Hello Louis, To help maintainers, can you please give us a complete working example on gcc / VC++ that fails with tcc?
Ill see how it goes on ARM 32/64. C. From: Tinycc-devel [mailto:[email protected]] On Behalf Of Louis Botha Sent: lundi 4 février 2019 01:54 To: [email protected] Subject: [Tinycc-devel] Bug in _Bool return values Hi TCC-fans, Think I found a bug in the implementation of _Bool in return values in version 0.9.27, found on i386, probably applies to x86_64, and possibly others as well: Since sizeof(_Bool) == 1 as implemented in TCC, I believe this comment in i386-gen.c applies: extend the return value to the whole register if necessary visual studio and gcc do not always set the whole eax register when assigning the return value of a function The scenario that broke for me was calling a function that only set the AL register on return, leaving the rest of EAX undefined, yet TCC checked the whole of EAX for the _Bool return value (true came out correct, but false tested as true when the undefined-bits were non-0) Assigning the _Bool return value to a _Bool variable and then checking that variable instead of the return value is one confirmed workaround (the emitted TCC code then uses just AL to generate a full EAX before checking EAX), but I think I have found the proper fix: Add case VT_BOOL: as shown here, just after line 365 of i386-gen.c: switch (rt & VT_BTYPE) { case VT_BYTE: case VT_BOOL: This modification fixed the problem I was having, I *think* the line in x86_64-gen.c that needs to change for the equivalent there is this (@ line 934): else if (bt == VT_BYTE || bt == VT_BOOL) Sorry, I dont know the other architectures or TCC in general well enough to comment on other places that may also need this fix. Best regards, Louis
_______________________________________________ Tinycc-devel mailing list [email protected] https://lists.nongnu.org/mailman/listinfo/tinycc-devel
