When compiling the files in the attachment for PR22574 using the command line:
gcc -fwhole-program --combine -march=i686 -O2 button.i charproc.i charsets.i
cursor.i data.i doublechr.i fontutils.i input.i main.i menu.i misc.i print.i
ptydata.i screen.i scrollbar.i tabs.i util.i xstrings.i VTPrsTbl.i -S
the function ClearLeft looks like:
ClearLeft.221553:
pushl %ebp
movl %esp, %ebp
subl $8, %esp
movl 3748(%eax), %ecx
movl 3752(%eax), %edx
movl $0, (%esp) ; <- 0 is passed on the stack
incl %ecx
movl %ecx, 4(%esp)
call ClearInLine.221545
leave
ret
When compiling just the file util.i that contains ClearLeft using
-march=i686 -O2 the assembly is:
ClearLeft:
pushl %ebp
movl %esp, %ebp
subl $8, %esp
movl 3748(%eax), %ecx
movl 3752(%eax), %edx
incl %ecx
movl %ecx, (%esp)
xorl %ecx, %ecx ; 0 is passed in a register
call ClearInLine
leave
ret
When using -fwhole-program --combine the parameter "0" to the ClearInLine
function is passed on the stack instead of being passed in a register.
Is there a reason for that? Shouldn't it be more better to pass it in a
register?
--
Summary: local calling convention not used when using -fwhole-
program --combine
Product: gcc
Version: 4.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P2
Component: rtl-optimization
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: dann at godzilla dot ics dot uci dot edu
CC: gcc-bugs at gcc dot gnu dot org
GCC target triplet: i686-pc-linux-gnus
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23828
