RE: [PATCH v5 42/48] target/nios2: Implement rdprs, wrprs

[Amir Gonnen]

Something is wrong when translating rdprs in an interrupt handler when CRS is 
0x1.
I'm hitting "../tcg/tcg.c:3466: tcg_reg_alloc_mov: Assertion `ts->val_type == 
TEMP_VAL_REG' failed."

When stopped on that assertion I can see that :
- ts->val_type  = TEMP_VAL_DEAD
- op->opc = INDEX_op_mov_i32
- ots->name = "pc"
- cpu->ctrl[0] = 0x5f9 (that's STATUS so CRS = 1)
- pc = 0xa2d5c

so, it looks related to an assignment to PC a little after rdprs.

When running with -d in_asm,op_ind,op_opt:
----------------
IN: 
0x000a2d5c:  ldw        r16,4(et)
0x000a2d60:  rdprs      sp,sp,0
0x000a2d64:  ldw        r4,8(et)
0x000a2d68:  callr      r16

OP before indirect lowering:
 ld_i32 tmp0,env,$0xfffffffffffffff0
 brcond_i32 tmp0,$0x0,lt,$L0              dead: 0

 ---- 000a2d5c
 add_i32 tmp0,et,$0x4                     dead: 2
 qemu_ld_i32 r16,tmp0,leul,0              sync: 0  dead: 1

 ---- 000a2d60
 call rdprs,$0x2,$1,sp,env,$0x1b          sync: 0  dead: 0 2

 ---- 000a2d64
 add_i32 tmp0,et,$0x8                     dead: 1 2
 qemu_ld_i32 r4,tmp0,leul,0               sync: 0  dead: 0 1

 ---- 000a2d68
 and_i32 tmp0,r16,$0x3                    dead: 2
 brcond_i32 tmp0,$0x0,ne,$L1              dead: 0 1
 mov_i32 pc,r16                           sync: 0  dead: 0 1
 mov_i32 ra,$0xa2d6c                      sync: 0  dead: 0 1
 call lookup_tb_ptr,$0x6,$1,tmp7,env      dead: 1
 goto_ptr tmp7                            dead: 0
 set_label $L1
 st_i32 r16,env,$0x2038                   dead: 0
 mov_i32 pc,$0xa2d68                      sync: 0  dead: 0 1
 call raise_exception,$0xa,$0,env,$0x7    dead: 0 1
 set_label $L0
 exit_tb $0x7f1878027e43

OP after optimization and liveness analysis:
 ld_i32 tmp0,env,$0xfffffffffffffff0      pref=0xffff
 brcond_i32 tmp0,$0x0,lt,$L0              dead: 0

 ---- 000a2d5c                         
 ld_i32 tmp34,crs,$0x60                   pref=0xf038
 add_i32 tmp0,tmp34,$0x4                  dead: 2  pref=0xff3f
 qemu_ld_i32 tmp26,tmp0,leul,0            dead: 1  pref=0xf038
 st_i32 tmp26,crs,$0x40                 

 ---- 000a2d60                         
 call rdprs,$0x2,$1,tmp37,env,$0x1b       dead: 2  pref=none
 st_i32 tmp37,crs,$0x6c                   dead: 0

 ---- 000a2d64                         
 add_i32 tmp0,tmp34,$0x8                  dead: 1 2  pref=0xff3f
 qemu_ld_i32 tmp14,tmp0,leul,0            dead: 1  pref=0xffff
 st_i32 tmp14,crs,$0x10                   dead: 0

 ---- 000a2d68                         
 and_i32 tmp0,tmp26,$0x3                  dead: 1 2  pref=0xffff
 brcond_i32 tmp0,$0x0,ne,$L1              dead: 0 1
 mov_i32 pc,tmp26                         sync: 0  dead: 0 1  pref=0xffff
 st_i32 $0xa2d6c,crs,$0x7c                dead: 0 1
 call lookup_tb_ptr,$0x6,$1,tmp7,env      dead: 1  pref=none
 goto_ptr tmp7                            dead: 0
 set_label $L1                          
 ld_i32 tmp26,crs,$0x40                   dead: 1  pref=0xffff
 st_i32 tmp26,env,$0x2038                 dead: 0
 mov_i32 pc,$0xa2d68                      sync: 0  dead: 0 1  pref=0xffff
 call raise_exception,$0xa,$0,env,$0x7    dead: 0 1
 set_label $L0                          
 exit_tb $0x7f1878027e43