Why does peephole not handle JUMP before barrier?

[Alan Lehotsky]

genpeep.c produces a peephole() function that explicitly excludes performing peepholes on
anything that's immediately followed by a barrier instruction.

I've got a machine that has branch delay slots.  If the instruction following a branch is another branch,
then the second branch is suppressed.  So, if I have something like

		jeq	$10
		  nop
		jmp	$12
		  ....

that can be replaced by

	jeq $10
	jmp $12
	...

avoiding the nop.

But, if I've got

		jmp	$10
		  nop
		jmp $12
		  nop

the peephole() NEVER looks at the jmp $10, as it's actually got a barrier after it.


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