Re: ARM: Invalid Stack Alignment BUG

[Jeffrey A Law <law at cygnus dot com>]

  In message <200003151343.NAA08727@cam-mail2.cambridge.arm.com>you write:
  > 
  > hubicka@atrey.karlin.mff.cuni.cz said:
  > > There is one purpose for doing the alignment to STACK_BOUNDARY in the
  > > backends anyway. There may be ways to use remaing few bytes as well as
  > > current scheme of aligning in reload is kind of wasting stack space
  > > (the stack boundary is repetativly aligned, not only in the last
  > > iteration). We was discussing this with Richard and I believe we
  > > concluded that proper way to handle this is to modify backends, but we
  > > wanted to do this later, so we did the "fix" to reload. 
  > 
  > Just because the current implementation is not particularly efficient in 
  > terms of stack usage doesn't mean that the rounding should be done in the 
  > backend.  Virtually every port has some definition for STACK_BOUNDARY, so 
  > it is a gross inefficiency if every port then has to also add code to 
  > correctly align the stack pointer.  Besides which, if backends are making 
  > adjustments to the amount of stack space pushed, how are they to know that 
  > they haven't altered a vital offset?  IMO this must be handled in a 
  > machine independent manner, based on the information already supplied.
Agreed,  if we are losing space due to inconvenient rounding, then we should
find a describe when rounding should occur so that we can write the code
once in the generic parts of the compiler rather than over and over again
in every backend.

jeff