http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53994
Bug #: 53994
Summary: different result copying doubles(nan)
Classification: Unclassified
Product: gcc
Version: 4.7.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
AssignedTo: [email protected]
ReportedBy: [email protected]
Created attachment 27811
--> http://gcc.gnu.org/bugzilla/attachment.cgi?id=27811
source code, just copy the numbers and does a memcmp over the results to check
its value
For the test I've used a structure with two unsigned char pointers. The
structure has 64 bits of length and it could have any value (memory addresses).
If I cast to double and copy the value of the structure to a new varable
(double) if the contents of the structure is a nan the bit 51 is set to one.
Attached a source file that copies two numbers:
Number copied Expected Result result
0x7ff0000000000001 0x7ff0000000000001 0x7ff8000000000001 -- WRONG
0x7ff8000000000001 0x7ff8000000000001 0x7ff8000000000001 -- OK
I know that these are nan and that probably they shouldn't be copied that way
but what may me think it's worng is the fact that these was not happening under
gcc 3.4.6.
Thanks,
Raul
