Upstream GCC has change this warning into error by default, so...we need
to explicitly convert the type from pointer from/to integer, generally
it's unsafe, but we know what we are doing here.
However it's not safe for ilp32 on RV64, but we didn't support that yet, so I
think this fix is good enough now :)
Previously, __internal_syscall() compiled into asm-code that unconditionally
sets the syscall argument registers a0 to a5.
For example, the instruction sequence for a exit syscall looked like
this:
li a0, 1 # in ther caller of exit()
# ... # in newlib:
li a1, 0 # unused arguments
li a2, 0
li a3, 0
li a4, 0
li a5, 0
li a7, 93 # exit syscall number
(i.e. the binary contains then 5 superfluous instructions for this
one argument syscall)
This commit changes the RISC-V syscall code such that only the required
syscall argument registers are set.
GCC detects that argc is known at compile time and thus evaluates all the
if-statements where argc is used at compile time (tested with -O2 and -Os).
Kito Cheng
Georg Sauthoff
Denis Ivanov
Jim Wilson