[Mono-dev] How to debug native code?
Hi all, I am trying to port Mono into Aix host, I have am very fundamental question: How are you guys debug native code? Because JIT compiler compiles assembly into native code then JIT invoke it, I am very curious if there errors in native code How do you find out the bug and fix it. And if you updates the cpu-.md or -codegen.h how do you verify your changes is ok? There must be somewhat effect method to debug the JIT and it specific architecture. Since I am porting Mono into Aix, I got assembler code which disassembled from native code: 0: 7c 08 02 a6 mflrr0 4: 90 01 00 04 stw r0,4(r1) 8: 94 21 ff b0 stwur1,-80(r1) c: 93 61 00 48 stw r27,72(r1) 10:93 e1 00 4c stw r31,76(r1) 14:7c 3f 0b 78 mr r31,r1 18:90 7f 00 28 stw r3,40(r31) 1c:90 9f 00 2c stw r4,44(r31) 20:90 bf 00 30 stw r5,48(r31) 24:90 df 00 34 stw r6,52(r31) 28:38 60 00 00 li r3,0 2c:90 7f 00 20 stw r3,32(r31) 30:38 60 00 00 li r3,0 34:90 7f 00 24 stw r3,36(r31) 38:80 7f 00 30 lwz r3,48(r31) 3c:2c 03 00 00 cmpwi r3,0 40:41 82 00 a4 beq 0xe4 44:3c 60 20 03 lis r3,8195 48:60 63 e5 04 ori r3,r3,58628 4c:80 63 00 00 lwz r3,0(r3) 50:2c 03 00 00 cmpwi r3,0 54:41 82 00 38 beq 0x8c 58:3d 80 30 3c lis r12,12348 5c:61 8c cd d8 ori r12,r12,52696 60:7d 88 03 a6 mtlrr12 64:4e 80 00 21 blrl 68:7c 64 1b 78 mr r4,r3 6c:7c 9b 23 78 mr r27,r4 70:2c 03 00 00 cmpwi r3,0 74:41 82 00 18 beq 0x8c 78:7f 63 db 78 mr r3,r27 7c:3d 80 30 00 lis r12,12288 80:61 8c 82 90 ori r12,r12,33424 84:7d 88 03 a6 mtlrr12 88:4e 80 00 21 blrl 8c:80 7f 00 2c lwz r3,44(r31) 90:80 83 00 00 lwz r4,0(r3) 94:80 7f 00 28 lwz r3,40(r31) 98:80 bf 00 34 lwz r5,52(r31) 9c:7c a8 03 a6 mtlrr5 a0:4e 80 00 21 blrl a4:48 00 00 38 b 0xdc a8:80 7f 00 1c lwz r3,28(r31) ac:80 7f 00 1c lwz r3,28(r31) b0:90 7f 00 24 stw r3,36(r31) b4:80 7f 00 30 lwz r3,48(r31) b8:80 9f 00 24 lwz r4,36(r31) bc:90 9f 00 40 stw r4,64(r31) c0:90 83 00 00 stw r4,0(r3) c4:3d 80 30 3c lis r12,12348 c8:61 8c cf 50ori r12,r12,53072 cc: 7d 88 03 a6 mtlrr12 d0:4e 80 00 21 blrl d4:80 7f 00 40 lwz r3,64(r31) d8:48 00 00 04 b 0xdc dc:80 7f 00 20 lwz r3,32(r31) e0:48 00 00 38 b 0x118 e4:3c 60 20 03 lis r3,8195 e8:60 63 e5 04 ori r3,r3,58628 ec:80 63 00 00 lwz r3,0(r3) f0: 28 03 00 00 cmplwi r3,0 f4: 40 82 00 40 bne 0x134 f8: 48 00 00 04 b 0xfc fc: 80 7f 00 2c lwz r3,44(r31) 100: 80 83 00 00 lwz r4,0(r3) 104: 80 7f 00 28 lwz r3,40(r31) 108: 80 bf 00 34 lwz r5,52(r31) 10c: 7c a8 03 a6 mtlrr5 110: 4e 80 00 21 blrl 114: 80 7f 00 20 lwz r3,32(r31) 118: 80 1f 00 54 lwz r0,84(r31) 11c: 7c 08 03 a6 mtlrr0 120: 7f ec fb 78 mr r12,r31 124: 83 7f 00 48 lwz r27,72(r31) 128: 83 ff 00 4clwz r31,76(r31) 12c: 38 2c 00 50 addir1,r12,80 130: 4e 80 00 20 blr 134: 3d 80 30 3c lis r12,12348 138: 61 8c cd d8 ori r12,r12,52696 13c: 7d 88 03 a6 mtlrr12 140: 4e 80 00 21 blrl 144: 7c 64 1b 78 mr r4,r3 148: 7c 9b 23 78 mr r27,r4 14c: 2c 03 00 00 cmpwi r3,0 150: 41 82 ff acbeq 0xfc 154: 7f 63 db 78 mr r3,r27 158: 3d 80 30 00 lis r12,12288 15c: 61 8c 82 90 ori r12,r12,33424 160: 7d 88 03 a6 mtlrr12 164: 4e 80 00 21
Re: [Mono-dev] How to debug native code?
When I am debugging problems with native code I use gdb to debug it. I have used other debuggers, too. If you watch the commands that are running you should be able to see when the mono program is called. Note the parameters. Then run the debugger on mono and then run the program within the debugger using the parameters you noted. When the segmentation fault occurs you can see where it happened. If you add -v options on mono (try using more than one) you can get a trace of what native functions are called and the assembler for those functions. Within the debugger you can use this command: print mono_pmip($pc) to see the name of the native function you are inside of. On 01/18/16 20:14, Pin Cheng wrote: Hi all, I am trying to port Mono into Aix host, I have am very fundamental question: How are you guys debug native code? Because JIT compiler compiles assembly into native code then JIT invoke it, I am very curious if there errors in native code How do you find out the bug and fix it. And if you updates the cpu-.md or -codegen.h how do you verify your changes is ok? There must be somewhat effect method to debug the JIT and it specific architecture. Since I am porting Mono into Aix, I got assembler code which disassembled from native code: 0: 7c 08 02 a6 mflrr0 4: 90 01 00 04 stw r0,4(r1) 8: 94 21 ff b0 stwur1,-80(r1) c: 93 61 00 48 stw r27,72(r1) 10:93 e1 00 4c stw r31,76(r1) 14:7c 3f 0b 78 mr r31,r1 18:90 7f 00 28 stw r3,40(r31) 1c:90 9f 00 2c stw r4,44(r31) 20:90 bf 00 30 stw r5,48(r31) 24:90 df 00 34 stw r6,52(r31) 28:38 60 00 00 li r3,0 2c:90 7f 00 20 stw r3,32(r31) 30:38 60 00 00 li r3,0 34:90 7f 00 24 stw r3,36(r31) 38:80 7f 00 30 lwz r3,48(r31) 3c:2c 03 00 00 cmpwi r3,0 40:41 82 00 a4 beq 0xe4 44:3c 60 20 03 lis r3,8195 48:60 63 e5 04 ori r3,r3,58628 4c:80 63 00 00 lwz r3,0(r3) 50:2c 03 00 00 cmpwi r3,0 54:41 82 00 38 beq 0x8c 58:3d 80 30 3c lis r12,12348 5c:61 8c cd d8 ori r12,r12,52696 60:7d 88 03 a6 mtlrr12 64:4e 80 00 21 blrl 68:7c 64 1b 78 mr r4,r3 6c:7c 9b 23 78 mr r27,r4 70:2c 03 00 00 cmpwi r3,0 74:41 82 00 18 beq 0x8c 78:7f 63 db 78 mr r3,r27 7c:3d 80 30 00 lis r12,12288 80:61 8c 82 90 ori r12,r12,33424 84:7d 88 03 a6 mtlrr12 88:4e 80 00 21 blrl 8c:80 7f 00 2c lwz r3,44(r31) 90:80 83 00 00 lwz r4,0(r3) 94:80 7f 00 28 lwz r3,40(r31) 98:80 bf 00 34 lwz r5,52(r31) 9c:7c a8 03 a6 mtlrr5 a0:4e 80 00 21 blrl a4:48 00 00 38 b 0xdc a8:80 7f 00 1c lwz r3,28(r31) ac:80 7f 00 1c lwz r3,28(r31) b0:90 7f 00 24 stw r3,36(r31) b4:80 7f 00 30 lwz r3,48(r31) b8:80 9f 00 24 lwz r4,36(r31) bc:90 9f 00 40 stw r4,64(r31) c0:90 83 00 00 stw r4,0(r3) c4:3d 80 30 3c lis r12,12348 c8:61 8c cf 50ori r12,r12,53072 cc: 7d 88 03 a6 mtlrr12 d0:4e 80 00 21 blrl d4:80 7f 00 40 lwz r3,64(r31) d8:48 00 00 04 b 0xdc dc:80 7f 00 20 lwz r3,32(r31) e0:48 00 00 38 b 0x118 e4:3c 60 20 03 lis r3,8195 e8:60 63 e5 04 ori r3,r3,58628 ec:80 63 00 00 lwz r3,0(r3) f0: 28 03 00 00 cmplwi r3,0 f4: 40 82 00 40 bne 0x134 f8: 48 00 00 04 b 0xfc fc: 80 7f 00 2c lwz r3,44(r31) 100: 80 83 00 00 lwz r4,0(r3) 104: 80 7f 00 28 lwz r3,40(r31) 108: 80 bf 00 34 lwz r5,52(r31) 10c: 7c a8 03 a6 mtlrr5 110: 4e 80 00 21 blrl 114: 80 7f 00 20 lwz r3,32(r31) 118: 80 1f 00 54 lwz r0,84(r31) 11c:
