avr-objdump and jump tables

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joeymorin

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Posted by joeymorin: Thu. Aug 1, 2013 - 07:55 PM

Hi folks,

I spent (far, far too much) time trying to isolate what I reluctantly suspected was a bug in avr-objdump or avr-gcc. The reluctance was warranted, because of course I was wrong.

I noticed there were extra RJMP instructions appended to the end of the interrupt vector table when looking at the output of avr-objdump -S. The extra RJMP instructions appeared in groups of at least 8, and appeared to point to random parts of the main code.

I whittled my 3800 line program down to 33 lines of code that reproduced the problem. Along the way I had thought to myself "Jump tables? Nah...!".

Turns out they are. The test code:

#include 
#define ONE_MORE
int main(void) {
  uint8_t mode;
  switch (mode) {
    case 0:
      TCNT0 = 0;
      break;
    case 1:
      TCNT0 = 0;
      break;
    case 2:
      TCNT0 = 0;
      break;
    case 3:
      TCNT0 = 0;
      break;
    case 4:
      TCNT0 = 0;
      break;
    case 5:
      TCNT0 = 0;
      break;
    case 6:       //  EDIT: OP was lacking this case, so
      TCNT0 = 0;  //  attempts by others to reproduce the
      break;      //  results below failed.  Apologies.
#ifdef ONE_MORE
    case 7:
      TCNT0 = 0;
      break;
#endif
  }
}

On an ATtiny85, compiling with #define ONE_MORE selects a switch statement with 8 cases, and generates a jump table:

00000000 <__vectors>:
   0:	16 c0       	rjmp	.+44     	; 0x2e <__ctors_end>
   2:	1d c0       	rjmp	.+58     	; 0x3e <__bad_interrupt>
   4:	1c c0       	rjmp	.+56     	; 0x3e <__bad_interrupt>
   6:	1b c0       	rjmp	.+54     	; 0x3e <__bad_interrupt>
   8:	1a c0       	rjmp	.+52     	; 0x3e <__bad_interrupt>
   a:	19 c0       	rjmp	.+50     	; 0x3e <__bad_interrupt>
   c:	18 c0       	rjmp	.+48     	; 0x3e <__bad_interrupt>
   e:	17 c0       	rjmp	.+46     	; 0x3e <__bad_interrupt>
  10:	16 c0       	rjmp	.+44     	; 0x3e <__bad_interrupt>
  12:	15 c0       	rjmp	.+42     	; 0x3e <__bad_interrupt>
  14:	14 c0       	rjmp	.+40     	; 0x3e <__bad_interrupt>
  16:	13 c0       	rjmp	.+38     	; 0x3e <__bad_interrupt>
  18:	12 c0       	rjmp	.+36     	; 0x3e <__bad_interrupt>
  1a:	11 c0       	rjmp	.+34     	; 0x3e <__bad_interrupt>
  1c:	10 c0       	rjmp	.+32     	; 0x3e <__bad_interrupt>
  1e:	18 c0       	rjmp	.+48     	; 0x50 
  20:	18 c0       	rjmp	.+48     	; 0x52 
  22:	18 c0       	rjmp	.+48     	; 0x54 
  24:	18 c0       	rjmp	.+48     	; 0x56 
  26:	18 c0       	rjmp	.+48     	; 0x58 
  28:	18 c0       	rjmp	.+48     	; 0x5a 
  2a:	10 c0       	rjmp	.+32     	; 0x4c 
  2c:	10 c0       	rjmp	.+32     	; 0x4e 

0000002e <__ctors_end>:
  2e:	11 24       	eor	r1, r1
  30:	1f be       	out	0x3f, r1	; 63
  32:	cf e5       	ldi	r28, 0x5F	; 95
  34:	d2 e0       	ldi	r29, 0x02	; 2
  36:	de bf       	out	0x3e, r29	; 62
  38:	cd bf       	out	0x3d, r28	; 61
  3a:	02 d0       	rcall	.+4      	; 0x40 
  3c:	0f c0       	rjmp	.+30     	; 0x5c <_exit>

0000003e <__bad_interrupt>:
  3e:	e0 cf       	rjmp	.-64     	; 0x0 <__vectors>

00000040 :
  40:	e0 e0       	ldi	r30, 0x00	; 0
  42:	f0 e0       	ldi	r31, 0x00	; 0
  44:	e1 5f       	subi	r30, 0xF1	; 241
  46:	ff 4f       	sbci	r31, 0xFF	; 255
  48:	12 be       	out	0x32, r1	; 50
  4a:	09 94       	ijmp
  4c:	08 95       	ret
  4e:	08 95       	ret
  50:	08 95       	ret
  52:	08 95       	ret
  54:	08 95       	ret
  56:	08 95       	ret
  58:	08 95       	ret
  5a:	08 95       	ret

0000005c <_exit>:
  5c:	f8 94       	cli

0000005e <__stop_program>:
  5e:	ff cf       	rjmp	.-2      	; 0x5e <__stop_program>

Less than 7 cases, no jump table.

Interestingly, the threshold seems to be different when compiling for the ATmega328P. Instead of prefering jump tables at 8 cases, the threshold is 17 cases. Additionally, these jump tables are easier to spot:

00000000 <__vectors>:
   0:	0c 94 45 00 	jmp	0x8a	; 0x8a <__ctors_end>
   4:	0c 94 4f 00 	jmp	0x9e	; 0x9e <__bad_interrupt>
   8:	0c 94 4f 00 	jmp	0x9e	; 0x9e <__bad_interrupt>
   c:	0c 94 4f 00 	jmp	0x9e	; 0x9e <__bad_interrupt>
  10:	0c 94 4f 00 	jmp	0x9e	; 0x9e <__bad_interrupt>
  14:	0c 94 4f 00 	jmp	0x9e	; 0x9e <__bad_interrupt>
  18:	0c 94 4f 00 	jmp	0x9e	; 0x9e <__bad_interrupt>
  1c:	0c 94 4f 00 	jmp	0x9e	; 0x9e <__bad_interrupt>
  20:	0c 94 4f 00 	jmp	0x9e	; 0x9e <__bad_interrupt>
  24:	0c 94 4f 00 	jmp	0x9e	; 0x9e <__bad_interrupt>
  28:	0c 94 4f 00 	jmp	0x9e	; 0x9e <__bad_interrupt>
  2c:	0c 94 4f 00 	jmp	0x9e	; 0x9e <__bad_interrupt>
  30:	0c 94 4f 00 	jmp	0x9e	; 0x9e <__bad_interrupt>
  34:	0c 94 4f 00 	jmp	0x9e	; 0x9e <__bad_interrupt>
  38:	0c 94 4f 00 	jmp	0x9e	; 0x9e <__bad_interrupt>
  3c:	0c 94 4f 00 	jmp	0x9e	; 0x9e <__bad_interrupt>
  40:	0c 94 4f 00 	jmp	0x9e	; 0x9e <__bad_interrupt>
  44:	0c 94 4f 00 	jmp	0x9e	; 0x9e <__bad_interrupt>
  48:	0c 94 4f 00 	jmp	0x9e	; 0x9e <__bad_interrupt>
  4c:	0c 94 4f 00 	jmp	0x9e	; 0x9e <__bad_interrupt>
  50:	0c 94 4f 00 	jmp	0x9e	; 0x9e <__bad_interrupt>
  54:	0c 94 4f 00 	jmp	0x9e	; 0x9e <__bad_interrupt>
  58:	0c 94 4f 00 	jmp	0x9e	; 0x9e <__bad_interrupt>
  5c:	0c 94 4f 00 	jmp	0x9e	; 0x9e <__bad_interrupt>
  60:	0c 94 4f 00 	jmp	0x9e	; 0x9e <__bad_interrupt>
  64:	0c 94 4f 00 	jmp	0x9e	; 0x9e <__bad_interrupt>
  68:	5a 00       	.word	0x005a	; ????
  6a:	5b 00       	.word	0x005b	; ????
  6c:	5c 00       	.word	0x005c	; ????
  6e:	5d 00       	.word	0x005d	; ????
  70:	5e 00       	.word	0x005e	; ????
  72:	5f 00       	.word	0x005f	; ????
  74:	60 00       	.word	0x0060	; ????
  76:	61 00       	.word	0x0061	; ????
  78:	62 00       	.word	0x0062	; ????
  7a:	63 00       	.word	0x0063	; ????
  7c:	64 00       	.word	0x0064	; ????
  7e:	65 00       	.word	0x0065	; ????
  80:	66 00       	.word	0x0066	; ????
  82:	67 00       	.word	0x0067	; ????
  84:	68 00       	.word	0x0068	; ????
  86:	58 00       	.word	0x0058	; ????
  88:	59 00       	.word	0x0059	; ????

0000008a <__ctors_end>:
  8a:	11 24       	eor	r1, r1
  8c:	1f be       	out	0x3f, r1	; 63
  8e:	cf ef       	ldi	r28, 0xFF	; 255
  90:	d8 e0       	ldi	r29, 0x08	; 8
  92:	de bf       	out	0x3e, r29	; 62
  94:	cd bf       	out	0x3d, r28	; 61
  96:	0e 94 51 00 	call	0xa2	; 0xa2 
  9a:	0c 94 6f 00 	jmp	0xde	; 0xde <_exit>

0000009e <__bad_interrupt>:
  9e:	0c 94 00 00 	jmp	0	; 0x0 <__vectors>

000000a2 :
  a2:	e0 e0       	ldi	r30, 0x00	; 0
  a4:	f0 e0       	ldi	r31, 0x00	; 0
  a6:	ec 5c       	subi	r30, 0xCC	; 204
  a8:	ff 4f       	sbci	r31, 0xFF	; 255
  aa:	16 bc       	out	0x26, r1	; 38
  ac:	0c 94 69 00 	jmp	0xd2	; 0xd2 <__tablejump2__>
  b0:	08 95       	ret
  b2:	08 95       	ret
  b4:	08 95       	ret
  b6:	08 95       	ret
  b8:	08 95       	ret
  ba:	08 95       	ret
  bc:	08 95       	ret
  be:	08 95       	ret
  c0:	08 95       	ret
  c2:	08 95       	ret
  c4:	08 95       	ret
  c6:	08 95       	ret
  c8:	08 95       	ret
  ca:	08 95       	ret
  cc:	08 95       	ret
  ce:	08 95       	ret
  d0:	08 95       	ret

000000d2 <__tablejump2__>:
  d2:	ee 0f       	add	r30, r30
  d4:	ff 1f       	adc	r31, r31

000000d6 <__tablejump__>:
  d6:	05 90       	lpm	r0, Z+
  d8:	f4 91       	lpm	r31, Z
  da:	e0 2d       	mov	r30, r0
  dc:	09 94       	ijmp

000000de <_exit>:
  de:	f8 94       	cli

000000e0 <__stop_program>:
  e0:	ff cf       	rjmp	.-2      	; 0xe0 <__stop_program>

... due to helpful label names like <__tablejump__>, and the fact that the tables are collections of addresses instead of RJMP instructions. I understand the reasons for the differences.

[edit]

I'd say the mechanism used here (jump to 'jump handler', address fetch, indirect jump) more closely resembles a trampoline, albeit not one used to cross 16-bit address boundaries.[/edit]

I'm left with one question, though. Is there any way to get avr-objdump to recognise these jump tables for what they are, and label them as such, instead of blindly disassembling them? It seems to me it might involve sections.

Any thoughts?

"Experience is what enables you to recognise a mistake the second time you make it."

"Good judgement comes from experience. Experience comes from bad judgement."

"Wisdom is always wont to arrive late, and to be a little approximate on first possession."

"When you hear hoofbeats, think horses, not unicorns."

"Fast. Cheap. Good. Pick two."

"We see a lot of arses on handlebars around here." - [J Ekdahl]

Tags:

Tools, Compilers and General Programming, ATmega32, ATmega328, ATmega328P, ATtiny85

Last Edited: Fri. Aug 2, 2013 - 03:36 PM

mikericetga

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Posted by mikericetga: Thu. Aug 1, 2013 - 09:19 PM

That would probably be a feature request for the binutils team...

http://www.gnu.org/software/binutils/

ezharkov

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Posted by ezharkov: Fri. Aug 2, 2013 - 12:50 AM

I don't know how objdump would know which ones are vectors and which ones are not. Even if it did have an -mmcu option (which it does not seem to), how would it know if someone used a part of the vector table for something else.

joeymorin

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Posted by joeymorin: Fri. Aug 2, 2013 - 03:44 AM

ezharkov wrote:

I don't know how objdump would know which ones are vectors and which ones are not. Even if it did have an -mmcu option (which it does not seem to), how would it know if someone used a part of the vector table for something else.

It doesn't know interrupt vectors. It simply disassembles the interrupt vectors as the JMP or RJMP instructions that they are.

What it does know is this:

00000000 <__vectors>:

... and this:

 0:   16 c0          rjmp   .+44        ; 0x2e <__ctors_end>

... and this:

0000002e <__ctors_end>:

It knows these things because of symbols contained within the object file it is dumping. A simple symbol emitted by the compiler/assembler/linker, included in the object file, would be enough for objdump to show:

0000001e <__jump_table_000>: 
  1e:   18 c0          rjmp   .+48        ; 0x50 
  20:   18 c0          rjmp   .+48        ; 0x52 
  22:   18 c0          rjmp   .+48        ; 0x54 
  24:   18 c0          rjmp   .+48        ; 0x56 
  26:   18 c0          rjmp   .+48        ; 0x58 
  28:   18 c0          rjmp   .+48        ; 0x5a 
  2a:   10 c0          rjmp   .+32        ; 0x4c 
  2c:   10 c0          rjmp   .+32        ; 0x4e

... which is why I think that:

Quote:

a feature request for the binutils team.

... isn't the right approach.

But then, I mis-spoke when I asked:

Quote:

Is there any way to get avr-objdump to recognise these jump tables

I should have asked if there was a way to get gcc/as/ld to emit jump table symbols when creating the object file, so that objdump could report them.

[edit]

0000003e :
  3e:	41 55 54 48 4f 52 3a 20 20 20 20 4a 6f 65 79 20     AUTHOR:    Joey 
  4e:	4d 6f 72 69 6e 20 28 43 29 20 32 30 31 33 0a 00     Morin (C) 2013..

... certainly because the symbol embedded_build_strings is associated with string data within the object file, and objdump knows how to interpret it. I expect it already has some facility for correctly displaying other types of non-instruction data, like addresses. Damned if I know how, though ;)

[/edit]

Or am I missing something?

"Experience is what enables you to recognise a mistake the second time you make it."

"Good judgement comes from experience. Experience comes from bad judgement."

"Wisdom is always wont to arrive late, and to be a little approximate on first possession."

"When you hear hoofbeats, think horses, not unicorns."

"Fast. Cheap. Good. Pick two."

"We see a lot of arses on handlebars around here." - [J Ekdahl]

clawson

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Posted by clawson: Fri. Aug 2, 2013 - 10:55 AM

Can you tell me what build options you used in the first code? I simply cannot get it to build as you illustrate at any -O setting.

saaadhu

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Posted by saaadhu: Fri. Aug 2, 2013 - 12:04 PM

There is actually a jumptables section - the default linker script has

    *(.jumptables) 
    *(.jumptables*)

inside the .text output section. Should be trivial to add a new symbol there. Something like

    ${CONSTRUCTING+ __jumptables_start = . ; } 
    *(.jumptables) 
    *(.jumptables*)

This should make avr-objdump show that symbol just before the start of jumptable code.

Regards

Senthil

blog | website

SprinterSB

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Posted by SprinterSB: Fri. Aug 2, 2013 - 01:05 PM

The jumptables sections are currently unused. Jump tables are in .progmem.gcc_sw_table, aren't they?

I see the jump tables with 4.8. It is generated by the compiler and is not a problem of binutils. You can influence jump tables generation by

value

value defaults to 7.

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joeymorin

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Posted by joeymorin: Fri. Aug 2, 2013 - 03:32 PM

clawson wrote:

Can you tell me what build options you used in the first code? I simply cannot get it to build as you illustrate at any -O setting.

Ah, crap. That's because I'm a jerk and I made a copy/paste error. There's a missing case in the code I posted. Specifically:

    case 6:
      TCNT0 = 0;
      break;

Sorry about that :oops: ... I was fiddling with the number of cases required to trigger the use of jump tables with different -mmcu... should have been more careful posting...

For the record, my build commands were simply:

avr-gcc -O3 -mmcu=attiny85 foo.c -o foo.c.elf

... and:

avr-gcc -O3 -mmcu=atmega328p foo.c -o foo.c.elf

Results were the same at -O3 and -Os.

SprinterSB wrote:

I see the jump tables with 4.8. It is generated by the compiler and is not a problem of binutils.

If by that you mean that if I compile with avr-gcc 4.8.0 that I should be able to see the jump tables identified by avr-objdump, perhaps I'm doing something wrong.

Mind you, I consider my install of 4.8.0 to be suspect. It seems to work fine, but I've never used it to generate code for real devices. I installed the toolchain from source, shortly after it was released, onto Ubuntu 10.04.4 LTS. Had quite a bit of trouble, and I'm not confident about using it. I keep it around for testing purposes when posting here :).

In any case, the version of avr-objdump that I installed from source was the same as it is in version 3.4.2 of Atmel's toolchain for Linux, version 2.23.1.

Quote:

You can influence jump tables generation by
--param case-values-threshold=value
value defaults to 7.

Thanks for the tip!

"Experience is what enables you to recognise a mistake the second time you make it."

"Good judgement comes from experience. Experience comes from bad judgement."

"Wisdom is always wont to arrive late, and to be a little approximate on first possession."

"When you hear hoofbeats, think horses, not unicorns."

"Fast. Cheap. Good. Pick two."

"We see a lot of arses on handlebars around here." - [J Ekdahl]

clawson

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Location: (using avr-gcc in) Finchingfield, Essex, England

Posted by clawson: Sat. Aug 3, 2013 - 11:56 AM

Quote:

There's a missing case in the code

Ah that fixed it. I just wanted to see the Asm passed from the compiler to binutils to see if there was anything there that could be used:

	.section	.text.startup.main,"ax",@progbits
.global	main
	.type	main, @function
main:
//==> int main(void) {
/* prologue: function */
/* frame size = 0 */
/* stack size = 0 */
.L__stack_usage = 0
//==> 	switch (mode) {
	ldi r30,0
	ldi r31,0
	subi r30,lo8(-(gs(.L11)))
	sbci r31,hi8(-(gs(.L11)))
//==> 		TCNT0 = 0;
	out 0x32,__zero_reg__
//==> 	switch (mode) {
	ijmp

	.section	.progmem.gcc_sw_table.main,"ax",@progbits
	.p2align	1
.L11:
	rjmp .L2
	rjmp .L2
	rjmp .L2
	rjmp .L2
	rjmp .L2
	rjmp .L2
	rjmp .L2
	rjmp .L2

	.section	.text.startup.main
.L2:
//==> }
	ldi r24,0
	ldi r25,0
	ret
	.size	main, .-main

Sadly no. You learn that the table is in:

.progmem.gcc_sw_table.main,"ax",@progbits

but apart from the local .L11 label there's nothing to aid access to it.

joeymorin

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#10

Posted by joeymorin: Sat. Aug 3, 2013 - 05:31 PM

clawson wrote:

I just wanted to see the Asm passed from the compiler to binutils to see if there was anything there that could be used

clawson wrote:

Sadly no. You learn that the table is in:
.progmem.gcc_sw_table.main,"ax",@progbits
but apart from the local .L11 label there's nothing to aid access to it.

I assume this could be amended in the upstream gcc?

What would be the correct approach? For each jump table, adding a .global label for that table? So:

   .section   .progmem.gcc_sw_table.main,"ax",@progbits
   .p2align   1
.L11:

... could become:

   .section   .progmem.gcc_sw_table.main,"ax",@progbits
   .p2align   1
.global gcc_sw_table_main:

It looks like the .section line has the correct information already, i.e. on devices with <= 8K of flash these tables are RJMP instructions and the .section descriptions have "ax", and on devices with > 8K of flash, the tables are simply addresses and the .section description have "a".

Would there be anything else needed to get avr-objdump to cough up a label for jump tables?

Where would be the appropriate place to make a feature request?

"Experience is what enables you to recognise a mistake the second time you make it."

"Good judgement comes from experience. Experience comes from bad judgement."

"Wisdom is always wont to arrive late, and to be a little approximate on first possession."

"When you hear hoofbeats, think horses, not unicorns."

"Fast. Cheap. Good. Pick two."

"We see a lot of arses on handlebars around here." - [J Ekdahl]

clawson

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#11

Posted by clawson: Sat. Aug 3, 2013 - 06:59 PM

Quote:

Where would be the appropriate place to make a feature request?

You're wasting your time. If you want this do it yourself. There aren't enough contributors to do the important stuff let alone trivial fluff, a bug report will just get bounced.

joeymorin

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#12

Posted by joeymorin: Sat. Aug 3, 2013 - 07:14 PM

clawson wrote:

Quote:

Where would be the appropriate place to make a feature request?

You're wasting your time. If you want this do it yourself. There aren't enough contributors to do the important stuff let alone trivial fluff, a bug report will just get bounced.

Fair enough.

I don't have a burning need. However, I suspect that this is actually something I might be able to contribute, and it seem innocuous enough that I imagine it would be hard to break anything by trying ;)

Can anyone suggest what source to check out, and where to do so?

"Experience is what enables you to recognise a mistake the second time you make it."

"Good judgement comes from experience. Experience comes from bad judgement."

"Wisdom is always wont to arrive late, and to be a little approximate on first possession."

"When you hear hoofbeats, think horses, not unicorns."

"Fast. Cheap. Good. Pick two."

"We see a lot of arses on handlebars around here." - [J Ekdahl]

clawson

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Location: (using avr-gcc in) Finchingfield, Essex, England

#13

Posted by clawson: Sat. Aug 3, 2013 - 07:19 PM

Quote:

Can anyone suggest what source to check out, and where to do so?

If you want .LL1 replaced or accompanied by a global symbol that has to happen in the compiler so pull the source for GCC. Be warned that if this change may affect the global compiler and not just AVR it could be close to impossible to convince the maintainers it is justified. There is a gcc manual dedicated to the internals.

joeymorin

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#14

Posted by joeymorin: Sat. Aug 3, 2013 - 08:07 PM

clawson wrote:

If you want .LL1 replaced or accompanied by a global symbol that has to happen in the compiler so pull the source for GCC. Be warned that if this change may affect the global compiler and not just AVR it could be close to impossible to convince the maintainers it is justified. There is a gcc manual dedicated to the internals.

I've started looking at it. The list of projects for beginner GCC hackers is [ahem] long.

Much as I generally like to, I don't want to re-invent a wheel:

joeymorin wrote:

SprinterSB wrote:
I see the jump tables with 4.8. It is generated by the compiler and is not a problem of binutils.
If by that you mean that if I compile with avr-gcc 4.8.0 that I should be able to see the jump tables identified by avr-objdump, perhaps I'm doing something wrong.

As mentioned, I see objdump output doesn't look any different when dumping an .elf built with avr-gcc 4.8.0 and avr binutils 2.23.1, at least not on my machine.

Can @SprinterSB or anyone else confirm this?

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SprinterSB

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#15

Posted by SprinterSB: Mon. Aug 5, 2013 - 04:32 PM

I still don't understand what you are trying to achieve and what the purpose of the change is. Understanding the code? Better dumps by tagging jump tables / offset tables by a global symbol?

To discuss changes in the tools, a far better place to discuss are the respective mailing lists. The forum here read by guys using the tools, I am not aware of any GCC or Binutils developer around here (expect, maybe, some Atmel stuff that work on their branch).

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joeymorin

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#16

Posted by joeymorin: Tue. Aug 6, 2013 - 04:08 AM

SprinterSB wrote:

I still don't understand what you are trying to achieve and what the purpose of the change is. Understanding the code?

No, I get it.

Quote:

Better dumps by tagging jump tables / offset tables by a global symbol?

Precisely. Truth be told, I realise it's not that big a deal. As I mentioned:

joeymorin wrote:

I don't have a burning need. However, I suspect that this is actually something I might be able to contribute, and it seem innocuous enough that I imagine it would be hard to break anything by trying ;)

SprinterSB wrote:

To discuss changes in the tools, a far better place to discuss are the respective mailing lists. The forum here read by guys using the tools, I am not aware of any GCC or Binutils developer around here (expect, maybe, some Atmel stuff that work on their branch).

Agreed. However as I said in my last post I wanted to avoid re-inventing the wheel. You mentioned in a previous post that you:

Quote:

... see the jump tables with 4.8.

... but (as mentioned in my last post) I cannot reproduce this result, and wondered simply if you could clarify. Obviously if 4.8.0 already identifies jump tables with global labels which objdump spits out, I'll consider the matter closed. If not, I'll pursue this elsewhere.

"Experience is what enables you to recognise a mistake the second time you make it."

"Good judgement comes from experience. Experience comes from bad judgement."

"Wisdom is always wont to arrive late, and to be a little approximate on first possession."

"When you hear hoofbeats, think horses, not unicorns."

"Fast. Cheap. Good. Pick two."

"We see a lot of arses on handlebars around here." - [J Ekdahl]

skeeve

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#17

Posted by skeeve: Tue. Aug 6, 2013 - 03:26 PM

If I wanted to label jump tables, I think that I would use Python or something to analyze the .lss file.

Moderation in all things. -- ancient proverb

ezharkov

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#18

Posted by ezharkov: Tue. Aug 6, 2013 - 05:09 PM

skeeve wrote:

If I wanted to label jump tables, I think that I would use Python or something to analyze the .lss file.

I use "something" to analyze, well, the .elf file rather than .lss. One of the things that I do is locate the jump tables. I can say that this is not that simple (well, for me, anyway).

skeeve

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#19

Posted by skeeve: Tue. Aug 6, 2013 - 09:29 PM

ezharkov wrote:

skeeve wrote:
If I wanted to label jump tables, I think that I would use Python or something to analyze the .lss file.
I use "something" to analyze, well, the .elf file rather than .lss. One of the things that I do is locate the jump tables. I can say that this is not that simple (well, for me, anyway).

Of course.
If they work well, use the tools one knows.
I know Python. I don't know .elf files.

Moderation in all things. -- ancient proverb

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