ARM: Bug in gcc-3.3 optimizer

["Rainer Keuchel" <keuchel at rainer-keuchel dot de>]

ARM: Bug in gcc-3.3 optimizer

After a conditional call the old condition code is used
for setting the return register.

Happens with -O2 -O1 -Os.
Does not happen when only turning on lots of -f options.

I did not find this in the bug-list, so I assume it is new/unfixed.

Should calls have (clobber (reg:CC CC_REGNUM)) set?

**********************************************************************

VMClassLoader::findClass

   b8864:	e1a00004 	mov	r0, r4
   b8868:	e8fd85f0 	ldmia	sp!, {r4, r5, r6, r7, r8, sl, pc}^

   b8910:	e3540000 	cmp	r4, #0	; 0x0
   b8914:	01a0000a 	moveq	r0, sl
   b8918:	01a01006 	moveq	r1, r6
   b891c:	0bfff9bc 	bleq	b7014 <URLClassLoader::findClass>
; conditions might have changed!!!! r4 unchanged!
   b8920:	01a04000 	moveq	r4, r0
   b8924:	eaffffce 	b	b8864

**********************************************************************
natVMClassLoader.cc:

jclass
gnu::gcj::runtime::VMClassLoader::findClass (jstring name)
{
  _Jv_Utf8Const *name_u = _Jv_makeUtf8Const (name);
  jclass klass = _Jv_FindClassInCache (name_u, 0);

  if (! klass)
    {
      // Skip inner classes
      jstring cn;
      jint ci = name->indexOf('$');
      if (ci == -1)
	cn = name;
      else
	cn = name->substring (0, ci);
      jstring so_base_name = (sb->append (cn)->toString ())->replace ('.',
'-');

      // Compare against `3' because that is the length of "lib".
      while (! klass && so_base_name && so_base_name->length() > 3)
	{
	  using namespace ::java::lang;
	  Runtime *rt = Runtime::getRuntime();
	  jboolean loaded = rt->loadLibraryInternal (so_base_name);

	  jint nd = so_base_name->lastIndexOf ('-');
	  if (nd == -1)
	    so_base_name = NULL;
	  else
	    so_base_name = so_base_name->substring (0, nd);

	  if (loaded)
	    klass = _Jv_FindClassInCache (name_u, 0);
	}
    }

  // Now try loading using the interpreter.
  if (! klass)
    klass = java::net::URLClassLoader::findClass (name);

  // klass is NULL

  return klass;
}

**********************************************************************

These also seem strange...

   51b3c:	0b03c8f9 	bleq	143f28 <___fixsfsi>
   51b40:	01a00c00 	moveq	r0, r0, lsl #24
   51b44:	01a02c40 	moveq	r2, r0, asr #24

   51c34:	0b03c8bb 	bleq	143f28 <___fixsfsi>
   51c38:	01a02000 	moveq	r2, r0

   169f4:	e3500102 	cmp	r0, #-2147483648	; 0x80000000
   169f8:	03710001 	cmneq	r1, #1	; 0x1
   169fc:	1b04abeb 	blne	1419b0 <___divsi3>
   16a00:	11a0c000 	movne	ip, r0

Also commonly used...

   1ee18:	1bffe6c0 	blne	18920 <NewStringUtf8ConstP13_Jv_Utf8Const>
   1ee1c:	15880000 	strne	r0, [r8]

**********************************************************************
Here is the -dP output:

@(insn 319 478 320 0x406e991c (set (reg:CC 24 cc)
@        (compare:CC (reg/v/f:SI 4 r4 [36])
@            (const_int 0 [0x0]))) 216 {*arm_cmpsi_insn} (nil)
@    (nil))
	cmp	r4, #0	@ 319	*arm_cmpsi_insn/1	[length = 4]
@(jump_insn 320 319 323 0x406e991c (set (pc)
@        (if_then_else (ne (reg:CC 24 cc)
@                (const_int 0 [0x0]))
@            (label_ref 338)
@            (pc))) 233 {*arm_cond_branch} (insn_list 319 (nil))
@    (expr_list:REG_DEAD (reg:CC 24 cc)
@        (expr_list:REG_BR_PROB (const_int 9087 [0x237f])
@            (nil))))
.stabn
68,0,64,LM23-__ZN3gnu3gcj7runtime13VMClassLoader9findClassEPN4java4lang6Stri
ngE
LM23:
@(insn 333 373 334 0x406e991c (set (reg:SI 0 r0)
@        (reg/v/u/f:SI 10 sl [33])) 175 {*arm_movsi_insn} (nil)
@    (nil))
	moveq	r0, sl	@ 333	*arm_movsi_insn/1	[length = 4]
@(insn 334 333 335 0x406e991c (set (reg:SI 1 r1)
@        (reg/v/f:SI 6 r6 [34])) 175 {*arm_movsi_insn} (nil)
@    (nil))
	moveq	r1, r6	@ 334	*arm_movsi_insn/1	[length = 4]
@(call_insn 335 334 336 0x406e991c (parallel [
@            (set (reg:SI 0 r0)
@                (call (mem:SI (symbol_ref:SI
("_ZN4java3net14URLClassLoader9findClassEPNS_4lang6StringE")) [0 S4 A32])
@                    (const_int 0 [0x0])))
@            (use (const_int 0 [0x0]))
@            (clobber (reg:SI 14 lr))
@        ]) 253 {*call_value_symbol} (insn_list 334 (insn_list 333 (nil)))
@    (expr_list:REG_DEAD (reg:SI 1 r1)
@        (nil))
@    (expr_list (use (reg:SI 1 r1))
@        (expr_list (use (reg:SI 0 r0))
@            (nil))))
	bleq	__ZN4java3net14URLClassLoader9findClassEPNS_4lang6StringE	@ 335
*call_value_symbol/1	[length = 4]
@(insn 336 335 445 0x406e991c (set (reg/v/f:SI 4 r4 [36])
@        (reg:SI 0 r0)) 175 {*arm_movsi_insn} (insn_list 335 (nil))
@    (expr_list:REG_DEAD (reg:SI 0 r0)
@        (nil)))
	moveq	r4, r0	@ 336	*arm_movsi_insn/1	[length = 4]
@(jump_insn 445 336 446 (nil) (set (pc)
@        (label_ref 338)) 244 {*arm_jump} (nil)
@    (nil))
	b	L15	@ 445	*arm_jump	[length = 4]