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i386.md: Add two peepholes to clean up code generated by cmpstr* expanders.

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* i386.md: Add two peepholes to clean up code generated by
	cmpstr* expanders.

From-SVN: r42183
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Zack Weinberg 2001-05-17 00:53:25 +00:00 committed by Zack Weinberg
parent 12b38507e6
commit a3e991f298
2 changed files with 90 additions and 0 deletions
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5
gcc/ChangeLog
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@ -1,3 +1,8 @@
2001-05-16 Zack Weinberg <zackw@stanford.edu>
* i386.md: Add two peepholes to clean up code generated by
cmpstr* expanders.
2001-05-16 Richard Henderson <rth@redhat.com>
* dwarf2asm.c (eh_data_format_name): Add names for "pointer size"

85
gcc/config/i386/i386.md
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@ -15463,6 +15463,91 @@
[(set_attr "type" "str")
(set_attr "mode" "QI")
(set_attr "prefix_rep" "1")])
;; Peephole optimizations to clean up after cmpstr*. This should be
;; handled in combine, but it is not currently up to the task.
;; When used for their truth value, the cmpstr* expanders generate
;; code like this:
;;
;; repz cmpsb
;; seta %al
;; setb %dl
;; cmpb %al, %dl
;; jcc label
;;
;; The intermediate three instructions are unnecessary.
;; This one handles cmpstr*_nz_1...
(define_peephole2
[(parallel[
(set (reg:CC 17)
(compare:CC (mem:BLK (match_operand 4 "register_operand" ""))
(mem:BLK (match_operand 5 "register_operand" ""))))
(use (match_operand 6 "register_operand" ""))
(use (match_operand:SI 3 "immediate_operand" ""))
(use (reg:SI 19))
(clobber (match_operand 0 "register_operand" ""))
(clobber (match_operand 1 "register_operand" ""))
(clobber (match_operand 2 "register_operand" ""))])
(set (match_operand:QI 7 "register_operand" "")
(gtu:QI (reg:CC 17) (const_int 0)))
(set (match_operand:QI 8 "register_operand" "")
(ltu:QI (reg:CC 17) (const_int 0)))
(set (reg 17)
(compare (match_dup 7) (match_dup 8)))
]
""
[(parallel[
(set (reg:CC 17)
(compare:CC (mem:BLK (match_dup 4))
(mem:BLK (match_dup 5))))
(use (match_dup 6))
(use (match_dup 3))
(use (reg:SI 19))
(clobber (match_dup 0))
(clobber (match_dup 1))
(clobber (match_dup 2))])]
"")
;; ...and this one handles cmpstr*_1.
(define_peephole2
[(parallel[
(set (reg:CC 17)
(if_then_else:CC (ne (match_operand 6 "register_operand" "")
(const_int 0))
(compare:CC (mem:BLK (match_operand 4 "register_operand" ""))
(mem:BLK (match_operand 5 "register_operand" "")))
(const_int 0)))
(use (match_operand:SI 3 "immediate_operand" ""))
(use (reg:CC 17))
(use (reg:SI 19))
(clobber (match_operand 0 "register_operand" ""))
(clobber (match_operand 1 "register_operand" ""))
(clobber (match_operand 2 "register_operand" ""))])
(set (match_operand:QI 7 "register_operand" "")
(gtu:QI (reg:CC 17) (const_int 0)))
(set (match_operand:QI 8 "register_operand" "")
(ltu:QI (reg:CC 17) (const_int 0)))
(set (reg 17)
(compare (match_dup 7) (match_dup 8)))
]
""
[(parallel[
(set (reg:CC 17)
(if_then_else:CC (ne (match_dup 6)
(const_int 0))
(compare:CC (mem:BLK (match_dup 4))
(mem:BLK (match_dup 5)))
(const_int 0)))
(use (match_dup 3))
(use (reg:CC 17))
(use (reg:SI 19))
(clobber (match_dup 0))
(clobber (match_dup 1))
(clobber (match_dup 2))])]
"")
;; Conditional move instructions.