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m68k peephole weirdness
- From: Paul Brook <paul at codesourcery dot com>
- To: "gcc at gcc dot gnu dot org" <gcc at gcc dot gnu dot org>
- Date: Thu, 15 Dec 2005 22:47:58 +0000
- Subject: m68k peephole weirdness
In m68k.md we have:
;; Speed up pushing a single byte but leaving four bytes of space.
(define_peephole
[(set (mem:QI (pre_dec:SI (reg:SI SP_REG)))
(match_operand:QI 1 "general_operand" "dami"))
(set (reg:SI SP_REG) (minus:SI (reg:SI SP_REG) (const_int 2)))]
The (const_int 2) looks very suspect. Shouldn't this be (const_int 3) ?
If not, could someone please explain to me what bit of arcane magic I'm
missing?
I'm also intrigued to know under what circumstances this peephole would
trigger.
Paul