Andreas Schwab <schwab@suse.de> wrote:
> On Mo, Jul 25 2016, Prathamesh Kulkarni <prathamesh.kulkarni@linaro.org> wrote:
>
>> diff --git a/gcc/testsuite/gcc.dg/pr70920-4.c b/gcc/testsuite/gcc.dg/pr70920-4.c
>> new file mode 100644
>> index 0000000..dedb895
>> --- /dev/null
>> +++ b/gcc/testsuite/gcc.dg/pr70920-4.c
>> @@ -0,0 +1,21 @@
>> +/* { dg-do compile } */
>> +/* { dg-options "-O2 -fdump-tree-ccp-details -Wno-int-to-pointer-cast" } */
>> +
>> +#include <stdint.h>
>> +
>> +void f1();
>> +void f2();
>> +
>> +void
>> +foo (int a)
>> +{
>> + void *cst = 0;
>> + if ((int *) a == cst)
>> + {
>> + f1 ();
>> + if (a)
>> + f2 ();
>> + }
>> +}
>> +
>> +/* { dg-final { scan-tree-dump "gimple_simplified to if \\(_\[0-9\]* == 0\\)" "ccp1" } } */
>
> This fails on all ilp32 platforms.
Oops, sorry for the breakage.
With -m32, the pattern is applied during forwprop1 rather than ccp1.
I wonder though why ccp1 fails to fold the pattern with -m32 ?
Looking at the dumps:
without -m32:
input to ccp1 pass:
<bb 2>:
cst_4 = 0B;
_1 = (long int) a_5(D);
_2 = (void *) _1;
if (cst_4 == _2)
goto <bb 3>;
else
goto <bb 5>;
cc1 pass dump shows:
Substituting values and folding statements
Folding statement: _1 = (long int) a_5(D);
Not folded
Folding statement: _2 = (void *) _1;
Not folded
Folding statement: if (cst_4 == _2)
which is likely CONSTANT
Applying pattern match.pd:2537, gimple-match.c:6530
gimple_simplified to if (_1 == 0)
Folded into: if (_1 == 0)
with -m32:
input to ccp1 pass:
<bb 2>:
cst_3 = 0B;
a.0_1 = (void *) a_4(D);
if (cst_3 == a.0_1)
goto <bb 3>;
else
goto <bb 5>;
ccp1 pass dump shows:
Substituting values and folding statements
Folding statement: a.0_1 = (void *) a_4(D);
Not folded
Folding statement: if (cst_3 == a.0_1)
which is likely CONSTANT
Folded into: if (a.0_1 == 0B)
I am not able to understand why it doesn't fold it to
if (a_4(D) == 0) ?
forwprop1 folds a.0_1 == 0B to a_4(D) == 0.
I suppose the test-case would need to scan ccp1 for non-ilp targets
and forwprop1 for
ilp targets. How do update the test-case to reflect this ?
Thanks,
Prathamesh
>
> Andreas.
>
> --
> Andreas Schwab, SUSE Labs, schwab@suse.de
> GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE 1748 E4D4 88E3 0EEA B9D7
> "And now for something completely different."