asking the flow analysis not to optimize

[thomas joseph <thomascanny at yahoo dot co dot nz>]

Hi All
  I am facing a small problem with my new gcc port.
 For generating code for compare and branches, I am
saving the operands in cmp patterns and generating
code in branch (beq, bgt etc.,) patterns.

   The word size is 16 bit and I do n't have 16 bit
  compare instruction on my machine. So
 for longs (32 bits), I generate code like this ....

   1).   < clear the flags>
   2).    sbc lo0, lo1
   3).    sbc  hio, hi1

  So , now I jump based on the flags. But actually 
 when I compile a sample code with optimization's on
 the first instruction is being pulled out during flow
analysis. So, I get the wrong code. So, how do I tell
the flow analysis  not to delete that particular
instruction or rtl insn (basically generated by
emit_insn () .)

    Any suggestions would be of great help.....


thanks and regards,
 
thomas