egcs 1.0.2 success and problem

[Sumner Reuben]

I successfully compiled egcs 1.0.2 on RedHat 5.0 (no surprise I'm sure)
I haven't included config.guess if you want it just ask.

I noticed an optimization problem with gcc 2.7.2 and it is still present
in egcs 1.0.2 (I specifically wanted to test this problem).  I have pared
down the sources a fair bit, if I need to do more I will try.

Here is the C source

typedef unsigned uword;
typedef unsigned long long udword;

#define mulmod(a,b,c) ((uword)(((udword)a*(udword)b)%(udword)c))

typedef struct {
uword p, count, *x, *den;
} server_struct;

int
transact_server(server_struct *server, uword client_no, uword cP)
{
   int i;

   for (i = 0; i < server->count; i += 1)
      if (server->x[i] == client_no) return 2;

   server->den[server->count] = 1;
   for (i = 0; i < server->count; i += 1) {
      cP = mulmod(cP, server->p - server->x[i], server->p);
      server->den[server->count] =
                  mulmod(server->den[server->count],client_no,server->p);
   }
   return 0;
}

Here is the generated assembly for a pentium.

	.file	"foo.c"
	.version	"01.01"
/ GNU C version egcs-2.90.27 980315 (egcs-1.0.2 release) (i586-pc-linux-gnu) compiled by GNU C version egcs-2.90.27 980315 (egcs-1.0.2 release).
/ options passed:  -O9 -Wall
/ options enabled:  -fdefer-pop -fcse-follow-jumps -fcse-skip-blocks
/ -fexpensive-optimizations -fthread-jumps -fstrength-reduce -fpeephole
/ -fforce-mem -ffunction-cse -finline-functions -finline
/ -fkeep-static-consts -fcaller-saves -fpcc-struct-return
/ -frerun-cse-after-loop -frerun-loop-opt -fschedule-insns2 -fcommon
/ -fverbose-asm -fgnu-linker -fregmove -falias-check -fargument-alias
/ -m80387 -mhard-float -mno-soft-float -mieee-fp -mfp-ret-in-387
/ -mschedule-prologue -mcpu=pentium -march=pentium

gcc2_compiled.:
.globl __umoddi3
.text
	.align 4
.globl transact_server
	.type	 transact_server,@function
transact_server:
	pushl %ebp
	movl %esp,%ebp
	subl $28,%esp
	pushl %edi
	pushl %esi
	pushl %ebx
	movl 8(%ebp),%eax
	xorl %edi,%edi
	movl 4(%eax),%ecx
	cmpl %ecx,%edi
	jae .L3
	movl %ecx,%ebx
	movl 8(%eax),%ecx
	.align 4
.L5:
	movl 12(%ebp),%edx        <-- why is this in the loop!!!
	cmpl %edx,(%ecx)
	jne .L4
	movl $2,%eax
	jmp .L13
	.align 4
.L4:
	addl $4,%ecx
	incl %edi
	cmpl %ebx,%edi
	jb .L5
.L3:
	movl 8(%ebp),%eax
	movl 8(%ebp),%edx
	movl 4(%eax),%eax
	movl 12(%edx),%edx
	movl $1,(%edx,%eax,4)
	movl 8(%ebp),%eax
	xorl %edi,%edi
	cmpl %edi,4(%eax)
	jbe .L9
	.align 4
.L11:
	movl 8(%ebp),%edx
	movl (%edx),%edx
	movl %edx,%eax
	xorl %edx,%edx
	movl %eax,-16(%ebp)
	movl %edx,-12(%ebp)
	movl 8(%ebp),%edx
	movl 4(%edx),%esi
	movl 12(%edx),%ebx
	movl 12(%ebp),%eax
	movl (%ebx,%esi,4),%ecx
	mull %ecx
	movl %eax,-8(%ebp)
	movl %edx,-4(%ebp)
	pushl -12(%ebp)
	pushl -16(%ebp)
	pushl -4(%ebp)
	pushl -8(%ebp)
	call __umoddi3
	movl %eax,-16(%ebp)
	movl %edx,-12(%ebp)
	addl $16,%esp
	movl -16(%ebp),%edx
	movl 8(%ebp),%eax
	incl %edi
	movl %edx,(%ebx,%esi,4)
	cmpl %edi,4(%eax)
	ja .L11
.L9:
	xorl %eax,%eax
.L13:
	leal -40(%ebp),%esp
	popl %ebx
	popl %esi
	popl %edi
	movl %ebp,%esp
	popl %ebp
	ret
.Lfe1:
	.size	 transact_server,.Lfe1-transact_server
	.ident	"GCC: (GNU) egcs-2.90.27 980315 (egcs-1.0.2 release)"

If you take out some more the junk in there then it does the right thing.
It also seems to me like the jumps could be optimized quite a bit (my
recollection is that branch not taken is the way the CPU is optimised so
the jne L4 should be reversed.

I also noticed that in the i386 machine description divide is

(define_insn "divqi3"
  [(set (match_operand:QI 0 "register_operand" "=a")
        (div:QI (match_operand:HI 1 "register_operand" "0")
                (match_operand:QI 2 "nonimmediate_operand" "qm")))]
  ""
  "idiv%B0 %2")
 
the "qm" doesn't allow for esi or edi which are valid.  Is this intentional?
(this is also the same in old gcc code of course)

Thanks,

Reuben