Given the C code:
              int i;
	      for(i = 0 ; i < 5; i++)
		;
the C4x generates assemble insn as follows:
	lda 4,ar0
  L2:
    	dbu ar0,L2

and in my platform, it generates such assemble:
	LDRI, R11,0
        LDRI  R10,5
   L2:
	ADDI  R11,1
	CMP   R11,5
	DJNZ  R10,L2
   The first two insn load immediate operand 0 and operand 5 into Reg R11 and R10, the " ADDI R11,1" insn 
adds R11 by 1, the "CMP R11,5" insn compares R11 between 5. 

    If I don't define "doloop_end" pattern, it generate such assemble:
	LDRI, R11,0
   L2:
	ADDI  R11,1
	CMP   R11,5
	BNE   L2

   Obviously the "decrement_and_branch_until_zero" replace the "BNE L2" and remains the "ADDI R11,1" and " CMP R11,5"
unchanged.