switch statement type incompatibilities ?

[Andrew MacLeod]

On 10/29/18 1:30 PM, Richard Biener wrote:
> On October 29, 2018 6:20:25 PM GMT+01:00, Andrew MacLeod <amacleod@redhat.com> wrote:
>> What is valid in a switch statement for type compatibility?
>>
>>  Â I would have expected it to follow what appears to be the gimple
>> "standard"Â  of allowing types that pass the
>> "useless_type_convserion_p()"Â  test.
>>
>> I am doing some switch analysis and an triggering a failure in ADA when
>>
>> the gimple_switch_index() is a signed 64 bit value and the case labels
>> are only 32 bit integers.  I would have expected that these needed to
>> be
>> the same precision?   I don't seem to get this failure anywhere else.
> They should be the same type (types_ compatible_p), the same conatraint as operands of comparisons. IIRC we have some checking somewhere - eventually it just checks whether the constants fit in the index type.
Fails that test too.

(gdb) p types_compatible_p ($19, $16->typed.type)
$26 = false
(gdb) p types_compatible_p ($16->typed.type, $19)
$27 = false


now clearly the 32 bit index fit within the 64 bit index, and the 
default labels handles the rest..   but I'll look and see if I can find 
why this isnt triggering some checking code somewhere...

Andrew
>> (gdb) p print_gimple_stmt (stderr, sw, 0, 0)
>>
>> switch (_22) <default: <L9> [67.00%], case 1: <L6> [33.00%]>
>>
>>
>> (gdb) p gimple_switch_index (sw)
>> $16 = (tree_node *) 0x7fffee3593f0
>> (gdb) p print_generic_expr (stderr, $16, 0)
>> _22
>> (gdb) p print_generic_expr (stderr, $16->typed.type, 0)
>> SIGNED_64Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â  << signed
>> 64
>> bit index
>>
>> low is the value of CASE_LOW()
>>
>> (gdb) p print_generic_expr (stderr, low, 0)
>> 1
>> (gdb) p low->typed.type
>> $19 = (tree) 0x7fffefacf5e8
>> (gdb) p print_generic_expr (stderr, $19, 0)
>> integer
>> (gdb) p low->typed.type->type_common.precision
>> $22 = 32 <<< 32 bit case label
>> (gdb) p type->type_common.precision
>> $23 = 64
>>
>> (gdb) p useless_type_conversion_p ($16->typed.type, $19)
>> $24 = false
>> (gdb) p useless_type_conversion_p ($19, $16->typed.type)
>> $25 = false
>>
>>
>> Is this valid?   If so I'll do the promotion myself  but this fails
>> the
>> "is_useless_type_conversion_p ()" Â  test....
>>
>> Andrew