Re: [rfa] mips argument passing fixes for o32

David B Anderson
2001-07-17T07:49:00Z

>
>The debate os over a possible exception to this rule. Given a very
>small structure and the code segment:
>
> struct c1 { char c; } s1;
> foo (struct c1);
> ...
> foo (s1);
>
>GCC is always left shifting s1 in a register (regardless of -EL or EB).

Well....
proton 25% cc -c -32 t3.c -show
/usr/lib/cc -DEFAULT:abi=n32:isa=mips4:proc=r10k -c -32 t3.c -show
/usr/lib/cfe -D_MIPS_FPSET=16 -D_MIPS_ISA=2 -D_ABIO32=1 -D_MIPS_SIM=_ABIO32 -D_MIPS_SZINT=32 -D_MIPS_SZLONG=32 -D_MIPS_SZPTR=32 -D_SIZE_INT=32 -D_SIZE_LONG=32 -D_SIZE_PTR=32 -D__EXTENSIONS__ -DLANGUAGE_C -D_LANGUAGE_C -D__INLINE_INTRINSICS -Dsgi -D__sgi -Dunix -Dmips -Dhost_mips -D__unix -D__host_mips -D_SVR4_SOURCE -D_MODERN_C -D_SGI_SOURCE -D_PIC -D__DSO__ -DSYSTYPE_SVR4 -D_SYSTYPE_SVR4 -D_LONGLONG -D__mips=2 -I -D_MIPSEB -DMIPSEB -D__STDC__=1 -I/usr/include t3.c -Xv -D_CFE -Amachine(mips) -Asystem(unix) -call_shared -G 0 -std -XS/tmp/ctmsta000Ss -mips2 -EB -Xg0 -O1 > /tmp/ctmfa000Ss
cfe: main /usr/lib/ugen -v -G 0 -pic2 -mips2 -EB -g0 -O1 /tmp/ctmfa000Ss -o /tmp/ctmca000Ss -t /tmp/ctmsta000Ss -temp /tmp/ctmgta000Ss
ugen: main
/usr/lib/as1 -t5_ll_sc_bug -elf -pic2 -v -G 0 -p0 -mips2 -EB -g0 -O1 /tmp/ctmca000Ss -o t3.o -t /tmp/ctmsta000Ss
as1: main
proton 26% dis t3.o
**** DISASSEMBLER ****

disassembly for t3.o

section .text
main:
[ 7] 0x 0: 3c 1c 00 00 lui gp,0
[ 7] 0x 4: 27 9c 00 00 addiu gp,gp,0
[ 7] 0x 8: 03 99 e0 21 addu gp,gp,t9
[ 8] 0x c: 8f 8e 00 00 lw t2,0(gp)
[ 8] 0x 10: 8f 99 00 00 lw t9,0(gp)
[ 7] 0x 14: 27 bd ff e0 addiu sp,sp,-32
[ 8] 0x 18: 91 ce 00 00 lbu t2,0(t2)
[ 7] 0x 1c: af bf 00 1c sw ra,28(sp)
[ 7] 0x 20: af bc 00 18 sw gp,24(sp)
[ 8] 0x 24: a3 ae 00 00 sb t2,0(sp)
[ 8] 0x 28: 03 20 f8 09 jalr t9
[ 8] 0x 2c: 8f a4 00 00 lw a0,0(sp)
[ 9] 0x 30: 8f bf 00 1c lw ra,28(sp)
[ 8] 0x 34: 8f bc 00 18 lw gp,24(sp)
[ 9] 0x 38: 27 bd 00 20 addiu sp,sp,32
[ 9] 0x 3c: 03 e0 00 08 jr ra
[ 9] 0x 40: 00 00 10 25 move v0,zero
[ 9] 0x 44: 00 00 00 00 nop
[ 9] 0x 48: 00 00 00 00 nop
[ 9] 0x 4c: 00 00 00 00 nop
proton 27% cat t3.c

struct c1 { char c; } s1;

int foo (struct c1);

int main()
{
foo (s1);
return 0;
}

And -EL seems to generate the same instructions (but I don't quite
trust -EL).

Regards,
David B. Anderson davea@sgi.com danderson@acm.org
< http://reality.sgi.com/davea >
(reality.sgi.com to be permanently turned off -- around Aug 15, 2001)