Re: [m32c-elf] losing track of register lifetime in combine?

[DJ Delorie]

I compared the generated code with an equivalent explicit test,
and discovered that gcc uses a separate rtx for the intermediate:

i = 0xfffff;
if (j >= 16)
  {
    int i2;
    i2 = i >> 8;
    i = i2 >> 8;
    j -= 16;
  }

This seems to avoid the combiner problem, becuase you don't have the
same register being set and being used in one insn.  Does this explain
why combine was having a problem, or was this a legitimate thing to do
and the combiner is still wrong?  Using a temp in the expander works
around the problem.