[Bug target/13309] New: Incorrect code generated for __udivdi3

["jch50 at comcast dot net" <gcc-bugzilla at gcc dot gnu dot org>]

GCC 3.3.1 was configured as follows:
~/mips-tools0/gcc-3.3.1/configure --target=mips-elf
--prefix=/usr/local/tools/mips-elf --enable-languages=c,c++ --with-gnu-as
--with-gnu-ld --with-newlib
--with-gxx-include-dir=/usr/local/tools/mips-elf/include -v 2>&

Binutils 2.14 was configured as follows:
~/mips-tools0/binutils-2.14/configure --target=mips-elf
--prefix=/usr/local/tools/mips-elf

It appears that __udivdi3 (libgcc2.c) contains incorrect code.  Specifically,

mips-elf-objdump -D libgcc.a
....
....
  cc:	006b0018 	mult	v1,t3
  d0:	00002812 	mflo	a1
  d4:	00c5182b 	sltu	v1,a2,a1
  d8:	1060000a 	beqz	v1,104 <__udivdi3+0x104>
  dc:	0147001b 	divu	zero,t2,a3
  e0:	00cc3021 	addu	a2,a2,t4
  e4:	00cc102b 	sltu	v0,a2,t4
  e8:	14400006 	bnez	v0,104 <__udivdi3+0x104>
  ec:	2529ffff 	addiu	t1,t1,-1
  f0:	00c5102b 	sltu	v0,a2,a1
  f4:	10400003 	beqz	v0,104 <__udivdi3+0x104>
  f8:	00000000 	nop
  fc:	2529ffff 	addiu	t1,t1,-1
 100:	00cc3021 	addu	a2,a2,t4
 104:	00c53023 	subu	a2,a2,a1
 108:	00c7001b 	divu	zero,a2,a3
 10c:	31e4ffff 	andi	a0,t7,0xffff
 110:	14e00002 	bnez	a3,11c <__udivdi3+0x11c>
 114:	00000000 	nop
 118:	0007000d 	break	0x7
 11c:	00001812 	mflo	v1
 120:	00001010 	mfhi	v0

The results from the first divu are never accessed, and a second divu is issued
before the first one has completed.  This appears to cause problems for r3000.
The following code produces incorrect results:

externC void cyg_start( void )
{ 
    volatile unsigned long long a = 0x23e3;
    volatile unsigned long long b = 0x15;
    volatile unsigned long c;

    c = a/b;
}

mips-elf-gcc -c  -I/home/chouston/ecos-projects/test0/test0_install/include
-I/home/chouston/ecos/packages/hal/common/current
-I/home/chouston/ecos/packages/hal/common/current/src
-I/home/chouston/ecos/packages/hal/common/current/tests -I.
-I/home/chouston/ecos/packages/hal/common/current/tests/ -mips1 -EB -msoft-float
-Wall -Wpointer-arith -Wstrict-prototypes -Winline -Wundef  -g -O2
-ffunction-sections -fdata-sections  -fno-exceptions   -G0
-Wp,-MD,tests/context.tmp -o tests/context.o
/home/chouston/ecos/packages/hal/common/current/tests/context.c

-- 
           Summary: Incorrect code generated for __udivdi3
           Product: gcc
           Version: 3.3.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: target
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: jch50 at comcast dot net
                CC: gcc-bugs at gcc dot gnu dot org
 GCC build triplet: i686-pc-linux
  GCC host triplet: i686-pc-linux
GCC target triplet: mips-elf-unkown


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=13309