Re: [Qemu-devel] [4496][Bug] Switch most MIPS logical and arithmetic instructions to TCG.

[Stefan Weil]

Since Qemu r4496, r4497, MIPS Malta no longer boots in big endian mode
(little endian still works). The Linux kernel hangs in prom_putchar.

A comparision of qemu.log shows a regression for at least rotr
(see extracts of qemu.log for r4495 and r4497). There seems to be
another regression for the code in prom_putchar.

r4497 also changes the initial values of the register HI, LO.
I patched these differences in the listings below.

Stefan

r4495 (register a2 changes correctly):

pc=0x80458760 HI=0x033d59d4 LO=0x033d5a24 ds 0090 80458740 0
GPR00: r0 00000000 at 00000008 v0 c0000000 v1 c0000000
GPR04: a0 bbe00000 a1 80480000 a2 00c00000 a3 bbe00048
GPR08: t0 bbe000f0 t1 00000020 t2 000000a0 t3 80490000
GPR12: t4 80480000 t5 80480000 t6 8042fe2e t7 ffffffff
GPR16: s0 80480000 s1 8042ffa0 s2 00000000 s3 00000000
GPR20: s4 00000000 s5 00000000 s6 80480000 s7 00000000
GPR24: t8 00000001 t9 00000006 k0 00000000 k1 00000000
GPR28: gp 8042e000 sp 8042ff08 s8 00000000 ra 80458564
CP0 Status  0x10000000 Cause   0x00000400 EPC    0x00000000
   Config0 0x80008482 Config1 0x9e190c8b LLAddr 0x804322dc
IN: prom_init
0x80458760:  ror    a2,a2,0x10

---------------- 0 00000090
OP:
ld_i32 T0,current_tc_gprs,$0x18
movi_i32 T1,$0x10
rotr
st_i32 T0,current_tc_gprs,$0x18
goto_tb $0x0
save_pc $0x80458764
exit_tb $0xbb7748

------------------------------------------------
pc=0x80458764 HI=0x033d59d4 LO=0x033d5a24 ds 0090 80458740 0
GPR00: r0 00000000 at 00000008 v0 c0000000 v1 c0000000
GPR04: a0 bbe00000 a1 80480000 a2 000000c0 a3 bbe00048
GPR08: t0 bbe000f0 t1 00000020 t2 000000a0 t3 80490000
GPR12: t4 80480000 t5 80480000 t6 8042fe2e t7 ffffffff
GPR16: s0 80480000 s1 8042ffa0 s2 00000000 s3 00000000



r4497 and later (register a2 remains unchanged):

pc=0x80458760 HI=0x03a609d4 LO=0x03a60a24 ds 0090 80458740 0
GPR00: r0 00000000 at 00000008 v0 c0000000 v1 c0000000
GPR04: a0 bbe00000 a1 80480000 a2 00c00000 a3 bbe00048
GPR08: t0 bbe000f0 t1 00000020 t2 000000a0 t3 80490000
GPR12: t4 80480000 t5 80480000 t6 8042fe2e t7 ffffffff
GPR16: s0 80480000 s1 8042ffa0 s2 00000000 s3 00000000
GPR20: s4 00000000 s5 00000000 s6 80480000 s7 00000000
GPR24: t8 00000001 t9 00000006 k0 00000000 k1 00000000
GPR28: gp 8042e000 sp 8042ff08 s8 00000000 ra 80458564
CP0 Status  0x10000000 Cause   0x00000400 EPC    0x00000000
   Config0 0x80008482 Config1 0x9e190c8b LLAddr 0x804322dc
IN: prom_init
0x80458760:  ror        a2,a2,0x10

---------------- 0 00000090
OP:
ld_i32 T0,current_tc_gprs,$0x18
mov_i32 tmp0,T0
movi_i32 tmp1,$0x20
sub_i32 tmp1,tmp1,$0x10
shl_i32 tmp1,tmp0,tmp1
shr_i32 tmp0,tmp0,$0x10
or_i32 tmp0,tmp0,tmp1
mov_i32 tmp0,T0
st_i32 T0,current_tc_gprs,$0x18
goto_tb $0x0
save_pc $0x80458764
exit_tb $0xbbefe8

------------------------------------------------
pc=0x80458764 HI=0x03a609d4 LO=0x03a60a24 ds 0090 80458740 0
GPR00: r0 00000000 at 00000008 v0 c0000000 v1 c0000000
GPR04: a0 bbe00000 a1 80480000 a2 00c00000 a3 bbe00048
GPR08: t0 bbe000f0 t1 00000020 t2 000000a0 t3 80490000
GPR12: t4 80480000 t5 80480000 t6 8042fe2e t7 ffffffff
GPR16: s0 80480000 s1 8042ffa0 s2 00000000 s3 00000000
GPR20: s4 00000000 s5 00000000 s6 80480000 s7 00000000



Thiemo Seufer schrieb:
> Revision: 4496
> http://svn.sv.gnu.org/viewvc/?view=rev&root=qemu&revision=4496
> Author: ths
> Date: 2008-05-18 22:50:49 +0000 (Sun, 18 May 2008)
>
> Log Message:
> -----------
> Switch most MIPS logical and arithmetic instructions to TCG.
>
> Modified Paths:
> --------------
> trunk/target-mips/exec.h
> trunk/target-mips/op.c
> trunk/target-mips/op_helper.c
> trunk/target-mips/translate.c
> trunk/tcg/tcg-op.h