Failure to apply trivial peephole optimizations

[Martin Buchholz]

>>>>> "R" == Richard Henderson <rth@redhat.com> writes:

R> On Sat, Dec 14, 2002 at 01:42:15AM -0800, Martin Buchholz wrote:
>> A trivial peephole optimizer with a two instruction window can convert
>> the sequence
>> 
>> subl	$40, %esp
>> movl	%ebp, %esp
>> to 
>> movl	%ebp, %esp

R> Peephole optimization is not the issue.  Policy with regards to
R> stack frame manipulation is.  What we want to do is enable
R> something akin to -momit-leaf-frame-pointer by default, but at
R> present this causes regressions in the gdb testsuite, so we can't.

I hope that means:

1. Eventually uses of the special register %esp will be optimized
   appropriately.

2. For other registers, stupid code like redundant stores are either
   never generated or already optimized away.

Martin