-fomit-frame-pointer interaction with alloca - egcs-1.0.1

[Jeffrey A Law]

  In message <01BD32F3.EF936D20@malvinas.AtlanTech.COM>you write:
  > 
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  > John> My problem is that in the presence of [alloca] -fomit-frame-pointer
  > John> generates WORSE code, instead of just being ignored.
  > 
  > Jeffrey> Now that's a suprise!
  > 
  > Here's one (small) example:
  > 
  > 	int test (int p) {
  > 	        char *s = alloca (p);
  > 	        fred (s);
  > 	        return 1;
  > 	}
  > 
  > Note that the code with -fomit-frame-pointer (on the right) has an
  > unnecessary "addl $4,%esp".  Not a huge difference, but why?
Thanks for the testcase.  Basically there's a test to determine when stack
adjustments can be ignored at function exit.

One of the tests includes a check to make sure a frame pointer will exist,
but it only checked that -fomit-frame-pointer was not specified -- ie it
didn't take into account that when a function calls alloca, it must always
have a frame pointer.

I've fixed this in the sources, so it should work as expected in the next
snapshot.

jeff