https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70955
Bug ID: 70955
Summary: regression in code generation for __builtin_ms_va_list
in GCC 6.1
Product: gcc
Version: 6.1.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: zenith432 at users dot sourceforge.net
Target Milestone: ---
I've tried on GCC 6.1.0 built for OS X, and GCC 6.1.1 on Fedora 23 supplied by
their rawhide. Same behavior.
- variadic function with x86-64 ms_abi calling convention.
- defines local variable of type __builtin_ms_va_list.
- iterates with __builtin_va_arg (note: there is no corresponding
__builtin_ms_va_arg).
- __builtin_va_arg treats the __builtin_ms_va_list variable as a sysv va_list,
and goes berserk.
I've anaylzed this by looking at the code generated.
Same wrong code generated if __builtin_va_list is used inside an ms_abi
function instead of __builtin_ms_va_list.
This functionality worked on both GCC 5.3 and GCC 4.9, so this is a regression.
I've compared the resulting code generated to GCC 5.3. The code generated on
GCC 5.3 is good.
As mentioned above, there is no __builtin_ms_va_arg, and never was. The
function __builtin_va_arg has previously been used to iterate on all types of
__builtin_*_va_list.
