Bug 991

Summary: operands mismatch on correct m68040 instruction
Product: binutils Reporter: Tomas Hurka <tom>
Component: gasAssignee: unassigned
Status: RESOLVED FIXED    
Severity: normal CC: bug-binutils
Priority: P2    
Version: 2.16   
Target Milestone: ---   
Host: powerpc-apple-darwin7.9.0 Target: m68k-bsd-elf
Build: powerpc-apple-darwin7.9.0 Last reconfirmed:
Project(s) to access: ssh public key:
Attachments: source file to trigger this bug
Proposed patch to fix problem with operand matching
Proposed patch to fix problem with opcode ordering

Description Tomas Hurka 2005-06-03 14:03:23 UTC
Cross m68k assembler on powerpc-apple-darwin is not able to assemble following instruction:

fmovem.l %fpcr,%d1

Terminal output:
[bobik:/tmp] thurka% uname -a
Darwin bobik 7.9.0 Darwin Kernel Version 7.9.0: Wed Mar 30 20:11:17 PST 2005; root:xnu/xnu
-517.12.7.obj~1/RELEASE_PPC  Power Macintosh powerpc
[d-eprg05-75-98:/tmp] thurka% cat bug.s
        fmovem.l %fpcr,%d1
[bobik:/tmp] thurka% ~/Projects/gcc_m68k/bin/m68k-bsd-elf-as -v -m68040 bug.s
GNU assembler version 2.16 (m68k-bsd-elf) using BFD version 2.16
bug.s: Assembler messages:
bug.s:1: Error: operands mismatch -- statement `fmovem.l %fpcr,%d1' ignored
[bobik:/tmp] thurka%
Comment 1 Tomas Hurka 2005-06-03 14:07:30 UTC
Created attachment 503 [details]
source file to trigger this bug
Comment 2 Tomas Hurka 2005-06-03 15:04:54 UTC
I believe that this bug is caused by two separate problems in gas/config/tc-m68k.c file.

First problem is in operands matching against opcode table (function m68k_ip, big for-loop around line   
1216). Information in the_ins.operands array are in some cases modified during operands matching 
(case 'L' and case 'l' in big switch). Subsequently such modified operand fails to match against correct 
opcode operands and instruction is rejected. 

Second problem is that function m68k_compare_opcode does not correctly compare instructions with 
the same name. The intension was that this function should honor order in opcode table, but if op1 and 
op2 has same names and op1 < op2 than m68k_compare_opcode return 0 instead of 1. Depending on 
implementation of qsort this may produce different results. I believe that this is reason why I cannot 
reproduce this bug on i386-redhat-linux, because on i386-redhat-linux the order of fmovem.l 
opcodes is different from powerpc-apple-darwin and does not trigger the problem with operands 
matching.
Order of fmovem.l on powerpc:
IiL8~s
Iis8%s
Ii*lL8
 
order on i386-redhat-linux:
Iis8%s
IiL8~s
Ii*lL8

I will attach patches to fix both problems mentioned above.
Comment 3 Tomas Hurka 2005-06-03 15:50:51 UTC
Created attachment 504 [details]
Proposed patch to fix problem with operand matching
Comment 4 Tomas Hurka 2005-06-03 15:51:57 UTC
Created attachment 505 [details]
Proposed patch to fix problem with opcode ordering
Comment 5 Tomas Hurka 2005-06-08 10:05:29 UTC
Proposed fix also fixed the problem reported in
http://lists.gnu.org/archive/html/bug-binutils/2005-06/msg00000.html
Comment 6 Nick Clifton 2005-06-08 17:04:06 UTC
Hi Tom,

  Thanks for reporting this problem and submit the patches to fix it.  I have
checked them in, with a little tidying up of the formatting and a few comments
added, and I also created this ChangeLog entry:

2005-06-08  Tomas Hurka  <tom@hukatronic.cz>

	PR991
	* config/tc-m68k.c (m68k_ip): Test for insn compatiblity using a
	temporary copy of the operands array so that changes can be safely
	backed out if the insn does not match.
	(m68k_compare_opcode): Shortcut the test when the parameters are
	the same.  Return 1 if the names match but the second opcode is
	further on in the array than the first.

Cheers
  Nick